JP2000315645A - Optical member, its manufacture, and aligner using optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of outgassing affecting a lens characteristic by covering a face touching a space where exposure energy passes by means of the coat of metal or a ceramic, which is formed by thermal spraying. SOLUTION: A lens-barrel 16 and a connection barrel 18 are manufactured by forming base materials by adjusting them to the forms, forming alumina base films on faces touching spaces 19a and 19b on the surfaces of the base materials and forming stainless metal coats 30 by plasma thermal spraying in cold thermal spraying from above the films. Since the meal coats 30 are formed by thermal spraying, contained impurity jumps out and is removed when thermal spraying materials become a high temperature and they are coated on the lens-barrel 16 and the connection barrel 18 in the state of high purity, outgassing from the metal coat 30 itself hardly occurs and outgassing from a base material side is interrupted. Since the coat is formed by cold thermal spraying, the base material is prevented from being heated to the high temperature and thermal distortion and the like are prevented from being added to the lens-barrel 16 and the connection barrel 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member such as a lens barrel disposed in a space through which exposure energy such as exposure light passes, a method of manufacturing the same, an optical device, and an exposure apparatus using the same.

[0002]

2. Description of the Related Art In a conventional exposure apparatus, when oxygen exists in a space through which exposure light passes in an illumination optical system or a projection optical system, if exposure light using a light source such as an ArF excimer laser is used, an emission spectrum line is obtained. Overlaps with the oxygen absorption spectrum line region, so that a phenomenon occurs in which oxygen absorbs exposure light and becomes ozonized. For this reason, a fogging substance may be deposited on the surface of the optical lens, which may adversely affect the lens characteristics.
Therefore, in a conventional exposure apparatus, a part or all of a space around an optical path from a light source to a substrate to be processed is covered with a cover, and the inside of the cover is filled with a gas inert to exposure light, for example, a nitrogen gas. ing.

[0003]

However, the optical members disposed around the passage of the exposure light and supporting the optical lens and the like are made of a casting, aluminum, copper, iron or the like, and are made of anodized or painted. And the like, and fine substances (for example, impurities released from casting nests) are released as outgas (degas) from these over time, and have become impurities in the nitrogen gas. . These substances adhere to the optical lens surface and reduce the transmittance of the lens to the exposure light, and further cause a chemical change when exposed to the exposure light, and the molecule that caused the chemical change adheres to the optical lens surface, This causes a decrease in the amount of exposure light (a decrease in the transmittance of the lens).

For example, siloxane (a substance having a Si—O chain as an axis) or silazane (Si—
However, silicon-based organic substances such as a substance having an N chain as its axis), a nitrogen compound such as ammonia, and a sulfide compound pose a problem. Siloxane is contained in paints and the like, a substance called “cyclic siloxane” in which Si—O chains are looped, and this is generated as degassing due to aging. Cyclic siloxane is known to adhere well to the surface of a semiconductor substrate such as a silicon wafer or the like or the surface of a dielectric such as a lens.
When light is applied to the optical element, it is oxidized and causes clouding of the silicon oxide on the surface of the optical element.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide an optical member which does not generate outgas which affects lens characteristics, a method of manufacturing the same, an optical apparatus, and an exposure apparatus using the same. And

[0006]

The present invention has the following features to attain the object mentioned above. In other words, the optical member according to the first embodiment will be described with reference to FIGS. 1 to 3.
9a, 19b), a technique is adopted in which the surfaces of the optical members (16, 18) in contact with the space are covered with a metal or ceramic film (30) formed by thermal spraying. Further, in the method of manufacturing an optical member according to the sixth aspect, the method of manufacturing an optical member (16, 18) disposed in a space through which exposure energy (IL) passes, the mother member being adapted to the shape of the optical member. A technique including a forming step of forming a material (M) and a spraying step of forming a metal or ceramic film (30) by spraying on a surface of the base material that is in contact with the space is employed.

In these optical members and the method of manufacturing the optical members, the space (19) through which the exposure energy (IL) passes
Since the surface in contact with a, 19b) is covered with a metal or ceramic film (30) formed by thermal spraying, outgas inside the optical member is blocked by the film, and emission into the space is suppressed.

