US20050028928A1

US20050028928A1 - Substrate processing apparatus and substrate processing method

Info

Publication number: US20050028928A1
Application number: US10/900,880
Authority: US
Inventors: Fuminori Asa
Original assignee: Dainippon Screen Manufacturing Co Ltd
Current assignee: Dainippon Screen Manufacturing Co Ltd
Priority date: 2003-08-05
Filing date: 2004-07-28
Publication date: 2005-02-10
Also published as: TW200531163A; JP2005072559A; TWI261876B

Abstract

A transmitting window is provided on one side of a casing opposite to a substrate outlet. An ionizer is provided outside the transmitting window of a cleaning unit. The transmitting window is made of a polyimide resin or an acrylic resin, for example. Weak X-rays emitted from the ionizer pass through the transmitting window to reach the substrate outlet, shutter, spin chuck, guard, and the like in the cleaning unit. The spin chuck comprises a plurality of conductive holding pins.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for performing a given processing to a substrate.
2. Description of the Background Art
In fabrication steps of a semiconductor device, a liquid crystal display or the like, a substrate such as a semiconductor wafer or a glass substrate is subjected to various processings, for example cleaning, resist-coating, exposure, development, etching, ion-implanting, resist-stripping, formation of an interlayer insulating film, and thermal treatment.
If the substrate is electrostatically charged in the coarse of a series of processings, a discharge phenomenon may cause damage to a circuit pattern on the surface of the substrate or particles such as dust are easily attached on the substrate. For this reason, static eliminators for removal of static electricity on substrates have been developed (refer to JP 9-102444 A, for example).
A discharge type static eliminator is used, for example, as the static eliminator. The discharge type static eliminator utilizes high voltage sparks generated from electrodes to plasma-ionize the atmosphere around the electrodes, and electrically neutralizes a charged substrate by plasma ions.
The high voltage sparks of the discharge type static eliminator, however, cause the electrodes to be fused and attached on the substrate as particles. Further, the discharge type static eliminator cannot be used in a flammable atmosphere, because the generated high voltage sparks may cause ignition. During treatments with highly corrosive chemicals (including chemical solutions, vapors from the chemical solutions, and chemical gases) the corrosive atmosphere may exert adverse influence on the static eliminator.
While the use of the discharge type static eliminator is possible in an atmosphere neither flammable nor corrosive, it is desired that static electricity on the substrate be removed more effectively.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a substrate processing apparatus and a substrate processing method capable of removing static electricity from a substrate even in a flammable atmosphere and a corrosive atmosphere without the generation of particles.
It is another object of the present invention to provide a substrate processing apparatus and a substrate processing method capable of removing static electricity from a substrate more effectively.
A substrate processing apparatus according to one aspect of the present invention comprises: a substrate holding device that holds a substrate; an X-ray irradiator that directs X-rays toward at least part of an atmosphere including the substrate holding device; and a partition arranged between the substrate holding device and the X-ray irradiator, the partition having an X-ray transparent part on at least one part thereof that transmits the X-rays generated by the X-ray irradiator.
In the substrate processing apparatus, the X-rays generated from the X-ray irradiator pass through the X-ray transparent part on the partition, and directed to at least part of the atmosphere including the substrate holding device holding the substrate.
In this case, atoms and molecules in the X-ray irradiated atmosphere are ionized, thus producing gas atomic ions and gas molecular ions with high concentration. Some of the produced ions having opposite polarity to charges on the substrate are thus allowed to bond with the charges on and around the substrate, resulting in the removal of static electricity from the substrate and its periphery.
As described above, in the substrate processing apparatus according to the present invention, high voltage sparks produced by such devices as a discharge-needle type static eliminator are not employed, and it is therefore possible to remove static electricity from the substrate in a flammable atmosphere without generating particles. In addition, since the partition is present between the X-ray irradiator and the substrate holding device, static electricity on and around the substrate can be removed also in a corrosive atmosphere.
The X-rays generated by the X-ray irradiator may be electromagnetic waves having a wavelength not smaller than 1.3 angstroms and an energy intensity ranging from 3 eV to 9.5 eV.
Emission of such X-rays from the X-ray irradiator causes ionization of gaseous atoms and molecular atoms in a stable state included in an irradiated region, thereby producing the gas atomic ions and gas molecular ions with high concentration. Some of the produced ions having opposite polarity to charges on the members within the irradiated region are thus allowed to bond with the charges on and around the charged members, resulting in the removal of static electricity.
At least one part of the substrate holding device coming into contact with the substrate may be made of a conductive material. In this case, the conductive material of the part of the substrate holding device being in contact with the substrate can be grounded, which rapidly removes static electricity generated on the substrate. Moreover, since the charges on the substrate are rapidly removed with the conductive material while the charges on and around the substrate are being removed by the X-ray irradiator, the substrate can be more effectively prevented from being charged.
The conductive material may include a conductive resin. In this case, since the conductive resin is resistant to corrosion, static electricity can be effectively removed from the substrate even if it is treated with a corrosive chemical.
The conductive resin may include conductive poly ether ether ketone. In this case, since the conductive poly ether ether ketone is highly resistant to corrosion, static electricity can be effectively removed from the substrate even if it is treated with a highly corrosive chemical.
The conductive material may include a metal material. In this case, since metal has high conductivity, static electricity can be removed from the substrate more effectively.
The metal material may include gold or platinum. In this case, since gold or platinum is highly resistant to corrosion and oxidation, static electricity can be removed from the substrate more effectively even if it is treated with a highly corrosive and oxidizing chemical. Gold or platinum shows an extremely low ionization tendency, thus hardly eluting as metallic ions. Therefore, the substrate can be effectively prevented from metallic contamination.
The X-ray transparent part may be made of a resin material. In this case, since the resin material easily transmits X-rays, the X-rays emitted from the X-ray irradiator reach the atmosphere including the substrate holding device without decreasing their intensity. This allows for efficient removal of static electricity from the substrate.
