CN100565821C - Laser aid and laser anneal method - Google Patents
Laser aid and laser anneal method Download PDFInfo
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- CN100565821C CN100565821C CN 200610099648 CN200610099648A CN100565821C CN 100565821 C CN100565821 C CN 100565821C CN 200610099648 CN200610099648 CN 200610099648 CN 200610099648 A CN200610099648 A CN 200610099648A CN 100565821 C CN100565821 C CN 100565821C
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Abstract
For the crystallizing amorphous semiconductor film of the method for using laser beam irradiation, used the upper surface and the rear surface of laser beam irradiation amorphous semiconductor film.In this case, the effective energy intensity I o ' of effective energy intensity I o and the laser beam that is applied to the rear surface that is applied to the laser beam of upper surface satisfies and to concern 0＜Io '/Io＜1 or 1＜Io '/Io.Provided the laser crystallization method that the crystallization semiconductor film with big crystal grain diameter can be provided thus.
Description
The application is application number the dividing an application for the patent application of " laser aid and laser anneal method " that be 200410086941.8 denominations of invention.
Technical field
The present invention relates to laser aid that an a kind of method of using laser beam that semiconductor film is annealed (after this being called laser annealing) and a cover realize this purpose (more specifically, one cover comprises the device of lasing light emitter and optical system, and wherein optical system is used for and will be directed to the object that needs are handled from lasing light emitter emitted laser bundle).
Background technology
In recent years, thin-film transistor (after this being called TFT) has had very big development, and especially, the TFT that adopts polysilicon film (polysilicon film) to make the crystalline semiconductor film has attracted a lot of attentions.In particular, in liquid crystal display device (liquid crystal display) or EL (electroluminescence) display device, these TFT are used as the element of switch pixel and constitute the element of the drive circuit of control pixel.
In obtaining the common technology of polysilicon film, amorphous silicon film by crystallization to obtain polysilicon film.Especially, use the method for the crystallizing amorphous silicon fiml of laser beam much to be paid close attention to.In this explanation, the method for using the crystallizing amorphous semiconductor film of laser beam to obtain the crystalline semiconductor film is called as laser crystallization.
Laser crystallization makes the instantaneous possibility that is heated as to semiconductor film, is a kind of effective technology that the semiconductor film that is formed on the substrate with low thermal resistance is annealed therefore, as glass substrate, plastic and similar substrate.In addition, compare with traditional employing electric furnace heating means (after this being called stove annealing), laser crystallization has more noteworthy high yield.
Though have various laser beams to use, in laser crystallization, generally use from pulse resonance excimer laser emitted laser bundle (to call excimer laser beam in the following text).Excimer laser can provide bigger power output, and can swash repeatedly with high-frequency and penetrate.Further, for silicon fiml, excimer laser beam has the advantage of high absorption coefficient.
One of sixty-four dollar question that needs solution is the crystal grain diameter that how to increase in the crystalline semiconductor film that uses the laser beam crystallization at present.Obviously, crystal grain (also being referred to as particle) is big more, TFT, especially its channel formation region territory, across number of dies few more.This just makes the electrology characteristic that improves TFT, as field effect mobility or threshold voltage, fluctuation become possibility.
In addition, because each crystal grain inside has kept satisfied relatively degree of crystallinity, therefore when making TFT, hope can be placed on the channel formation region territory single intragranular, to improve the above-mentioned various operating characteristic of TFT.
But, the crystalline semiconductor film that uses present available technology to obtain to have enough big crystal grain diameter is quite difficult.Can obtain this crystalline semiconductor film with enough big crystal grain diameter although some results that reported show in experiment, these technology of having reported do not reach realistic scale as yet.
For example, on experimental level, the available K.Shimizu of these results, O.Sugiura and M.Matsumura is at IEEE Transactions on Electron Devices, vol.40, No.1, the method for describing in the paper of delivering on the pp.112-117 (1993) that is entitled as " the high mobility polycrystalline SiTFT (High-mobility poly-Si thin-filmtransistors fabricated by novel excimer laser crystallization method) of the excimer laser crystallization method preparation by novelty " obtains.In this piece paper, at first on substrate, form Si/SiO
2/ n
+The Si three-decker uses excimer laser beam simultaneously from Si one side and n then
+Si one side is shone it.This paper has also been explained the reason that so obtains big crystal grain diameter.
Summary of the invention
The objective of the invention is to: the laser anneal method of the crystalline semiconductor film with big crystal grain diameter can be provided and can be used for laser aid in this laser anneal method by adopting, to overcome the above-mentioned shortcoming in the technology.
According to the present invention, in the crystallization process of amorphous semiconductor film, shine upper surface (depositing thin film on it) and rear surface (with the upper surface facing surfaces) of amorphous semiconductor film simultaneously with laser beam, and the effective energy intensity that is applied to the laser beam (after this being called first laser beam) of upper surface can be set to the different magnitude of effective energy intensity with the laser beam that is applied to the rear surface (after this being called second laser beam).
More accurately, satisfied 0＜Io '/Io＜1 or the 1＜Io '/Io of concerning of effective energy strength ratio Io/Io ' between the effective energy intensity I o that the laser beam irradiation condition that is provided with makes first laser beam and the effective energy intensity I o ' of second laser beam, wherein Io and Io ' (Io ' * Io) product is not equal to 0.
In this explanation, term " effective energy intensity " is defined as to be considered by a variety of causes, as reflection or analogue, after the energy loss that causes, shines the energy intensity of the laser beam of the upper surface of amorphous semiconductor film or rear surface.The unit of effective energy intensity is identical with the unit of effective energy density, just mJ/cm
2Though can not directly measure effective energy intensity, according to known parameter, as reflection coefficient and transmission coefficient, and the medium in the known light path that appears at laser beam, just can calculate its value.
As an example, the situation that is applied to structure as shown in Figure 6 with the present invention is an example, describes the computational methods of effective energy intensity in detail.In Fig. 6, the reflector that reference number 601 expressions are formed from aluminium, 602 expression Corning#1737 substrates (thickness is 0.7mm), 603 expression thickness are the oxygen silicon nitride membrane (after this being called the SiON film) of 200nm, 604 expression thickness are the amorphous silicon film of 55nm.Use air medium wavelength this sample of XeCl excimer laser beam irradiation as 308nm.
The energy intensity of excimer laser beam (wavelength is 308nm) before arriving amorphous silicon film 604 just represented with Ia.Consider the reflection of laser beam on the amorphous silicon film surface, the effective energy intensity I o of first laser beam can be expressed as Io=Ia * (1-R
Si), R wherein
SiThe reflectivity of expression laser beam.In this case, the Io that calculates is 0.45 * Ia.
Further, the effective energy intensity of second laser beam can be expressed as Io '=Ia * T
1737* R
Al* T
1737* (1-R
SiON-Si), T wherein
1737The transmissivity of expression #1737 substrate, R
AlThe reflectivity on expression Al surface, and R
SiON-SiThe reflectivity of the light beam experience on the amorphous silicon film is incided in expression from the SiON film.Can find from experimental result, from air, incide the reflection of the light beam experience on the SiON film, transmission in the SiON film, incide the reflection of the light beam experience on the #1737 substrate from the SiON film, and all be insignificant from the reflection that the #1737 substrate incides the light beam experience on the SiON film, therefore in calculating, do not consider.In this case, the Io ' that calculates is 0.13 * Ia.
