JPH1114876A - Optical structural body, projection exposing optical system incorporating the same and projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fluctuation of optical characteristics of an optical member due to the irradiation of a radiant beam by providing a protective member on the surface of adhesive or a filling material. SOLUTION: A quartz glass substrate 2 as optical member on which an antireflection film is formed is fixed to the fixing part 3a' formed as a stepped part on the inner wall of a lens supporting member 3' with a silicon-compound adhesive 1 and an annular stainless cover 5 covering the adhesive 1 is fixed to the supporting member 3' by screws 6. In this case, the upper surface 3b of the fixing part of the supporting member 3' is made higher than the stepped part provided at the surroundings of the quartz glass substrate 2 so that the adhesive 1 is not protruded higher than the upper surface 3b. Then, the metal of tainless whose ultraviolet ray-resistance is satistactory or the like, or ceramics of SiC or the like is used as the material of the cover 5. The cover 5 has a light shielding property preventing the adhesive 1 from being irradiated with the ultraviolet rays and it can seal the scattering of out-gas to be generated from the adhesive 1 to some extent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical structure suitable for ultraviolet irradiation and light cleaning, and an optical system for a projection exposure apparatus incorporating the same.

[0002]

2. Description of the Related Art In recent years, in order to increase the degree of integration of semiconductor devices,
There is an increasing demand for a high-resolution projection exposure apparatus for semiconductor manufacturing (hereinafter, referred to as a projection exposure apparatus). One method of increasing the resolution of photolithography by this projection exposure apparatus is to shorten the wavelength of a light source. Therefore, an exposure apparatus using an excimer laser having an oscillation spectrum in an ultraviolet region (λ ≦ 350 nm) as a light source has begun to be used.

As shown in FIG. 8, an optical member 2 (a lens, a mirror, etc.) constituting an optical system such as a projection exposure apparatus is used by being fixed to a fixing portion (step portion) 3a of an annular support member 3. However, in order to fix the outer peripheral surface of the optical member 2 to the fixing portion 3a in the support member 3, an adhesive or a filler 1 is generally used (hereinafter, these are referred to as (1 to 3) 3a)
Are collectively referred to as an “optical structure”). In particular, in the case of an optical structure used for precision equipment such as a projection exposure apparatus, the optical member 2 held by the fixing portion 3a is not deformed so that
A silicone adhesive or filler 1 is used.

[0004]

In the projection exposure apparatus and its optical system, scattering phenomena also occur in places other than a portion (light path formed by an optical member) where light passes through wave optics geometrically. Irradiates ultraviolet rays. Further, when the optical member is incorporated in a projection exposure apparatus and irradiated with ultraviolet rays, the transmittance (or reflectance) calculated from the intrinsic characteristics of the optical member cannot be achieved, or the transmittance (or reflectance) cannot be achieved. ). That is, the above-described problem occurs due to contamination of the optical member by organic substances or the like in the process of incorporating the optical member into the projection exposure apparatus.

For this reason, recently, in addition to light cleaning in a manufacturing process of an optical member, a process of assembling an optical member into a supporting member, and assembling the supporting member (a supporting member in which the optical member is incorporated) into a lens barrel. Process and its lens barrel (optical system)
Cleaning in the step of incorporating into a projection exposure apparatus, that is, an optical member in a state of being incorporated in a support member, an optical member in a state of being incorporated in a lens barrel, and an optical member in a state of being incorporated in a projection exposure apparatus The necessity of light washing has come to be shouted.

[0006] The most effective light cleaning is light cleaning using light of 185 nm and 254 nm emitted from a low-pressure mercury lamp. To briefly explain the mechanism of light cleaning, oxygen (O ₂ ) absorbs light of 185 nm and becomes active oxygen, and a part of the active oxygen reacts with oxygen to form ozone (O ₃ ). Ozone absorbs light of 254 nm and generates active oxygen and oxygen.

