JP2005175324A - Mask-contamination preventing method and apparatus, and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a mask (reticle) from being contaminated due to impurity gases. <P>SOLUTION: For preventing further a reticle R present in an exposure chamber 21 whose clearness is kept about constant from any contamination caused by impurity gases, an optical catalytic film 70 exhibiting an optical catalytic effect by an exposure light is so utilized as to decompose and remove by the optical catalytic film 70 the impurity gases present in the atmosphere of the reticle. When coating the reticle R itself with the optical catalytic film 70, there is a possibility of reducing the productivity of wafers by the optical catalytic film 70 so absorbing an exposure light that the illuminance of the wafers is reduced due to the optical catalytic film 70. Therefore, non-transmitting portions 61 of a pattern present in an exposure area 62 of the reticle R are so coated with the optical catalytic film 70 (Fig.6, not shown), or a non-exposure area 63 of the reticle R is so coated with the optical catalytic film 70, or both the non-exposure area 63 and the non-transmitting portions 61 of the pattern portion present in the exposure area 62 are so coated with the optical catalytic film 70 as to be able to obtain the optical catalytic effect without any loss of exposure energy. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a mask contamination that prevents a mask provided in an exposure apparatus for manufacturing a semiconductor element or a liquid crystal display element by using a lithography technique from being contaminated by an impurity gas component in an atmosphere near the mask. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prevention method, a mask contamination prevention apparatus, an exposure apparatus that uses a mask that is prevented from contamination by the mask contamination prevention method, and an exposure apparatus equipped with the mask contamination prevention apparatus.

Conventionally, when a semiconductor element or a liquid crystal display element is manufactured using a lithography technique, an exposure illumination light (exposure light) is irradiated onto a reticle as a mask on which a pattern is formed, and an image of the pattern of the reticle is obtained. An exposure apparatus is used that projects and exposes a photosensitive substrate such as a semiconductor wafer or glass template coated with a photosensitive agent such as a photoresist via a projection optical system. In recent years, along with the demand for miniaturization of the pattern shape projected on the shot area on the substrate, the exposure light used tends to be shortened in wavelength. Instead of the conventional mercury lamp, KrF (krypton fluorine) is used. ) Exposure apparatuses using excimer laser (248 nm) and ArF (argon fluorine) excimer laser (193 nm) are being put into practical use. Development of an exposure apparatus using an F ₂ (fluorine) laser (157 nm) has also been promoted with the aim of further miniaturizing the pattern shape.

  When such exposure light with a shorter wavelength is used, a chemically amplified resist to which a photoacid generator is added is the mainstream as a resist to be applied on the substrate. This chemically amplified resist forms a pattern due to sensitization by generating acid during exposure, and if there is an alkali component such as ammonia in the atmosphere, it will be neutralized with the oxygen generated by this alkali component. There is a problem that hinders pattern formation.

In addition, when the wavelength of exposure light is shortened and there is an impurity gas containing oxides such as all organic components and ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) in the atmosphere of the exposure apparatus, these organic components and oxides The photochemical reaction is caused by the energy from the exposure light, and it may be deposited on the lens or the like. When this amount of deposition and adhesion reaches a certain amount, for example, in an illumination optical system, the illuminance decreases and the scattered light increases.

  For this reason, in the exposure apparatus, an illumination optical system, a reticle stage, a projection optical system, a wafer stage, etc. are accommodated in a chamber with an air conditioner to perform environmental control (cleanness, temperature, pressure). The chamber is equipped with a chemical filter for removing impurity gas components and a ULPA filter (Ultra Low Penetration Air filter) for removing particles, and the cleanliness of the gas circulating in the chamber is kept almost constant. Yes.

  For example, in the vicinity of a wafer coated with a resist (wafer atmosphere), circulating air that has passed through a chemical filter for alkali removal is supplied and neutralized with oxygen generated by an alkali component to inhibit pattern formation. Is preventing. In the illumination optical system and the projection optical system, the optical path atmosphere is replaced with a clean inert gas to protect it from contamination by impurity gases.

  On the other hand, with respect to the reticle, the surface on which the pattern is formed or both surfaces of the reticle are protected by a pellicle that is a dust-proof cover so that particles do not adhere to the reticle surface. No measures were taken.

  In other words, the reticle is protected from the particles by the pellicle in the environment where the particles are removed from the gas circulating in the chamber by the ULPA filter provided in the air conditioner or the chamber. Since it is temporarily removed by an air conditioner or a chemical filter provided in the chamber, impurity gas is not further removed in the vicinity of the reticle (in the reticle atmosphere).

  This is because the reticle is mounted on the reticle stage, and it is difficult to replace the reticle atmosphere with a clean inert gas as in the illumination optical system and projection optical system described above, and a reticle pattern is formed. This is because it was thought that there would be no inconvenience if the surface to be protected was protected with a pellicle.

  Impurity gas present in the reticle atmosphere causes photochemical reaction due to exposure light, and when impurities are deposited and deposited on the light transmission part of the reticle, even if it is slight, it is transferred to the resist as it is. Was considered to be negligible as compared to the case where the film adheres to the reticle.