In the optical device according to the fourth aspect, the optical system (L, 4, PL) for guiding the exposure energy (IL) to a predetermined position.
An optical device (IU, PU) comprising: a space (19a, 19b) through which the exposure energy passes;
An optical member (16, 18) for holding the optical system;
The optical member employs a technology that is the optical member according to any one of claims 1 to 3.

In this optical device, the optical system (L, 4, P)
L) The optical member holding the optical member (16, 18).
Is used, it is possible to prevent the characteristics of the optical system from deteriorating due to a chemical change due to outgas from the optical member.

According to a fifth aspect of the present invention, in the exposure apparatus, the exposure energy (IL) is guided to the mask (R) to form a pattern on the mask on the surface of the substrate (W). An optical system (4) for guiding the light to the mask or an optical system (P for guiding the pattern to the substrate)
The optical member (1) according to claim 4, wherein at least one of L) is used.
The technology held in 6, 18) is adopted.

In this exposure apparatus, the exposure energy (I
At least one of an optical system (L, 4) for guiding L) to the mask (R) or an optical system (L, PL) for guiding the pattern to the substrate (W) is held by the optical member (16, 18) according to claim 4. Therefore, it is possible to prevent the characteristics of these optical systems from deteriorating due to a chemical change due to outgas from the optical member, and to maintain good exposure characteristics.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical member, a method of manufacturing the same, an optical device and an exposure apparatus using the same according to the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram schematically showing the entire configuration of an exposure apparatus according to the present embodiment, and an exposure light source 1 used.
Is far ultraviolet light (wavelength 19) by an ArF excimer laser.
(3.4 nm) of exposure light (exposure energy) IL. Exposure light IL emitted from exposure light source 1
Is transmitted through the window 2a and passes through the illumination system unit (optical device) I.
The light enters the mirror 3a in U. The exposure light IL reflected by the mirror 3a is reflected by the mirror 3b and enters the illumination optical system 4.

The illumination optical system 4 includes a relay lens, an exposure light I,
An optical integrator (such as a fly-eye lens) for making L uniform, an input lens for exposing the exposure light IL to the optical integrator, and a relay for condensing the exposure light IL emitted from the optical integrator onto a reticle (mask) R It has a plurality of lens elements such as a lens and a condenser lens.

Exposure light IL emitted from illumination optical system 4
Is reflected by the mirror 3c, passes through the window 2b, and enters the reticle R on the reticle stage RST that can move two-dimensionally. Further, the exposure light IL transmitted through the reticle R
Is a projection system unit (optical device) PU through the window 2c.
Is incident on the projection optical system PL, passes through a plurality of lens elements constituting the projection optical system PL, and is incident on the wafer (substrate) W.
Form on the surface. Each of the windows 2a, 2b, and 2c is a glass plate or the like made of quartz or the like that transmits far ultraviolet rays.

The wafer W is mounted on a wafer stage WST that can move in a three-dimensional direction (XYZ directions). The position of the wafer stage WST in the XY plane is measured by the laser interferometer 5. The wafer stage WST is stepped and moved based on the measurement value of the laser interferometer 5,
Stepping movement and exposure are repeated by a so-called stepping and repeat method, and a pattern is sequentially exposed on the wafer W.

Further, above wafer stage WST,
A light projecting system 6a and a light receiving system 6b of a focus detection system for optically detecting the height position of the wafer W are provided, and measurement light is obliquely incident on the surface of the wafer W from the light projecting system 6a. The reflected measurement light is received by the light receiving system 6b and output to the control device C. Then, the controller C detects the height position of the wafer W based on the received light receiving signal, and moves the wafer stage WST in the height direction to adjust the focus of the projection optical system PL.

As shown in FIG. 2, the illumination system unit IU and the projection system unit PU each include an inner cover 12 that covers a space around the exposure light IL that is transmitted therethrough, and an outer cover that covers the space around the inner cover 12. 13 form a double structure. Note that the inner cover 12 and the outer cover 13 in the illumination system unit IU are
The optical path of the exposure light IL up to
The inner cover 12 and the outer cover 13 in FIG.
The optical path of the exposure light IL from the lens to the lens immediately above the wafer W is sealed. Note that the reticle R and the reticle stage RST are also sealed by the sealing member 7. That is, the hatched portion in FIG. 1 is sealed from the outside.