The resin material may include a polyimide resin. In this case, since the polyimide resin easily transmits X-rays, the X-rays emitted from the X-ray irradiator reach the atmosphere including the substrate holding device without decreasing their intensity. This allows for efficient removal of static electricity from the substrate.
The resin material may include an acrylic resin. In this case, since the acrylic resin easily transmits X-rays, the X-rays emitted from the X-ray irradiator reach the atmosphere including the substrate holding device without decreasing their intensity. This allows for efficient removal of static electricity on and around the substrate.
The substrate holding device may rotate the substrate while holding the substrate. In this case, the substrate can be treated uniformly.
The substrate processing apparatus may further comprise a process fluid supplier that supplies a process fluid such as a process liquid or a process gas to the substrate held by the substrate holding device. In this case, static electricity can be removed from the substrate while the process fluid from the process fluid supplier is being supplied to the substrate.
This is especially effective in some cases where the substrate is discharged at the time of collision of the process fluid on the substrate surface. This prevents damage to a pattern formed on the substrate while preventing particles from attaching to the substrate.
The substrate processing apparatus may further comprise a splash guard surrounding the periphery of the substrate held by said substrate holding device, and preventing the process fluid from splashing, the X-ray irradiator directing X-rays toward an atmosphere near the splash guards.
In this case, the X-rays serve to remove static electricity from the splash guard. This prevents particles from attaching to the splash guard. As a result, the substrate is prevented from being contaminated by dropped particles and the like.
The substrate processing apparatus may further comprise a thermal processor that performs thermal treatment such as heating or cooling treatment to the substrate held by the substrate holding device. In this case, static electricity can be removed from the substrate while the substrate is being thermally treated.
The X-ray irradiator may direct X-rays toward an atmosphere near the substrate holding device, for example, toward a position close to but avoiding the substrate holding device. In this case, since the atmosphere near the substrate holding device is ionized, static electricity on and around the substrate holding device can be efficiently removed.
The X-ray irradiator may direct X-rays toward a downflow above the substrate holding device. In this case, since the downflow above the substrate holding device is ionized, ions are efficiently supplied to the substrate. This allows for efficient removal of static electricity from the substrate.
The substrate processing apparatus may further comprise a process chamber surrounding the periphery of the substrate holding device, the partition being one side of the process chamber. In this case, since the atmosphere in the process chamber and the X-ray irradiator are completely isolated from each other, corrosion of the X-ray irradiator due to the atmosphere in the process chamber is prevented.
The process chamber may have an opening for carrying the substrate into/out of the process chamber, the X-ray irradiator directing X-rays toward an atmosphere near the opening.
In this case, static electricity is removed from the opening. Thispreventsparticlesfromattachingtotheopening. As a result, the substrate is prevented from being contaminated by dropped particles and the like.
The substrate processing apparatus may further comprise a substrate transport device, the X-ray irradiator directing X-rays such that the X-rays cross a moving path of the substrate transported by the substrate transport device. In this case, static electricity is efficiently removed from the substrate being transported. This invalidates an electrostatic attraction between the particles attached on the substrate because of static electricity and the substrate. As a result, the particles attached on the substrate are easily removed.
In addition, the X-ray irradiator may direct X-rays toward a downflow above the moving path of the substrate transported by the substrate transport device. In this case, since the downflow above the moving path of the substrate is ionized, ions are efficiently supplied to the substrate being transported. This allows for efficient removal of static electricity from the substrate.
A substrate processing apparatus according to another aspect of the present invention comprises: a substrate holding device that holds a substrate; and a static eliminator that removes static electricity from an atmosphere including the substrate holding device, at least one part of the substrate holding device coming into contact with the substrate being made of a conductive material.
In the substrate processing apparatus, static electricity is removed from the atmosphere including the substrate holding device by the static eliminator. This prevents static electricity in the atmosphere from being transferred to the substrate. Also, the conductive material of the part of the substrate holding device being in contact with the substrate can be grounded, which rapidly removes static electricity generated on the substrate. Moreover, since the charges on the substrate are rapidly removed with the conductive material while the charges on and around the substrate are being removed, the charges on the substrate can be more effectively removed.
A substrate processing method according to still another aspect of the present invention comprises the steps of: holding a substrate by a substrate holding device; processing the substrate held by the substrate holding device; and directing X-rays to an atmosphere including the substrate holding device through an X-ray transparent part provided on at least one part of a partition.
In the substrate processing method, the X-rays pass through the X-ray transparent part on the partition, and directed to the atmosphere including the substrate holding device holding the substrate.
In this case, atoms and molecules in the X-ray irradiated atmosphere are ionized, thus producing gas atomic ions and gas molecular ions with high concentration. Some of the produced ions having opposite polarity to charges on the substrate are thus allowed to bond with the charges on and around the substrate, resulting in the removal of static electricity from the substrate and its periphery.
As described above, in the substrate processing apparatus according to the present invention, high voltage sparks produced by such devices as a discharge-needle type static eliminator are not employed, and it is therefore possible to remove static electricity from the substrate in a flammable atmosphere without generating particles. In addition, since the X-rays are directed through the partition to the atmosphere including the substrate, static electricity on and around the substrate can be removed also in a corrosive atmosphere.
The step of holding the substrate may include the step of holding the substrate by a substrate holding device whose at least one part coming into contact with the substrate is made of a conductive material. In this case, the conductive material of the part of the substrate holding device being in contact with the substrate can be grounded, which rapidly removes static electricity generated on the substrate. Moreover, since the charges on the substrate are rapidly removed with the conductive material while the charges on and around the substrate are being removed by the X-ray irradiator, the substrate can be more effectively prevented from being charged.