  However, with the demand for further miniaturization of the pattern shape, there is a situation that cannot be ignored if even a small amount of impurities are deposited and deposited on the reticle. For example, in an exposure apparatus that uses an ArF excimer laser as exposure light, there is a light transmissive portion having a very narrow width of less than 1 μm on the reticle. It becomes a transmissive part and is transferred to the resist, causing a pattern defect.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a mask contamination prevention method and a mask contamination prevention device for preventing a reticle mask from being contaminated by an impurity gas.

  It is another object of the present invention to provide an exposure apparatus using a mask in which contamination is prevented by a mask contamination prevention method and an exposure apparatus equipped with the mask contamination prevention apparatus.

  The mask contamination prevention method according to claim 1 of the present invention, which achieves the above object, prevents a mask on which an exposure transfer pattern is formed, which is disposed in an environmentally controlled chamber, from being contaminated by an impurity gas. A method for preventing mask contamination, characterized in that the concentration of impurity gas around the mask is controlled to a predetermined value or less.

In the mask contamination prevention method according to claim 1, when the impurity gas is an oxide, the air concentration of the oxide is controlled to 0.1 μg / m ³ or less (claim 2).

Examples of the oxide include oxides containing sulfur oxide (SOx) or sulfate ions (SO ₄ ²⁻ ) (Claim 3).

Further, in the mask contamination prevention method according to claim 1, when the impurity gas is an organic substance, the total amount of organic substances in the atmosphere around the mask is controlled to 1.0 μg / m ³ or less (benzene molecule or more, toluene equivalent value). (Claim 4).

  In the mask contamination prevention method according to claim 1, there is a photocatalyst film 70 as one of means for controlling the concentration of the impurity gas around the mask to a predetermined value or less (claim 5). The photocatalyst film 70 exhibits a photocatalytic effect by exposure light applied to the mask to expose and transfer the pattern onto the substrate to be exposed, decomposes and removes the impurity gas, and prevents impurities from depositing and adhering to the mask. .

  The photocatalytic film is formed, for example, in a non-transmission portion 65 of the mask through which the exposure light is not transmitted (Claim 6), or formed in a non-pattern portion of the mask where the pattern is not formed. (Claim 7).

  The photocatalyst film is formed on the inner wall surface of a dust-proof cover frame (pellicle frame) 51 between the mask and the dust-proof cover (pellicle film) 52 of the mask, where the exposure light irradiated on the mask is reflected and scattered. (Claim 8).

  Examples of the photocatalyst 70 include titanium oxide.

  2. The mask contamination prevention method according to claim 1, wherein the impurity gas around the mask is disposed in the supply passage 27 as another means for controlling the concentration of the impurity gas below a predetermined value to supply a purified gas around the mask. There is a chemical filter 35 for removing an acid component (claim 10).

  2. The mask contamination prevention method according to claim 1, wherein the mask is a mask mounted on a mask stage RS of the exposure apparatus main body 11 (claim 11) or a mask mask disposed in the chamber 20. A mask stored in the storage chamber 40 (claim 12) is also included.

  The mask contamination prevention apparatus according to claim 13 of the present invention is a contamination prevention device for a mask on which an exposure transfer pattern is formed, which is disposed in an environmentally controlled chamber 20, and includes impurities around the mask. Impurity gas concentration control means for controlling the gas concentration to a predetermined value or less is provided in the mask or an arbitrary portion around the mask.

  14. The mask contamination prevention apparatus according to claim 13, wherein the impurity gas concentration control means includes a photocatalyst film 70. The photocatalyst film 70 is a non-transmissive portion 65 of a mask through which exposure light does not pass, and a mask on which no pattern is formed. Or at least one part of an inner wall surface portion of a dust-proof cover frame (pellicle frame) 51 disposed between the mask and a dust-proof cover (pellicle film) 52 of the mask (claims) Item 14).

  The mask contamination prevention apparatus according to claim 15 of the present invention is a contamination prevention device for a mask on which an exposure transfer pattern is formed, which is disposed in an environmentally controlled chamber 20, and is an impurity around the mask. Impurity gas concentration control means for controlling the gas concentration below a predetermined value is provided in the supply passage 27 for supplying the purified gas around the mask.

  As the impurity gas removing means, an acid component removing chemical filter 35 is used (claim 16).

  An exposure apparatus according to claim 17 of the present invention includes an exposure apparatus main body 11 that irradiates a mask with exposure light and exposes and transfers a pattern formed on the mask onto a substrate to be exposed in an environmentally controlled chamber 20. In the arranged exposure apparatus 10, the mask is prevented from being contaminated by the mask contamination preventing method according to any one of claims 1 to 12.

  The exposure apparatus according to claim 17, wherein a mask storage chamber 40 of the mask is disposed in the chamber 20, and the mask in the mask storage chamber 40 is mask contamination according to any one of claims 1 to 12. Contamination can be prevented by the prevention method (claim 18).