[0007] The organic substances on the object to be cleaned are oxidized and cleaned by the ozone and active oxygen thus generated. However, the silicon-based adhesive or filler that fixes the optical member to the fixing portion of the support member is irradiated with ultraviolet light,
When exposed to a gas such as ozone or active oxygen generated at the time of light cleaning, deterioration occurs, resulting in a decrease in adhesive strength and a change in elastic force.

[0008] Further, the deterioration of the adhesive or the filler may cause a change in the support state of the optical member or an unnecessary stress on the optical member to cause deformation. Further, when the silicon-based adhesive or filler is irradiated with ultraviolet rays or exposed to a gas such as ozone or active oxygen generated during optical cleaning, outgas is generated. Outgas (molecule) generated
Deposits (organic substances, etc.) that adhere to the optical member due to
It causes absorption of ultraviolet rays emitted from the light source.

The deposit (organic substance or the like) is formed when the outgas (molecules) adheres to the optical member, and when the outgas reacts in the gas, the reactant is formed on the optical member. Case. In particular, when used in a projection exposure apparatus that uses ultraviolet light as the exposure light, the outgassing from the silicon-based adhesive or filler irradiated with the excimer laser adheres to the surface of the optical member, thereby reducing the durability of the optical member. Causes a decline in sex.

As described above, although the silicon-based adhesive and the filler have problems in resistance to ultraviolet rays, resistance to oxidation and corrosive gas, they are used as a material for fixing an optical member to a metal or ceramic supporting member. At present, there is no material having excellent characteristics. Therefore, the present invention provides an optical member having an optical characteristic (for example, transmittance or reflectance) upon irradiation with a radiation beam (for example, a light beam having a wavelength of 350 nm or less).
It is an object of the present invention to provide an optical structure and an optical system, and a projection exposure apparatus, which can prevent the fluctuation of the image. further,
An optical member fixed to a support member or a lens barrel with an adhesive or a filler, an optical member incorporated in an optical system composed of a plurality of optical elements, and an optical member of an optical system incorporated in a projection exposure apparatus can be optically cleaned. It is another object to provide an optical structure, an optical system, and a projection exposure apparatus.

[0011]

According to the present invention, there is firstly provided an optical structure comprising at least one optical member 2 fixed to a support member 3, 3 'by an adhesive or a filler 1. A protective member 4 on the surface of the adhesive or filler 1
5 and 7 are provided.

In the optical structure according to the first aspect, since the protective member is provided on the surface of the adhesive or the filler, the light beam in the ultraviolet wavelength range is not irradiated on the adhesive or the filler. Therefore, generation of outgas from the adhesive or the filler can be prevented, and foreign substances such as organic substances do not adhere to the surface of the optical member. Thus, it is possible to prevent a change in optical characteristics (transmittance, reflectance, etc.) of the optical member due to the light beam irradiation. In addition, while the optical member is fixed on the support member with an adhesive or a filler, a light beam of, for example, 185 nm and 254 nm is irradiated on the optical member, and a substance (for example, water, hydrocarbon, or other material) adheres to the surface of the optical member. It is possible to perform light cleaning for removing a substance that diffuses a light beam).

The present invention also provides a second aspect of the present invention, wherein the optical member 2 to which the light beam is irradiated is fixed to the supporting members 3 and 3 ′ by an adhesive or a filler 1. An optical structure comprising shielding members (4, 5, 7) for preventing irradiation of the adhesive or filler (1) or generation of gas from the adhesive or filler (1) due to the irradiation. Claim 2) "is provided.

The optical structure according to the second aspect of the present invention is provided with a shielding member for preventing the light beam from irradiating the adhesive or the filler or generating outgas from the adhesive or the filler due to the irradiation. Foreign substances such as organic substances generated due to the material or filler do not adhere to the surface of the optical member,
Fluctuations in the optical characteristics (transmittance, reflectance, etc.) of the optical member due to light beam irradiation can be prevented. In addition, light cleaning can be performed while the optical member is fixed on the support member with an adhesive or a filler.

Thirdly, the present invention provides "the optical structure according to claim 1 or 2, wherein the protective member or the shielding member is a thin film 4."
In the optical structure according to the third aspect, since the protective member or the shielding member is a thin film 4, the operation according to the first or second aspect is achieved with a simple structure in which a thin film is formed on an adhesive or a filler. be able to.