A substrate processing method according to yet another aspect of the present invention comprises the steps of: holding a substrate by a substrate holding device whose at least one part coming into contact with a substrate is made of a conductive material; processing the substrate held by the substrate holding device; and removing static electricity from an atmosphere including the substrate holding device.
In the substrate processing method, static electricity is removed from the atmosphere including the substrate holding device by the static eliminator. This prevents static electricity in the atmosphere from being transferred to the substrate. Also, the conductive material of the part of the substrate holding device being in contact with the substrate can be grounded, which rapidly removes static electricity generated on the substrate. Further, since the charges on the substrate are rapidly removed with the conductive material while the charges on and around the substrate are being removed, static electricity can be more effectively removed from the substrate.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a substrate processing apparatus according to the embodiment;
FIG. 2 is a schematic cross section of the cleaning units in the substrate processing apparatus according to the embodiment;
FIG. 3 is a schematic diagram of the cleaning units performing cleaning processing to a substrate;
FIG. 4 is a diagram for use in illustrating static removal operation performed by the ionizer in the cleaning unit;
FIG. 5 is a side view showing an example of the holding pins;
FIG. 6 is a schematic cross section and a plan view showing another example of the holding pin;
FIG. 7 is a block diagram showing the structure of a control system in the substrate processing apparatus of FIG. 1;
FIG. 8 is a plan view of a substrate processing apparatus according to a second embodiment;
FIG. 9 is a schematic cross section showing an example of the structure of the cooling plate;
FIG. 10 is a diagram for use in illustrating a method for measuring the amount of charge in the cleaning unit;
FIG. 11 shows measurement results of the amount of charge in the cleaning unit in each of the inventive example and comparative example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Description will, hereinafter, be made of an embodiment of the present invention with reference to the drawings.
A substrate in the following description refers to a semiconductor wafer, glass substrate for a liquid crystal display, glass substrate for a PDP (Plasma Display Panel), glass substrate for a photomask, glass substrate for an optical disc or the like.
FIG. 1 is a plan view of a substrate processing apparatus according to the embodiment. As shown in FIG. 1, the substrate processing apparatus 100 has process regions A, B, and a transport region C between them.
A main controller 4, cleaning units MPC1, MPC2, fluid boxes 2 a, 2 b, and ionizers 5 are arranged in the process region A.
The fluid boxes 2 a, 2 b each house fluid related equipment, such as piping for the supply of a process liquid to the cleaning units MPC1, MPC2 and discharge of used process liquid from the cleaning units MPC1, MPC2, joints, valves, flow meters, pumps, temperature controllers, process liquid storage tanks, and the like.
In the cleaning units MPC1, MPC2, a substrate having residues such as impurities and particles attached on its surface, after ashing processing by an ashing unit described below, is subjected to cleaning processing including the removal of residues, and also to drying processing after the cleaning processing.
In the embodiment, the two cleaning units MPC1, MPC2 with an equivalent function are mounted for improved throughput of substrate processing. Note that only the cleaning unit MPC1 maybe mounted, for example, when the throughput of the substrate processing is sufficiently ensured.
The ionizers 5 are provided outside the cleaning units MPC1, MPC2, respectively. The ionizers 5 emit weak X-rays with an antistatic effect to the inside of the cleaning units MPC1, MPC2. This will be detailed below.
The ashing unit ASH, a plurality of cooling plate units CP, and an asher controller 3 are arranged in the process region B. In the ashing unit ASH, the ashing processing is performed to the substrate being placed on a heating plate (not shown) under reduced pressure using oxygen plasma.
In each of the plurality of cooling plate units CP, the substrate being placed on a cooling plate described below is cooled to a given temperature (23° C., for example) by a Peltier element, a thermostatic recirculation or the like. The cooling plate units CP are used for cooling the substrate W, heated mainly by the ashing processing, to a temperature acceptable for the residue removal or cleaning processing.
The ashing unit ASH, cooling plate units CP, cleaning units MPC1, MPC2 will, hereinafter, be collectively called processing units. A substrate transport robot CR is arranged in the transport region C.
An indexer ID for loading/unloading the substrate W is arranged on one end of the process regions A, B. Carriers C housing the substrates W are mounted in the indexer ID. In the embodiment, FOUPs (Front Opening Unified Pods) which house substrates Win a sealed state are used as the carriers 1; however, SMIF (Standard Mechanical Inter Face) pods, OCs (Open Cassettes) or the like may also be used without limited to the one mentioned herein.
An indexer robot IR in the indexer ID moves in the direction of arrow U to take out a substrate W from a carrier 1 and transfer it to the substrate transport robot CR, and reversely receives the substrate W which has been subjected to a series of processings from the substrate transport robot CR to return it to the carrier C.
The substrate transport robot CR transports the substrate W transferred from the indexer robot IR to a designated processing unit or transports the substrate W received from one processing unit to another or to the indexer robot IR.
The asher controller 3, which is composed of a computer including a CPU (Central Processing Unit) or the like, controls the operations of the ashing unit ASH and cooling plate unit CP in the process region A. The main controller 4, which is composed of a computer including a CPU (Central Processing Unit) or the like, controls the operations of each of the processing units in the process regions A, B, the plurality of ionizers 5, the substrate transport robot CR in the transport region C, and the indexer robot IR in the indexer ID.
FIG. 2 is a schematic cross section of the cleaning unit MPC1 or MPC2 in the substrate processing apparatus according to the embodiment.
The cleaning unit MPC1 or MPC2 of FIG. 2 performs such processings as removal of the residues attached on the surface of the substrate W after the ashing processing using a process liquid such as pure water or chemical solution, and drying of the substrate W after the cleaning processing.
As shown in FIG. 2, the cleaning unit MPC1 or MPC2 have a structure surrounded by a casing 20. A substrate outlet 7 is provided to a side of the casing 20 toward the transport region C. The substrate outlet 7 is provided with a shutter SH which can be freely opened and closed by a driving mechanism (not shown). The substrate W is transported from the substrate outlet 7 by the substrate transport robot CR.
The cleaning unit MPC1 or MPC2 comprises a spin chuck 21 inside the casing 20 for rotating the substrate W around a vertical rotation axis passing through the center of the substrate W. The spin chuck 21 comprises a plurality of conductive holding pins P for horizontally holding the substrate W. The holding pins P will be detailed below.