  An exposure apparatus according to claim 19 of the present invention includes an exposure apparatus main body 11 that irradiates a mask with exposure light and exposes and transfers a pattern formed on the mask onto a substrate to be exposed in an environmentally controlled chamber 20. The arranged exposure apparatus is provided with the mask contamination prevention apparatus according to any one of claims 13 to 16.

  The exposure apparatus according to claim 19, wherein a mask storage chamber 40 of the mask is disposed in the chamber 20, and the mask contamination prevention apparatus according to any one of claims 13 to 16 is provided in the mask storage chamber 40. Equipped to prevent contamination of the mask in the mask storage chamber from the impurity gas (claim 20).

  According to the present invention as set forth in claims 1 and 13, since the concentration of the impurity gas around the mask is controlled to a predetermined value or less, the contamination of the mask by the impurity gas is reduced as much as possible. Can be prevented from depositing and adhering to the mask, there is no risk of mask failure, and the yield of products can be improved.

According to the second aspect of the present invention, when the impurity gas is an oxide, the air concentration of the oxide is controlled to be 0.1 μg / m ³ or less. Contamination can be reduced as much as possible to prevent the oxide from depositing and adhering to the mask, and there is no risk of mask failure, and the yield of products can be improved.

According to the fourth aspect of the present invention, when the impurity gas is an organic substance, the total amount of organic substances in the atmosphere around the mask is controlled to 1.0 μg / m ³ or less (above benzene molecules, toluene equivalent value). As a result, it is possible to reduce the contamination of the mask by organic matter as much as possible, prevent the organic matter from precipitating and adhering to the mask, there is no possibility of mask failure, and the product yield can be improved. Is possible.

  According to the inventions of claims 5 and 14, since the impurity gas is decomposed and removed by the photocatalyst film 70, the impurity gas in the mask atmosphere can be easily decomposed and removed, and contamination of the mask by the impurity gas is possible. As much as possible, impurities can be prevented from precipitating and adhering to the mask, there is no risk of mask failure, and the yield of products can be improved. Also, a photocatalytic film can be applied to the mask itself, or it can be applied to a dust-proof cover frame (pellicle frame) 51 that protects the mask from particles, so that no structural member is required.

  According to the invention described in claim 10, 15 or 16, the concentration of impurity gas around the mask is provided by disposing the chemical filter 35 for acid component removal in the supply passage 27 for supplying the purified gas around the mask. Is controlled to a predetermined value or less, contamination of the mask by impurity gas is reduced as much as possible, and impurities can be prevented from precipitating and adhering to the mask. It is possible to improve the product yield. In addition, it is possible to use existing equipment, and cost can be reduced.

  According to the invention described in claim 17, since the mask is prevented from being contaminated by impurity gas by the mask contamination prevention method according to any one of claims 1 to 12, the mask defect is prevented and the product yield is reduced. It is possible to improve.

  According to the nineteenth aspect of the present invention, since the mask contamination prevention device according to any one of the thirteenth to sixteenth aspects is provided, it is possible to prevent mask defects and improve the product yield. It is.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a mask contamination prevention method and apparatus according to the present invention and an exposure apparatus in which mask contamination is prevented by the mask contamination prevention method and apparatus will be described below with reference to FIGS.

  FIG. 1 is an overall configuration diagram showing a first embodiment of an exposure apparatus in which mask contamination is prevented by the mask contamination prevention method and apparatus of the present invention, and FIG. 2 is equipped on a reticle as a mask of the exposure apparatus of FIG. 3 is an exploded perspective view of the pellicle, FIG. 3 is a cross-sectional view of the reticle and the pellicle, FIG. 4 is an explanatory view for explaining the light transmitting and non-transmitting portions of the reticle, and FIG. 5 is an embodiment in which a photocatalytic film is formed on the reticle itself. FIG. 6 is a side view for explaining another embodiment in which a photocatalytic film is formed on the reticle itself, and FIG. 7 is a second view of an exposure apparatus in which mask contamination is prevented by the mask contamination prevention method and apparatus of the present invention. It is a whole lineblock diagram showing an embodiment.

  The exposure apparatus 10 of the present embodiment is accommodated in a chamber 20 in which the exposure apparatus main body 11 maintains environmental conditions (cleanness, temperature, pressure, etc.) substantially constant. The chamber 20 includes an exposure chamber 21 containing the exposure apparatus main body 11, a reticle library 40 as a mask storage chamber storing a plurality of reticles R as a mask, and a reticle loader (not shown) including an articulated robot. An accommodated reticle accommodating chamber 22 is provided. The reticle loader carries the reticle R from the reticle library 40 onto the reticle stage RS of the main body portion 11, and carries the reticle R from the reticle stage RS to the reticle library 40.

  Although the case where the reticle library 40 is disposed in the reticle storage chamber 22 as a mask storage chamber has been shown, for example, a bottom open type sealed cassette (container) for storing a plurality of reticles is used instead of the reticle library 40. You may arrange.