Correspondingly, in structure shown in Figure 6, the effective energy intensity I o ' of the effective energy intensity I o of first laser beam that calculates and second laser beam is respectively 0.45Ia and 0.13Ia.Therefore, the effective energy strength ratio Io '/Io that calculates is 0.29.The fact that the effective energy strength ratio that calculates satisfies 0＜Io '/Io＜1 relation is one of feature of the present invention.
Further, the present invention can be used for first intensity of laser beam situation littler than second intensity of laser beam.In other words, the present invention can be used for satisfying the situation of 1＜1o '/1o relation.
For instance, effective energy intensity that in accordance with the following methods can first and second laser beams is set to different magnitudes:
1 when upper surface that uses laser beam by being positioned over the reflector irradiation amorphous semiconductor film under the substrate and rear surface, the reflectivity of accommodation reflex device can reduce the effective energy intensity of second laser beam, and it is little to make it the effective energy intensity that becomes than first laser beam.
2 can cut apart first laser beam, to form second laser beam, use suitable filter (for example variable attenuator or other similar devices) can reduce the effective energy intensity of first laser beam or the effective energy intensity of second laser beam, so that the effective energy intensity of first and second laser beams is arranged on the mutually different magnitude.
3 reduce the effective energy intensity of second laser beam according to the backing material that deposits amorphous silicon film on it, so that it is little to make it the effective energy intensity that becomes than first laser beam.
4 place insulating barrier between substrate and amorphous semiconductor film, so that utilize this insulating barrier to reduce the effective energy intensity of second laser beam, thereby cause the effective energy intensity of effective energy strength ratio first laser beam of second laser beam little.
5 use insulating layer films to cover amorphous semiconductor films, so that first laser beam is diminished in the reflection of the surface of amorphous semiconductor film, thereby cause the effective energy intensity of effective energy strength ratio second laser beam of first laser beam big.
6 use insulating layer film to cover amorphous semiconductor film, so that utilize this dielectric film to reduce the effective energy intensity of first laser beam, thereby cause the effective energy intensity of its effective energy strength ratio second laser beam little.
7 use first and second laser beams of emission since the different sources of resonant excitation respectively, so that the effective energy intensity of two laser beams is set to different magnitudes.
Have to be noted that the present invention is not limited to the laser of certain particular type.On the contrary, can use various lasers in the present invention: for example, usually familiar excimer laser (typically being KrF laser or XeCl laser), solid state laser (typically being Nd:YAG laser or ruby laser), gas laser (typically being Ar laser or He-Ne laser), metal vapor laser (typically being Cu vapor laser or He-Cd laser) or semiconductor laser.
Using the laser of (the Nd:YAG laser the is 1064nm) first-harmonic (first harmonic) that has the long wavelength, Nd:YAG laser for example, situation under, recommend to use the second, the three or the 4th harmonic wave.Use nonlinear crystal (nonlinear device) to obtain these high-order harmonic waves.As a kind of alternative method, also can use well-known Q-switch to obtain high-order harmonic wave.
Description of drawings
Figure 1A and 1B are the structural maps according to a cover laser aid of the present invention.
Fig. 2 A is the end view of the optical system structure of the laser aid shown in Figure 1A and the 1B.
Fig. 2 B is the top view of the optical system structure of the laser aid shown in Figure 1A and the 1B.
Fig. 3 is the profile that is used to explain laser anneal method.
Fig. 4 A and 4B are the structural maps according to another set of laser aid of the present invention.
Fig. 5 is the end view of the optical system structure of the laser aid shown in Fig. 4 A and the 4B.
Fig. 6 is the profile that is used to explain first and second laser beams.
Fig. 7 A and 7B are the SEM photos of the crystal grain of polysilicon film.
Fig. 8 A and 8B are the SEM photos of the crystal grain of polysilicon film.
Fig. 9 is the SEM photo of the crystal grain of polysilicon film.
Figure 10 is the SEM photo of the crystal grain of polysilicon film.
Figure 11 is the SEM photo of the crystal grain of polysilicon film.
Figure 12 is the SEM photo of the crystal grain of polysilicon film.
Figure 13 A is to be used for explaining making comprising the various steps of TFT in the technology of interior cmos circuit to Figure 13 E.
Figure 14 A and 14B are the profiles of sample arrangement.
Figure 15 A and 15B are the SEM photos of the crystal grain of polysilicon film.
Figure 16 is the structural map according to another set of laser aid of the present invention.
Figure 17 A and 17B are the schematic diagrames that is used to explain transmission changeable type half mirror.
Figure 18 A and 18B are the SEM photos of the crystallization condition of polysilicon film.
Figure 19 A and 19B are the SEM photos of the crystallization condition of polysilicon film.
Figure 20 is the schematic diagram that concerns between irradiation energy and the crystallization state.With
Figure 21 A and 21B are the schematic diagrames that concerns between projectile energy or effective projectile energy and the crystallization state.
Specific embodiment describes in detail
Before preferred specific embodiment is elaborated to the present invention, at first briefly introduce the inventor and be how to obtain of the present invention.Fig. 7 A and Fig. 7 B are SEM (scanning electron microscopy) photos after the polysilicon film that obtains of laser annealing is handled with the Secco etch.The details that the Secco etch is handled, as an example, please be published in J.Electrochem.Soc.Vol.119 referring to F.Secco D ' Aragon, No.7, the paper on the pp.948-950 (1972) " dislocation corrosion (Dislocation etch for (100) planes in Silicon) that is used for silicon (100) face ".
Fig. 7 A and and Fig. 7 B in, be formed on amorphous silicon film (thickness is 55nm) on the Corning#1737 substrate (thickness is 0.7mm) with excimer pulsed laser beam irradiation, one deck silicon oxide film (thickness is 200nm) is then between substrate and amorphous silicon film.The excimer laser light beam be to be the pulsed laser beam of 308nm by the wavelength that XeCl provides as excited gas, pulse duration is 30ns.The irradiation number of times is 20, and energy density is 370mJ/cm
2
Fig. 7 A is a polysilicon film of handling crystallization by laser crystallization, wherein have only top end surface to be subjected to the irradiation (its average crystal grain diameter is approximately 0.3 μ m) of laser beam, and Fig. 7 B shows is the polysilicon film of handling crystallization by laser crystallization, and wherein top end surface and rear surface all have been subjected to the irradiation (its average crystal grain diameter is approximately 1.5 μ m) of laser beam.These results can prove conclusively, handle crystallization by laser crystallization, and top end surface and rear surface all have been subjected to the polysilicon film of laser beam irradiation, its crystal grain diameter is to have only top end surface to be subjected to five times of polysilicon film of laser beam irradiation, therefore, all carry out laser radiation from both sides remarkable result is arranged.
The term " average crystal grain diameter " that uses in this explanation is to define according to the term of describing in the explanation among the Japanese patent application No.10-020566 " average diameter of grained region ".
As mentioned above, confirm, carry out laser radiation from the two sides of amorphous semiconductor film and can cause the crystal grain diameter of the crystalline semiconductor film that synthesizes bigger.Should be noted that according to the experiment of describing in the technical papers before above-mentioned, the back side of amorphous semiconductor film that needs crystallization is without the laser beam direct irradiation, and tends to by utilizing n
+The method of after-heat adopts the technology of heat sink effect in the Si layer, and this method with the present inventor who describes later is different fully.