The spin chuck 21 is fixed at an upper end of the rotation axis 25 which is rotated by a chuck rotating mechanism (not shown). The substrate W being held horizontally by the spin chuck 21 rotates during such processings as the removal of residues after the ashing processing, and drying of the substrate W after the cleaning processing.
The rotation axis 25 in the spin chuck 21 is composed of a hollow shaft. A process liquid supply pipe 26 is inserted into the rotation axis 25. The process liquid supply pipe 26 is supplied with a process liquid such as pure water or a chemical solution serving as an etching liquid. The process liquid supply pipe 26 extends to a position close to a back face of the substrate W held on the spin chuck 21. At an end of the process liquid supply pipe 26 is provided a back face nozzle 27 which spits out the process liquid toward the center of the back face of the substrate W.
The spin chuck 21 is housed in a process cup 23. A cylindrical partition 33 is provided inside the process cup 23. A liquid discharge space 31 is also formed to surround the spin chuck 21 for discharging the process liquid which has been used for processing the substrate W. Additionally, a liquid collect space 32 is formed between the process cup 23 and the partition 33 to surround the liquid discharge space 31 for collecting the process liquid used for processing the substrate W.
The liquid discharge space 31 is connected with a drain pipe 34 for directing the process liquid to a waste liquid treatment apparatus (not shown), and the liquid collect space 32 is connected with a collect pipe 35 for directing the process liquid to a collecting device (not shown).
A guard 24 is provided above the process cup 23 in order to prevent the process liquid on the substrate W from splashing outwardly. The shape of the guard 24 is rotational symmetric with respect to the rotation axis 25. A waste liquid guiding groove 41 having a V-shaped cross section, is formed on an inside face close to an upper end of the guard 24.
On the inside face close to a lower end of the guard 24 is also formed a collected liquid guide 42 made of a plane inclining outwardly downward. A partition housing groove 43 is formed near an upper end of the collected liquid guide 42 for housing the partition 33 of the process cup 23.
The guard 24 is provided with a guard lifting mechanism (not shown) composed of a ball screw mechanism or the like. The guard lifting mechanism moves the guard 24 up and down between a collection position where the collected liquid guide 42 is positioned opposite to an outer edge of the substrate W and a discharge position where the waste liquid guiding groove 41 is positioned opposite to the outer edge of the substrate W held by the spin chuck 21. When the guard 24 is in the collection position, the process liquid outwardly splashed from the substrate W is directed to the liquid collect space 32 by the collected liquid guide 42 to be collected through the collection pipe 35. When, on the other hand, the guard 24 is in the discharge position, the process liquid outwardly splashed from the substrate W is directed to the liquid discharge space 31 by the waste liquid guiding groove 41 to be discharged through the drain pipe 34. Discharge and collection of the process liquid is carried out with such a structure.
As shown in FIG. 2, when the substrate W is carried onto the spin chuck 21, the guard lifting mechanism withdraws the guard 24 to a substrate receiving position further below the discharge position, and moves the guard 24 so that its upper end may be in a position lower than a level at which the spin chuck 21 holds the substrate W.
Above the spin chuck 21 is provided a round shield plate 22 with an opening at its center. A support shaft 29 is vertically provided near an end of an arm 28, and at a lower end of the support shaft 29 is mounted the shield plate 22 so as to face opposite to an upper face of the substrate W held on the spin chuck 21.
A nitrogen gas supply path 30 communicating with the opening of the shield plate 22 is inserted into the support shaft 29. The nitrogen gas supply path 30 is supplied with nitrogen gas (N₂). The nitrogen gas supply path 30 supplies nitrogen gas to the substrate W during the drying processing after the cleaning processing. Note that any inert gases other than nitrogen gas may be employed as the gas supplied to the substrate.
Where the substrate W is made of a hydrophobic material such as silicon (Si), the surface of the substrate W is often not dried uniformly with a resultant stain on the surface after dried (hereinafter called a watermark). The watermark on the surface of the substrate W can be prevented by supplying, during the drying processing of the substrate W after the cleaning processing, nitrogen gas to a gap between the substrate W and the shield plate 22 with the shield plate 22 and the substrate W being brought close to each other.
Further, a process liquid supply pipe 39 communicating with the opening of the shield plate 22 is inserted into the nitrogen gas supply path 30. The process liquid supply pipe 39 is supplied with a rinse such as pure water. Supplying the rinse to the surface of the substrate W through the process liquid supply pipe 39 allows the process liquid remaining on the surface of the substrate W after the cleaning processing to be washed off. As another example of the rinse, an organic solvent such as isopropyl alcohol (IPA), ozone water including ozone dissolved in pure water, or hydrogen water including hydrogen dissolved in pure water may be mentioned.
The arm 28 is connected with a shield plate lifting mechanism (not shown) and a shield plate rotating mechanism (not shown). The shield plate lifting mechanism moves the shield plate 22 up and down between a position where the shield plate is close to the upper face of the substrate W held on the spin chuck and a position where it is distant above from the spin chuck 21.
A transmitting window 6 is provided at a side of the casing 20 opposite to the substrate outlet 7. The ionizer 5 is provided outside the transmitting window 6 of the cleaning units MPC1, MPC2. The ionizer 5 is an X-ray irradiator emitting weak X-rays, i.e., electromagnetic waves with an antistatic effect.
The transmitting window 6 is made of a polyimide resin, acrylic resin or the like. The polyimide resin or acrylic resin has a property of easily transmitting X-rays. This allows the weak X-rays generated from the ionizer to be transmitted through the transmitting window 6. Note that the transmitting window 6 may be made of any other kinds of resins that can easily transmit X-rays.
As shown in FIG. 2, when the guard 24 is in the substrate receiving position, and the arm 28 is positioned above distant from the spin chuck 28, the weak X-rays emitted from the ionizer 5 pass through the transmitting window 6 to reach the atmosphere near the substrate outlet 7, shutter SH, spin chuck 21, guard 24 and the like in the cleaning unit MPC1 or MPC2.
This removes static electricity from the substrate outlet 7, shutter SH, spin chuck 21, guard 24, and the like. As a result, particles in the atmosphere of the cleaning unit MPC1 or MPC2 are prevented from electrostatically attaching to the substrate outlet 7, shutter SH, spin chuck 21, guard 24, and the like, so that the substrate W is prevented from being contaminated by dropped particles and the like.
Moreover, the weak X-rays are emitted from the ionizer 5 such that they cross a transport path of the substrate W by the substrate transport robot CR. This invalidates an electrostatic attraction between the substrate W and the particles even if the particles are attached to the substrate W being transported. The particles can thus be efficiently removed during the cleaning processing. In addition, the substrate W after the cleaning processing is prevented from being charged, so that the particles may not re-attach to the substrate W. Static removal operation performed by the ionizer 5 will later be detailed.