Further, the present invention is directed to a fourth aspect, wherein "the thin film 4 is
4. A metal film containing one or more components selected from the group consisting of Ni, Si, Au, Pt, W, Mo, Cr, Ti, Al and alloys or compounds thereof. Optical structure (Claim 4) "is provided. In the optical structure according to the fourth aspect, since the thin film is made of a metal film, it is possible to almost completely prevent the light beam from irradiating the adhesive or the filler or generating outgas from the adhesive or the filler due to the irradiation. Thus, the operation according to claim 1 or 2 is achieved.

The present invention also provides a fifth aspect of the present invention wherein the protective member or the shielding member covers the adhesive or filler 1 to form a substantially sealed space, and the sealed space 7a
Gas introduction pipe 7 ′ for introducing gas into the space and its sealed space 7 a
An optical structure (Claim 5) "according to claim 1 or 2, characterized by having a gas discharge pipe 7" for discharging gas from the optical system.

According to a fifth aspect of the present invention, in the optical structure, the protective member or the shielding member for preventing the light beam from irradiating the adhesive or the filler or generating outgas from the adhesive or the filler due to the irradiation is formed by the adhesive. A gas inlet pipe for introducing gas into the sealed space, and a gas exhaust pipe for discharging gas from the sealed space; By introducing gas into the sealed space from and exhausting gas from the gas exhaust pipe,
Ozone and active oxygen generated during cleaning can be prevented from entering the sealed space.

The present invention is also directed to a sixth aspect of the present invention.
The gas introduced into a is a gas selected from N ₂ , Ar, He and H ₂ , or a mixed gas containing two or more gases selected from these gases. Item 5 (claim 6) "is provided. The optical structure according to claim 6, wherein the gas is N in the sealed space.
_2, Ar, the He, or selected gas H _2, or since a mixed gas comprising two or more gases selected from these gases without reacting with adhesive or filler, washed In this case, ozone and active oxygen generated at this time can be prevented from entering the sealed space.

The present invention seventhly provides a "optical system for a projection exposure apparatus incorporating the optical structure according to any one of claims 1 to 6 (claim 7)". The optical structure according to claim 1 is mounted on a projection exposure apparatus used in a lithography process for manufacturing a micro device such as a semiconductor device, a thin film magnetic head, and an imaging device (CCD). Since it is incorporated into the optical system, exposure light in the ultraviolet wavelength range (for example, an ArF excimer laser having a wavelength of 193 nm, or a KrF excimer laser having a wavelength of 248 nm), alignment light, or the like is not irradiated on the adhesive or the filler. Outgassing from the adhesive or filler can be prevented. Therefore, a foreign substance such as an organic substance generated due to the adhesive or the filler does not adhere to the surface of the optical member, and fluctuations in optical characteristics (transmittance, reflectance, etc.) of the optical member can be prevented. In addition, light cleaning can be performed in a state where the optical member is incorporated in the optical system (barrel),
It becomes possible to remove the above-mentioned substances adhered to the surface.

An optical system in which the optical structure of the present invention is incorporated has a plurality of optical elements such as an optical integrator (fly-eye lens) and a condenser lens, an illumination optical system for irradiating a mask with exposure light, and an optical system. It consists of a plurality of optical elements (refractive or reflective elements, or both refractive and reflective elements) arranged along an axis, and projects an image of a pattern formed on a mask onto a substrate (such as a semiconductor wafer). There is a projection optical system and the like. Further, for example, illumination light emitted from a light source disposed separately from the main body of the projection exposure apparatus under the floor of a clean room is guided to the illumination optical system in the main body, and the optical axis of the illumination optical system and the position of the illumination light A light transmission system having at least one optical element (such as a movable mirror) for adjusting the relationship, an alignment optical system that irradiates an alignment mark on a mask or a substrate with illumination light in an ultraviolet wavelength range and detects the position thereof, and Exposure light or exposure is performed on a reference mark on a stage on which a mask or a substrate is mounted or a measurement mark on a mask in order to detect optical characteristics of the projection optical system (for example, focus position, projection magnification, Seidel's five aberrations, etc.). There is also a measurement optical system that irradiates illumination light having substantially the same wavelength as light and receives light generated from the mark and passing through the projection optical system.

