CN100482853C - Sputtering target - Google Patents

Abstract

A sputtering target for forming the aluminum-alloy film includes 0.1-6 atomic% at least one kind of Ag, Zn, Cu and Ni, and 0.1-6 atomic% at least one kind of Nd, Y, Fe, Co as the alloy component.

Description

Sputtering target

The application is that application number is 200310123124.0, the applying date be December 19 in 2003 day, be called the dividing an application of patent application of " electron device and manufacture method thereof, sputtering target ".

Technical field

The present invention relates to film like electron device and manufacture method thereof, sputtering target, particularly relate to the pixel capacitors of use in flat-panel monitor active and passive matrix resembling semi-conductor or liquid-crystal display, reflectance coating, the optics etc. and new display device that aluminium alloy film comprises as integrant and manufacture method thereof, sputtering target.

Background technology

The liquid crystal indicator of active array type comprises: thin film transistor (TFT) as switching element, is had the tft array substrate of the wiring portion of pixel capacitors, sweep trace and signal wire etc.; Separate the given interval opposed substrate with public electrode of configuration relatively for this tft array substrate; Be filled in the liquid crystal layer between these tft array substrates and the opposed substrate.As pixel capacitors, use at Indium sesquioxide (In ₂O ₃) in contain tin indium oxide (ITO) film of the stannic oxide (SnO) about 10 quality % etc.

In addition, the signal wire that is connected electrically in the wiring portion on this pixel capacitors directly contacts with pixel capacitors in order not make aluminium alloys such as fine aluminium or Al-Nd, there is the stacked film that constitutes by refractory metals such as Mo, Cr, Ti, W as hindering metal betwixt, but also just omitting these refractory metals recently, pixel capacitors directly is being connected trial on the signal wire.

Open flat 11-337976 communique according to the spy,, then become possibility with direct contact of signal wire if use the pixel capacitors that constitutes by the ITO film that in Indium sesquioxide, contains the zinc oxide about 10 quality %.

In addition, in No. 6218206 communiques of United States Patent (USP), proposed drain electrode by Cement Composite Treated by Plasma or ion implantation enforcement surface-treated method, in this external patent documentation 3, proposed grid, source electrode and drain electrode, formed the method for the stacked stacked film that contains second phase of impurity such as N, O, Si, C and get, if adopt these methods as the first layer, even when then omitting described refractory metal, also can maintain contact resistance with pixel capacitors low-level on.

In described conventional art, the reason that hinders the metal existence is: if the aluminum or aluminum alloy wiring that constitutes signal wire is directly contacted with pixel capacitors, then contact resistance rises, and the display quality of picture descends.This is that the surface is oxidized easily in atmosphere because aluminium is very easy to oxidation, and pixel capacitors is a metal oxide in addition, so the oxygen that adds when oxygen that produces during by film forming or film forming, aluminium is oxidized, generates alumina layer on the surface.And if form the insulant layer like this on the contact interface of signal wire and pixel capacitors, then the contact resistance between signal wire and pixel capacitors improves, and the display quality of picture descends.

Has the surface oxidation that prevents aluminium alloy and hinder metal, and make the good effect that contacts of aluminium alloy film and pixel capacitors, but in order to obtain on described contact interface, there is the structure in the past that hinders metal, the formation step that hinders metal becomes requisite, so use on the basis of sputter equipment in the film forming that the formation of gate electrode, source electrode, drain electrode is required, also must be equipped with and be used to form the filming chamber that hinders metal., along with progress, follow the formation that hinders metal and the manufacturing cost that produces risen or the decline of productivity becomes and can't ignore based on the cost degradation of the liquid crystal panel of producing in batches etc.

Therefore, require recently to omit electrode materials or the manufacturing process that hinders metal.For such requirement, in described patent documentation 2, added and be used to implement 1 operation of surface-treated.And in No. 6252247 communiques of United States Patent (USP), can carry out the film forming of gate electrode, source electrode, drain electrode continuously, but can't avoid increasing of process number with same filming chamber.And because the thermal expansivity of the film that the film that impurity is sneaked into and impurity are not sneaked into is different, when using continuously, film frequently takes place from the phenomenon that the wall of chamber peels off, so must frequent stop gear in order to safeguard.Open in the flat 11-337976 communique the spy, owing to must change to indium zinc oxide (IZO) film to the most universal present tin indium oxide (ITO) film, so material cost rises.

In order to ensure the display quality of display device,, require low resistance and high-caliber thermotolerance as electrode materials.For example, when using as the source electrode of the noncrystal TFT of one of element of display device or drain electrode material, the characteristic of requirement is that resistivity is 8 μ Ω cm following (preferred 5 μ Ω cm are following), and heat resisting temperature is 300～350 ℃.In addition, the characteristic that requires when using as gate material is that heat resisting temperature is 400～450 ℃ below the 8 μ Ω cm as resistivity.Source electrode and drain electrode always have electric current to flow through for reading and writing of pixel, so preferably suppress resistance, reduce the power consumption of display device.In addition, be necessary to reduce time constant,, also can keep display quality even when display panel maximizes by the long-pending decision of resistance and limiting capacitance.In addition, the thermotolerance of requirement is according to the structure of display device and difference exists with ... the film-forming temperature of the insulating film that uses in the back operation after electrode forms or the film forming and the thermal treatment temp of semiconductor layer.

Summary of the invention

The present invention proposes in view of the described fact, and its purpose is: establish and to omit described obstruction metal, and do not increase process number, the simplification step can make aluminium alloy film for pixel capacitors directly and the technology that contacts reliably.Other purposes are: establish to have simultaneously and can realize low-resistivity and such excellent electrical characteristic and the thermotolerance of low contact resistance, and in display device, can make the technology of reflecting electrode or TAB (tab) connection electrode publicization on material.

The electron device of the present invention that can solve described problem is by constituting with the lower section: first electrode that is made of metal oxide; Second electrode that constitutes by aluminium alloy film that directly contacts, is electrically connected with described first electrode.Here, in described first electrode and contact interface that described second electrode directly contacts, at least a portion that constitutes the alloying constituent of described aluminium alloy film exists as precipitate or denseization layer.

Described aluminium alloy film preferably, as alloying constituent, contain 0.1～6 atom % from constitute by Au, Ag, Zn, Cu, Ni, Sr, Sm, Ge, Bi one group, select at least a, wherein, the aluminium alloy film that contains Ni at least is for preferred.

As described first electrode that becomes integrant of the present invention, preferably tin indium oxide or indium zinc oxide.

In described aluminium alloy film, as other alloying constituent, can also contain in 0.1～6 atom % scope from constitute by Nd, Y, Fe, Co one group, select at least a.

Particularly preferably be in the described aluminium alloy film,, contain X1 (X1=Ag, Zn, Cu, Ni's is at least a) and X2 (X2=Nd, Y's is at least a), and their content satisfies the aluminium alloy film of note formula (I) relation down as described alloying constituent.

0.2≦0.5×CX1+CX2≦4.5······(I)

[in the formula, CX1 represents Ag, the Zn in the aluminium alloy, the content (atom %) of Cu, Ni, and CX2 represents the content (atom %) of Nd, Y in the aluminium alloy]

Or, as alloying constituent, contain Y1 (Y1=Ag, Zn, Cu, Ni's is at least a) and Y2 (Y2=Fe, Co's is at least a), and their content satisfies the aluminium alloy film of the relation of note formula (II) down.

0.4≦CY1+CY2≦6······(II)

[in the formula, CY1 represents Ag, the Zn in the aluminium alloy, the content (atom %) of Cu, Ni, and CY2 represents the content (atom %) of Fe, Co in the aluminium alloy].

In addition, as described aluminium alloy film preferably, part or all of the alloying constituent of solid solution exists as precipitate or denseization layer under nonequilibrium situations, and resistivity is suppressed in below the 8 μ Ω cm.And preferably on the contact interface of described aluminium alloy film and described first electrode, precipitate is as the material of major diameter above the size of 0.01 μ m, with per 100 μ m ²The number that exceeds 0.13 exists, and perhaps exists above 0.5% with area occupation ratio.

Contain the described aluminium alloy film of Ni, preferably have Ni content from this film surface beginning 1～10nm thickness area and be denseization of Ni layer below the 10 atom % as alloying constituent.Here, denseization of Ni layer means that its Ni content surpasses the layer of the Ni content of aluminium alloy film inside.And, these aluminium alloy films in display device as the reflecting layer or play a part useful as the TAB connection electrode.