The inside of the outer cover 13 is an airtight chamber 14 which is shielded from surrounding air. Inside the inner cover 12, each lens system 15 constituting the illumination optical system 4 or the projection optical system PL is arranged in series along the exposure light IL. Each lens system 15 includes a lens barrel (optical member)
And a plurality of lenses L serially arranged in the lens barrel 16 along the exposure light IL.

The outer peripheral portion of each of these lenses L is a lens barrel 16
Is held by a holding portion 16a provided on the inner peripheral portion of.
The inner cover 12 is provided with each lens barrel 16 and each lens barrel 16.
And a connection cylinder 18 connected between them. Inner cover 1
The inside space of the lens 2 is a lens L adjacent to each other in the lens barrel 16.
, A lens 19 held by the lens barrel 16 adjacent to the lens barrel 16, and a space 19b sandwiched by the lens L.

Each of these spaces 19a and 19b is
The inside of the inner cover 12 forms an airtight chamber 19 which is communicated with each other by a passage 20 formed in the inside 6. The airtight chamber 19 is provided inside the airtight chamber 14 inside the outer cover 13 and is isolated from the airtight chamber 14. The exposure light IL passes through each of the spaces 19a and 19b and each lens L of each lens system 15.

An optical path gas supply path 21 is connected to the inner cover 12. In the present embodiment, the optical path gas supply path 21 is connected to a predetermined connection tube 18 among the plurality of connection tubes (optical members) 18. An optical path gas is supplied to the optical path gas supply path 21 from a gas supply source 22. As the optical path gas, an inert gas inert to the exposure light IL, for example, a nitrogen gas is used.

The optical path gas is supplied from the optical path gas supply path 21 to the space 19 b in the connecting tube 18, and further passes through the passage 20 in each lens barrel 16 to each space 19 a in the lens barrel 16 and other connecting tubes 18. Is supplied to the space 19b in the inside. An airtight chamber 14 between the inner cover 12 and the outer cover 13
Is filled with a predetermined shielding gas. The shielding gas may be different from or the same as the optical path gas that fills the airtight chamber 19 inside the inner cover 12, but is preferably a clean gas from which a substance that causes contamination of the optical member is removed. For example, the optical path gas may be nitrogen gas and dry air may be used as the shielding gas, or both the optical path gas and the shielding gas may be nitrogen gas.

The outer cover 13 is connected to a shielding gas supply path 23. The shielding gas is supplied from the gas supply unit 24 to the shielding gas supply path 23. The shielding gas is supplied from the shielding gas supply path 23 to the hermetic chamber 14 between the inner cover 12 and the outer cover 13. In the shielding gas supply path 23, an impurity removing member 25 such as an impurity gas removing filter is provided at an outlet to the hermetic chamber 14. Although not shown, an impurity removing member 25 may be provided at the outlet of the optical path gas supply path 21 to the space 19 b in the connection tube 18.

In the airtight chamber 19 inside the inner cover 12, the pressure sensor 2 is connected to the connecting cylinder 18 having the optical path gas supply path 21.
6 is attached. This pressure sensor 26 detects the gas pressure in the airtight chamber 19 inside the inner cover 12,
This is output to the control device C. The shielding gas supply path 2 is provided in an airtight chamber 14 between the inner cover 12 and the outer cover 13.
The pressure sensor 27 is attached to the outer cover 13 in the vicinity of the outlet 3. The pressure sensor 27 detects the gas pressure in the airtight chamber 14 inside the outer cover 13 and controls the control device C
Is output to

The control device C controls these pressure sensors 26,
The gas pressure values calculated on the basis of the detection signal from 27 are compared, and the optical path gas supply is performed so that the pressure in the airtight chamber 19 inside the inner cover 12 is higher than the pressure in the airtight chamber 14 inside the outer cover 13. Gas supply unit 2 in road 21
2 and the driving of the gas supply unit 24 in the shielding gas supply path 23 is controlled.

In the airtight chamber 19 inside the inner cover 12, an oxygen concentration measuring sensor 28a for measuring the oxygen concentration in the airtight chamber 19 is attached to the connection tube 18.
The oxygen concentration measurement sensor 28a detects the oxygen concentration in the hermetic chamber 19 inside the inner cover 12, and outputs the oxygen concentration to the control device C. The controller C activates a buzzer (not shown) when the oxygen concentration value calculated based on the detection signal from the sensor 28a becomes equal to or higher than a certain value.