Then, the present inventor has done to be similar to the experiment of above-mentioned paper, and (in addition, energy density is set to 200mJ/cm just to have adopted quartz substrate to substitute glass substrate
2), consequently, in other words, the SEM photo after having obtained Secco etch shown in Fig. 8 A and 8B and handling.
What Fig. 8 A showed is the polysilicon film that utilizes the various laser crystallization technology crystallization of only using its upper surface of laser beam irradiation, and Fig. 8 B demonstration is the polysilicon film that utilizes the various laser crystallization technology crystallization of using its upper surface of laser beam irradiation and rear surface.Find out that from these results use quartz substrate, average crystal grain diameter is approximately 0.4 to 0.5 μ m, but does not observe the big crystal grain diameter that obtains in situation as shown in Figure 7.In addition, when upper surface that uses the laser beam irradiation amorphous semiconductor film and rear surface, without any marked difference.In other words, although the effect that increases average crystal grain diameter is not observed in the upper surface and the rear surface of amorphous semiconductor film of having used laser beam irradiation.
By the above-mentioned difference between comparison diagram 7A and 7B and Fig. 8 A and the 8B, present inventor's supposition, these difference come from the different of glass substrate transmissivity (about 50%) and quartz substrate transmissivity (about 93%), that is to say, come from the difference of the effective energy density of the laser beam that is applied on the amorphous semiconductor film rear surface.Therefore, done following experiment to determine this situation.
More particularly, prepare to have the sample of substrate as shown in Figure 6, wherein used quartz substrate to make substrate 602, used the nitrogenize tantalum film to make reflector 601.Under the condition identical, use this sample of XeCl laser beam irradiation then, and after the Secco corrosion treatment, use the average crystal grain diameter of the observable polysilicon film of SEM formation method with the condition that obtains the SEM photo employing shown in Fig. 7 B.Its result as shown in Figure 9.
As can be seen from Figure 9, the crystal grain in the polysilicon film that obtains disperses, and the dispersion pattern in the polysilicon film shown in its dispersion pattern and Fig. 7 B is basic identical.Further, as noted earlier, under the situation of the SEM photo that obtains Fig. 7 B, the effective energy strength ratio of first and second laser beams is 0.29.This result shows that second laser beam is decayed by glass substrate basically.Under the situation of sample of the present invention, the effective energy strength ratio that calculates is 0.33.This result shows that second laser beam is decayed by reflector basically.
Has identical structure by making up among quartzy and sample that the aluminium reflector obtains and Fig. 9 among Fig. 8 B, except the material difference of reflector surface by making up quartz and sample that nitrogenize tantalum film reflector obtains.Therefore, just the reflectivity of reflector surface has tangible difference, more specifically, and luminance factor Fig. 8 B sample of the reflector surface of Fig. 9 sample little.
From The above results as can be seen, the upper surface that uses the laser beam irradiation amorphous semiconductor film and rear surface with the situation that makes it crystallization under, when the effective energy intensity of the laser beam that is applied to the rear surface (second laser beam) during less than the effective energy intensity of the laser beam that is applied to upper surface (first laser beam), the crystal grain diameter that can obtain increasing.
A kind of in the preferred embodiments of the present invention pattern described.Figure 1A is the structural map according to a cover laser aid of the present invention.This laser aid comprises lasing light emitter 101, is used for from the optical system 201 of the linear shaping of lasing light emitter 101 emitted laser Shu Jinhang be used for fixing the platform 102 of transparent substrates.Platform 102 is equipped with heater 103 and heater controller 104, so that substrate temperature is maintained in the temperature range of room temperature to 550 ℃.On platform 102, be placed with reflector 105, placed the substrate 106 that is formed with amorphous semiconductor film on it above.
Be described in method with support substrate 106 in the laser aid of shown in Figure 1A, constructing in conjunction with Figure 1B.Prop up the substrate 106 that is held on the platform 102 and be placed in the reative cell 107, and shine by the linear beam of emission self-excitation light source 101.Reative cell is arranged on condition of negative pressure, perhaps is full of inert gas by gas extraction system or gas charging system (not showing), and therefore can guarantee semiconductor film is heated to 100 to 450 ℃ and not contaminated.
Load/unload chamber 111 is equipped with the box 111 that can put into a plurality of substrates.These substrates are by transportation automation 115 transportations that are provided in the Freight Office 109.Reference number 106 ' mark be a substrate that is in the transportation.Use such structure, can carry out laser annealing under decompression state or in the inert gas continuously and handle.
In conjunction with Fig. 2 A and 2B the structure that is used for laser beam is carried out the optical system 201 of linear shaping is described.More accurately, what Fig. 2 A showed is the optical system of seeing from its side 201, and Fig. 2 B then is the square from it optical system of seeing 201.
The laser beam of emission self-excitation light source 101 is longitudinally cut apart by cylindrical lens array 202.And the laser beam after cutting apart is further cut apart by another cylindrical lens array 203, but is to cut apart along side direction specifically.Therefore, laser beam finally is divided into matrix by cylindrical lens array 202 and 203.
Use cylindrical lens 204 to focus on divided laser beam then.The aggregation laser bundle passes and follows cylindrical lens 204 another cylindrical lens 205 afterwards closely.Light beam passes cylindrical lens 207 by mirror 206 reflections then, and arriving needs irradiated surperficial 208.
Herein, the laser beam that projects on the surface 208 has the linearized radiation face.More accurately, the laser beam that passes cylindrical lens 207 has linear cross section.Cylindrical lens array 202, cylindrical lens 204, can cause the uniformity of laser beam on its Width (direction of shorter size) with cylindrical lens 207, cylindrical lens 203 and cylindrical lens 205 then can cause the uniformity of laser beam on its length direction (direction of longer size).
Then, in conjunction with Fig. 3 description laser beam is applied to be formed on the upper surface of the semiconductor film on the substrate and the structure of rear surface.Fig. 3 is that the position between substrate 106 shown in Figure 1A and the reflector 105 concerns schematic diagram.
In Fig. 3, on the upper surface of transparent substrates 301, (be formed with film or device on it), be formed with insulator-semiconductor film (or microcrystalline semiconductor film) 303.In addition, the reflector 304 that is used for reflection lasering beam is placed under the transparent substrates 301.
Glass substrate, quartz substrate, the glass substrate of crystallization, or plastic all can be used as transparent substrates 301.Use the just effective energy intensity of scalable second laser beam of transparent substrates 301 self.Dielectric film 302 can be by the dielectric film that comprises silicon, such as silicon oxide film or silicon oxynitride (SiO
xN
y) the film formation.The effective energy intensity of using dielectric film 302 can regulate second laser beam.Amorphous semiconductor film 303 can be a compound semiconductor film, such as amorphous SiGe film, rather than amorphous silicon film.
Further, reflector 304 can be placed on and transparent substrates 301 contacted positions, or is positioned over the position that is separated with it.As substituting of the reflector 304 that is equipped with, can directly go up and form above-mentioned metal film on substrate 301 rear surfaces (with respect to the surface of upper surface), herein can reflection lasering beam so that make.Under any situation, control the reflectivity of reflector 304, just the effective energy intensity of scalable second laser beam therein.Further, be positioned at reflector 304 under the situation of the position that is separated with transparent substrates 301, can control the effective energy intensity of second laser beam by being filled in therebetween gaseous matter (gas).