In addition, electron device of the present invention is by constituting with the lower section: first electrode that is made of metal oxide; Second electrode that constitutes with aluminium alloy film that described first electrode directly contacts, is electrically connected by the Sm that contains 0.1～6 atom %; Here, on described first electrode and contact interface that described second electrode directly contacts, form the Sm that contains in the described aluminium alloy film and constitute the element layer of diffusion mutually of the metal oxide of described first electrode.

In addition, manufacture method of the present invention is as the effective ways that are used to make described electron device, will being intended to of its structure comprises: by being formed on the aluminium alloy film on the substrate with 150～400 ℃ temperature heating, forming part or all the operation of precipitate that contains the described alloying element that contains in the described aluminium alloy film.

When this method of enforcement, by making in the described aluminium alloy film, can form intermetallic compound at the contact interface of described aluminium alloy film and described first electrode with part or all of the alloying constituent of nonequilibrium situations solid solution and the alloying constituent mutual diffusion mutually of described first electrode.In addition, as the preferred method that forms described aluminium alloy film, can enumerate sputtering method.And, stratification insulating film on described aluminium alloy film, after this insulating film being carried out the etching of contact hole, then from aluminum alloy surface 1～200nm, the more preferably light etching aluminium alloy wiring of 3～100nm, make in this aluminium alloy film with part or all precipitate (intermetallic compound) part of the alloying constituent of nonequilibrium situations solid solution and expose, then can further reduce and the contact resistance that forms pixel capacitors thereon, so preferred.

Described light etching can be undertaken by dry etching or wet etching, use the gas of the described aluminium alloy film of energy etching in the described dry etching, and the soup of the described aluminium alloy film of use energy etching in the described wet etching, as the soup that in this light etching work procedure, uses, can use the stripping liquid of employed photo-resist in pattern forms.

Sputtering target of the present invention is the useful target material that is used to form described aluminium alloy film, it is characterized in that as alloying constituent, contain 0.1～6 atom % from constitute by Ag, Zn, Cu and Ni one group, select at least a, contain simultaneously 0.1～6 atom % from constitute by Nd, Y, Fe and Co one group, select at least a.

The present invention makes direct contact of aluminium alloy film and electrode become possibility by as above constituting, and hinders metal by omitting, and reduces man-hour and the cost of making significantly, and cheapness and high performance electronic device and used for electronic device array substrate can be provided.

According to described the present invention, by making the Au or the Ag etc. that contain trace in the film that constitutes by aluminium be difficult to oxidized noble metal, or Zn, Cu, Ni, Sr, Ge, Sm etc. are as the low element of the electric conductivity of oxide compound, the low element of solid solution limit in aluminium that Bi is such, electroconductibility as the film self of wiring material can not worsen, and it is local or form the low zone of resistance all sidedly on the contact interface of first electrode and second electrode (aluminium alloy film), thus, reduce the contact resistance of first electrode and second electrode (aluminium alloy film) significantly, the display quality of liquid-crystal display is maintained high level, and can cut down process number and manufacturing cost significantly.In addition, by in described aluminium alloy film, add from Nd, Y, Fe, Co select at least a, can increase substantially thermotolerance.

Description of drawings

Following brief description accompanying drawing.

Fig. 1 is that expression has been used display device of the present invention and analysed and observe the amplification explanatory view with the summary of the structure of the liquid-crystal display substrate of array substrate and liquid crystal display device.

Fig. 2 is that the display device that expression is applied to the embodiment of the invention 1 is analysed and observe explanatory view with the summary of the structure of the thin film transistor in the array substrate.

Fig. 3 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Fig. 4 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Fig. 5 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Fig. 6 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Fig. 7 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Fig. 8 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Fig. 9 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Figure 10 represents the above-mentioned display device shown in Figure 2 explanatory view of manufacturing process's one example of array substrate in order.

Figure 11 is the display device that obtains in the embodiment of the invention of expression with the mode chart of analysing and observe of the structure of the contact interface of aluminium alloy film in the array substrate and pixel capacitors.

Figure 12 forms precipitate, and forms the concept map of the contact hole of denseization of Ni layer at the interface.

Figure 13 be display device that expression obtains in the embodiment of the invention connect up with the aluminium alloy in the array substrate and other structures of the contact interface of pixel capacitors analyse and observe mode chart.

Figure 14 is that the display device that expression is applied to the embodiment of the invention 2 is analysed and observe explanatory view with the summary of the structure of the thin film transistor in the array substrate.

Figure 15 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 16 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 17 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 18 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 19 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 20 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 21 represents the above-mentioned display device shown in Figure 14 explanatory view of manufacturing process's one example of array substrate in order.

Figure 22 is the figure of the degree Kelvin pattern of use during the contact resistance of expression aluminium alloy film and pixel capacitors is measured.

Figure 23 is the graphic representation of expression by the relation of etch depth of testing the aluminium alloy film surface that obtains and contact resistance.

Figure 24 (a) is the graphic representation of the X content of expression Al-X-Nd (X=Ni) to the influence of electrical characteristic, (b) is the graphic representation of expression X content to stable on heating influence.

Figure 25 (a) is the graphic representation of the Nd content of expression Al-X-Nd (X=Ni) to the influence of electrical characteristic, (b) is the graphic representation of expression Nd content to stable on heating influence.

Figure 26 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ni of Al-Ni-Nd and the composition of Nd.

Figure 27 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ni of Al-Ni-Y and the composition of Y.

Figure 28 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ni of Al-Ni-Fe and the composition of Fe.

Figure 29 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ni of Al-Ni-Co and the composition of Co.

Figure 30 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ag of Al-Ag-Nd and the composition of Nd.

Figure 31 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ag of Al-Ag-Y and the composition of Y.

Figure 32 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ag of Al-Ag-Fe and the composition of Fe.

Figure 33 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Ag of Al-Ag-Co and the composition of Co.

Figure 34 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Zn of Al-Zn-Nd and the composition of Nd.

Figure 35 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Zn of Al-Zn-Y and the composition of Y.

Figure 36 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Zn of Al-Zn-Fe and the composition of Fe.

Figure 37 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Zn of Al-Zn-Co and the composition of Co.

Figure 38 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Cu of Al-Cu-Nd and the composition of Nd.

Figure 39 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Cu of Al-Cu-Y and the composition of Y.

Figure 40 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Cu of Al-Cu-Fe and the composition of Fe.

Figure 41 represents can guarantee the resistivity of 8 μ Ω cm and the figure of the stable on heating compositing range more than 300 ℃ for the Cu of Al-Cu-Co and the composition of Co.

Embodiment

Below, the display device of one example of the electron device that present invention will be described in detail with reference to the accompanying and the display device embodiment of array substrate, but the present invention is not limited to illustrated embodiment, state before and after being fit in the scope of aim and can suitably implement after changing, they are included in the technical scope of the present invention.

In addition, for the reflecting electrode of the driving device of the passive matrix that does not comprise thin film transistor, reflective type liquid crystal display device etc., be used for connection electrode to the TAB of outside input and output signal, can use aluminium alloy film too, but omit these embodiments.

Fig. 1 is that the amplification explanatory view analysed and observe in the summary that carries the liquid crystal panel structure in having used liquid crystal indicator of the present invention.

The liquid crystal panel of Fig. 1 has: tft array substrate 1; Opposed substrate 2 with this tft array substrate 1 relative configuration; Be configured between tft array substrate 1 and the opposed substrate 2 liquid crystal layer 3 that works as the light transform layer.Tft array substrate 1 is made of the thin film transistor on the glass substrate 1a that is configured in insulativity (TFT) 4, pixel capacitors 5, the wiring portion 6 that comprises sweep trace or signal wire.

Opposed substrate 2 by be formed on public electrode 7 on whole of tft array substrate 1 one sides, be configured in the position relative with pixel capacitors 5 colour filter 8, be configured in tft array substrate 1 on the light shielding part 9 of the relative position of thin film transistor (TFT) 4 or wiring portion 6 constitute.

In addition, in the outside surface one side configuration polarization plates 10,10 of the insulativity substrate that constitutes tft array substrate 1 and opposed substrate 2, and on opposed substrate 2, be provided for the oriented film 11 of the liquid crystal molecule that contains in the liquid crystal layer 3 to the assigned direction orientation.

In the liquid crystal panel of such structure, by being formed on the electric field between opposed substrate 2 and the pixel capacitors 5, the orientation direction of the liquid crystal molecule in the control liquid crystal layer 3, modulation is by the light of the liquid crystal layer 3 between tft array substrate 1 and the opposed substrate 2, thus, control see through opposed substrate 2 light see through light quantity, show image.

In addition, tft array is with 12 by the TAB that draws to the tft array outside, is driven by driving circuit 13 and pilot circuit 14.

