JP2006088128A - Cleaning method, cleaning apparatus, exposure apparatus and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for cleaning an optical component, in each of which an organic contaminant, which can not be removed by the ultraviolet ray-used cleaning, can effectively be removed efficiently from the optical component in a short time and the temperature rising of the optical component owing to this cleaning work is hardly found. <P>SOLUTION: This cleaning method comprises the steps of: reducing the pressure in a vessel; supplying a predetermined gas in which plasma can be generated into the pressure-reduced vessel; and impressing a voltage between electrodes arranged in the vessel. The object which is to be cleaned and is arranged in the vessel is cleaned by using the plasma generated in the vessel by impressing the voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element cleaning method and a cleaning apparatus using a plasma processing apparatus suitable for surface treatment of an optical element and a holder for holding the optical element, particularly a part used in a semiconductor exposure apparatus, and more particularly, an ultraviolet ray. Optical glass lenses used in the wavelength region, optical elements in which these optical glass lenses are provided with an antireflection film or an increased reflection film, a holder for holding the optical element, and semiconductor exposure in which the optical element and the holder are integrated The present invention relates to a cleaning method for apparatus parts and a cleaning apparatus.

  Conventionally, cleaning of optical elements such as lenses and mirrors used in semiconductor exposure apparatuses and cleaning of holders for holding optical elements include ultrasonic cleaning using a neutral detergent, an alkaline detergent, an organic solvent or the like as a cleaning liquid, Wet cleaning combined with acid cleaning was the mainstream.

  These cleanings are performed for inorganic contaminants such as abrasive grains adhering when polishing optical elements such as lenses, organic contaminants such as wax used as a protective film, and metal holders that hold optical elements. Is to remove contamination caused by machining powder and lubricating oil components during machining by applying ultrasonic vibration to the cleaning liquid.

Also, UV / O ₃ cleaning using ultraviolet light, ozone, and active oxygen species in combination to remove organic contamination contaminated during storage from wet cleaning to film formation for optical glass lenses (for example, m Patent Literature 1 to 3)), and dry cleaning represented by the above-mentioned is frequently used. In particular, the removal of organic contaminants attached to the film after the film forming process that applies an antireflection film, an increased reflection film, etc. to the optical glass lens may adversely affect the optical characteristics when the wet cleaning process is performed. Therefore, it can be said that dry cleaning is an extremely effective cleaning method in this respect.
Japanese Patent Laid-Open No. 2000-66003 JP-A-11-169806 Japanese Patent Laid-Open No. 11-221536

  However, in wet cleaning and dry cleaning, the cleaning conditions differ depending on whether the optical glass lens component is cleaned or the optical glass component holder is cleaned. In addition, an adhesive or the like may be used in the assembly process for fixing the optical glass lens component and the holder, and there is a problem that both cannot be cleaned at the same time.

Also, in the assembly process of the optical glass lens component and the holder, there is a possibility that considerable organic contamination may adhere during the process work. It is also advantageous in terms of influence on performance. However, wet cleaning cannot be applied due to problems such as adverse effects on optical characteristics and deterioration of the adhesive used in the assembly process, as described above. Further, even if optical cleaning such as UV / O ₃ cleaning is performed, some organic contaminants adhering during the assembly process cannot be easily removed in a short time. In particular, the 193 nm ArF excimer laser and the 157 nm F ₂ laser wavelength region cause a significant optical absorption loss, and there is a problem that the transmittance and laser durability of the optical element are also lowered.

  Furthermore, the holder has a complicated shape such as a screw hole that cannot be cleaned due to mechanical processing. Therefore, if such contamination remains and adheres to an optical element or the like in the exposure apparatus, It becomes a factor which reduces performance remarkably.