The above-mentioned optical system of describing in conjunction with Fig. 2 A and 2B (only showing cylindrical lens 207 in the drawings) of passing through has been carried out the laser beam of linear shaping and is allowed to shine on the amorphous semiconductor film 303.The irradiation of having carried out the laser beam of linear shaping is that the scanning by laser beam realizes.
Therein under any situation, for passing cylindrical lens 207 and shining first laser beam 305 and once and shine second laser beam 306 on the rear surface of amorphous semiconductor film 303 on the upper surface of amorphous semiconductor film 303 in the reflection of reflector 304 places, importantly the effective energy strength ratio (Io '/Io) satisfy and concern o＜Io '/Io＜1 or 1＜Io '/Io.For reaching this purpose, reflector 304 must be arranged on just for the reflectivity of laser beam in 20 to 80% the scope.In addition, can be used in combination a plurality of distinct methods that reduce the effective energy intensity of second laser beam of describing in this specific embodiment pattern, with the strength ratio that obtains wishing.
Laser beam incidence angle with respect to substrate surface in accumulation process of passing cylindrical lens 207 is 45 ° to 90 °.Therefore, second laser beam 306 can pass around amorphous semiconductor film 303, and incides on the rear surface of this film.In addition, by on the reflecting surface of reflector 304, being equipped with the method for projection, can the random reflected laser beam, thus more effectively obtain second laser beam 306.
Another specific embodiment pattern of the present invention that is different from previous specific embodiment pattern is below described.More accurately, in this specific embodiment pattern, do not adopt the reflector of in previous specific embodiment pattern, describing, and two laser beam series being cut apart by optical system are used for from it surface and rear surface to the irradiation of amorphous semiconductor film.
What Fig. 4 A showed is the laser aid structural map consistent with this embodiment mould.The basic structure of the basic structure of the device shown in Fig. 4 A and the laser aid shown in Figure 1A and 1B is similar, therefore, has only different piece to use different reference numbers to make mark.Like has identical reference number.
This laser aid comprises lasing light emitter 101, is used for the laser of emission self-excitation light source 101 is carried out linear shaping and with it transparent platform 402 that is divided into the optical system 401 of two series and is used for transparent substrates is fixed thereon.Substrate 403a is fixed on the platform 402, is formed with amorphous semiconductor film 403b on it.
In the present embodiment pattern, platform 402 is transparent, and its reason is to use the laser beam irradiation amorphous semiconductor film 403b that passes platform 402.In addition, a part that is applied to the laser beam (second laser beam just) on the amorphous semiconductor film 403b from the side near platform 402 is passed platform 402, therefore, when obtaining effective energy intensity, must consider to occur in the decay in the process of spanning platform 402.
Fig. 4 B has explained the method for supporting substrate 403a in the laser aid shown in Fig. 4 A.Its structure is identical with the structure of laser aid shown in Figure 1B, only has been to use transparent substrates 402, therefore, and herein with the explanation of slightly going there.
The structure of the optical system shown in Fig. 4 A is described in conjunction with Fig. 5.What more accurately, Fig. 5 showed is observed optical system 401 from its side.The laser beam of emission self-excitation light source 501 is longitudinally cut apart by cylindrical lens array 502.And the laser beam after cutting apart is further cut apart by another cylindrical lens array 503, but is to cut apart along side direction specifically.Therefore, laser beam finally is divided into matrix by cylindrical lens array 202 and 203.
Use cylindrical lens 504 to focus on divided laser beam then.The aggregation laser bundle passes and follows cylindrical lens 504 another cylindrical lens 505 afterwards closely.Till now, the above-mentioned structure of optical system is identical with the structure shown in Fig. 2 A and the 2B.
Laser beam incident is to half mirror 506, to make it to be divided into first laser beam 507 and second laser beam 508 then.First laser beam reflects at mirror 509 and 510 places continuously, and passes cylindrical lens 511, reaches the upper surface of amorphous semiconductor film 403b.
Owing to second laser beam 508 that obtains cutting apart of half mirror 506 in mirror 512,513 and 514 place's continuous reflection, and pass cylindrical lens 515, then after passing substrate 403a, reach the rear surface of amorphous semiconductor film 403b.
Just as in previous specific embodiment pattern, the laser beam that projects on the substrate surface has linear shadow surface.Cylindrical lens array 502, cylindrical lens 504 and cylindrical lens 515 can cause this linearity shaping the uniformity of laser beam on its Width (direction of shorter size), and cylindrical lens 503,511 of cylindrical lens 505 and cylindrical lens can cause the uniformity of laser beam on its length direction (direction of longer size).
Therein under any situation, for passing cylindrical lens 511 and inciding first laser beam on the upper surface of amorphous semiconductor film 403b and pass cylindrical lens 515 and incide second laser beam on the rear surface of amorphous semiconductor film 403b, importantly the effective energy strength ratio (Io '/Io) satisfy and concern o＜Io '/Io＜1 or 1＜Io '/Io.
In the present embodiment pattern, use glass substrate (by have be approximately 50% or the material of higher laser beam transmission rate make) make substrate 403a and satisfied above-mentioned relation.Should be noted that, in the method for the effective energy intensity that reduces second laser beam, except the method for using substrate, can also adopt to use to be provided to the method for the dielectric film (not marking among the figure) on the substrate 403a, or regulate the transmissivity of the platform (not marking among the figure) that its deploy has substrate 403a or the method for reflectivity at the interface.
Further, the optical attenuator filter can be placed in the optical system 401 along any position of the light path of second laser beam, to reduce the effective energy intensity of second laser beam.Substitute as a kind of, the optical attenuator filter also can be placed in the optical system 401 along any position of the light path of first laser beam, to reduce the effective energy intensity of first laser beam.
In addition, can be used in combination a plurality of distinct methods that reduce the effective energy intensity of first or second laser beam of explaining in this specific embodiment pattern, with the strength ratio that obtains wishing.
Specific embodiments of the invention are below described.
In this specific embodiment, the situation of the crystallizing amorphous silicon fiml of structure described in the pattern 1 is according to the preferred embodiment described in conjunction with Fig. 3.
In this specific embodiment, substrate 301 is that thickness is the quartz substrate 301 of 1.1mm, and dielectric film 302 is that thickness is the oxygen silicon nitride membrane (SiON film) of 200nm, and amorphous semiconductor film 303 is amorphous silicon films.SiON film 302 and amorphous silicon film 303 all use the plasma CVD method to form.
In this specific embodiment, at first with SiH
4And N
2O imports reative cell, and flow is respectively 4sccm and 400sccm, and the depositing temperature that forms SiON film 302 is 40 ℃, and reative cell pressure is 30Pa, and discharge energy density is 0.41W/cm
2, discharge frequency is 60MHz.After this with SiH
4Import reative cell, flow is 100sccm, and the deposition temperature seat that forms amorphous silicon film 303 is 300 ℃, and reative cell pressure is 45Pa, and discharge energy density is 0.037W/cm
2, discharge frequency is 13.56MHz.In actual process, amorphous silicon is patterned into island-shaped pattern.