When the optical structure of the present invention is incorporated in the above-described light transmission system, it is possible to prevent a decrease in transmittance or reflectance of an optical member in the light transmission system, and to attenuate illumination light incident on the illumination optical system. By suppressing (reduction in intensity) and emitting illumination light from the light source prior to the exposure operation, that is, by performing light cleaning, the above-described foreign matter attached to the optical member can be removed.

When the optical structure of the present invention is incorporated in the above-mentioned alignment optical system, it is possible to prevent a change in the intensity of illumination light applied to the alignment mark due to a change in the transmittance or the reflectance of the optical member. Further, it is possible to prevent a reduction in the illuminance uniformity of illumination light on the alignment mark (generation of illuminance unevenness) due to a reactant generated by the reaction of the arato gas or the out gas in the gas, and also to prevent a reduction in the pupil plane of the alignment optical system Of the illumination light can be prevented from deteriorating (deteriorating) due to a reduction in the uniformity of the light intensity in a region through which the illumination light flux converged at one point on the alignment mark passes. Therefore, the mask and the substrate can be aligned with high accuracy without lowering the position detection accuracy of the alignment mark.

Further, when the optical structure of the present invention is incorporated in the above-described measurement optical system, the intensity change of the illumination light on the mark due to the change in the transmittance or the reflectance of the optical member, similarly to the alignment optical system. , And a decrease in illuminance uniformity and telecentricity can be prevented. Therefore, it is possible to detect the optical characteristics of the projection optical system (for example, focus position, projection magnification, Seidel's five aberrations, etc.) with high accuracy.

Eighth, the present invention provides an illumination optical system 21 for illuminating a mask, a projection optical system 25 for projecting and exposing a pattern formed on the mask R onto a substrate W,
In the projection exposure apparatus having:
Alternatively, there is provided a projection exposure apparatus (claim 8), wherein the projection optical system 25 uses the optical system for a projection exposure apparatus according to claim 7.

Since the optical system according to claim 7 is incorporated in the illumination optical system or the projection optical system of the projection exposure apparatus, the exposure light does not irradiate the adhesive or the filler. Outgassing can be prevented. Therefore,
No foreign matter such as organic substances generated due to the adhesive or the filler adheres to the surface of the optical member, and does not enter (float) in the illumination optical path or the imaging optical path. Variations in characteristics (transmittance, reflectance, etc.) can be prevented. In addition, optical cleaning of the optical member can be performed in a state where the illumination optical system and the projection optical system are incorporated in the projection exposure apparatus, and the above-mentioned substance attached to the surface can be removed.

Further, it is possible to prevent a change in the intensity of the illumination light on the mask or the substrate due to a change in the transmittance or the reflectance of the illumination optical system or the projection optical system, so that the mask pattern is always transferred onto the substrate with an appropriate exposure amount. It is possible to do. Further, the outgassing or the reactant generated by the outgassing reaction in the gas reduces the illuminance uniformity of the illuminating light on the mask or the substrate, and the optical characteristics of the projection optical system (for example, focus position, projection magnification, Manufacturing microdevices such as semiconductor elements that can prevent fluctuations in Seidel's five aberrations, telecentricity, etc., always project a pattern image on a substrate in a good imaging state, and satisfy desired characteristics. Becomes possible.

When a part of the exposure light is branched by an optical element disposed in the illumination optical system and received by a photoelectric detector, the exposure light is disposed between the optical element in the illumination optical system and the photoelectric detector. The protective member or the shielding member of the present invention may be provided on an optical member and / or an adhesive or a filler for fixing the photoelectric detector to the support member. Also in this case, the exposure light is not irradiated to the adhesive or the filler, and generation of outgas from the adhesive or the filler can be prevented. Therefore, foreign substances such as organic substances caused by the adhesive or the filler do not adhere to the optical member or the photoelectric detector (light receiving surface) and do not enter (float) in the optical path. Intensity) can be detected.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical structure according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of an optical structure according to a first embodiment of the present invention. In the optical structure according to the first embodiment, an optical member (optical glass material such as a lens or a mirror) 2 is fixed to a fixing portion 3a formed as a step on the inner wall of a support member 3 with an adhesive or a filler 1. A metal film 4 is formed on the exposed surface of the adhesive or filler 1.