  Further, it has been pointed out that when surface treatment of an optical component is performed using plasma, charged particles having kinetic energy collide with the glass surface and damage causing optical absorption loss occurs. In particular, in a crystalline optical glass such as fluorite used in the ultraviolet wavelength region, a color center due to a chemical dangling bond (dangling bond) is generated by breaking the chemical bond on the surface. As a result, the optical absorption loss in the ultraviolet region increases, and the transmittance of optical components such as an optical glass lens used in the semiconductor exposure apparatus deteriorates.

  The present invention has been made in view of the above circumstances, and can effectively remove organic contaminants that cannot be removed by optical cleaning in an effective manner in a short time. It is an exemplary object to provide a cleaning method and a cleaning apparatus for optical components that are hardly present.

  In order to achieve the above object, a cleaning method as an exemplary aspect of the present invention includes a step of depressurizing a container, a step of supplying a predetermined gas capable of generating plasma in the depressurized container, and a container. And applying a power to an electrode provided therein, and cleaning a target to be cleaned disposed in the container using plasma generated in the container by the power application.

  The predetermined gas may be oxygen gas or a mixed gas of oxygen gas and inert gas. The inert gas may include at least one of argon gas, krypton gas, xenon gas, radon gas, neon gas, and nitrogen gas. The cleaning target may be an optical component in which an optical element or an optical element and a holder that holds the optical element are integrated. The optical element may be an optical glass lens that can be used in an ultraviolet wavelength region of 250 nm or less, or an optical glass lens on which an antireflection film or an increased reflection film is formed.

  A cleaning apparatus according to another exemplary aspect of the present invention includes a decompression container capable of decompressing the inside, a gas supply unit that supplies a predetermined gas capable of generating plasma in the decompression container, and the decompression container. It has an electrode, a high-frequency power source for applying power to the electrode, an atmospheric pressure release means for opening the inside of the decompression vessel to atmospheric pressure, and a holding means for holding an object to be cleaned to be cleaned by plasma in the decompression vessel. To do.

  A partition plate in which a plurality of holes are formed may be disposed in the decompression vessel between the electrode and the object to be cleaned held by the holding means.

  An exposure apparatus according to still another exemplary aspect of the present invention includes an illumination optical system that guides exposure light from an exposure light source to a reticle, a reticle drive system that drives the reticle, and a projection that projects a pattern on the reticle onto a substrate. An exposure apparatus having an optical system and a substrate driving system for driving a substrate, wherein an optical element cleaned by the cleaning apparatus is used in at least one of an illumination optical system and a projection optical system. Features.

  According to still another exemplary aspect of the present invention, there is provided a device manufacturing method including a step of projecting a pattern onto a substrate by the exposure apparatus, and a step of performing a predetermined process on the substrate subjected to the projection exposure. To do.

  Other objects and further features of the present invention will be made clear by embodiments described below with reference to the accompanying drawings.

  A cleaning apparatus for realizing a cleaning method according to the present invention includes a partition plate having a plurality of holes between a high-frequency electrode and an optical component to be cleaned, in a plasma processing apparatus for performing a surface treatment of an optical component. A mechanism for generating plasma only between the electrode and the partition plate and confining the plasma in this space is provided. Thereby, the ion energy and electron temperature which cause damage can be suppressed to extremely low values of about 10 eV or less and 2 eV or less, respectively. In addition, the active oxygen species generated by the plasma can effectively remove organic contamination on the surface without damaging the optical parts, particularly the fluorite lens and the fluoride optical thin film sensitive to damage by the energy particles. Furthermore, according to the present invention, since the cleaning atmosphere is placed under reduced pressure, the holder for holding the optical component has a complicated machined shape, and adheres depending on the reduced pressure atmosphere and the active oxygen species. Even if the organic matter is a substance having a low vapor pressure, the contamination can be effectively cleaned in a short time, and the removed contamination is quickly exhausted. There is no contamination due to reattachment. In addition, when the present invention is applied to a method for cleaning a semiconductor exposure apparatus component, even if the optical glass lens and the holder for holding the optical glass lens are integrated, the optical glass lens is not damaged by plasma. In addition, the presence of active oxygen species under reduced pressure enables efficient and effective cleaning.