Among the figure, the 15th, spacing block, the 16th, sealing material, the 17th, protective membrane, the 18th, diffuser plate, the 19th, prism plate, the 20th, light guiding plate, the 21st, reflector, the 22nd, backlight, the 23rd, keep frame, 24 expression printed substrate, them will be described in the back.

Fig. 2 is that explanatory view analysed and observe in the summary of the structure of the expression thin film transistor portion that uses the embodiment 1 in the array substrate adopted in the present invention.Form sweep trace 25 by aluminium alloy film on glass substrate 1a shown in Figure 2, the part of this sweep trace 25 works as the conducting of control thin film transistor and the grid 26 of disconnection.In addition, in order to intersect with sweep trace 25 by gate insulating film 27, form signal wire by aluminium alloy film, the part of this signal wire works as the source electrode 28 of thin film transistor.

For example dispose in the pixel area on gate insulating film 27 by at In ₂O ₃In contain the film formed pixel capacitors 5 of ITO of SnO.Drain electrode 29 by the film formed thin film transistor of aluminium alloy directly contacts with pixel capacitors 5, is electrically connected.

On this tft array substrate 1, if supply with gate voltage by sweep trace 25 to gate electrode 26, then thin film transistor becomes conducting state, and the driving voltage that offers signal wire in advance offers pixel capacitors 5 from source electrode 28 by drain electrode 29.And, if provide the driving voltage of preset level, then as illustrated in fig. 1, producing potential difference between the opposed substrate 2 to pixel capacitors 5, the liquid crystal molecule orientation that contains in the liquid crystal layer 3 is carried out optical modulation.

Below, the manufacture method of the tft array substrate 1 that simple declaration is shown in Figure 2.It should be noted that the thin film transistor that forms as switching element is enumerated the non-crystalline silicon tft that the hydrogen non-crystalline silicon is used as semiconductor layer.

Summary below with reference to the manufacturing process of the tft array substrate 1 of Fig. 3～10 explanation embodiment 1.

At first, the aluminium alloy film forming with methods such as sputters on the glass substrate 1a about thickness 200nm by to this aluminium alloy film composition, forms gate electrode 26 and sweep trace 25 (Fig. 3).At this moment, for the covering that makes the gate insulating film of describing later 27 improves, can be etched to the coniform of about 30～40 degree to the periphery of aluminium alloy film.Then, as shown in Figure 4, for example, form gate insulating film 27, hydrogenated amorphous silicon film (a-Si:H) about formation thickness 50nm and the silicon nitride film (SiNx) about thickness 300nm with the silicon oxide film (SiOx) about the about 300nm of thickness with methods such as plasma CVD methods.

Then, by being the back-exposure of mask,, form channel protection film to silicon nitride film shown in Figure 5 (SiNx) composition with gate electrode 26.Then form the n about for example thickness 50nm of Doping Phosphorus thereon ⁺Type hydrogenated amorphous silicon film (n ⁺A-Si:H) after, as shown in Figure 6, to hydrogenated amorphous silicon film (a-Si:H) and n ⁺Type hydrogenated amorphous silicon film (n ⁺A-Si:H) composition.

Then, form for example aluminium alloy film about thickness 300nm thereon,, form and the source electrode 28 of signal wire one, the drain electrode 29 that contacts with pixel capacitors 5 by resembling composition as shown in Figure 7.And then, source electrode 28 and drain electrode 29 as mask, are removed the n on the channel protection film (SiNx) ⁺Type hydrogenated amorphous silicon film (n ⁺A-Si:H).

Then, as shown in Figure 8, for example use plasma CVD equipment etc.,, form interlayer dielectric by for example forming silicon nitride film 30 with the thickness about 300nm.At this moment film forming is for example carried out about 300 ℃.Then, after forming photo-resist layer 31 on this silicon nitride film 30,, for example on silicon nitride film 30, form contact hole 32 by dry etching to these silicon nitride film 30 compositions.At this moment, after the etching of silicon nitride film 30 finishes, also carry out the etching of crossing about etching required time+10% of silicon nitride.In this is handled, about the also etched tens of nm of aluminum alloy surface.

As shown in Figure 9, for example pass through ashing operation based on oxygen plasma after, use the stripping liquid of amine to carry out the lift-off processing of photo-resist layer 31, at last, form the ITO film about thickness 40nm shown in Figure 10, form pixel capacitors 5 by composition, thereby the tft array substrate is finished.

The tft array substrate that forms with such manufacturing process become pixel capacitors 5 and with aluminium alloy form as drain electrode 29 direct contacting structure.In addition, the aluminium alloy that uses among the present invention also can be used as the reflecting electrode or the use of TAB connection electrode of reflective liquid crystal.

When implementing described manufacture method, as the aluminium alloy film material that constitutes drain electrode 29, if use at least a aluminium alloy of from constitute by Au, Ag, Zn, Cu, Ni, Sr, Sm, Ge, Bi a group, selecting that contains 0.1～6 atom % as alloying constituent, then, on the contact interface of this aluminium alloy film that constitutes drain electrode 29 and pixel capacitors 5, form analysing and observe of Figure 11～13 and amplify 3 kinds of interfaces shown in the concept map according to the formation condition of this drain electrode 29.

Carry out sputter in order to form the aluminium alloy film that contains described alloying constituent, can use the target that constitutes by the aluminium alloy that contains described alloying constituent.This target can contain 0.1～6 atom % from constitute by Nd, Y, Fe, Co one group, select at least a.

In addition, when the amount of the described alloying constituent that contains in the aluminium alloy film is lower than 0.1 atom %, with the contact interface of pixel capacitors on the amount of the denseization layer that forms or precipitate (intermetallic compound) insufficient, be difficult to obtain the reduction effect of the contact resistance of the level that the present invention seeks, opposite, it is excessive to contain if surpass 6 atom %, then the resistance of aluminium alloy film raises, and the response speed of pixel is slack-off, and power consumption increases, as the downgrade of indicating meter, can't be used for practicality.Therefore, if consider these advantages and disadvantages, preferably the content with described alloying constituent is controlled at more than the 0.1 atom %, more preferably more than the 0.2 atom %, and preferably below 6 atom %, more preferably below the 5 atom %.

Figure 11 forms the electroconductibility precipitate that contains described alloying constituent (solid solution element) on the conceptive contact interface that is illustrated in aluminium alloy film and pixel capacitors 5, and flow through, thereby conduct the figure of the state of aluminium alloy and pixel capacitors by the most pickup current of this precipitate.Such state applies thermal process in the time of can forming by insulating film described as follows or heat-treats before wiring membrane forms the etching of back contact hole, and formation comprises the electroconductibility precipitate of solid solution element and obtains on the aluminium grain border.

Promptly, by when insulating film forms, applying thermal process or preferred before the etching of contact hole after the formation of wiring membrane 150～400 ℃ of thermal treatments of carrying out more than 15 minutes, and recrystallize, on the aluminium grain border, generate the intermetallic compound that contains the precipitate of described solid solution element or contain the solid solution element of aluminium.

Then, in the etching work procedure of the contact hole of insulating film, appended etching period, so that, more preferably about etching 3～100nm, light etching is implemented on the surface of aluminium alloy film from the surface etching 1～200nm of aluminium alloy film.As identical effect, also can be in the photo-resist stripping process behind the etching work procedure of the contact hole of insulating film, use has the amine stripping liquid that cleans its surface and light etched effect to aluminium, and the part of the precipitate (intermetallic compound) of solid solution element is exposed.At this moment, even be formed with insulating film on the surface of aluminium alloy, the part of exposing is because the characteristic of described solid solution element, compares with aluminium to be difficult to form oxide film, so form insulating film hardly, in addition, forms the oxide compound of electroconductibility according to element.And exposed portions serve so electric current flows through easily, even aluminium alloy film directly is connected with pixel capacitors 5, also can be suppressed at contact resistance very low because resistance is low.

It should be noted that, be not specially limited the kind of stripping liquid used herein, but preferably, contain the stripping liquid of the monoethanolamine about 5～70 quality %, more preferably contain the stripping liquid of the monoethanolamine about 25～70 quality % as main component.This stripping liquid is for rotten film residual after the etching of removing various metallic substance or polymeric film and normally used stripping liquid, removes the effect height for pollutent.Therefore, by in cleaning, using such stripping liquid, can guarantee fully low contact resistance value.

In addition, the stripping liquid of amine main bodys such as azanol or have excellent light etch effect at the stripping liquid that also contains the water about 5～25 quality % on the basis of amine principal constituent is if thin aluminum oxide just can be removed., this stripping liquid price height, and also fast to the etching speed of aluminium alloy, so be difficult to control a little.