  The exposure apparatus main body 11 holds an illumination optical system 12, a projection optical system 13 disposed below the illumination optical system 12, and a reticle R disposed between the illumination optical system 12 and the projection optical system 13. A reticle stage RS, a wafer stage WST arranged under the projection optical system 13 and holding a wafer W as a substrate, a main body column 14 holding the projection optical system 13 and mounting the wafer stage WST, etc. Prepare.

  The illumination optical system 12 includes optical components such as an optical integrator and a field stop (both not shown) in addition to the mirrors M1, M2, and M3 in the illumination system housing 15 in a predetermined positional relationship. Are connected to an excimer laser 16 as a light source, such as an ArF excimer laser (output wavelength 193 nm) or a KrF excimer laser (output wavelength 248 nm). The relay optical system includes an optical system for adjusting the optical axis between the excimer laser 16 and the illumination optical system 12, which is called a beam matching unit at least in part. The inside of the lens barrel that houses the illumination system housing 15 and the relay optical system is purged with an inert gas, respectively, and the cleanliness is maintained well.

  For example, a double-sided telecentric reduction system is used as the projection optical system 13, and the projection magnification is set to, for example, 1/4, 1/5, or 1/6. When the reticle R is illuminated by the illumination optical system 12, the pattern formed on the reticle R is reduced at the projection magnification by the projection optical system 13, and is projected and transferred onto the wafer W coated with the photoresist. Although not shown, the projection optical system 13 has a plurality of lens elements arranged along the optical axis in the lens barrel, and the interior of the lens barrel is purged with an inert gas, so that the cleanliness is kept good. Is done.

  The reticle stage RS causes the reticle R to finely move in the optical axis direction of the projection optical system 13, to move in a two-dimensional manner in the horizontal plane, and to rotate slightly by a drive system (not shown). A movable mirror that reflects a laser beam from a laser beam interferometer (not shown) is fixed to the end of the reticle stage RS. The two-dimensional position of reticle stage RS is always detected by this interferometer with a resolution of about 0.01 μm, for example.

  Wafer stage WST is driven in a two-dimensional direction in a horizontal plane by a drive system (not shown) on the stage base of main body column 14. Wafer W is fixed on wafer stage WST by vacuum suction or the like via a wafer holder (not shown). A movable mirror that reflects a laser beam from a laser light wave interferometer (not shown) is fixed on wafer stage WST. The two-dimensional position of the wafer stage is always detected by this interferometer with a resolution of about 0.01 μm, for example.

  While the outside air is introduced into the chamber 20 and sent to the exposure chamber 21 and the reticle housing chamber 22, the temperature of the fan 23 circulated in the chamber 20, the outside air taken in by the fan 23 and the gas circulated in the chamber 20. A temperature air conditioner 24 for adjusting the temperature is arranged. Further, a chemical filter 25 for removing organic components, acid components, alkali components, etc. in the outside air and a particle filter 26 for removing particles in the outside air are arranged at the outside air intake port of the chamber 20. After being cleaned through the chemical filter 25 and the particle filter 26 and adjusted in temperature by the temperature air conditioner 24, the temperature is adjusted and sent to the exposure chamber 21 and the reticle storage chamber 22, and the exposure chamber 21 and the reticle storage chamber 22 are cleaned. The temperature and temperature are kept almost constant. In addition, a filter 28 for particle removal is disposed in the supply passage 27 that feeds the gas whose temperature is adjusted in the space in the exposure chamber 21 where the reticle R is disposed. Further, a chemical filter 30 and a particle removal filter 31 are arranged in a supply passage 29 through which a gas whose temperature has been cleaned and adjusted in the space in the exposure chamber 21 where the wafer W is arranged is sent. A filter 32 for particle removal is disposed in the air supply port of the reticle storage chamber 22 through which a clean and temperature-controlled gas is supplied. A chemical filter 33 is disposed at the exhaust port of the exposure chamber 21, and a chemical filter 34 is disposed at the exhaust port of the reticle housing chamber 22, and the gas that has passed through the chemical filters 33, 34 is supplied from the outside air intake port. Along with the outside air, the air is again circulated into the exposure chamber 21 and the reticle storage chamber 22 by the fan 23.

  In addition, by using a filter that removes alkali components as the chemical filter 30 disposed in the supply passage 29 that feeds the gas whose temperature is adjusted in the space in which the wafer W is disposed in the exposure chamber 21, Even when a chemically amplified resist is used as the resist applied to the wafer W, it is possible to prevent the oxygen and alkali components of the resist generated by exposure from reacting and neutralizing, thereby preventing pattern formation from being inhibited.

  As shown in FIGS. 2 and 3, a pellicle film 52 as a dust-proof cover attached to a pellicle frame 51 as a dust-proof cover frame so as to cover the pattern surface of the reticle R is adhered on both surfaces of the reticle R. The configured pellicles 50 are respectively arranged to further protect the reticle R on the reticle stage RS in the exposure chamber 21 in which the particles are removed and the cleanliness is maintained almost constant from the particles.