The lens barrel 16 and the connection cylinder 18 are covered with a stainless metal film 30 formed by plasma spraying, of the surfaces of the lens barrel 16 and the connection cylinder 18 that are in contact with the spaces 19a and 19b. That is, these lens barrel 16 and connecting cylinder 18
As shown in FIG. 3, the base material M (the barrel 1 before the formation of the alumina base film and the plasma spraying) is adjusted to these shapes.
6 and the connection cylinder 18), the alumina base film 30 is formed on the surface of the base material M which is in contact with the spaces 19a and 19b.
a, and a stainless steel metal film 30 is formed thereon by plasma spraying in cold spraying (at a temperature of 250 ° C. or less applied to the base material M).

As described above, since the metal film 30 is formed by thermal spraying, the impurities contained when the thermal sprayed material once becomes high in temperature are ejected and removed, and the lens barrel 16 and the connecting cylinder 18 are kept in a high purity state. Since it is coated on the upper side, almost no outgas is generated from the metal film 30 itself, and the outgas from the base material M side is shut off. Further, since the metal film 30 is formed by cold irradiation, the base material is not heated to a high temperature unlike hot spraying.
It is possible to suppress the thermal distortion or the like from being applied to the lens barrel 16 and the connection cylinder 18.

Further, in the case of plasma spraying, nests such as bubbles serving as a source of outgas are hardly generated in the metal film 30, and a good quality film can be obtained. Further, since the metal film 30 is made of stainless steel, an oxide film is formed on the surface unlike aluminum or the like, and the oxide film does not peel off and become an impurity. Before the thermal spraying, the alumina base film 30a is formed on the surface in contact with the spaces 19a and 19b.
Rather than spraying directly on the surface, the metal film 30 is formed with high adhesion and high quality.

Therefore, in the present embodiment, of the surfaces of the lens barrel 16 and the connecting tube 18, the surfaces in contact with the spaces 19a and 19b through which the exposure light IL passes are covered with the metal film 30 formed by thermal spraying. Inside tube 16 and connection tube 18
Outgas inside is blocked by the metal film 30 and the space 19 is prevented.
a, 19b. For this reason, it is possible to prevent the outgas in the nitrogen gas from chemically changing and adhering to the surface of the lens L, greatly extending the life of the lens L of the exposure apparatus, and preventing a decrease in the amount of the exposure light IL. be able to.

The present invention also includes the following embodiments. In each of the above embodiments, the coating is formed on the lens barrel holding the lens. However, the coating may be formed on other optical members arranged in the space through which the exposure light passes. For example, a coating may be formed on a plastic member such as a wiring, a harness, and a socket by thermal spraying.

Although stainless steel is used as a thermal spray material for plasma spraying, other metals such as aluminum, copper and nickel phosphorus may be used. As described above, stainless steel has an advantage that an oxide film is hardly generated. Although the metal coating is formed on the optical member surface using plasma spraying as the thermal spraying, the ceramic coating may be formed by ceramic spraying. In this case, nests of bubbles and the like, which are sources of outgas, are less likely to occur in the formed film than the metal film, and a higher quality film can be obtained. In the present embodiment, the illumination system unit IU and the projection system unit PU
In the above, the configuration in which the optical path of the exposure light is covered with the double structure has been described, but the present invention is not limited to this configuration. That is, the present invention can be applied to a lens barrel having a configuration in which the optical path of the exposure light is covered by a single layer. In addition, it is desirable to apply the thermal spraying of metal or ceramic in the present invention to a location where the overall shape is complicated and it is necessary to rely on molding such as casting. Therefore, in the present embodiment, not all surfaces in contact with the space through which exposure light passes do not need to be covered with metal or ceramic coating by thermal spraying, and at least a part of the space through which exposure light passes may be covered. . In this case, for the other part of the space through which the exposure light passes, a material in which generation of impurities is suppressed, such as a solid material such as stainless steel, which is not coated, may be used. In the present embodiment, a description has been made using nitrogen gas or dry air as the optical path gas and the shielding gas. However, an inert gas such as helium, neon, argon, krypton, xenon, and radon may be used. Also, as dry air conditions,
It is desirable that the air be a substance that causes clouding of the lens, for example, air from which ammonium ions floating in the clean room have been removed, or air having a humidity of 5% or less.
Further, as described above, the same type of gas may be used as the combination of the optical path gas and the shielding gas, or the combination may be different.