Figure 12 is illustrated in the aluminium alloy film that contains Ni, as the structure of further minimizing contact resistance, has formed the concept map of denseization of Ni layer on the aluminum alloy surface at pixel capacitors interface.The thickness of preferred denseization of Ni layer is 1～10nm, and Ni concentration is that the concentration of aluminium alloy of film inside is above and Ni content+8 atom % aluminium alloy film inside are following (when the Ni content that is aluminium alloy film inside is 2 atom %, being below the 10 atom %).For example, on the interface of Al-2 atom %Ni alloy film,, confirm to exist denseization of the Ni layer of thickness 4nm, Ni concentration 8.7 atom % by cross section tem observation and EDX compositional analysis.

In containing the aluminium alloy of Ni, there is the Ni atom do not separate out fully, to exist with solid solution condition.When removing Al by dry etching and alkali etching, because the Ni rate of etch is low and be insoluble to basic solution, thus adhere to once more from the teeth outwards, residual as residue.Think so formed the denseization layer of Ni.Promptly think: by thermal treatment etc., the Ni of the solid solution limit (0.11%) that surpasses Ni in the aluminium alloy separates out on the aluminium grain border, and a part concentrates to the aluminium surface diffusion, forms denseization of Ni layer.Perhaps think: when the etching work procedure of contact hole, the halogenide of Ni so be difficult to volatilization, becomes the state that remains in aluminum alloy surface because steam forces down, and therefore, becomes than the Ni concentration of a large amount of in appearance aluminium alloys state of high density also.In the etching condition of contact hole, if crossing an etching period (promptly with respect to a contact hole required time of the etching thickness degree of depth, the time of appending for contact resistance is stablized) increase to 2 times, then Ni concentration is increased to 8.7 atom % from 5 atom %, so think that dependency is arranged.

In addition, Ni has not only on aluminium alloy film and near pixel capacitors contacts interface, and in the tendency of also some denseization of near interface that contact with insulating film.But, with denseization of the Ni at the interface of insulating film, with the pixel capacitors interfacial phase than little.This can be interpreted as, with the interface of pixel capacitors because above reason and being reamed has a little produced above-mentioned residue composition.In addition, as Ni accumulative reason on the interface, except above-mentioned factor, also can be speculated as, be insulated on the surface under the state that film retrains when aluminium alloy film heat-treated, the transient state stress distribution takes place in film, and make Ni along the grain boundary to interfacial diffusion.Therefore, can infer and formed denseization of Ni layer by the combination of above-mentioned multiple factor.

When the aluminium alloy film that contains Ni and ITO or IZO are directly contacted, be below the 4nm at the thickness of the al oxide layer of the high resistance reason that forms and become contact resistance on the interface with precipitate simultaneously.This is 5～8nm thin in comparison with the thickness of formed al oxide layer under the situation of fine aluminium or Al-Nd.In addition, contain under the situation of aluminium alloy of Ni, the oxygen level in the al oxide layer is 20at%, and is lower, compares little with containing ratio 50～60at% under the situation of fine aluminium or Al-Nd.That is, the aluminium alloy film that contains Ni is expected to have the effect that suppresses surface oxidation.Here if, under the little situation of the content of oxygen, al oxide layer has electroconductibility to a certain degree, simultaneously by applying voltage between ITO or IZO and aluminium alloy film, and applies electric field to the interface, then causes insulation breakdown easily with less strength of electric field.

As mentioned above, think: the multiple factors combine of these precipitates and denseization layer and al oxide layer etc. and make contact resistance descend.

Select Bi as alloying constituent, the optimum condition that obtains described contact condition is, for example after forming insulating film (SiNx) on the aluminum alloy films that contains the Bi about 0.1～6 atom %, by at 150～400 ℃, more preferably, Bi is separated out on the aluminium grain border 200～350 ℃ of thermal treatments of carrying out about 15 minutes～1 hour.Then, when the formation of contact hole, adopt dry etching carry out the required etching period of etching insulating film about 10% cross etching, use the light etched surfaces of stripping liquid of amine, on the interface of ITO/Al-Bi alloy film, generate the Bi precipitate.At this moment, the size of Bi precipitate and number can be adjusted by the addition of Bi, heat treated temperature or the time, mistake etch quantity etc.

Figure 13 represents alloying constituent (solid solution element) and element (In, the Sn etc.) mutual diffusion mutually that constitutes pixel capacitors 5, forms the diffusion layer mutually of solid solution element and In or Sn on the interface of aluminium alloy film and pixel capacitors 5, obtains the concept map that conducts.That is, when selecting Sm,, obtain the contact condition shown in the illustrated example according to filming condition as described solid solution element.

Select Sm as alloying constituent, the actual conditions that obtains described contact condition is, for example, after forming insulating film (SiNx) on the aluminum alloy films that contains the Sm about 0.1～6 atom %, by at 150～400 ℃, more preferably, Sm is separated out on the aluminium grain border 200～350 ℃ of thermal treatments of carrying out about 15 minutes～1 hour.Then, when the formation of contact hole, adopt dry etching carry out the required etching period of etching insulating film about 10% cross etching, use the light etched surfaces of stripping liquid of amine.Here think,, form interfacial layer as quilt oxidations selectively such as the residual Sm of residue.This interfacial layer is more coarse than Al oxide compound, so electric current flows through easily, helps low resistanceization.By on its interfacial layer, forming the ITO film, on the interface of ITO/Al-Sm alloy film, form the In among Sm and the ITO, the diffusion layer of Sn.The thickness of this diffusion layer can be the scope of 5～50nm, and this thickness can be according to adjustment such as the addition of Sm, heat treated temperature or time, mistake etch quantities.

In the example of described Figure 12, Figure 13, all on the interface of aluminium alloy film and pixel capacitors, be difficult to form insulation layer, so both directly connect, can connect so that more the low resistance realization is reliable.

If the flat panel display device of the tft array substrate with such formation is for example used as liquid crystal indicator, just can be suppressed at inferior limit to the contact resistance between pixel capacitors and the connecting wiring portion, so can suppress detrimentally affect to the display quality of display frame.

Below, illustrate to be applied in the structure that array of the present invention serves as a contrast the thin film transistor of the embodiment 2 in hanging down.

Figure 14 is that explanatory view is analysed and observe in the amplification of structure of roughly representing to be applied in the thin film transistor of the embodiment 2 in the array substrate of the present invention, in the present example, has used the thin film transistor of top grid structure.

As shown in figure 14, form sweep trace by aluminum alloy films on glass substrate 1a, the part of this sweep trace works as the conducting of control thin film transistor and the gate electrode 26 of disconnection.In addition, in order to intersect with this sweep trace by interlayer dielectric (SiOx), form signal wire with aluminium alloy, the part of this signal wire works as the source electrode 28 of thin film transistor.

Configuration is by at In in the pixel area on interlayer dielectric (SiOx) ₂O ₃In contain the film formed pixel capacitors 5 of ITO of SnO, in addition, the drain electrode 29 of the thin film transistor that is formed by aluminium alloy works as the connection electrode portion that is connected electrically on the pixel capacitors 5.That is, the drain electrode 29 of the thin film transistor that is formed by aluminium alloy directly contacts with pixel capacitors 5, is electrically connected.

Therefore, same with the example of described Fig. 2, on the tft array substrate, if supply with gate voltage by sweep trace to gate electrode 26, then thin film transistor becomes conducting state, and the driving voltage that offers signal wire in advance offers pixel capacitors 5 from source electrode 28 by drain electrode 29, if pixel capacitors 5 is provided the driving voltage of preset level, then and opposed substrate illustrated in fig. 1 10 between produce potential difference, the liquid crystal molecule orientation that comprises in the liquid crystal layer 3 is carried out optical modulation.

Below, the manufacture method of the tft array substrate 1 that simple declaration is shown in Figure 14.The thin film transistor that has in the T array substrate of this embodiment 2 is to be the top grid structure of semiconductor layer with polysilicon (poly-Si), Figure 15～21st, and the figure of manufacturing process of the array substrate of embodiment 2 represented in summary.

At first, on glass substrate 1a, pass through plasma CVD method, for example with about 300 ℃ of underlayer temperatures, silicon nitride film (SiNx) about formation thickness 50nm and the silicon oxide film (SiOx) about thickness 100nm, the hydrogenated amorphous silicon film (a-Si:H) about thickness 50nm, for this hydrogenated amorphous silicon film (a-Si:H) multi-crystal silicification, heat-treat and laser annealing.Thermal treatment is for example by about 470 ℃, and the thermal treatment of atmosphere gas is about 1 hour and carry out, and after carrying out dehydrogenation and handling, for example uses the excimer laser annealing device, with the about 230mJ/cm of energy ²About condition to hydrogenated amorphous silicon film (a-Si:H) irradiating laser, for example obtain the polysilicon film (poly-Si) about thickness 0.3 μ m (Figure 15).