[Embodiment 1]
Hereinafter, the cleaning method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a plasma processing apparatus Q as a cleaning apparatus for realizing this cleaning method. Reference numeral 1 in the figure denotes a container that can be depressurized, and can be brought into a depressurized state by a pressure regulating valve 4 while exhausting air in the container 1 through an exhaust pipe 3 by an exhaust pump 2. Reference numeral W denotes a lens which is an optical element, and reference numeral 5 denotes a holder for holding the lens W. This lens is an optical element used in a semiconductor exposure apparatus. Reference numeral 6 denotes a component holder (holding means) for installing a lens W attached to and integrated with the holder 5 (hereinafter referred to as an object to be cleaned) in the vicinity of the center in the decompression vessel 1. Reference numeral 7 denotes a high-frequency power source, and high-frequency electrodes 8a and 8b and partition plates 9a and 9b are arranged on the upper surface and the lower surface of the object to be cleaned as shown in the drawing to generate plasma in the decompression vessel 1.

Reference numeral 10 denotes a gas supply unit (gas supply means) for introducing a gas to be converted into plasma (hereinafter referred to as plasma generation gas) into the decompression vessel 1 as a predetermined gas through the gas supply pipes 11a and 11b. It is. Reference numeral 12 denotes a nitrogen (N ₂ ) gas supply pipe (atmospheric pressure releasing means), and the decompression vessel 1 is opened from the reduced pressure state to the atmospheric pressure by the nitrogen gas introduced therethrough.

  The object to be cleaned (lens W and lens holder 5) is installed and fixed by the component holder 6 in the decompression container 1 opened to the atmospheric pressure. The lens W is, for example, a glass lens after wet cleaning or an optical element after an antireflection film or an increased reflection film is applied to the glass lens. The lens holder 5 is also subjected to wet cleaning.

  The decompression vessel 1 is decompressed by the exhaust pump 2 until the pressure reaches about 1 Pa or less. The decompression container 1 and each component built in it are sufficiently cleaned so that there is no contamination by organic matter having a high vapor pressure by reducing the pressure, and the exhaust pump 2 is also put into the decompression container (cleaning container) 1 for oil and fat. It has been devised so that there is no despreading.

A mixed gas (plasma generated gas) composed of oxygen (O ₂ ) gas and inert (Ar, Kr, Xe, Rn, Ne, He, N _2, etc.) gas is supplied to the gas supply pipe 11 a and the decompressed vacuum vessel 1. Through 11b, it introduce | transduces into the plasma space P of the upper surface of a washing | cleaning target, and a lower surface at a respectively predetermined flow rate. At this time, the concentration of oxygen gas contained in the plasma generation gas is adjusted by the gas supply unit 10, and the appropriate concentration is 5 to 20%. The oxygen concentration may exceed 20%, but when compared to the case of 20% or less, there is no significant difference in the cleaning effect between the two. Conversely, if there is a large amount of oxygen gas, a large amount of negative ions will be generated, which may reduce the electron density of the plasma and thus the cleaning ability.

  Ar is generally used as a gas species used for the inert gas, but for optical elements with a crystalline fluoride or fluoride optical thin film typified by fluorite, where damage or the like is a concern. , Kr and Xe are more appropriate. Further, Kr is desirable for more efficiently generating oxygen active species.

  The introduced mixed gas is exhausted by the exhaust pump 2, and pressure control is performed by the pressure regulating valve 4 connected to the exhaust pipe 3, so that the inside of the decompression vessel 1 becomes a decompressed atmosphere in which plasma can be generated. The pressure at this time is suitably about 1 to 100 Pa. Within this pressure range, plasma can be generated stably.