FIG. 3 is a schematic diagram of the cleaning unit MPC1 or MPC2 performing the cleaning processing to the substrate W.
During cleaning of the substrate W, the weak X-rays emitted from the ionizer 5 are transmitted through the transmitting window 6 to reach the guard 24, shield plate 22, substrate W, and the like in the cleaning unit MPC1 or MPC2. This prevents the substrate W from being charged, which prevents damage to a pattern formed on the substrate.
Further, the chemical solution splashed during the cleaning processing of the substrate W is blocked by the casing 20 and the transmitting window 6 so that it may not attach to the ionizer 5. This prevents a breakage of the ionizer 5.
In this manner, during both the transport of the substrate W by the substrate transport robot CR and the cleaning of the substrate W by the cleaning unit MPC1 or MPC2, the members in the cleaning unit MPC1 or MPC2, and the substrate Ware prevented from being charged, so as to prevent particles from attaching to the substrate W while preventing damage to the pattern formed on the substrate.
FIG. 4 is a diagram for use in illustrating static removal operation performed by the ionizer 5 in the cleaning unit MPC1.
The weak X-rays emitted from the ionizer 5 spread in the form of a cone having an angle of 120 degrees around the irradiation hole of the ionizer 5.
The weak X-rays emitted from the ionizer 5 are electromagnetic waves having an energy intensity of 3 to 9.5 eV and a wavelength range including wavelengths of not smaller than 1.3 angstroms with its center being a wavelength of 2 angstroms. The emission of weak X-rays from the ionizer 5 cause ionization of gaseous atoms and gaseous molecules in a stable state included in an irradiated region, resulting in production of gas atomic ions and gas molecular ions with high concentration. Some of the produced ions having opposite polarity to charges on the members within the irradiated region are thus allowed to bond with the charges on the charged members, resulting in the removal of static electricity.
Where the substrate processing apparatus 100 is arranged in a clean room of the downflow type, in particular, it is preferable that the weak X-rays from the ionizer 5 are emitted also to space above the spin chuck 21 so that a downflow toward the spin chuck 21 from above (shown by the broken arrow of FIG. 2) may be irradiated. This allows the gas atomic ions and gas molecular ions with high concentration to be efficiently supplied to the spin chuck 21.
In addition, it is preferred that the weak X-rays from the ionizer 5 are emitted also to the transport path of the substrate and space above the substrate outlet 7 so that a downflow toward the substrate transport path from above may be irradiated. As a result, static electricity on the substrate W being transported and cleaned can be efficiently removed.
Note that since the ions produced by the ionizer 5 have high concentration and an excellent ion balance, static electricity is instantaneously removed from the charged members, which prevents the members from being oppositely charged.
FIG. 5 is a side view showing an example of the holding pin P in the cleaning unit MPC1 or MPC2 of FIGS. 2 and 3.
The holding pin P of FIG. 5 comprises a support pin 51, a rod-like pin member 52, a pin fixing plate 53, and a coupling member 54. The support pin 51 and the pin coupling member 52 are fixed on the pin fixing plate 53. The support pin 51 supports a back surface of the substrate W. The pin member 52 with a V-shaped groove supports the edge of the substrate W. The pin fixing plate 53 is rotatably mounted to the link 55 through the coupling member 54. The link 55 is provided in the spin chuck 21 of FIGS. 2 and 3.
The holding pin P is formed of a conductive resin. As the conductive resin, the conductive PEEK (Poly Ether Ether Ketone) containing carbon, for example, is employed. The link 55 is made of a conductive material such as metal, for example. The link 55 is grounded (earthed) through the conductive member or wires. This causes the holding pin P to be grounded.
Grounding the holding pin P allows rapid removal of static electricity generated on the substrate W. As a result, the substrate W is prevented from being charged.
FIG. 6(a) is a schematic cross section showing another example of the holding pin P in the cleaning unit MPC1 or MPC2 of FIGS. 2 and 3. FIG. 6(b) is a plan view of the pin member 52 of FIG. 6(a).
The support pin 51, pin member 52, pin fixing plate 53, and coupling member 54 of the holding pin P shown in FIG. 6 are each formed of a non-conductive resin. As the non-conductive resin, a resin not containing carbon, for example non-conductive PEEK (Poly Ether Ether Ketone), a flurororesin, or a vinyl chloride resin may be employed. A plate-like member M1 made of a conductive material is radially inserted to the pin member 52. The pin member 52 and the plate-like member M1 have a V-shaped groove formed therein, with a part of the plate-like member M1 being exposed at least on an inside surface of the groove.
Wiring members M2, M3, M4 made of conductive materials are inserted into the pin fixing plate 53 and coupling member 54, and the plate-like member M1 is electrically connected to the link 55 through the wiring members M2, M3, M4. As the conductive materials for the plate-like member M1 and wiring members M2, M3, M4, pure gold or high impurity platinum, for example, is used. The link 55 is grounded. This causes the holding pin P to be grounded.
Grounding the holding pin P allows rapid removal of static electricity generated on the substrate W. This means that a static removing speed (speed at which the amount of charge decreases) exceeds a charging speed (speed at which the amount of charge increases) due to processing of the substrate W or its peripheral atmosphere, and as a result, the substrate W is prevented from being charged.
Note that the substrate W is charged, for example, when the process liquid (pure water, in particular) is supplied to the substrate W and allowed to collide on the surface of the substrate W, when the atmosphere around the substrate W is already charged itself, or when the substrate W is rotated to cause a friction between the substrate W and its peripheral atmosphere or the process liquid.
FIG. 7 is a block diagram showing the structure of a control system in the substrate processing apparatus 100 of FIG. 1.
The ashier controller 3 is composed of a CPU (Central Processing Unit) or the like, and controls various operations for the ashing processing of the substrate W performed in the ashing unit ASH. The asher controller 3 also controls various operations for the cooling of the substrate W performed in the cooling plate unit CP.
In addition, the main controller 4 is composed of a CPU (Central Processing Unit) or the like, and controls the substrate transport operation by the indexer robot IR and the substrate transport robot CR, and the operations of the cleaning units MPC1, MPC2 and ionizer 5.
As described above, in the substrate processing apparatus according to the embodiment, high voltage sparks produced by such devices as a discharge-needle type static eliminator are not employed, and it is therefore possible to perform removal of static electricity from the substrate W in a flammable atmosphere without generating particles. In addition, since the casing 20 is present between the ionizer 5 and the spin chuck 21, static removal from the substrate W can be performed also in a corrosive atmosphere.