  If particles adhere to the pattern surface of the reticle R, for example, a light transmission portion, this becomes a non-transmission portion and is transferred to the resist applied to the wafer W, causing a pattern defect. Since the pattern surface is covered, particles around the reticle R do not adhere to the pattern surface, and the cause of pattern defects can be eliminated. Note that even if particles adhere to the pellicle film 52, the particles do not form an image on the wafer W, which does not cause a pattern defect.

  The pellicle frame 51 is a rectangular frame and is made of, for example, an aluminum alloy. The entire surface of the pellicle frame 51 is, for example, anodized so as to prevent cracks on the surface of the frame so that no dust is generated from the surface of the frame.

  The pellicle film 52 is formed of, for example, a fluorine polymer film having high and stable light transmittance and durability against the exposure light from the excimer laser 16. A non-reflective coating is applied to both surfaces of the pellicle film 52.

  As an adhesive that bonds the pellicle film 52 to the pellicle frame 51, for example, a fluorine-based adhesive is used. In order to fix the pellicle frame 51 to the reticle R, for example, an adhesive tape or a silicone-based adhesive having excellent adhesion and removability is used.

  A hole 53 is formed at an appropriate location of the pellicle frame 51 in order to relieve the pressure difference between the space sandwiched between the reticle R and the pellicle film 52 and the outside of the space. The bulge and the dent 52 can be immediately recovered. A filter 54 for removing particles is attached to the hole 53 so that particles do not enter the pellicle 50 through the hole 53.

  As shown in FIG. 4, the reticle R has an exposure area 62 that is irradiated with exposure light and a non-exposure area 63 that is located outside the exposure area 62 and is not irradiated with exposure light.

  In this exposure area 62, as shown in FIG. 3, a pattern portion formed of a thin film layer made of metal chromium or the like is formed. That is, in the exposure area 62, the non-transmission part 61 by the pattern part and the light transmission part 60 between the pattern parts are formed.

  In the present embodiment, the exposure light is used to further prevent the reticle R held on the reticle stage RS in the exposure chamber 21 where the cleanliness is held almost constant from being contaminated by the impurity gas. A photocatalytic film 70 that exhibits a photocatalytic effect by ultraviolet rays is used, and the impurity gas around the reticle R is decomposed and removed by the photocatalytic film 70.

  The photocatalyst can decompose and remove organic substances, sulfur oxides (SOx), nitrogen oxides (NOx), etc., and the photocatalytic film 70 made of this photocatalyst exhibits a photocatalytic effect by ultraviolet rays as exposure light, Any material can be used as long as it decomposes and removes the impurity gas. As a photocatalyst material constituting the photocatalyst film 70, a semiconductor material is usually effective, can be easily obtained, and has good workability. .

As a photocatalyst material, for example, Se, Ge, Si, Ti, Zn, Cu, Al, Sn, Ga, In, P, As, Sb, C, Cd, S, Te, Ni, Fe, Co, Ag, Mo, Any of Sr, W, Cr, Ba, Pb, etc., or these compounds (AlP, AlAs, GaP, AlSb, GaAs, InP, GaSb, InAs, InSb, CdS, CdSe, ZnS, MoS ₂ , WTe ₂ , Cr ₂ Te ₃ , MoTe, Cu ₂ S, WS ₂ ), or alloy, or oxide (TiO ₂ , Bi ₂ O ₃ , CuO, Cu ₂ O, ZnO, MoO ₃ , InO ₃ , Ag ₂ O, PbO, SrTiO 3) ₃ , BaTiO ₃ , Co ₃ O ₄ , Fe ₂ O ₃ , NiO) are known, and these can be used alone or in combination of two or more.

Among the photocatalytic materials described above, titanium dioxide (TiO ₂ ), which is a titanium oxide, is preferable. When the photocatalyst film 70 is formed of this titanium dioxide, there is a strong photo-oxidation power (organic substance decomposition function, oxidative decomposition function). For example, an organic component is decomposed into carbon dioxide and water, and an organic pollutant gas is formed on the reticle R. Prevents components from precipitating and adhering. In addition, it is possible to improve the photocatalytic effect, for example, the decomposition | disassembly effect | action of an organic component, by adding Pt, Ag, Pd etc. to the photocatalyst material mentioned above.