Then, as shown in figure 16, by plasma etching with polysilicon film (poly-Si) patterning.Then as shown in figure 17, for example form silicon oxide film (SiOx), as gate insulating film 27 with the thickness about 100nm.On the gate insulating film 27 that obtains by sputter etc., for example with the thickness about 200nm form as with the aluminium alloy film of sweep trace all-in-one-piece gate electrode 26 after, with method pattern-makings such as plasma etchings, form and the gate electrode 26 of sweep trace one.

Then as shown in figure 18, form masks with photo-resist 31, for example by ion implantation apparatus etc., for example with about 50Kev, 1 * 10 ¹⁵Individual/cm ²Left and right sides Doping Phosphorus is at the part formation n of polysilicon film (poly-Si) ⁺Type polysilicon film (n ⁺Poly-Si) after, peel off photo-resist 31, for example about 500 ℃, spread by thermal treatment.

Then as shown in figure 19, for example use plasma CVD equipment, with about thickness 500nm, underlayer temperature forms silicon oxide film (SiOx) for about 300 ℃, form interlayer dielectric after, same by with the photo-resist patterning, the silicon oxide film of dry etching interlayer dielectric (SiOx) and gate insulating film 27, form contact hole, by sputter, for example with after forming aluminium alloy film about thickness 450nm, by patterning, on signal wire, form the source electrode 28 and the drain electrode 29 of one.As a result, source electrode 28 and drain electrode 29 are by each contact holes contact n ⁺Type polysilicon film (n ⁺Poly-Si).

Then, as shown in figure 20, by plasma CVD equipment etc., with about thickness 500nm, underlayer temperature forms silicon nitride film (SiNx) for about 300 ℃, as interlayer dielectric.Then, form photo-resist 31 thereon after, with silicon nitride film (SiNx) patterning, for example by dry etching, after this silicon nitride film (SiNx) forms contact hole 32, implement silicon nitride etching required time about 10% cross etching.In this is handled, about the also etched tens of nm of aluminum alloy surface.

Then, as shown in figure 21, for example pass through ashing operation based on oxygen plasma, with described same, after use amine stripping liquid etc. carries out the lift-off processing of photo-resist, for example by the ITO film about sputter formation thickness 100nm, by wet etching pattern-making, form pixel capacitors 5.In this was handled, drain electrode 29 directly contacted pixel capacitors 5.

Then, stable in order to make characteristics of transistor, if carry out annealing about 1 hour with about 350 ℃, then the multi-crystal TFT array substrate is just finished.

According to the tft array substrate of the foregoing description 2, have the liquid crystal indicator of this tft array substrate, obtain with in the equal effect of the embodiment 1 of above explanation.In addition, similarly to Example 1, in embodiment 2, aluminium alloy of the present invention also can use as the reflecting electrode of reflective liquid crystal.

In addition, material as described pixel capacitors 5, be fit to use tin indium oxide or indium zinc oxide, in the described in addition aluminium alloy film, form precipitate, intermetallic compound or denseization layer with part or all of the alloying constituent of nonequilibrium situations solid solution, resistivity is below the 8 μ Ω cm, more preferably is adjusted to below the 5 μ Ω cm.And the precipitate that exists on the contact interface of described aluminium alloy film and pixel capacitors (intermetallic compound) is if major diameter is above 0.01 μ m and with per 100 μ m ²The number that exceeds 0.13 exists, and just can reduce contact resistance, so desirable.

In addition, when implementing described manufacture method, if in described aluminium alloy film, with the alloying constituent of part or all and pixel capacitors of the alloying constituent (particularly Sm) of nonequilibrium situations solid solution preferably by 150～400 ℃, thermal treatment more than 15 minutes, diffusion mutually then forms precipitate easily on the contact interface of described aluminium alloy film and pixel capacitors.In addition,, enumerated vapour deposition method or sputtering method etc., but wherein particularly preferably be sputtering method as the method that forms described aluminium alloy film.

And, if stratification insulating film on described aluminium alloy film, after carrying out contact etch on this insulating film, then light etching 1～200nm, the more preferably aluminium alloy film of 3～100nm from this surface, in this aluminium alloy film, part or all precipitate with the alloying constituent of nonequilibrium situations solid solution is partly exposed, then can further reduce the contact resistance of formation pixel capacitors thereon.

Described light etching can be by using gas that can the described aluminium alloy film of etching dry etching or use the wet etching of soup that can the etching aluminium alloy film to carry out, as the soup that in this light etching work procedure, uses, can use the stripping liquid of the photo-resist that uses in the patterning.

Use the tft array substrate that obtains like this, finish liquid crystal indicator as described flat panel display device shown in Figure 1.

That is,, after the drying, carry out friction treatment, form oriented film at surface applied polyimide by the above-mentioned tft array substrate of finishing 1.

In addition, at first on glass substrate, rectangular by chromium is patterned into, form photomask 9.Then, form the colour filter 8 of resinous red, green, blue in the gap of this photomask 9.By on this photomask 9 and colour filter 8, disposing the such transparent and electrically conductive film of ITO, form opposite electrode as public electrode 7.Then, apply for example polyimide, after the drying, carry out friction treatment, form oriented film 11 in the superiors of this opposite electrode.

Then, the respectively relative configuration of the face that is formed with oriented film 11 of array substrate 1 and opposed substrate 2, the sealing material 16 by resin system etc. except the sealing liquid crystal mouth, is pasted together two substrates.At this moment, between two substrates, across spacing block 15 etc., make two intervals between substrate keep certain.

The dummy cell that obtains like this is placed in the vacuum, seal is immersed under the state in the liquid crystal, return to normal atmosphere gradually, in dummy cell, inject the liquid crystal material that comprises liquid crystal molecule, form liquid crystal layer, seal up seal.At last, paste polarization plates 10, finish liquid crystal panel on the two sides in the outside, unit.

In addition, as shown in Figure 1, on liquid crystal panel, be electrically connected and drive LCD drive circuits, be configured in the sidepiece or the back side portion of liquid crystal panel.Then, the frame of the opening by comprising the display surface that limits liquid crystal panel, form backlight 22, the light guiding plate 20 of area source and keep frame 23 to keep liquid crystal panels, finish liquid crystal indicator.

[embodiment 1

Below, pixel capacitors 5 when in table 1, having represented to measure the pixel capacitors 5 on the direct contact array substrate of the present invention and contact resistance between aluminium alloy film and the result that obtains.

This determination experiment is as described below.

1) formation of pixel capacitors: add the tin indium oxide (ITO) of the stannic oxide of 10 quality % in Indium sesquioxide, or add the indium zinc oxide (IZO) of the zinc oxide of 10 quality % in Indium sesquioxide, thickness all is 200nm.

2) formation of aluminium alloy film: alloying constituent content is as shown in table 1.

3) heat-treat condition: after forming the insulating film (SiNx) of thickness 300nm, in a vacuum with 300 ℃, thermal treatment 1 hour.

4) light etching: after using fluorine class plasma body described insulating film (SiNx) dry etching, then, the about 10nm of each aluminium wiring material etching, re-use stripping liquid (" stripping liquid 106 " that Tokyo Ying Huashe makes), with the pollution layer on the top layer about 5nm of etching together, add up to etching 15nm (thickness 5%).

5) assay method of contact resistance:

Make degree Kelvin pattern shown in Figure 22, carry out 4 terminals measurement [making electric current flow through ITO (or IZO)-Al alloy, the method that the voltage between other terminals measurement ITO (or IZO)-Al alloy descends].That is, at the I of Figure 22 ₁-I ₂Between flow through electric current I, by monitoring V ₁-V ₂Between voltage V, the contact resistance R of contact part C as [R=(V ₂-V ₁)/I ₂] obtain.In addition, the making method of described pattern is as described below.

In addition, the mensuration of the interpolation element of described aluminium alloy is undertaken by ICP luminescence analysis (inductively coupled plasma luminescence analysis) method.