After this, use the crystallization process of the excimer laser apparatus enforcement amorphous silicon film 303 shown in Figure 1B.As at the reflector shown in Fig. 3 304, used the tungsten nitride film that is formed on the silicon substrate.And, between reflector 304 and quartz substrate 301, leave the wide slit of 150 μ m.
With this understanding, in room temperature and air, use excimer laser beam (first laser beam 305 and second laser beam 306 more accurately) irradiation amorphous silicon film 303.Excimer laser beam is shaped as and has linear cross section (0.4mm * 160mm), and Be Controlled to pass through substrate is scanned by the optical system shown in Fig. 2 A and 2B.Sweep speed is set to 1mm/ second, and energy density (its energy intensity is corresponding to the Ia among Fig. 6) is set to 336mJ/em
2, pulse duration is set to 30ns, and repetition rate is set to 30Hz, and Duplication is set to 90%.Therefore, the laser beam pulses that can reach the same area of amorphous silicon film 303 has 20 altogether.
In order to use the structure in this specific embodiment to carry out laser crystallization, the effective energy intensity I o of first laser beam is set to 151.2mJ/cm
2, and the effective energy intensity I o ' of second laser beam is set to 77.3mJ/em
2Correspondingly, effective energy strength ratio Io '/Io in this case is 0.51.
According to the SEM photo of the polysilicon film of this specific embodiment crystallization as shown in figure 10.What the photo among Figure 10 showed is through the situation after the Secco corrosion treatment.Secco corrosion treatment herein is to use room-temperature corrosive to carry out, and wherein corrosive agent is by the hydrofluoric acid solution of 50cc, and 25cc water and 1.14g chromic acid (divalence) potassium mix.
The result can recognize around the center of island-shaped pattern and has the big relatively crystal grain that average crystal grain diameter is about 0.5 to 0.6 μ m as shown in figure 10.Although the crystal grain in that the edge/end portion of island pattern exists some to have less crystal grain diameter by changing the energy density of the laser beam that uses, can move the position that these little crystal grain form.Under the situation of using the active layer of making TFT according to the polysilicon film of this specific embodiment crystallization, can design these parts with less crystal grain diameter, with it eliminating outside the channel formation region territory.
In this specific embodiment, the situation according to the crystallizing amorphous silicon fiml of structure in the specific embodiment pattern 1 is described.Laser crystallization process in this specific embodiment is identical with laser crystallization process in the specific embodiment 1, just formed tungsten film on the surface of reflector 304, and laser energy density is revised as 369mJ/cm
2The detailed description of other conditions is please referring to specific embodiment 1.
According to the SEM photo of the polysilicon film of this specific embodiment crystallization as shown in figure 11.As in specific embodiment 1, what the photo among Figure 11 showed is through the situation after the Secco corrosion treatment.The condition of Secco corrosion treatment is identical with condition in the specific embodiment 1.
In order to use the structure in this specific embodiment to carry out laser crystallization, the effective energy intensity I o of first laser beam is set to 166.1mJ/cm
2, and the effective energy intensity I o ' of second laser beam is set to 88.6mJ/cm
2Correspondingly, effective energy strength ratio Io '/Io in this case is 0.53.
The result can recognize in whole island-shaped pattern and has the big relatively crystal grain that average crystal grain diameter is about 0.6 to 0.7 μ m as shown in figure 11.In Figure 11, recognize the crystal grain that some have less crystal grain diameter not too significantly in the edge/end portion of island-shaped pattern, these are different with situation among Figure 10.But, change the energy density of the laser beam that uses, can recognize the crystal grain that some have less crystal grain diameter significantly sometimes, therefore, the optimization of laser energy density is very crucial.Identical with the situation in the specific embodiment 1, both made to have crystal grain with less crystal grain diameter, also be enough to will have these parts eliminatings of less crystal grain diameter outside the channel formation region territory by design TFT.
In this specific embodiment, the situation according to the crystallizing amorphous silicon fiml of structure in the specific embodiment pattern 1 is described.Laser crystallization process in this specific embodiment is identical with laser crystallization process in the specific embodiment 1, has just formed the oxidation tungsten film on the surface of reflector 304, and laser energy density is revised as 384mJ/cm
2The detailed description of other conditions is please referring to embodiment 1.
According to the SEM photo of the polysilicon film of this specific embodiment crystallization as shown in figure 12.As in specific embodiment 1, what the photo among Figure 12 showed is through the situation after the Secco corrosion treatment.The condition of Secco corrosion treatment is identical with condition in the specific embodiment 1.
In order to use the structure in this specific embodiment to carry out laser crystallization, the effective energy intensity I o of first laser beam is set to 172.8mJ/cm
2, and the effective energy intensity I o ' of second laser beam is set to 57.6mJ/cm
2Correspondingly, effective energy strength ratio Io '/Io in this case is 0.33.
The result can recognize in whole island pattern and has the big relatively crystal grain that average crystal grain diameter is about 0.8 to 1.0 μ m as shown in figure 12.Within the photo scope, crystal grain all has the shape of elongation in the horizontal direction, this means that crystallization process may begin to carry out from the marginal portion along the side direction of island-shaped pattern.In Figure 11, also can recognize this trend slightly.
In addition, change the energy density of the laser beam that uses, can recognize the crystal grain that some have less crystal grain diameter significantly sometimes, therefore, the optimization of laser energy density is very crucial.Identical with the situation in the specific embodiment 1, both made to have crystal grain with less crystal grain diameter, also be enough to will have these parts eliminatings of less crystal grain diameter outside the channel formation region territory of TFT by design TFT.
In this specific embodiment, in conjunction with Figure 13 A-13E the method for describing according in specific embodiment pattern 1 or 2 is described, form method as the polysilicon film of TFT active layer.
At first forming thickness on glass substrate is the oxygen silicon nitride membrane (not marking among the figure) of 200nm, form thickness then thereon and be 50nm amorphous silicon film (not marking among the figure).After this with island-shaped pattern 701a and the 701b (referring to Figure 13 A) of amorphous silicon film medelling for constituting by amorphous silicon.
Then according to the method for describing in specific embodiment pattern 1 or 2, the island-shaped pattern 701a and the 701b of formation like this carried out laser crystallization.Obtain by laser crystallization, the island-shaped pattern 702a and the 702b that are made of polysilicon film may comprise less grained region 703a and 703b respectively in its edge/end portion.And edge/end portion of island-shaped pattern 702a and 702b includes a large amount of crystal defects and/or crystal lattice stress (referring to Figure 13 B).
In Figure 13 B, represent the island-shaped pattern 701a that constitutes by amorphous silicon film and the original size of 701b respectively with the broken string of reference number 704a and 704b mark.Therefore, laser crystallization can reduce the size of these island-shaped pattern about 1 to 15%.The reason that consideration causes size to reduce may be that silicon fiml has more perfect crystal structure and/or silicon fiml is evaporated.But, the details of any mechanism all it be unclear that here.
After this, further the island-shaped pattern 702a that constitutes by polysilicon film of composition and 702b to form active layer 705a and 705b.The original circumference (referring to Figure 13 C) of representing little grained region 703a and 703b with the broken string of reference number 706a and 706b mark respectively.
Then, the oxygen silicon nitride membrane that forms thickness and be 80nm to be covering active layer 705a and 705b, and forms gate insulating film thus.Further form gate electrode 707 thereon.Gate electrode 707 typically is made of the layer structure that comprises tungsten nitride film and tungsten film, and gross thickness is 300nm (referring to Figure 13 D).