  Furthermore, if the pressure is within this range, it is appropriate to keep the energy of charged particles such as ion energy and electron temperature low, and when the pressure is lower than 1 Pa, the energy of charged particles increases and damages the optical element. there is a possibility. Further, under such a low pressure, the density of active oxygen species that remove organic contamination is relatively low, and the cleaning effect is reduced. When the pressure exceeds 100 Pa, the high frequency discharge becomes unstable, and the optical element is damaged by abnormal discharge or the like.

  Thereafter, high-frequency power is applied from the high-frequency power source 7 to the high-frequency electrodes 8a and 8b through the high-frequency power supply rod with a predetermined output. The frequency of the high frequency power supply is generally 13.56 MHz, but higher frequencies such as 100 MHz and 200 MHz may be used. An output of about 800 to 1500 W or less is appropriate.

  Partition plates (hereinafter referred to as perforated plates) 9a and 9b having a plurality of holes are provided between the high-frequency electrodes 8a and 8b and the object to be cleaned. The porous plates 9a and 9b are electrically grounded in the same manner as the decompression vessel 1, and can arbitrarily control the gap (plasma space) P between the high frequency electrodes 8a and 8b. Moreover, the diameter and aperture ratio of the holes of the perforated plates 9a and 9b can be arbitrarily controlled. In the first embodiment, the interval between the high frequency electrodes 8a, 8b and the porous plates 9a, 9b is 30 mm, the hole diameter is 5 mm, and the aperture ratio is 50%.

  Each parameter of such perforated plates 9a, 9b is determined while confirming the cleaning effect and the degree of damage to the object to be cleaned. Damage is likely to occur when the hole diameter or aperture ratio of the perforated plate is too large. In the case of optical glass that is not very sensitive to damage, such as synthetic quartz, it is not always necessary to install a porous plate.

  The high frequency power applied to the high frequency electrodes 8a and 8b excites the plasma generating gas introduced into the plasma space P in the decompression vessel 1, and plasma is generated between the high frequency electrodes 8a and 8b and the perforated plates 9a and 9b. Is done.

  Active oxygen species and low energy particles diffuse from the plasma generated in this way through the holes of the perforated plates 9a and 9b, reach the upper surface and the lower surface of the object to be cleaned, and adhere to the surface and machining holes of the object to be cleaned. The cleaning process for organic contamination is effectively performed in a short time. At this time, the energy (ion energy, electron temperature) of the charged particles that reach the surface to be cleaned is extremely low, the ion energy is 10 eV or less, and the electron temperature is about 2 eV or less. At such low ion energy and low electron temperature, there is no damage to the target optical lens glass, optical thin film and other optical elements, so this cleaning method is very effective in that respect.

  The distance between the perforated plates 9a and 9b facing the upper and lower surfaces of the lens W and the lens W can be arbitrarily controlled. In the first embodiment, the cleaning effect is obtained even when the distance from the lens surface is 50 mm or more. Was sufficiently high, and no damage was caused to the lens surface even when approaching 20 mm. Therefore, it is possible to deal with various shapes of lenses having different thicknesses. The cleaning process time of the lens W and the holder 5 is within about 10 minutes, and the temperature of the lens W during this time hardly increases.

  After the elapse of a predetermined cleaning time (plasma excitation time), the output of the high frequency power supply 7 is stopped and the plasma is extinguished. Thereafter, the supply of plasma generation gas is stopped, the pressure regulating valve 4 is closed, nitrogen gas is introduced from the nitrogen supply pipe 12, the pressure in the decompression vessel 1 is released to atmospheric pressure, and the cleaned lens component By removing W and the holder 5, the cleaning process is completed.

  The cleaning effect by the surface treatment using the plasma according to the present invention is low enough not to damage the optical glass element in addition to the cleaning effect by the active oxygen species that effectively decomposes organic substances on the glass lens element. It is thought that the application of kinetic energy by energetic particles acts as a synergistic effect. Regarding cleaning of lens holders with complicated processing shapes, even for large-diameter parts with a diameter of 500 mm or more to which lenses used for projection optical systems are fixed, and for various parts shapes used for illumination optical systems, The cleaning treatment can be effectively performed by the presence of the oxygen active species under reduced pressure.