In this embodiment, the photocatalytic film 70 is coated (formed) on the reticle R itself. However, since the photocatalyst film 70 absorbs exposure light, the illuminance is lowered by the photocatalyst film 70 and the productivity may be lowered. For example, when an ArF excimer laser (output wavelength: 193 nm) is irradiated onto a photocatalyst film 70 made of titanium oxide (TiO ₂ ) and having a thickness of 40 nm to 50 nm, the light absorptance is about 65%. Therefore, although the photocatalytic film 70 can be coated on both the exposure area 62 and the non-exposure area 63 of the reticle R as shown in FIG. 5, there is no exposure energy loss as shown in FIG. It is preferable to coat the photocatalytic film 70 on the non-transmissive portion 61 as the pattern portion in the 62. The non-exposure area 63 may be coated with the photocatalyst film 70. In this case, the exposure light is not directly irradiated to the non-exposure area 63, but the reflected light or scattered light of the exposure light irradiated to the exposure area 62 is reflected. Since the photocatalyst film 70 is coated on the non-exposed area 63, the photocatalyst film 70 is irradiated with reflected light and scattered light of the exposure light, and the photocatalytic effect can be exhibited. It is also preferable to coat the photocatalytic film 70 on both the non-exposure area 63 and the non-transmissive portion 61 of the pattern portion in the exposure area 62. That is, this case is preferable because the photocatalytic film 70 is coated on the reticle R in a manner that can obtain the photocatalytic effect without losing exposure energy (without reducing productivity).

In this embodiment, since the photocatalyst film 70 is coated on the reticle R itself as described above, an impurity gas containing impurities such as organic substances contained in the outside air and not removed by the chemical filter 25, Impurities such as organic matter remaining in the gas circulating in the chamber 20 and not removed by the chemical filter 33 provided at the exhaust port of the exposure chamber 21 or the chemical filter 34 provided at the exhaust port of the reticle storage chamber 22 When the reticle R is irradiated with exposure light even when an impurity gas containing impurities such as organic substances due to degassing generated in the exposure apparatus main body 11 is present in the reticle atmosphere. The photocatalytic film 70 exhibits a photocatalytic effect by this exposure light, and impurities such as organic substances (general organic components and ammonium sulfate (NH ₄ ) ₂ SO ₄ ) and the like.

For example, the total amount of organic substances in the atmosphere of the reticle atmosphere can be reduced (controlled) to 1.0 μg / m ³ or less (above benzene molecules, converted to toluene). In addition, the concentration of oxides such as sulfur oxides (sulfur oxide SOx) and sulfate ions (SO ₄ ²⁻ ) in the gas near the reticle R (reticle atmosphere) is reduced to 0.1 μg / m ³ or less (control) )

  Therefore, impurities in the impurity gas do not precipitate and adhere to the reticle R, and pattern defects transferred to the resist can be avoided. Further, the impurities in the impurity gas cause the light transmitting portion 60 of the reticle R to be fogged, causing no loss of light transmittance, and there is no possibility of reducing productivity.

  Further, it is only necessary to coat the photocatalyst film 70 on the reticle R, it is not necessary to provide any equipment, it is economical, and it can be applied to an existing exposure apparatus.

  Further, if the photocatalyst film 70 is coated by selecting a portion where the light transmittance loss such as the non-transmissive portion 61 of the reticle R does not occur, the productivity is not affected at all.

  In this embodiment, the case where the photocatalyst film 70 is coated on the reticle R itself has been described. However, for example, the photocatalyst film 70 may be coated on the inner peripheral surface of the pellicle frame 51 (see FIG. 3). Although the exposure light is not directly irradiated to the inner peripheral surface of the pellicle frame 51, reflected light and scattered light of the exposure light are irradiated. Therefore, if a photocatalytic film 70 is coated on the inner surface, a photocatalytic effect is expected. Can do. Further, there is no reduction in productivity due to loss of light transmittance (light absorption) of exposure light. Further, the workability is excellent as compared with the case where the photocatalyst film 70 is coated on the reticle R itself.

  FIG. 7 shows another embodiment of the exposure apparatus in which the mask contamination is prevented by the mask contamination prevention method and apparatus of the present invention. In the figure, the same components as those shown in FIG.

  In the present embodiment, the reticle R in the exposure chamber 21 is arranged in order to prevent the reticle R held on the reticle stage RS and the reticle R stored in the reticle library 40 from being contaminated by impurity gas. In addition to the particle filter 28 for particle removal, a chemical filter 35 for acid component removal is disposed in the supply passage 27 for sending the gas that has been cleaned and temperature-adjusted into the space. In addition to the particle filter 32 for removing particles, a chemical filter 36 for removing acid components is disposed at an air supply port for feeding a clean and temperature-controlled gas into the reticle housing chamber 22. In order to prevent particles generated from the chemical filters 35 and 36 from adhering to the reticle R, the chemical filters 35 and 36 are preferably disposed outside the particle filters 28 and 32.

In the present embodiment, the space near the reticle R in the exposure chamber 21 and the interior of the reticle storage chamber 22 in which the cleanliness and the like are maintained substantially constant are further cleaned by the chemical filters 35 and 36 for removing the acid components, and the reticle stage. Reticle R on RS and reticle R in reticle library 40 are reduced to 0.1 μg / m ³ or less in the air concentration of acid components, particularly ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), which are the main factors of reticle contamination. Reduced (controlled) to prevent contamination by impurity gas.

  Examples of the chemical filters 35 and 36 include an ion exchange resin membrane type and an activated carbon base type, and an EPIX filter (trade name) manufactured by Ebara Manufacturing Co., Ltd. and a Gigasorb (trade name) manufactured by Nitta Co., Ltd. are available. is there.