Moreover, since the charges are removed from the atmosphere including the spin chuck 21 by the ionizer 5, static electricity in the atmosphere can be prevented from transferring to the substrate W. Also, static electricity on the substrate W held by the holding pins P is rapidly removed by grounding the holding pins P. This results in more effective removal of charge from the substrate W.
In the embodiment, the spin chuck 21 corresponds to a substrate holding device, the ionizer 5 corresponds to an X-ray irradiator or a static eliminator, the side of the casing 20 toward the ionizer 5 corresponds to a partition, the transmitting window 6 corresponds to an X-ray transparent part, the process liquid supply pipes 26, 39 correspond to a process fluid supplier, the cooling plate unit CP corresponds to a thermal processor, the guard 24 corresponds to a splash guard, the casing 20 corresponds to a process chamber, the substrate transport robot CR corresponds to a substrate transport device, and the substrate outlet 7 corresponds to an opening.
(Second Embodiment)
FIG. 8 is a plan view of a substrate processing apparatus 10 a according to a second embodiment.
The substrate processing apparatus 100 a differs from the substrate processing apparatus 100 of FIG. 1 in that the ionizer 5 is provided outside the cooling plate unit CP. The ionizer 5 emits weak X-rays toward the inside of the cooling plate unit CP.
FIG. 9 is a schematic cross section showing an example of the structure of the cooling plate unit CP.
In FIG. 9, the cooling plate unit CP comprises a casing 60 with a substrate outlet OS. The substrate outlet OS of the casing 60 is provided with a shutter SH which can be opened and closed freely with a driving device PS which is an air cylinder or the like.
A cooling plate PL is provided inside the casing 60. Three spherical spacers 61 are arranged on an upper face of the cooling plate PL in the form of almost a regular triangle to support a back face of the substrate W. The cooling plate PL is composed of a highly heat conductive member, and cools the substrate W supported above the cooling plate PL with a slight gap to a given temperature. A temperature sensor 62 is embedded in the cooling plate PL. An output from the temperature sensor 62 is input to the main controller 4 of FIG. 8. The spherical spacers 61 are each formed of a conductive material such as a metal material or glass containing carbon. These spherical spacers are grounded.
Additionally, a cooler 63 is provided at a lower face of the cooling plate PL. The cooler 63 is composed of a Peltier element, for example. The Peltier element absorbs heat on one side and dissipates heat on the other side with the supply of current. This allows for heat transfer. The cooler 6 using such Peltier element is capable of controlling the temperature of the cooling plate PL in a short time.
A cooling water jacket 64 is provided at a lower face of the cooler 63. The cooling water jacket 64 has a water cooling channel 65 for circulating the cooling water inside the plate-like member having high heat conductivity. The cooling water channel 65 is connected through a circulation pipe 66 to the outside, for example to a water cooling utility 67 in a factory where the substrate processing apparatus 100 is located. The cooler 63 transfers the heat of the substrate W to the water cooling jacket 64.
A plurality of through holes 69 are formed in the cooling plate PL, cooler 63, and water cooling jacket 64. There are three through holes 69 in the embodiment. A plurality of lifting pins 68 for supporting the back face of the substrate W are provided inside the through holes 69. The plurality of lifting pins 68 are moved vertically by the substrate lifting device 70 to receive/transfer the substrate W from/to the substrate transport robot CR.
An inert gas supply chamber 15 is arranged in an upper part of the casing 60. An inert gas inlet 14 is provided on an upper face of the inert gas supply chamber 15, and a plurality of inert gas injection holes 16 are provided on a lower face thereof.
The inert gas inlet 14 of the inert gas supply chamber 15 is connected with a gas supply pipe 13 for directing an inert gas such as nitrogen gas or the like. The gas supply pipe 13 is connected through a flow regulating valve V1 to a gas utility (not shown) which supplies an inert gas such nitrogen gas.
Additionally, an exhaust port 17 is provided at a lower part of the casing 60. The exhaust port 17 is connected with a gas exhaust pipe 18 which exhausts an exhaust gas. The gas exhaust pipe 18 is connected through a flow regulating valve V2 to an exhaust facility in a factory (not shown).
Opening the flow regulating valve V1 causes an inert gas such as nitrogen gas to be injected to the substrate W through the inert gas inlet 14 and the plurality of inert gas injection holes 16. Also, opening the flow regulating valve V2 causes the inert gas injected to the substrate W to be discharged from the exhaust port 17 and the gas exhaust pipe 18.
A transmitting window 60 a is provided opposite to the substrate outlet OS of the casing 60. The transmitting window 60 a is composed of the same material as that of the transmitting window 6 of FIG. 2.
The ionizer 5 outside the cooling plate unit CP emits weak X-rays through the transmitting window 60 a to the inert gas in the cooling plate unit CP. This causes ionization of the inert gas to produce gas molecular ions with high concentration. Some of the produced ions having opposite polarity to the charged members within the irradiated region are thus allowed to bond with the charges on the charged members, resulting in the removal of static electricity.
In this case, since the inert gas is injected from the inert gas injection holes 16 toward the substrate W, the ionized inert gas efficiently removes static electricity from the substrate W.
As described above, in the substrate processing apparatus according to the embodiment, high voltage sparks produced by such devices as a discharge-needle type static eliminator are not employed, and it is therefore possible to perform removal of static electricity from the substrate W in a flammable atmosphere without generating particles. In addition, since the casing 60 is present between the ionizer 5 and the cooling plate PL, static electricity can be removed from the substrate W also in a corrosive atmosphere.
Moreover, since the charges are removed from the atmosphere including the cooling plate PL by the ionizer 5, static electricity in the atmosphere can be prevented from transferring to the substrate W. Also, static electricity is rapidly removed from the substrate W by grounding the spherical spacers 61. This results in more effective removal of charges from the substrate W.
In the embodiment, the cooling plate PL corresponds to a substrate holding device, the ionizer 5 corresponds to an X-ray irradiator or a static eliminator, the side of the casing 60 toward the ionizer 5 corresponds to a partition, the transmitting window 60 a corresponds to an X-ray transparent part, the cooling plate unit CP corresponds to a thermal processor, the casing 60 corresponds to a process chamber, the substrate transport robot CR corresponds to a substrate transport device, and the substrate outlet OS corresponds to an opening.
Although the cooling plate unit CP is used as the thermal processor, and the ionizer 5 performs removal of charges from the substrate W cooled by the cooling plate unit CP in the embodiment, the invention is not limited as such. The substrate processing apparatus may have a structure in which a hotplate unit or the like is used as the thermal processor for thermally treating the substrate W, and the ionizer 5 is provided outside the hot plate unit to perform removal of charge from the thermally treated substrate W.