In order to replace glass substrate, realize insulation on the surface with substrate, use the oxide film (SiO that forms thickness 400nm on the surface ₂Heat oxide film) silicon chip forms Al alloy film 300nm by sputtering method, behind the patterning, forms the insulating film (SiNx) of thickness 300nm by the CVD method.Then, former state is carried out 1 hour thermal treatment in the filming chamber of vacuum after, take out.Then, by photoetching, the contact hole of patterning 80 μ m * 80 μ m carries out etching by fluorine class plasma body, forms contact hole.At this moment, append the etching excessively of carrying out being scaled the etching period 10% of insulating film after the etching of insulating film with the time.In this was handled, the top layer of aluminium alloy film was removed the about 10nm of thickness (thickness 3.3%).

Then, carry out based on oxygen plasma ashing, peel off based on the photo-resist of stripping liquid.It should be noted that as stripping liquid, " stripping liquid 106 " that uses Tokyo Ying Huashe to make carries out cleaning in 10 minutes at 100 ℃.At this moment, fluorochemical or the pollutents such as oxide compound, carbon (thickness approximate number nm) that are formed on the aluminium alloy top layer are removed.Then, ITO (or IZO) film by sputter formation 200nm carries out composition.

Then, in the mensuration of contact resistance, use the artificial detector and the analyzing parameters of semiconductor instrument " HP4156A " (Hewlett-Packard's manufacturing) of 4 terminals.In this is measured, with R (contact resistance)=[I ₂/ (V ₂-V ₁)] represent, can measure the pure resistance value of ITO (or IZO)/Al alloy bond part of the influence of removing the cloth line resistance.

In addition, for each sample, observation by the sweep trace electron microscope and based on 2 mappingizations of the composition of Auger optical spectroscopy, the size and the number of the precipitate that investigation exists in the ITO of contact hole (or IZO)/Al alloy bond portion, its result, when being Al-Ag, confirm that size is about precipitate about 0.3 μ m with 1/100 μ m ²Above density exists.Equally, when being Al-Zn, the size and the number of the precipitate that in the ITO of contact hole (or IZO)/Al alloy bond portion, exists of investigation, its result confirms that size is about precipitate about 0.3 μ m with 3/100 μ m ²Above density exists.

In addition, add the material behind Nd, Y, Fe, the Co in described aluminium alloy, the crystallization particle diameter of its tissue becomes fine, so the size of precipitate reduces.For example, size for the precipitate that is present in ITO/Al alloy bond portion, be difficult to carry out the tem observation at ITO/Al alloy bond interface, so by the tissue in the film of plane tem observation aluminium alloy, its result, in Al-Ni, observe the precipitate of major diameter 0.05 μ m, in Al-Ni-Nd, observe the precipitate of major diameter 0.02～0.04 μ m, in Al-Ni-Y, observe the precipitate of major diameter 0.01～0.03 μ m.Think that the size of precipitate at interface is also identical with these.

Table 1

As known from Table 1, when making aluminium alloy film directly contact the ITO film, contact resistance is 1.5 * 10 ⁵Ω is an Al-Nd alloy when directly contacting the ITO film when making representational aluminium alloy film, and contact resistance is 8.4 * 10 ⁴Ω.In addition, as construct in the past, the contact resistance when configuration Mo is as the obstruction metal between ITO film and Al-Nd wiring is 7.4 * 10 ¹Ω.

And the contact resistance of Al-Au alloy is 7.6 * 10 ¹Ω, the contact resistance of Al-Ag alloy are 5.7 * 10 ¹Ω, the contact resistance of Al-Zn alloy are 9.3 * 10 ¹Ω, the contact resistance of Al-Cu alloy are 2.3 * 10 ²Ω, the contact resistance of Al-Ni alloy are 1.7 * 10 ¹Ω, the contact resistance of Al-Sr alloy are 2.3 * 10 ¹Ω, the contact resistance of Al-Sm alloy are 8.6 * 10 ¹Ω, the contact resistance of Al-Ge alloy are 2.3 * 10 ¹Ω, the contact resistance of Al-Bi alloy are 9.2 * 10 ¹Ω, all and in the past structure with Mo be when hindering metal about equally.

In addition, in table 1, also represented as the result who pixel capacitors has been used the IZO film of the Zn that contains ionization voltage and same height of aluminium and reducing resistance excellence.

The IZO film is at In ₂O ₃The middle transparent film that adds the ZnO about 10 quality %, at this moment, contact resistance further descends, and compares with the ITO film, becomes number/.As its reason, consider following two.

At first, the voltage of IZO (work function) is than ITO height, so supposition forms insulant layer as thin as a wafer on the interface of aluminium alloy wiring and pixel capacitors, use the MIM structure (Metal-Insulator-Metal) that constitutes by metal-insulator film-pixel capacitors, even the thickness of insulating film is identical, the high pixel capacitors of work function is when the externally-applied potential difference, and the thickness of the insulating film at interface seems thin, and the tunnel current composition increases.

In addition, the Zn among the IZO compares with Sn among the ITO, has ionization voltage height, is difficult to by the character of aluminium reducing, so be difficult to form insulant at the interface of aluminium alloy and pixel capacitors.

The contact area of pixel capacitors of using in said determination in addition, and contact layout portion is the square of 80 * 80 μ m.

In addition, in table 3, represented alloy, the data of the area occupation ratio of precipitate when the plane tem observation of alloy film is carried out in cloth line resistance after 1 hour of when changing the addition of solid solution element and contact resistance IT0,300 ℃ of thermal treatment, 300 ℃ of thermal treatment after 1 hour for described 2 metaclass.Also represented at this moment observed main electroconductibility precipitate.Contact resistance and table 1 have been manufactured experimently the evaluation element equally, estimate.In addition, composition is meant the content that is contained in the solid solution element in the aluminium alloy.In the tem observation of plane,,, observe the appearance of the interior tissue of alloy with surperficial parallel slices to the alloy wiring portion.Along with the content increase of solid solution element, the contact resistance of ITO reduces, and resistance increases.The area occupation ratio of precipitate is relevant with composition, and the area occupation ratio of contact resistance and precipitate is the relation of inverse ratio.

In addition, the area occupation ratio of precipitate is, by the plane tem observation, distinguishes the precipitate that occurs in the visual field of multiplying power at 500,000 times, 0.3 μ m * 0.3 μ m by EDX, and obtains its value for the ratio of Al phase by calculating.Thus, aluminium alloy is near area occupation ratio 0.5% arbitrarily, and contact resistance all becomes 200 Ω, if surpass 0.5%, just becomes below 200 Ω.If the electric current composition that flows through by this precipitate is main electric current composition, then also exist with ... the resistivity of precipitate, but area occupation ratio is the principal element of decision contact resistance.

The composition of precipitate is for using the identical observed a plurality of precipitates of plane tem observation sample, by forming back quantification result and X-ray diffraction result with the EDX analysis, to obtain the composition of observed main precipitate.

For example, contain the aluminium alloy of Ni, its electroconductibility precipitate contains from by Al ₃Ni, Al ₃Ni ₂, AlNi, AlNi ₃That selects in one group of formation is at least a; The aluminium alloy that contains Ag, its electroconductibility precipitate contain from by Ag, Al ₂That selects in one group that Ag, AlAg constitute is at least a; The aluminium alloy that contains Zn, its electroconductibility precipitate contains select at least a from AlZn, Zn, ZnO; The aluminium alloy that contains Cu, its electroconductibility precipitate contains from AlCu, Cu, CuO, Cu ₂That selects among the O is at least a.

And in following table 4, represented: when the content of Al-Ag alloy is fixed on 2 atom %, changed etch quantity and made the etch depth that begins from the top layer of Al-Ag alloy range at 0～50mm, utilize surperficial SEM to observe, observe contact part the most surperficial that the contact hole bottom surfaces are the Al-Ag alloy with 60,000 times multiplying powers, by the above precipitate number of the 0.3 μ m of the major diameter in the visual field that appears at 1.5 μ m * 1.5 μ m, calculate the value of the precipitate number that occurs on the contact hole bottom surface of the 10 μ m * 10 μ m that obtain; And at this moment and contact resistance ITO.In addition, be because Al-Ag alloy energy number goes out the number of most of precipitate.At this moment, the counting of number is by observing picture, EDX and carrying out based on 2 mappings of Auger.

If etch depth strengthens, observing the precipitate number of obtaining by surperficial SEM increases, then contact resistance descends, so being accompanied by etch depth increases, the electroconductibility precipitate exposes from the Al-Ag alloy surface gradually, be accompanied by this, the contact area of the ITO that forms in electroconductibility precipitate and the operation after this increases, and contact resistance descends.And, surpass 30nm from etch depth, observe the precipitate number convergence that the surface draws with SEM, meanwhile, contact resistance converges to certain value.