The chemical filters 35 and 36 may be combined with a chemical filter for removing organic components, a chemical filter for removing alkaline components, or the like. As a result, in addition to the acid component, the total amount of organic matter in the atmosphere near the reticle R is set to 1. It becomes possible to reduce to 0 μg / m ³ or less (a benzene molecule or more, a toluene conversion value) or to reduce an alkali component.

  In the first embodiment shown in FIG. 1, the particle filter 28 is arranged, and in the second embodiment shown in FIG. 7, the particle filter 28 and the chemical filter 35 are arranged in the vicinity of the reticle stage RS. The atmosphere is filled with gas that has passed through the particle filter 28 and / or the chemical filter 35.

  In the first and second embodiments described above, the particle filter 28 and / or the chemical filter 35 are arranged at one location in the vicinity of the reticle stage RS, and the atmosphere of the reticle stage RS is passed through the particle filter 28 and the chemical filter 35. However, the arrangement of the particle filter 28 and / or the chemical filter 35 is not limited to one place, and may be provided at a plurality of places. For example, in FIG. 1 and FIG. 7, if the particle filter 28 and / or the chemical filter 35 are arranged in the left-right direction of the drawing, they are arranged in a direction perpendicular to the drawing (up-down direction or front-rear surface direction). Also good. The arrangement of the particle filter 28 and / or the chemical filter 35 is such that the gas flow that has passed through the particle filter 28 and / or the chemical filter 35 is substantially parallel to the optical axis of the interferometer that measures the position of the reticle stage RS. You may set as follows.

  In the first embodiment shown in FIGS. 1 to 6, the photocatalyst film 70 prevents contamination of the reticle R on the reticle stage RS by the impurity gas in the reticle atmosphere. The reticle R stored in the 40 may also be prevented from being contaminated by the impurity gas by the photocatalyst film 70. In this case, each reticle R itself stored in the reticle library 40 is coated with the photocatalyst film 70, or the inner wall of the reticle library 40 is coated with the photocatalyst film 70, and the reticle library 40 is irradiated with ultraviolet rays.

  In the first embodiment shown in FIGS. 1 to 6, the photocatalyst film 70 is used, and in the second embodiment shown in FIG. 7, chemical filters 35 and 36 are used to introduce impurities in the reticle atmosphere. Although the case where the contamination of the reticle R by the gas is prevented has been shown, the reticle R due to the impurity gas in the reticle atmosphere using both the photocatalyst film 70 of the first embodiment and the chemical filters 35 and 36 of the second embodiment. Contamination may be prevented. In the case of the photocatalyst film 70, the photocatalytic effect can be exhibited and decomposed and removed only while the exposure light is irradiated. However, the impurity cannot be decomposed and removed while the exposure light is not irradiated. By combining with the chemical filters 35 and 36 that can remove impurities regardless of the condition, the reticle R can be surely protected from contamination by the impurity gas at all times.

  Further, a chemical filter for removing impurity gas may be disposed in the hole 53 provided in the pellicle frame 51 together with the filter 54 for removing particles. In this case, there is a possibility that particles generated from the chemical filter may adhere to the pattern 61 of the reticle R, so that the chemical filter is arranged outside and the particle removal filter 54 is arranged inside or the chemical filter is produced. It is preferable to cover with a non-woven fabric for dust protection. In addition, filters for organic component removal, acid component removal, and alkali component removal may be used in combination as chemical filters, thereby reducing contamination from organic components, acids, and alkali components. It is. As the chemical filter, an ion exchange resin membrane type, an activated carbon base type, or the like can be used in the same manner as the chemical filters 35 and 36 described above.

1 is an overall configuration diagram showing a first embodiment of an exposure apparatus in which mask contamination is prevented by the mask contamination prevention method and apparatus of the present invention.

FIG. 2 is an exploded perspective view of a pellicle mounted on a reticle as a mask of the exposure apparatus in FIG. 1.

It is sectional drawing of a reticle and a pellicle.

It is explanatory drawing explaining the light transmission part, non-transmission part, etc. of a reticle.

It is explanatory drawing explaining one Embodiment which formed the photocatalyst film | membrane in the reticle itself.

It is a side view explaining other embodiment which formed the photocatalyst film | membrane in the reticle itself.