EXAMPLES OF OTHER MODIFICATIONS

Although in the above first and second embodiments the ionizers 5 emitting weak X-rays are used, other ionizers may also be used. For example, for a substrate processing apparatus performing substrate processing in an atmosphere neither flammable nor corrosive, a discharge type static eliminator may be provided inside the casing 20 or casing 60 as an ionizer.
Although in the above first embodiment the conductive holding pins Pare provided to the spin chuck 21, non-conductive holding pins may also be be used. Further, although in the above second embodiment the conductive spherical spacers 61 are provided on the cooling plate PL, non-conductive spherical spacers may also be used.

EXAMPLES

In each of an inventive example and a comparative example, a substrate W undergone hydrophobic-treatment with HF (hydrogen fluoride) was cleaned and dried under the following conditions, using the cleaning units MPC1 having the structure shown in FIG. 2.

Inventive Example

Holding pins P with the structure shown in FIG. 5 were used in the inventive example. As a material for each of the holding pins P, PEEK (PK-450CA) prepared by NIPPON POLYPENCO KABUSHIKI GAISHA was employed. During cleaning processing, the substrate W was cleaned with pure water while being rotated by the spin chuck 21. During drying processing, the substrate W was dried by shaking off the pure water while being rotated by the spin chuck 21. A polyimide resin film was employed for the transmitting window 6.
The shield plate 22 was fixed on a position about 70 meters above from the surface of the substrate W during the cleaning and drying processings.
During the cleaning processing, drying processing, and a subsequent standby period, weak X-rays were continuously emitted from the ionizer 5 into the casing 20.