With the structure that above-mentioned Figure 11 represents, when solid solution element was Ag, Zn, the contact resistance of each alloy shown in the above-mentioned table 1, the precipitate of solid solution element or the relation that contains between the density of intermetallic compound of solid solution element of aluminium became the value shown in the table 2.This table is the table roughly calculate supposition contact resistance number of necessary precipitate when being 200 Ω by calculating.And the value of this table be the value of contact resistance is the calculation result of 200 Ω, but in an embodiment, the contact resistance of Al-3.8%Ag is 58 Ω, and the contact resistance of Al-2.4%Zn is 93 Ω.

When the supposition precipitate is that diameter is when being 0.01 μ m circular all, if infer the number of precipitate by calculating from the contact resistance value of embodiment, then shown in table 5,6, the number of precipitate is: Al-3.8%Ag is 45 (10 μ m * 10 μ m), and Al-2.4%Zn is 110 (10 μ m * 10 μ m).

In addition, suppose that the precipitate among the Al-Ag is, when actual diameter with plane TEM or the observation of scanning electron ray microscope was 0.3 μ m circular, this number was 0.5 (10 μ m * 10 μ m).When Al-Ag, the addition difference, but be almost the same order of magnitude with the number of in the experiment shown in the table 4, counting the precipitate that.By the way, when being ITO, the reducing resistance height of Zn so have the effect that prevents the Al catalytic oxidation, therefore, is suppressed at the formation of precipitate with the resistive formation of outside part, helps precipitate to increase part with the electric current of outside part.

Table 2

Table 3

Table 4

Table 5

The size of the precipitate of the solid solution element that satisfies when making contact resistance be 57 Ω/80 μ m identical * 80 μ m and the relation of density with the measured value of Al-Ag

Table 6

The size of the precipitate of the solid solution element that satisfies when making contact resistance be 93 Ω/80 μ m identical * 80 μ m and the relation of density with the measured value of Al-Zn

Below, represent the embodiment of 3 metaclass.

Same with the situation of 2 metaclass, measure contact resistance value with the ITO of contact hole by 80 μ m * 80 μ m.The contact resistance of Al-Ag-Nd film is 1.3 * 10 ²Ω, the contact resistance of Al-Zn-Nd film are 4.3 * 10 ²Ω, the contact resistance of Al-Ni-Nd film are 1.7 * 10 ²Ω, arbitrarily contact resistance value compare with the structure in the past that uses Mo to hinder metal all exceed some, but all be unchallenged level.In other Au, Ge, Sr, Sm, Bi, also almost be equal 1.0 * 10 ²～5.0 * 10 ³The scope of Ω.

And between the composition of aluminium alloy film and contact resistance and electric conductivity, thermotolerance, there is correlationship.For example, if increase the X content of Al-X-Nd (X=Ni), then contact resistance reduces, but resistance increases, and thermotolerance improves (with reference to Figure 24 (a) and (b)).In addition, if Nd content increases, then thermotolerance improves, but resistivity and contact resistance increase (with reference to Figure 25 (a) and (b)).Such tendency all is same for X arbitrarily.In addition, the contact resistance of requirement is according to the structure of display device or manufacturers and difference is 150 Ω～5k Ω in the square contact hole of 80 μ m.There are compromise relation in electrical characteristic and thermotolerance, so form by adjusting, can satisfy desired scope.

In addition, same with Nd when X is Ni in the Al-X-Nd alloy, Ni embeds (pinning) the effect that suppresses the Al migration when heating.For example, as shown in figure 26, [in the formula, CX1 represents the Ni content (atom %) in the aluminium alloy at " 0.7 〉=0.5CX1+CNd ", CNd represents the Nd content (atom %) in the aluminium alloy] the zone in, in 300 ℃ thermal treatment, the thermotolerance deficiency takes place to separate out unusually in the zone of (hillock), on the other hand, in the zone of " 0.5CX1+CNd 〉=4.5 ", because the resistivity of wiring surpasses 8 μ Ω cm, so can not be practical.Therefore, optimum range becomes " 0.7 ≦ 0.5CX1+CNd ≦ 4.5 ".

Equally, when the yttrium (Y) that contains as same 3A family, as shown in figure 27, almost equal electrical characteristic and thermotolerance when also obtaining with Nd.

Equally, in the composition of Al-Ni-Fe, as shown in figure 28, in " 1 〉=CY1+CY2 " scope of [in the formula, CY1 represents the Ni content (atom %) in the aluminium alloy, and CY2 represents the Fe content (atom %) in the aluminium alloy], in 300 ℃ thermal treatment, the thermotolerance deficiency takes place to separate out unusually.And in the zone of " CY1+CY2 〉=6 ", the resistivity of wiring surpasses 8 μ Ω cm, so can not be practical.Therefore, optimum range becomes " 1 ≦ CY1+CY2 ≦ 6 ".

In addition, Co and Fe can think that as identical transitional metal effect is almost equal.When Al-Ni-Co, as shown in figure 29, obtain the characteristic identical with Al-Ni-Fe.Here, thermotolerance is meant not to produce owing to heat-treating and separates out unusually or the space, and the top temperature that the morphology (morphology) of aluminum alloy surface is worsened.The density of separating out unusually that takes place when in the drawings, carrying out 300 ℃ thermal treatment is 3 * 10 ⁸m ^-2Following is qualified.

Equally, Figure 30,31,32,33 is illustrated in Al-X-Nd, Y, Fe, the Co alloy, the situation during X=Ag, and Figure 34,35,36,37 is illustrated in Al-X-Nd, Y, Fe, the Co alloy, the situation during X=Zn.In addition, Figure 38,39,40,41 is illustrated in Al-X-Nd, Y, Fe, the Co alloy, the situation during X=Cu.No matter add which kind of alloying element, all can obtain approximate same result.

Under the lower situation of thermal treatment temp, above-mentioned optimum content range.Thermal treatment temp depends on the temperature (being the temperature that forms insulating film here) that forms in the processing of carrying out after the aluminium alloy film.Recrystallize by the heating aluminium alloy film.Even improve thermal treatment temp membrane stress is relaxed fully, if further heat, the crystal grain misgrowth of aluminium takes place to separate out unusually.Satisfy the lower limit and the upper limit of stable on heating thermal treatment temp, change with the composition of alloy.In other words, the lower limit of optimum content and the upper limit change with thermal treatment temp.For example, the content composition relevant with above-mentioned CX1, CX2 recrystallizes no longer when Heating temperature is 150 ℃ and carries out, and separates out unusually so be difficult to produce.Therefore, the lower limit of optimum range reduces to 0.2.Equally, relevant with above-mentioned CX1, the CX2 composition that contains, the optimum range lower limit reduces to 0.4.

In the present invention, precipitate by solid solution element, when realizing the conducting of pixel capacitors and aluminium alloy film, promptly, in each aluminium alloy, except the part of separating out of solid solution element, the aluminium of oxidation contacts with pixel capacitors easily on the interface of pixel capacitors and aluminium alloy film, when there was high-resistance aluminum oxide in its surface, contact resistance was by the resistivity decision of the precipitate of the low solid solution element of resistance.Suppose all to realize conducting, then, can stipulate to satisfy the surface-area and the density of the necessary precipitate of required contact resistance by calculating by the single precipitate of solid solution element.

Necessary contact resistance is assumed to below 200 Ω when now, contact size being 80 * 80 μ m.When solid solution element was zinc, the resistivity of zinc was 5.92 μ Ω cm, supposed that the single precipitate of the zinc of major diameter 0.03 μ m is separated out on the plane on pixel capacitors and aluminium alloy interface, then needed the precipitate more than 3297.That is, need 51.4/100 μ m with densometer ²More than.In addition, when solid solution element was silver, the resistivity of silver was 1.5 μ Ω cm, supposes that the single precipitate of the silver of major diameter 0.03 μ m is separated out on the plane on pixel capacitors and aluminium alloy interface, then needs the precipitate more than 833.Promptly need 12.9/100 μ m with densometer ²More than.

In addition, be the 0.3 μ m identical if make the major diameter of precipitate with measured value, then as shown in table 7, under the situation of Al-Ag, in 80 * 80 μ m square, need the precipitate more than 8.3, under the situation of Al-Zn, need the precipitate more than 32.9.That is, need 0.13/100 μ m with densometer ²More than, 0.51/100 μ m ²More than.