  In the first embodiment of the present invention described above, not only an optical glass as an optical element or an optical glass lens substrate in which an antireflection film and an increased reflection film are formed on the optical glass, but also such a lens substrate is a holder. Therefore, the lens component immediately before being incorporated into the exposure apparatus can be efficiently and effectively cleaned. In particular, the present invention can also be applied to cleaning various machine parts used in a semiconductor exposure apparatus. Needless to say, the present invention can also be applied to parts of general optical apparatuses and devices, and can also be applied to various substrates used for semiconductor manufacturing and parts for semiconductor manufacturing apparatuses.

  Hereinafter, an example will be described in which cleaning (plasma cleaning) of components for a semiconductor exposure apparatus is actually attempted by the plasma processing apparatus Q as the cleaning apparatus described in the first embodiment.

[Example 1]
FIG. 2 is a graph showing spectral transmittance measurement results before and after plasma cleaning of the fluorite substrate. The plasma cleaning was performed with a mixed gas plasma of 20% O ₂ / Ar using the plasma processing apparatus Q shown in FIG. The pressure in the decompression vessel 1 during cleaning is 50 Pa, and the cleaning processing time is 10 minutes.

When the transmittance before cleaning in the ultraviolet wavelength region of 140 nm to 200 nm of the fluorite glass lens substrate is compared with the transmittance after plasma cleaning, the transmittance is clearly improved after plasma cleaning as can be seen from FIG. . The effect is observed not only in the 193 nm ArF laser wavelength region but also in the 157 nm F ₂ laser wavelength region. In particular, the transmittance value at 157 nm after the plasma cleaning is a value close to the theoretical transmittance considering the internal absorption of the substrate, and no damage due to charged energy particles is observed.

[Example 2]
FIG. 3 shows a film immediately after forming a 157 nm antireflection film made of a fluoride optical thin film on the fluorite substrate after plasma cleaning in Example 1, and further plasma cleaning processing after the film processing. It is a graph which shows the spectral transmission factor measurement result of what performed. The plasma cleaning after the film forming process was also performed by a mixed gas plasma of 20% O ₂ / Ar using the plasma processing apparatus Q shown in FIG. The pressure in the decompression vessel 1 during cleaning is 50 Pa, and the processing time is 10 minutes.

  When the transmittance immediately after film formation in the ultraviolet wavelength region of 140 nm to 200 nm of the fluorite substrate was compared with the transmittance after film formation and plasma cleaning, as shown in FIG. 3, there was almost no change in the transmittance. . From this, it can be seen that the plasma cleaning according to the present invention does not damage the fluoride optical thin film formed on the fluorite substrate due to the energy particles.

[Example 3]
FIG. 4 shows spectral transmittance before and after plasma cleaning of a semiconductor exposure apparatus component in which a lens element obtained by forming a 157 nm antireflection film made of a fluoride optical thin film on a fluorite substrate is bonded and fixed to a lens holder. It is a graph which shows a measurement result. The plasma cleaning was performed using a plasma processing apparatus Q shown in FIG. 1 using a mixed gas plasma of 20% O ₂ / Ar. The pressure in the decompression vessel 1 during the cleaning process is 50 Pa, and the processing time is 10 minutes.

When the transmittance before cleaning in the ultraviolet wavelength region of 140 nm to 200 nm of the semiconductor exposure apparatus component is compared with the transmittance after plasma cleaning, the transmittance is clearly improved after plasma cleaning as can be seen from FIG. . In this example 3, “before cleaning” means that the lens element after film formation is left standing while being fixed to the holder. In particular, in the 157 nm F ₂ laser wavelength region, the transmittance value after the plasma cleaning exceeds 99%, and the transmittance before the cleaning, that is, the transmission deteriorated to 98.5% or less by leaving it after film formation. It was confirmed that the rate recovered to the transmittance immediately after film formation. Moreover, although confirmed also in Example 2, it turned out that the transmittance | permeability degradation by the damage resulting from an energy particle etc. is not seen. Further, it was found that there is no influence on the transmittance by washing the lens and the holder at the same time, and no reattachment of the removed contamination is observed even when the contaminated parts are washed.