After forming gate electrode 707, use can provide the impurity of n type conductivity to mix, to form source region 708a, drain region 709a and LDD district 710.In addition, use can provide the impurity of p type conductivity to select to mix, to be formed with source region 708b and drain region 709b.In this p type doping process, form channel formation region territory 711a and 711b (part that does not just have impurity in the active area) simultaneously.
Form thickness then and be interlayer dielectric (not marking among the figure) 1 μ m, that constitute by silica.After this, be equipped with contact hole to form source line 712a and 712b and thread cast-off 713.These electric wires can be that low-resistance conducting film of aluminium film forms (referring to Figure 13 E) by main composition component wherein.
According to above-mentioned making step, just can form the cmos circuit 716 with the structure shown in Figure 13 E, wherein n channel-type TFT714 and p channel-type TFT715 combine complementaryly.
This specific embodiment is the demonstration specific embodiment that the present invention is used to form the TFT active layer.The present invention is not limited to above-mentioned manufacture craft.And the present invention can be applied to any other known manufacture craft of TFT.But, should be noted that the present invention can not be applied to be equipped with the situation of photoprotection film or other similar films under active layer, that is to say, can not be applied to the situation that to carry out laser annealing simultaneously to the upper surface and the rear surface of amorphous semiconductor film.
Although can be formed according to the present invention cmos circuit, be to use known technology can be produced on the pixel TFT that is equipped with in the pixel region of activated matrix type image display device like a cork.
Specific embodiment 5
Although the present invention has been applied to the making of the active layer of TFT in the specific embodiment 4, the present invention can be applicable to all semiconductor device that use TFT.For example, the present invention can be applicable to the active array type liquid crystal display, and active matrix EL (electroluminescence) shows, or active array type EC (electronics chromium) shows.
Further, the present invention can be applied to the formation of the load transistor of the SRAM that uses in IC or LSI.The present invention is also effective to the TFT that forms in the three-dimensional structure that surpasses IC or LST.
Specific embodiment 6
In the present invention, under the condition that can in specific embodiment 1, describe, use the structure of laser beam irradiation shown in Figure 14 A and 14B.
In the structure shown in Figure 14 A, reference number 801 marks be that thickness is the quartz substrate of 1.1mm, 802 marks be that thickness is the oxygen silicon nitride membrane of 200nm, and 803 marks is that thickness is the amorphous silicon film of 55nm.After this, the structure shown in Figure 14 A is carried out traditional laser crystallization.
On the other hand, in structure as shown in Figure 14B, reference number 804 marks be the reflector that constitutes by the nitrogenize tantalum film of surface (reflecting surface), 805 marks be that thickness is the quartz substrate of 1.1mm, 806 marks be that thickness is the oxygen silicon nitride membrane of 200nm, and 807 marks is that thickness is the amorphous silicon film of 55nm.After this according to the present invention structure is as shown in Figure 14B carried out laser crystallization.
The polysilicon film that obtains has TEM (transmission electron microscope) photo shown in Figure 15 and 15B.More particularly, Figure 15 A shows is the TEM photo that has the polysilicon film that the amorphous silicon film 803 of structure shown in Figure 14 A obtains by crystallization, is the TEM photo that is positioned at the polysilicon film that the amorphous silicon film 807 on the substrate as shown in Figure 14B obtains by crystallization and Figure 15 B shows.
Comparison diagram 15A and 15B as can be seen, the polysilicon of crystallization has bigger crystal grain diameter significantly according to the present invention among Figure 15 B.Therefore, can confirm that the present invention can provide the crystal semiconductor film of the average crystal grain diameter with increase from these TEM photos.
Specific embodiment 7
The experiment that the present inventor did shown, when available energy strength ratio Io '/Io satisfies when concerning 0＜Io '/Io＜1 and 1＜Io '/Io, can enlarge markedly the special conditions of contract of average crystal grain diameter.
In this specific embodiment, the reflector (more strictly saying the reflecting surface of reflector) that uses various substrates (thickness of each substrate is 1.1mm) or different materials to make is tested.Table 1 has provided sample (A)-(H) uses in the experiment substrate and reflector, has also provided the effective energy strength ratio simultaneously.
Table 1
| Sample | Substrate | Reflector | The effective energy strength ratio |
| (A) | Quartzy | Al | 1.00 |
| (B) | Quartzy | Si | 0.67 |
| (C) | Quartzy | W | 0.53 |
| (D) | Quartzy | Tin | 0.33 |
| (E) | #1737 | Al | 0.29 |
| (F) | #1737 | W | 0.16 |
| (G) | #1737 | Ta | 0.11 |
| (H) | AN100 | Al | 0.07 |
In table 1, " #1737 " is the article number from the glass substrate of Corning company, and " AN100 " is the article number from the glass substrate of Asahi Glass Company.
Under the condition identical with condition among the specific embodiment 1-3, with XeCl laser beam irradiation sample, wherein the scope of effective energy strength ratio is 0.07 to 1.0, and uses the observable polysilicon film of SEM method.
As a result of, confirming, is 0.29,0.33 in the effective energy strength ratio, 0.35 and 0.67 o'clock, can obtain the average crystal grain diameter of about 1 μ m, and be 1.0 in the effective energy strength ratio, 0.16,0.11 and 0.07 o'clock, can obtain the average crystal grain diameter of about 0.3 μ m.Correspondingly, the effective energy intensity of first and second laser beams differ 20% or more condition under, believe to increase average crystal grain diameter significantly.Believe that The above results demonstrates, when in the scope (scope preferably is 0.3 to 0.7) of available energy strength ratio Io '/Io 0.2 to 0.9, reached best crystallization condition.
In this specific embodiment, the situation of another optical system with structure different with the structure of describing is described in conjunction with Figure 16 in specific embodiment pattern 2.More accurately, the permission of the structure in this specific embodiment linear beam is variable in the length of length direction or Width.
During optical system 10 in using this specific embodiment, carry out the semiconductor film of crystallization for needing the higher-energy input, can be the short length of linear beam setting in the longitudinal direction, and for the semiconductor film that under low relatively energy input, just can carry out crystallization, can be the long length of linear beam setting in the longitudinal direction.Therefore often can reach maximum power efficiency.In addition, be variable owing to allow the length of linear beam on Width, just can determine the lateral length of optimum semiconductor film crystallization.
Optical system as shown in Figure 16 is different with optical system as shown in Figure 5, except being used on Width, cutting apart the cylindricality lens-array 502 of laser beam, also adopt another cylindricality lens-array 11 to show identical functions, and cut apart in the longitudinal direction the cylindricality lens-array 503 of laser beam except being used for, also adopt another cylindricality lens-array 12 to show identical functions.
In this specific embodiment,, in the longitudinal direction the cross section of linear beam is revised according to the method for on Width, the cross section of linear beam being revised.Correspondingly, two cylindrical lens that are used to carry out the function of cutting apart laser beam are in the longitudinal direction only described here.