And when Al-Ni, the major diameter of tissue is 0.05 μ m, but at this moment, is 6.84 μ Ω cm if make the resistivity of Ni, with the resistivity of precipitate much at one, then calculate and know 80 * 80 μ m square from summary, when major diameter is 0.05 μ m, need 1345.I.e. 21/100 μ m ²

In addition, if add a kind that selects from Nd, Y, Fe, Co in containing the aluminium alloy of Ni, then tissue attenuates, and when Al-Ni-Y, the major diameter of tissue is 0.01～0.03 μ m.At this moment,, then calculate and know 80 * 80 μ m square, when major diameter is 0.03 μ m, need 3740 from summary if the resistivity of the resistivity of Ni and precipitate much at one.I.e. 58/100 μ m ²In addition, when whole major diameters is 0.01 μ m, become 526/100 μ m ²

Perhaps, when Al-Ni-Nd, the major diameter of tissue is 0.02～0.04 μ m.At this moment, calculate from summary and to know 80 * 80 μ m square, when major diameter is 0.04 μ m, need 2104.I.e. 33/100 μ m ²In addition, when whole major diameters is 0.02 μ m, become 132/100 μ m ²

Table 7

The size of the main precipitate in each aluminium alloy and density

	The diameter (μ m) of main precipitate	The number of precipitate (per 100 μ m 2)
			Al—Ag	0.3	0.13
|Al—Zn	0.3	0.51
			Al—Ni	0.05	21
Al—Ni—Nd	0.02	132
			Al—Ni—Y	0.01	526

In sum, when using the minimum Ag of monomeric resistivity,, be the precipitate of 0.3 μ m as major diameter in order to satisfy desired contact resistance 200 Ω, require density at 0.13/100 μ m ²More than.In addition, when using the Al-Ni-Y of precipitate minimum, be the precipitate of 0.01 μ m as major diameter, require density at 526/100 μ m ²More than.In addition, in Al-Ag class alloy, when precipitate is a major diameter when being 0.01 μ m, precipitate density is 115/100 μ m ²

, described value is the resistivity of supposition precipitate and obtain after interpolation element monomer equates.Sometimes, the precipitate that comprises this element and aluminium is compared with the element monomer, and resistivity is significantly big.At this moment, might carry out tem observation with contact surface with area occupation ratio that number is calculated and the area occupation ratio of deriving is different from the size of precipitate in reality.This is because when realizing contact resistance 200 Ω, and the number of this precipitate increases according to precipitate and the ratio that adds the monomeric resistivity of element.

, in fact, under the situation of the alloy system that generates precipitate, with the form of precipitate, and size mixes and exists, but is to use the calculation result of the contact resistance of zinc and Yin Shi to be almost the identical order of magnitude with experimental result.

Like this, compare when making fine aluminium wiring directly contact the ITO film, when using aluminium alloy of the present invention, contact resistance becomes 1/10 approximately ⁴

In addition, if the underlayer temperature the during sputter that improves transparency electrode, then contact resistance descends.When for example being ITO, if underlayer temperature becomes more than 50 ℃, then contact resistance reduces by half.More preferably, if by the heating of the substrate more than 100 ℃, the crystallinity of ITO improves, and then contact resistance is reduced to about about 1/5 approximately.

In addition, be room temperature when carrying out film forming when making underlayer temperature, if after film forming, carry out the thermal treatment more than 150 ℃ about 30 minutes, make the ITO polycrystallization, then contact resistance reduces by half.Usually, the etching difficulty of polycrystalline ITO so usually be the film forming of carrying out ITO at room temperature, behind the formation pattern, is carried out etching, and then thermal treatment, carries out polycrystallization, and the resistivity of ITO is reduced.

Therefore, in order to reduce contact resistance, the underlayer temperature when making the film forming of transparency electrode is more than 50 ℃, more preferably more than 100 ℃, when carrying out room temperature film-forming, after the film forming of transparency electrode, preferably implements the thermal treatment more than 150 ℃, more than 30 minutes.In addition, when transparency electrode is IZO, have same effect, but in the temperature province of this degree, the crystallization of IZO does not carry out, so the decline of contact resistance is few yet.

As mentioned above, manufacture experimently the result of liquid crystal display device in embodiments of the present invention, fabrication yield, display quality are all with combination ITO film be complete equal level when hindering metal.Therefore, in this liquid crystal display device, do not dispose the obstruction metal, can obtain and the equal performance of liquid crystal display device in the past yet.

Therefore, can omit the obstruction metal, can simplify manufacturing step, so can reduce manufacturing cost significantly.

That is, replace in the past fine aluminium or aluminium alloy, Mo-W film, by the aluminium alloy that comprises above-mentioned element-specific is used as electrode materials, can realize contacting with the direct of pixel capacitors, the simplification manufacturing step reduces manufacturing cost significantly.

In addition, same with the test method(s) of described table 1, at Al-2 atom %Ag alloy (thickness: 300nm) behind last formation silicon nitride (SiNx) film, carry out 300 ℃ * 1 hour thermal treatment, by photoetching with 80 μ m quadrate contact hole patternizations after, use fluorine class plasma body to carry out dry etching.At this moment, the time when carrying out etching, make etch depth variations for aluminium alloy by adjusting the etching of following silicon nitride film (SiNx).Then, carry out ashing and, form the ITO film based on the cleaning of " stripping liquid 106 ".By cross-section, measure the etch depth of aluminum alloy surface based on scanning electron microscope and transmission electron microscope.

Figure 23 represents the relation of the etch depth and the contact resistance of aluminum alloy surface, and from this figure as can be known, even aluminum alloy surface is etched a little, contact resistance just sharply reduces.This is considered to by etching, exposes the precipitate of solid solution element on aluminum alloy surface, can be electrically connected with pixel capacitors.

And, experimentally, even the etch depth from about aluminum alloy surface 5nm also can be obtained the contact resistance of about 56 Ω.Obtain of the decisions such as thickness of so necessary etch depth of low-resistance contact by the oxide layer of the size of the tissue of precipitate or distribution, aluminium alloy.According to the Auger electron optical spectroscopy, confirming to expose with Ag in this aluminum alloy surface is the precipitate of principal constituent.In addition, there are not insulant layers such as oxide compound on the surface of precipitate.

The test portion of observing be from the aluminum alloy surface etching state of 5nm, if precipitate is exposed in aluminum alloy surface, then can obtain and be electrically connected, but have the pollution layer on necessary etching top layer at least with pixel capacitors.In addition, the oxide skin thickness of oxidized aluminum alloy surface is about about 3～5nm, so at this moment, in order to remove oxide skin, aluminum alloy surface is exposed, and needs etch depth above about 3nm at least.

And if etch depth is dark excessively, then as the thickness attenuation of wiring, resistance takes place increases the problem of reliability decrease.The source electrode that for example uses in the present embodiment and the thickness of drain electrode are 300nm, are used to guarantee that the direct etch depth that contacts of aluminium alloy and pixel capacitors is 1～200nm, more preferably the scope of 3～100nm.

Preferably do one's utmost to reduce the impurity that comprises in the wiring material of aluminium alloy.For example, oxygen or carbon make the film gonorrhoea, or wiring resistivity is increased.Therefore, when wanting to make resistivity is that 5 μ Ω cm are when below horizontal, for these impurity concentrations that comprise in the wiring material, use compositional analysis quantitative values based on XPS analysis, should be suppressed at the oxygen amount below the 7 atom %, the carbon amount is suppressed at below the 0.4 atom %, more preferably is suppressed at below the 0.2 atom %.

For example, when impurity is carbon, at Al ₄C ₃Or in the carbon compound such as NiC, the material of stoichiometric composition is a pottery, has electrical insulating property originally, though also according to addition and difference, self the resistivity increase of connecting up.In addition, the precipitate that occurs on the Al grain boundary by thermal treatment becomes the intermetallic compound that comprises described carbon compound.When the electric current route of ITO and wiring material was described precipitate via major portion of the present invention, if compare with carbon-free precipitate, contact resistance uprised.Therefore, the contact resistance with ITO is not wrap a carbonaceous side in the preferred aluminium alloy part material.

In addition, when forming carbonaceous wiring material, adhere to carbon compounds such as aluminium carbide compound in sputter equipment indoor and contaminated, so have the problem of necessary frequent maintenance device by sputter.When impurity is oxygen, generate the aluminum oxide (Al of electrical insulating property equally ₂O ₃), so the resistivity of wiring increases.If will prevent described this situation, preferably prevent the sneaking into of pollutent in the manufacturing step, the device when taking to make sputter reaches 5 * 10 ^-6About the measure of following high vacuum.

Claims (1)

1. sputtering target that constitutes by aluminium alloy, wherein: as alloying constituent, comprise 0.1～6 atom % from constitute by Ag, Zn, Cu and Ni one group, select at least a, and comprise at least a from the group selection that constitutes by Nd, Y, Fe and Co of 0.1～6 atom %.

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