  From these results of Examples 1 to 3, the plasma cleaning according to the present invention is also applied to a lens element provided with a glass lens element or an optical thin film, and also to an exposure apparatus component in which the lens element and the holder are integrated. It became clear that it was possible.

Here, it is considered that the deterioration of the transmittance before the cleaning is mainly caused by organic contamination, but the transmittance deterioration was not recovered in a short time even when the conventional UV · O ₃ cleaning was attempted. Furthermore, not only the plasma cleaning according to the present invention is only ArF excimer laser wavelength of 193 nm, is very effective in organic decontamination of 157NmF ₂ laser wavelength near, yet know that performed in a short time of processing, optical components It was confirmed that it is advantageous not only for optical characteristics but also for improving the productivity of the exposure apparatus.

[Embodiment 2]
FIG. 5 schematically shows an exposure apparatus according to Embodiment 2 of the present invention. The exposure apparatus S is for exposing a circuit pattern on a reticle 51 serving as an exposure original onto a wafer 52 serving as an object to be processed. The exposure apparatus S includes an illumination optical system 54 that guides light from a laser light source 53 having a wavelength of 193 nm onto a reticle 51, and a projection optical system 55 that projects a circuit pattern image on the reticle 51 onto a wafer 52, for example. Is done.

  The illumination optical system 54 has a lens 54a as an optical element. The projection optical system 55 also has a lens 55a as an optical element. These lenses 54a and 55a are subjected to a plasma cleaning process by the cleaning method according to the first embodiment. Accordingly, the lenses 54a and 55a exhibit good optical performance even in the ultraviolet region, and the exposure apparatus S can perform exposure with high accuracy.

[Embodiment 3]
Next, with reference to FIGS. 6 and 7, an embodiment of a device manufacturing method using the above-described exposure apparatus S will be described. FIG. 6 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, the manufacture of a semiconductor chip will be described as an example. In step 101 (circuit design), a device circuit is designed. In step 102 (reticle fabrication), a reticle on which the designed circuit pattern is formed is fabricated. In step 103 (wafer manufacture), a wafer (substrate) is manufactured using a material such as silicon. Step 104 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the reticle and wafer. Step 105 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 104, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). . In step 106 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 105 are performed. Through these steps, the semiconductor device is completed and shipped (step 107).

  FIG. 7 is a detailed flowchart of the wafer process in Step 104. In step 111 (oxidation), the wafer surface is oxidized. In step 112 (CVD), an insulating film is formed on the surface of the wafer. In step 113 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. In step 114 (ion implantation), ions are implanted into the wafer. In step 115 (resist process), a photosensitive agent is applied to the wafer. Step 116 (exposure) uses the exposure apparatus S to expose a reticle circuit pattern onto the wafer. In step 117 (development), the exposed wafer is developed. In step 118 (etching), portions other than the developed resist image are removed. In step 119 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to the manufacturing method of the present embodiment, it is possible to manufacture a higher-quality device than before.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these, A various deformation | transformation and change are possible within the range of the summary.

The cleaning method according to the present invention is a dry cleaning technique for optical parts provided with optical glass lenses and optical thin films, and has improved optical properties and productivity compared to conventional optical cleaning represented by UV / O ₃ cleaning. It is a very effective cleaning method for improvement. The 193 nm ArF excimer laser exposure apparatus at the stage of practical use, as well as the optical components used in the 157 nm F ₂ laser exposure apparatus, which is being developed, and all parts used in the exposure apparatus are sufficiently practical as a dry cleaning technique for removing organic contaminants. It can be expected to dramatically improve the performance of the device system.