Comparative Example

In the comparative example, the substrate W was cleaned and dried under the same conditions as in the inventive example 1 with the same cleaning unit MPC1 except that weak X-rays were not emitted from the ionizer 5.
(Method of Measuring Amount of Charge)
The amount of charge in the cleaning unit MPC1 was measured in each of the inventive example and comparative example, using the following method.
FIG. 10 is a diagram for use in illustrating a method for measuring the amount of charge. An electrostatic measuring equipment S was mounted at a lower face of the shield plate 22. During cleaning and drying processings, the electrostatic measuring equipment S measured the amount of charge at a measurement point Q on the surface of the substrate W. After the substrate W was carried outside the casing 20, the electrostatic measuring equipment S was lifted with the shield plate 22, so that the amount of charge in the atmosphere above the spin chuck 21 was measured.
FIG. 11 shows measurement results of the amount of charge in each of the inventive example and comparative example. Note that T1 represents a standby period between the substrate W is held by the spin chuck 21 and the cleaning processing begins, T2 represents a period in which the cleaning processing is performed, T3 represents a period in which the drying processing is performed, T4 represents a standby period after the drying processing, T5 represents a period in which the substrate W is carried from the spin chuck 21 outside the casing 20, and T6 represents a standby period until a next substrate W is carried into the spin chuck 21 after the substrate W has been taken out.
During the period T2, the amount of charge in each of the inventive example and comparative example is hardly increased. In other words, it is assumed that static electricity was rapidly removed from the substrate W by grounding the holding pins P made of the conductive PEEK, which prevented the substrate W from being charged.
During the periods T3 and T4, the amount of charge on the substrate W in the comparative example tends to increase. This is probably because the substrate W was rapidly rotated in a dried state, so that a friction occurred between the charged atmosphere in the cleaning unit MPC1 and the surface of the substrate W, thereby causing the substrate W to be charged. In contrast, the amount of charge on the substrate W in the inventive example is hardly increased. This is probably because static electricity in the atmosphere in the cleaning unit MPC1 was removed by the ionizer 5, so that the substrate W was prevented from being charged.
During the periods T5 and T6, the amount of charge in the comparative example is further increased. Note that during the period T6 the amount of charge in the atmosphere above the spin chuck 21 was measured. In other words, it is assumed that the atmosphere in the cleaning unit MPC1 was charged in the aforementioned cleaning processing. In contrast, the amount of charge in the inventive example is hardly increased. In other words, it is assumed that static electricity in the cleaning unit MPC1 was removed by the ionizer 5. This prevents static electricity in the atmosphere from being transferred to the next substrate W and charging the substrate W.
It was found from the above results that the amount of charge on the substrate W and the amount of charge in the atmosphere in the cleaning unit MPC1 can be reduced during both the periods in which the substrate W is being processed and not being processed, by using the holding pins P made of conductive materials in the spin chuck 21, and by emitting weak X-rays from the ionizer 5 into the cleaning unit MPC1. Since it is assumed that similar results as those shown above may be obtained by using the aforementioned discharge type static eliminator as the ionizer 5 in the above inventive example, the discharge type static eliminator may also be used as the static eliminator in place of the ionizer 5 of the weak X-ray type.
As described above, the present invention is suitable for use in performing a given processing to a substrate such as a semiconductor wafer, glass substrate for a liquid crystal display, glass substrate for a PDP, glass substrate for a photomask, substrate for an optical disc or the like.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.

Claims

1. A substrate processing apparatus comprising:

a substrate holding device that holds a substrate;

an X-ray irradiator that directs X-rays toward at least part of an atmosphere including said substrate holding device; and

a partition arranged between said substrate holding device and said X-ray irradiator,

said partition having an X-ray transparent part on at least one part thereof that transmits the X-rays generated by said X-ray irradiator.

2. The substrate processing apparatus according to claim 1, wherein the X-rays generated by said X-ray irradiator are electromagnetic waves having a wavelength not smaller than 1.3 angstroms and an energy intensity ranging from 3 eV to 9.5 eV.

3. The substrate processing apparatus according to claim 1, wherein at least one part of said substrate holding device coming into contact with said substrate is made of a conductive material.

4. The substrate processing apparatus according to claim 3, wherein said conductive material includes a conductive resin.

5. The substrate processing apparatus according to claim 4, wherein said conductive resin includes conductive poly ether ether ketone.

6. The substrate processing apparatus according to claim 3, wherein said conductive material includes a metal material.

7. The substrate processing apparatus according to claim 6, wherein said metal material includes gold or platinum.

8. The substrate processing apparatus according to claim 1, wherein said X-ray transparent part is made of a resin material.

9. The substrate processing apparatus according to claim 8, wherein said resin material includes a polyimide resin.

10. The substrate processing apparatus according to claim 8, wherein said resin material includes an acrylic resin.

11. The substrate processing apparatus according to claim 1, wherein said substrate holding device rotates the substrate while holding the substrate.

12. The substrate processing apparatus according to claim 1, further comprising a process fluid supplier that supplies a process fluid to the substrate held by said substrate holding device.

13. The substrate processing apparatus according to claim 12, further comprising a splash guard surrounding the periphery of the substrate held by said substrate holding device, and preventing the process fluid from splashing,

said X-ray irradiator directing X-rays toward an atmosphere near said splash guard.

14. The substrate processing apparatus according to claim 1, further comprising a thermal processor that thermally treats the substrate held by said substrate holding device.

15. The substrate processing apparatus according to claim 1, wherein said X-ray irradiator directs X-rays toward an atmosphere near said substrate holding device.

16. The substrate processing apparatus according to claim 1, wherein said X-ray irradiator directs X-rays toward a downflow above said substrate holding device.

17. The substrate processing apparatus according to claim 1, further comprising a process chamber surrounding the periphery of said substrate holding device,

said partition being one side of said process chamber.

18. The substrate processing apparatus according to claim 17, wherein said process chamber has an opening for carrying the substrate into/out of said process chamber,

said X-ray irradiator directing X-rays toward an atmosphere near said opening.

19. The substrate processing apparatus according to claim 1, further comprising a substrate transport device,

said X-ray irradiator directing X-rays such that the X-rays cross a moving path of the substrate transported by said substrate transport device.

20. The substrate processing apparatus according to claim 1, further comprising a substrate transport device,

said X-ray irradiator directing X-rays toward a downflow above the moving path of the substrate transported by said substrate transport device.

21. A substrate processing apparatus comprising:

a substrate holding device that holds a substrate; and

a static eliminator that removes static electricity from an atmosphere including said substrate holding device,

at least one part of said substrate holding device coming into contact with said substrate being made of a conductive material.

22. A substrate processing method comprising the steps of:

holding a substrate by a substrate holding device;

processing the substrate held by said substrate holding device; and

directing X-rays to an atmosphere including said substrate holding device through an X-ray transparent part provided on at least one part of a partition.

23. The substrate processing method according to claim 22, wherein said step of holding the substrate includes the step of holding the substrate by a substrate holding device whose at least one part coming into contact with the substrate is made of a conductive material.

24. A substrate processing method comprising the steps of:

holding a substrate by a substrate holding device whose at least one part coming into contact with a substrate is made of a conductive material;

processing the substrate held by said substrate holding device; and

removing static electricity from an atmosphere including said substrate holding device.