The exposure apparatus of the above embodiment can be applied to a proximity exposure apparatus that exposes a mask pattern by bringing a mask and a substrate into close contact with each other instead of a reticle without using a projection optical system. In this case, the optical member according to the present invention is employed as a member for supporting the illumination optical system. The application of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor, and is, for example, an exposure apparatus for a liquid crystal that exposes a liquid crystal display element pattern to a square glass plate, and an exposure apparatus for manufacturing a thin film magnetic head. Widely applicable to equipment.

In this embodiment, the light source of the exposure apparatus is
g-line (436 nm), i-line (365 nm), KrF excimer laser (248 nm), ArF excimer laser (1
93 nm), an F2 laser (157 nm), or a light source having a shorter wavelength. Further, the present invention can be applied to an exposure apparatus using a charged particle beam such as an X-ray or an electron beam. For example, when an electron beam is used, the configuration of an exposure apparatus uses thermionic emission type lanthanum hexaborite (LaB6) or tantalum (Ta) as an electron gun, and the optical system at that time uses an electron lens and a deflector. Is used. The optical path through which the electron beam passes is in a vacuum state. The magnification of the projection optical system may be not only a reduction system but also an equal magnification and an enlargement system.

As the projection optical system, when far ultraviolet rays such as an excimer laser are used, a material that transmits the far ultraviolet rays such as quartz or fluorite is used as a glass material, and when a F2 laser or X-ray is used, a catadioptric system or a refracting system is used. If the reticle is of a reflection type, an electron optical system including an electron lens and a deflector may be used as the optical system. It goes without saying that the optical path through which the electron beam passes is in a vacuum state.

When a linear motor (see US Pat. No. 5,623,853 or US Pat. No. 5,528,118) is used for the wafer stage or reticle stage, either an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force is used. You can. The stage may be of a type that moves along a guide or a guideless type that does not have a guide.

The reaction force generated by the movement of the wafer stage may be mechanically released to the floor (ground) using a frame member (as described in US Pat. No. 5,528,118).
The reaction force generated by the movement of the reticle stage is (US S
As described in / N 416558, a frame member may be used to mechanically escape to the floor (ground).

As described above, the exposure apparatus of the present embodiment is
Each component (e) recited in the claims of the present application (claims)
It is manufactured by assembling various subsystems including lements) so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. To ensure these various precisions,
Before and after this assembly, adjustments to achieve optical accuracy for various optical systems, adjustments to achieve mechanical accuracy for various mechanical systems, and adjustments to achieve electrical accuracy for various electrical systems Adjustments are made. The process of assembling the exposure apparatus from various subsystems includes mechanical connections, wiring connections of electric circuits, and piping connections of pneumatic circuits among the various subsystems. It goes without saying that there is an assembling process for each subsystem before the assembling process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are secured. It is desirable that the manufacture of the exposure apparatus be performed in a clean room in which the temperature, cleanliness, and the like are controlled.

For a semiconductor device, a step of designing the function and performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and a step of forming a reticle pattern by the exposure apparatus of the above-described embodiment. It is manufactured through a step of exposing a wafer, a device assembling step (including a dicing step, a bonding step, and a package step), an inspection step, and the like.

[0041]

According to the present invention, the following effects can be obtained.
According to the optical member according to the first aspect and the method for manufacturing the optical member according to the sixth aspect, the surface in contact with the space through which the exposure energy passes is covered with the metal or ceramic film formed by thermal spraying, so that the inside of the optical member is formed. Outgassing is prevented by the film to prevent the gas from being released into the space, and the release of impurities from the film itself can be suppressed. Therefore, it is possible to significantly improve the life of the lens by suppressing the adhesion of impurities to the lens or the like, and also to prevent a decrease in exposure energy such as exposure light.