It is a block diagram which shows schematic structure of the plasma processing apparatus for implement | achieving the cleaning method which concerns on Embodiment 1 of this invention. It is a graph of Example 1 which shows the spectral transmittance measurement result before and after the plasma cleaning of the fluorite substrate. In Example 1, a film immediately after the 157 nm antireflection film made of a fluoride optical thin film was formed on the fluorite substrate after the plasma cleaning, and a plasma cleaning process after the film processing. It is a graph of Example 2 which shows a spectral transmittance measurement result. The spectral transmittance measurement results before and after plasma cleaning of a semiconductor exposure apparatus component in which a lens element obtained by forming a 157 nm antireflection film made of a fluoride optical thin film on a fluorite substrate is bonded and fixed to a lens holder are shown. 10 is a graph of Example 3. It is a block diagram which shows schematic structure of the exposure apparatus which concerns on Embodiment 2 of this invention. It is a flowchart for demonstrating the device manufacturing method by the exposure apparatus shown in FIG. It is a detailed flowchart of step 104 shown in FIG.

Explanation of symbols

P: Plasma space Q: Plasma processing apparatus S: Exposure apparatus W: Lens (optical element, part of object to be cleaned)
1: Pressure reducing container 2: Exhaust pump 3: Exhaust pipe 4: Pressure adjusting valve 5: Lens holder (holder, part of object to be cleaned)
6: Parts holder (holding means)
7: High frequency power supplies 8a, 8b: High frequency electrodes (electrodes)
9a, 9b: Perforated plate (partition plate)
10: Gas supply unit (gas supply means)
11a, 11b: Gas supply pipe 12: Nitrogen supply pipe (atmospheric pressure release means)
51: Reticle 52: Wafer (object to be processed)
53: Laser light source 54: Illumination optical system 54a, 55a: Lens 55: Projection optical system

Claims (9)

Depressurizing the interior of the container;
Supplying a predetermined gas capable of generating plasma into the decompressed container;
Applying power to the electrodes provided in the container,
A cleaning method, comprising: cleaning an object to be cleaned disposed in the container using plasma generated in the container by applying the electric power.   The cleaning method according to claim 1, wherein the predetermined gas is oxygen gas or a mixed gas of oxygen gas and inert gas.   The cleaning method according to claim 2, wherein the inert gas includes at least one of argon gas, krypton gas, xenon gas, radon gas, neon gas, and nitrogen gas.   The cleaning method according to claim 1, wherein the object to be cleaned is an optical element or an optical component in which an optical element and a holder that holds the optical element are integrated.   The cleaning method according to claim 4, wherein the optical element is an optical glass usable in an ultraviolet wavelength region of 250 nm or less, or an antireflection film or an increased reflection film formed on the optical glass. . A decompression vessel whose inside can be decompressed;
Gas supply means for supplying a predetermined gas capable of generating plasma in the decompression vessel;
An electrode provided in the vacuum vessel;
A high frequency power source for applying power to the electrode;
Atmospheric pressure release means for opening the inside of the vacuum vessel to atmospheric pressure;
A cleaning apparatus comprising: holding means for holding a cleaning object to be cleaned by the plasma in the vacuum container.   The partition plate in which a plurality of holes are formed is disposed in the decompression vessel between the electrode and the object to be cleaned held by the holding means. Cleaning device. An illumination optical system that guides the exposure light from the exposure light source to the reticle;
A reticle driving system for driving the reticle;
A projection optical system for projecting a pattern on the reticle onto a substrate;
An exposure apparatus having a substrate driving system for driving the substrate, wherein the optical element is cleaned by the cleaning device according to claim 6 or 7 in at least one of the illumination optical system and the projection optical system. An exposure apparatus characterized in that is used. Projecting and exposing a pattern on the substrate by the exposure apparatus according to claim 8;
And a step of performing a predetermined process on the projection-exposed substrate.