It is a whole block diagram which shows 2nd embodiment of the exposure apparatus which prevented the contamination of the mask with the mask contamination prevention method and apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Exposure apparatus 11 Exposure apparatus main-body part 20 Chamber 21 Exposure room 22 Reticle room 27 Supply path 28, 29 Particle filter 35, 36 Chemical filter 40 Reticle library 50 Pellicle 51 Pellicle frame 52 Pellicle film 60 Light transmission part 61 Non-transmission part 62 Exposure Area 63 Non-exposure area 70 Photocatalyst film R Reticle W Wafer

Claims (20)

A mask contamination prevention method for preventing a mask, on which an exposure transfer pattern is formed, placed in an environmentally controlled chamber from being contaminated by an impurity gas,
A mask contamination prevention method, wherein the concentration of impurity gas around the mask is controlled to a predetermined value or less. In the mask contamination prevention method of Claim 1,
A mask contamination prevention method, wherein the impurity gas is an oxide, and the air concentration of the oxide is controlled to 0.1 μg / m ³ or less. In the mask contamination prevention method of Claim 2,
The mask contamination prevention method, wherein the oxide is an oxide containing sulfur oxide (SOx) or sulfate ion (SO ₄ ²⁻ ). In the mask contamination prevention method of Claim 1,
A mask contamination prevention method, wherein the impurity gas is an organic substance, and the total amount of organic substances in the atmosphere around the mask is controlled to 1.0 μg / m ³ or less (benzene molecule or more, toluene equivalent value). In the mask contamination prevention method as described in any one of Claims 1 thru | or 4,
The impurity gas is decomposed and removed by a photocatalytic film exhibiting a photocatalytic effect by exposure light irradiated on the mask in order to cause the pattern to be exposed and transferred to an exposed substrate, and the concentration of the impurity gas around the mask is set to a predetermined value. A mask contamination prevention method comprising the following control. In the mask contamination prevention method according to claim 5,
A mask contamination prevention method, wherein the photocatalyst film is formed on a non-transmissive portion of the mask through which the exposure light does not pass. In the mask contamination prevention method according to claim 5,
The mask contamination prevention method, wherein the photocatalyst film is formed in a non-pattern portion where the pattern of the mask is not formed. In the mask contamination prevention method according to claim 5,
A mask contamination prevention method, wherein the photocatalyst film is formed on an inner wall surface of a dustproof cover frame between the mask and a dustproof cover of the mask. In the mask contamination prevention method according to any one of claims 5 to 8,
A method for preventing mask contamination, wherein the photocatalyst is titanium oxide. In the mask contamination prevention method as described in any one of Claims 1 thru | or 4,
The impurity gas is removed by an acid component removing chemical filter disposed in a supply passage for supplying a purified gas around the mask, and the impurity gas concentration around the mask is controlled to be a predetermined value or less. Mask contamination prevention method characterized by In the mask pollution prevention method according to any one of claims 1 to 10,
A mask contamination prevention method, wherein the mask is a mask mounted on a mask stage of an exposure apparatus main body, which is disposed in the chamber and exposes and transfers the pattern onto a substrate to be exposed. In the mask pollution prevention method according to any one of claims 1 to 10,
A mask contamination prevention method, wherein the mask is a mask stored in a mask storage chamber of the mask, which is disposed in the chamber. An anti-contamination device for a mask having a pattern for exposure transfer formed in an environmentally controlled chamber,
An apparatus for preventing contamination of a mask, characterized in that an impurity gas concentration control means for controlling the concentration of impurity gas around the mask to a predetermined value or less is provided at the mask or an arbitrary portion around the mask. The mask contamination prevention apparatus according to claim 13,
The impurity gas concentration control means is a photocatalytic film that exhibits a photocatalytic effect by exposure light that irradiates the mask to decompose and remove impurity gas around the mask,
The photocatalytic film is a non-transparent portion of the mask through which the exposure light is not transmitted, a non-pattern portion of the mask where the pattern is not formed, or a dust-proof cover disposed between the mask and the dust-proof cover of the mask A mask contamination prevention device, characterized in that the mask contamination prevention device is formed on at least one of the inner wall surfaces of the frame. An anti-contamination device for a mask having a pattern for exposure transfer formed in an environmentally controlled chamber,
Mask contamination prevention characterized in that an impurity gas concentration control means for controlling the concentration of impurity gas around the mask to a predetermined value or less is provided in a supply passage for supplying a purified gas around the mask. apparatus. The mask contamination prevention apparatus according to claim 15,
The mask contamination prevention apparatus, wherein the impurity gas removing means is a chemical filter for removing acid components. In an exposure apparatus in which an exposure apparatus main body for irradiating a mask with exposure light and exposing and transferring a pattern formed on the mask to an exposure substrate is disposed in an environmentally controlled chamber.
An exposure apparatus, wherein the mask is prevented from being contaminated by the mask contamination prevention method according to any one of claims 1 to 12. The exposure apparatus according to claim 17, wherein
A mask storage room for storing the mask is disposed in the chamber,
An exposure apparatus, wherein the mask in the mask storage chamber is prevented from being contaminated by the mask contamination prevention method according to any one of claims 1 to 12. In an exposure apparatus in which an exposure apparatus main body for irradiating a mask with exposure light and exposing and transferring a pattern formed on the mask to an exposure substrate is disposed in an environmentally controlled chamber.
An exposure apparatus comprising the mask contamination prevention apparatus according to any one of claims 13 to 16. The exposure apparatus according to claim 19,
A mask storage room for storing the mask is disposed in the chamber,
An exposure apparatus, wherein the mask storage chamber is equipped with the mask contamination prevention apparatus according to any one of claims 13 to 16.

Images