Each part of the laser beam of being cut apart by cylindricality lens-array 503 is allowed to incide on the cylindrical lens corresponding in the cylindricality lens-array 12 in the longitudinal direction.More accurately, when cylindricality lens-array 507 was divided into seven parts, cylindricality lens-array 12 also will be divided into seven parts according to the mode of correspondence.Cylindricality lens-array 503 and 12 can be of similar shape.As an alternative, except that radius of curvature, these cylindricality lens-array 503 and 12 can be identical.
In this, just can determine the variable range of laser beam length according to the combination of focal length.More accurately, by changing the distance between cylindricality lens-array 503 and 12, just can determine linear beam length in the longitudinal direction.
Distance between the cylindricality lens-array 503 and 12 is preferred than the short twice of the focal length of cylindricality lens-array 503.In this case, each partitioning portion of the laser beam of being cut apart by cylindricality lens-array 503 can incide on the cylindrical lens corresponding in the cylindricality lens-array 12 with man-to-man relation.
Further, in this specific embodiment, use transmissivity changeable type half mirror to make half mirror 13.Its structure is described with reference to Figure 17 A and 17B.At first explain the exemplary configuration of transmissivity changeable type half mirror shown in Figure 17 A.
When transmissivity changeable type half mirror 901 when arrow 909 marks and direction that be parallel to transmissivity changeable type half mirror 901 move, the energy intensity that passes the laser beam of transmissivity changeable type half mirror 901 can be set on the magnitude different with the energy intensity of reflection lasering beam 904.Although four regional 905-908 are arranged in the structure shown in Figure 17 A, these regional numbers are not limited to 4, and two or more zones can be arranged.
It shown in Figure 17 B another exemplary configuration of transmissivity changeable type half mirror.In this case, the laser beam 912 from the left side is divided into laser beam 913 and 914 by transmissivity changeable type half mirror 911 among the figure.Compare with transmissivity changeable type half mirror 901 among Figure 17 A, transmissivity changeable type half mirror 911 is split into more zone, and each regional transmissivity is set to change with trickle stepped form.
This transmissivity changeable type half mirror is can buy on the market.Even disposed the zone with the different transmissivities that change by trickle stepped form, the energy intensity that passes the laser beam 913 of transmissivity changeable type half mirror 911 also can be set to and the different magnitude of energy intensity at transmissivity changeable type half mirror 911 laser light reflected bundle 914 when the direction of arrow 915 marks moves.
Use a system in the above-mentioned optical system, can fine adjustments be used to shine the effective energy intensity of the laser beam of semiconductor film.The structure of the optical system of describing in this specific embodiment also is applicable to the laser aid of describing in the specific embodiment 1.
Specific embodiment 9
In this specific embodiment, under situation about having considered, calculated the effective energy strength ratio in the specific embodiment 7 in the repeatedly reflection at the reflecting surface place of reflector.The sample that uses in the experiment of this specific embodiment (A)-(H) is identical with sample (A)-(H) in the specific embodiment 7.Should be noted that in this specific embodiment the effective energy intensity I o ' of second laser beam can be expressed as Io '=Ia * T
Sub* R
Mirror* T
Sub* (1-R
SiON-Si)/1-R
SiON-Si* T
Sub* R
Mirror* T
Sub
In above-mentioned formula, T
SubThe transmissivity of expression substrate, R
MirrorBe illustrated in the reflection at reflector reflecting surface place, and R
SiON-SiThe reflection of the light beam experience on the amorphous silicon film is incided in expression from the SiON film.Experimental result is found, incide the reflection of the light beam experience on the SiON film from air, the transmissivity of SiON film, incide the reflection of the light beam experience on the substrate from the SiON film, can ignore with the reflection of inciding the light beam experience on the SiON film from substrate, therefore in calculating, not consider these reflections.
The data that more than calculate all are listed in the table 2.More accurately, the data in the table 2 are revisions of the data in the table 1, have considered repeatedly reflection during correction.
Table 2
| Sample | Substrate | Reflector | The effective energy strength ratio |
| (A) | Quartzy | Al | 1.66 |
| (B) | Quartzy | Si | 0.81 |
| (C) | Quartzy | W | 0.61 |
| (D) | Quartzy | Tin | 0.33 |
| (E) | #1737 | Al | 0.32 |
| (F) | #1737 | W | 0.17 |
| (G) | #1737 | Ta | 0.14 |
| (H) | AN100 | Al | 0.06 |
Based on these data, can obtain with specific embodiment 7 in identical best crystallization condition, that is to say that the scope of effective energy strength ratio Io '/Io is 0.2 to 0.9 (scope preferably is 0.3 to 0.7).
In this specific embodiment, advantage of the present invention is described based on experimental result.In the description of following specific embodiment, will assess degree of crystallinity relatively by five grades.More accurately, in this explanation, degree of crystallinity is divided into following five evaluation grades:
Crystallization state (0): under this state, film is disappeared owing to ablate;
Crystallization state (1): under this state, can recognize small grains, shown in Figure 18 A;
Crystallization state (2): under this state, can recognize the crystal grain of average crystal grain diameter about 300 to 450nm, shown in Figure 18 B;
Crystallization state (3): under this state, can recognize the big relatively crystal grain of average crystal grain diameter about 600 to 800nm, shown in Figure 19 A;
Crystallization state (4): under this state, can recognize and have about 3 μ m or bigger larger-diameter significantly big crystal grain, shown in Figure 19 B.
Especially, in this specific embodiment, what the crystal grain in the crystallization state (4) referred to also is the crystal grain that is formed by SLG (super cross growth).
Based on above-mentioned evaluation criteria, the condition of laser crystallization and the relation between the crystallization state have been investigated.To the relation between irradiation energy in single irradiation mode (corresponding to the energy intensity Ia of laser beam before just arriving amorphous silicon film) and the crystallization state and in the dual-radiation pattern relation between the two compared, just can obtain data as shown in figure 20.In single irradiation mode, only use the upper surface of laser beam irradiation amorphous silicon film, and in the dual-radiation pattern, use the upper surface and the rear surface of laser beam irradiation amorphous silicon film simultaneously.
Can be clear that from data as shown in figure 20, compare that the dual-radiation pattern can obtain having the crystallization film of gratifying crystallization state under lower irradiation energy with single irradiation mode.More accurately, under the situation of single irradiation mode, realize that the irradiation energy that SLG needs is approximately 510mJ/cm
2, and under the situation of dual-radiation pattern, irradiation energy is approximately 440 to 460mJ/cm
2Just be enough to realize SLG.This shows, according to the present invention, compares with traditional single irradiation mode, adopts the dual-radiation pattern can obtain having the crystallization semiconductor film of high crystallization state under lower irradiation energy.
Further, can know that from experiment irradiation energy is high more, the effective energy of first laser beam is high more, and the surface roughness of the crystallization semiconductor film that obtains is also big more.This means, to the film surface of the crystal grain that is used to obtain form, less by the damage that the dual-radiation pattern causes by SLG.
The result of experiment that changes the effective energy strength ratio by the reflectivity that changes reflector is described then.Figure 21 A shows is relation between irradiation energy and the crystallization state, and Figure 21 B demonstration is relation between effective projectile energy and the crystallization state.
Shown in Figure 21 A, the reflectivity of reflector high more (that is to say that the effective energy intensity of second laser beam is high more), even under same irradiation energy, the crystallization state that obtains is satisfactory more.Can determine that its reason is, under identical irradiation energy, effective projectile energy height that effective projectile energy that the dual-radiation pattern provides provides than single irradiation mode.Effectively projectile energy is all summations that are input to the effective energy in the amorphous semiconductor film, more accurately, and corresponding to the summation of the effective energy intensity of first laser beam and second laser beam.