According to the optical member according to the second aspect and the method for manufacturing the optical member according to the eighth aspect, since the film is a metal film formed by plasma spraying, it becomes a source of outgas in the metal film. There are few nests of bubbles and the like, and the release of impurities can be further reduced by a high quality film.

According to the optical member according to the third aspect and the method for manufacturing an optical member according to the ninth aspect, since the film is formed of stainless steel, an oxide film is not easily formed on the film surface, and the oxide film is peeled off. Can prevent the generation of impurities.

According to the optical device of the fourth aspect, since the above-mentioned optical member is used as the optical member for holding the optical system,
It is possible to prevent the characteristics of the optical system from deteriorating due to a chemical change due to outgassing from the optical member, and to improve the life of the optical system.

According to the exposure apparatus of the fifth aspect, at least one of the optical system for guiding the exposure energy to the mask or the optical system for guiding the pattern to the substrate is held by the optical member of the fourth aspect. Prevents the characteristics of these optical systems from deteriorating due to chemical changes due to outgassing,
The service life of these optical systems can be improved, and a reduction in exposure energy such as exposure light can be prevented, so that exposure can be performed efficiently.

According to the method for manufacturing an optical member of the present invention, since the thermal spraying step is performed by cold thermal spraying, the influence of thermal stress and the like is minimized as compared with hot thermal spraying in which the base material is in a high temperature state. Can be.

According to a tenth aspect of the present invention, the thermal spraying step includes a base treatment step of forming an alumina base film on a surface in contact with the space before performing the thermal spraying. Thus, the film can be formed with a higher adhesion than when sprayed directly on the substrate, and a high-quality film can be obtained.

[Brief description of the drawings]

FIG. 1 is an optical member according to the present invention and a method for manufacturing the same,
FIG. 1 is a schematic overall configuration diagram showing an exposure apparatus in an embodiment of an optical apparatus and an exposure apparatus using the same.

FIG. 2 is an optical member and a method of manufacturing the same according to the present invention;
FIG. 2 is a cross-sectional view illustrating an illumination system unit and a projection system unit in an embodiment of an optical apparatus and an exposure apparatus using the same.

FIG. 3 is an optical member and a method of manufacturing the same according to the present invention;
FIG. 4 is a cross-sectional view of a main part showing a thermal spraying procedure in an optical device and an exposure apparatus using the same in one embodiment in the order of steps.

[Explanation of symbols]

 Reference Signs List 1 exposure light source 4 illumination optical system 16 lens barrel 18 connection cylinder 30 metal film 30a alumina base film IL exposure light (exposure energy) IU illumination system unit L lens M base material PL projection optical system PU projection system unit R reticle (mask) W Wafer (substrate)

Claims (10)

[Claims] 1. An optical member disposed in a space through which exposure energy passes, wherein a surface in contact with the space is covered with a metal or ceramic film formed by thermal spraying. . 2. The optical member according to claim 1, wherein the film is a metal film formed by plasma spraying. 3. The optical member according to claim 1, wherein the film is formed of stainless steel. 4. An optical device having an optical system for guiding exposure energy to a predetermined position, comprising: an optical member arranged in a space through which the exposure energy passes and holding the optical system. An optical device, comprising the optical member according to claim 1. 5. An exposure apparatus for guiding exposure energy to a mask and forming a pattern on the mask on a substrate surface, comprising: an optical system for guiding the exposure energy to the mask or an optical system for guiding the pattern to the substrate. An exposure apparatus wherein at least one is held by the optical member according to claim 4. 6. A method for manufacturing an optical member disposed in a space through which exposure energy passes, comprising: a forming step of forming a base material according to a shape of the optical member; and a surface of the base material contacting the space. A thermal spraying step of forming a metal or ceramic film by thermal spraying. 7. The method for manufacturing an optical member according to claim 6, wherein said spraying step is performed by cold spraying. 8. The method for manufacturing an optical member according to claim 6, wherein in the thermal spraying step, a metal film is formed by plasma thermal spraying. 9. The method of manufacturing an optical member according to claim 6, wherein in the thermal spraying step, the coating is formed of stainless steel. 10. The method according to claim 6, wherein the spraying step includes a base treatment step of forming an alumina base film on a surface in contact with the space before performing the spraying. A method for manufacturing an optical member.