From above-mentioned viewpoint, in the relation of having investigated under the situation that irradiation energy is arranged on same magnitude between effective projectile energy and the crystallization state.Its result is, reflectivity is high more, and it is many more to obtain the required effective projectile energy of the crystal grain (that is to say that crystallization state (4) is to higher-energy one side shifting) that formed by SLG, shown in Figure 21 B.In other words, the reflector with antiradar reflectivity is suitable for providing the crystal grain that is formed by SLG under lower effective projectile energy, can realize the crystallization of more low-yield loss thus.
Further, shown in Figure 21 B, reduce the reflectivity of reflector, can reduce to reach the required effective projectile energy of SLG.But, confirming, is 0 o'clock at reflectivity, SLG can not take place.Therefore, there is optimum value in the reflectivity of believing the reflector that can reach SLG.
As mentioned above, according to the present invention, in the laser crystallization process of amorphous semiconductor film, shine simultaneously upper surface and the rear surface of amorphous semiconductor film with laser beam, and the effective energy intensity that is applied to the laser beam of rear surface is set to the magnitude different from the effective energy intensity of the laser beam that is applied to upper surface, thereby the crystallization semiconductor film that obtains and use conventional art to obtain is compared, the crystallization semiconductor film that average crystal grain diameter is larger.
Owing to obtained having the crystallization semiconductor film of large average crystal grain diameter, so the performance of TFT, the semiconductor devices that is perhaps formed by TFT, such as active array type display device, performance obtained remarkable improvement.
Claims (17)
1. laser aid comprises:
Be used to launch the lasing light emitter of laser;
Transmissivity changeable type half-reflecting mirror is used for above-mentioned laser is divided into first laser and second laser;
The first cylindrical array lens;
The second cylindrical array lens;
The 3rd cylindrical array lens;
The 4th cylindrical array lens;
First cylindrical lens; With
Second cylindrical lens, the wherein said first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens are placed in proper order;
Be used for first laser and second laser are directed into the upper surface of pending object and the optical system on the rear surface respectively; And
Block substrate is used to support to be provided with the substrate of pending object,
The wherein said first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens are between described lasing light emitter and described transmissivity changeable type half-reflecting mirror; And
Wherein, this pending object comprises semiconductor film.
2. laser aid comprises:
Be used to launch the lasing light emitter of laser;
Transmissivity changeable type half-reflecting mirror is used for above-mentioned laser is divided into first laser and second laser;
The first cylindrical array lens;
The second cylindrical array lens;
The 3rd cylindrical array lens;
The 4th cylindrical array lens;
First cylindrical lens; With
Second cylindrical lens, the wherein said first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens are placed in proper order;
Be used for first laser and second laser are directed into the upper surface of pending object and the optical system on the rear surface respectively,
The wherein said first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens are between described lasing light emitter and described transmissivity changeable type half-reflecting mirror; And
Wherein, described first laser and second laser are shaped as by this optical system and have linear cross section.
3. method that forms semiconductor device, described method comprises:
Produce laser from lasing light emitter as oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror above-mentioned laser is divided into first laser and second laser;
Upper surface with the first laser radiation object of decaying; And
With the rear surface of the second laser radiation object,
Wherein said object comprises semiconductor film,
Thereby formation semiconductor device.
4. according to the method for claim 3, further comprise first and second laser are carried out linear shaping.
5. according to the method for claim 3, wherein, described semiconductor film is amorphous or crystallite.
6. method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
Upper surface with the first laser radiation object; With
With the rear surface of second this object of laser radiation, and
Wherein said object comprises semiconductor film,
Wherein, be applied to the effective energy intensity I of first laser of upper surface
oBe set to and be applied to the effective energy intensity I of second laser of rear surface
o' different grade;
Thereby formation semiconductor device.
7. according to the method for claim 6, further comprise first and second laser are carried out linear shaping.
8. according to the method for claim 6, wherein, described semiconductor film is amorphous or crystallite.
9. method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
Upper surface with the first laser radiation object; With
With the rear surface of the described object of second laser radiation,
Wherein, be applied to the effective energy intensity I of first laser of upper surface
oEffective energy intensity I with second laser that will be applied to the rear surface
o' satisfied 0＜the I that concerns
o'/I
o＜1 or 1＜I
o'/I
o, and
Wherein said object comprises semiconductor film,
Thereby formation semiconductor device.
10. according to the method for claim 9, further comprise first and second laser are carried out linear shaping.
11. according to the method for claim 9, wherein, described semiconductor film is amorphous or crystallite.
12. a laser aid comprises:
Be used to launch the lasing light emitter of laser;
Transmissivity changeable type half-reflecting mirror is used for above-mentioned laser is divided into first laser and second laser;
The first cylindrical array lens;
The second cylindrical array lens;
The 3rd cylindrical array lens;
The 4th cylindrical array lens;
First cylindrical lens; With
Second cylindrical lens, the wherein said first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens are placed in proper order;
Be used for first laser and second laser are directed into the upper surface of pending object and the optical system on the rear surface respectively;
Be used to support the block substrate of substrate,
The wherein said first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens are between described lasing light emitter and described transmissivity changeable type half-reflecting mirror; And
Wherein, this optical system comprises cylindrical lens, be used for first and second laser are carried out linear shaping, and
Wherein, on this substrate, form semiconductor film.
13. a method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
First and second laser are carried out linear shaping;
Upper surface with the first laser radiation object; With
Rear surface with the described object of second laser radiation;
Thereby formation semiconductor device.
14. a method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
First and second laser are carried out linear shaping;
Upper surface with the first laser radiation object; With
Rear surface with the described object of second laser radiation;
Wherein, be applied to the effective energy intensity I of first laser of upper surface
oBe set to and be applied to the effective energy intensity I of second laser of rear surface
o' different grade;
Thereby formation semiconductor device.
15. a method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
First and second laser are carried out linear shaping;
Upper surface with first laser radiation, one object; With
Rear surface with the described object of second laser radiation;
Wherein, be applied to the effective energy intensity I of first laser of upper surface
oEffective energy intensity I with second laser that is applied to the rear surface
o' satisfied 0＜the I that concerns
o'/I
o＜1 or 1＜I
o'/I
o
16. a method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
First and second laser are carried out linear shaping; With
With first laser and the surface of second laser at identical position irradiating object;
Wherein, the effective energy intensity I of first laser
oBe set to and effective energy intensity I at second laser of same position
o' different grade.
17. a method that forms semiconductor device, described method comprises:
From producing laser as the lasing light emitter of oscillation source;
Described laser is passed through the first cylindrical array lens, the second cylindrical array lens, the 3rd cylindrical array lens, the 4th cylindrical array lens, first cylindrical lens and second cylindrical lens;
By transmissivity changeable type half-reflecting mirror described laser is divided into first laser and second laser;
First and second laser are carried out linear shaping;
With first laser and the surface of second laser at identical position irradiating object; With
Wherein, the effective energy intensity I of first laser
oEffective energy intensity I with second laser
o' satisfied 0＜the I that concerns in identical position
o'/I
o＜1 or 1＜I
o'/I
o
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