As the metal film 4, one or more selected from the group consisting of chemically stable and dense Ni, Si, Au, Pt, W, Mo, Cr, Ti, Al, and alloys or compounds thereof. It is preferable to use a metal film containing components. These metal films have good light-shielding properties against ultraviolet rays when they are made to have an appropriate thickness, and at the same time, seal off scattering of outgas. The film can be formed by a vacuum deposition method, a sputtering method, or the like. However, the film is formed without heating or at the operating temperature of the optical system so that the optical member 2 is not deformed, and further, the deterioration of the adhesive 1 is avoided. Therefore, it is preferable to adopt a film formation method which is not exposed to plasma.

When the adhesive or filler 1 is formed over the entire periphery along the peripheral edge of the optical member 2, a metal film is formed on the entire surface. To describe the first embodiment more specifically, the optical structure is formed by forming a ガ ラ ス 20 mm quartz glass substrate 2 as an optical member on which an antireflection film is formed as a step on the inner wall of an annular lens support member 3. The fixing portion 3a is fixed with a silicon-based adhesive 1 and a metal film 4 made of Ni having a thickness of 200 nm is formed on the surface of the silicon-based adhesive 1.

The metal film 4 was formed without heating using an ion beam sputtering method. At the time of film formation, masking was performed so that a Ni film was not formed within the effective optical diameter of the quartz glass substrate 2. FIG. 2 is a schematic sectional view of an optical structure according to a second embodiment of the present invention. In the optical structure of the second embodiment, the optical member 2 is fixed to a fixing portion 3a 'formed as a step on the inner wall of the support member 3' with an adhesive or a filler 1, and the adhesive or the filler 1 is attached to the optical member 2. This is a configuration in which a cover 5 (hereinafter, referred to as a cover) that covers and forms a substantially sealed space (sealed space) is provided. The cover 5 is provided with a screw 6 so as to press the step 2a formed on the peripheral edge of the optical member 2 from above.
Is fastened to the support member 3 '.

The material of the cover 5 can be a metal such as stainless steel or the like, which has good UV resistance, or a ceramic such as SiC or SiN3, but is not limited thereto. Also in the case of the present embodiment, the cover 5 has a light-shielding property for preventing ultraviolet rays from being irradiated on the adhesive 1, and can also seal the scattering of outgas generated from the adhesive 1 to some extent.

To describe the second embodiment more specifically, the optical structure is such that a ガ ラ ス 20 mm quartz glass substrate 2 as an optical member on which an antireflection film is formed is formed as a step on the inner wall of a lens supporting member 3 ′. The silicon-based adhesive material 1 is fixed to the formed fixing portion 3a 'with the silicon-based adhesive material 1.
An annular stainless steel cover 5 that covers the lens support member 3 ′ is fixed by screws 6.

In the present embodiment, the adhesive 1 is prevented from protruding above the upper surface 3b of the fixing portion of the lens supporting member 3 '.
The upper surface 3b of the lens supporting member 3 'is higher than the step 2a provided on the periphery of the quartz glass substrate 2. The cover 5 may be a shielding plate that shields the exposure light. FIG. 3 is a schematic sectional view of an optical structure according to a third embodiment of the present invention.

In the optical structure of the third embodiment, the cover 5 in the configuration of the optical structure of the second embodiment is replaced with an annular cover 7 having a gas inlet pipe 7 'and a gas outlet pipe 7 ". More specifically, in the third embodiment, the optical structure includes a quartz glass substrate 2 of Ф20 mm as an optical member on which an antireflection film is formed and a step on the inner wall of the lens supporting member 3 ′. The silicon-based adhesive 1 is fixed to the fixing portion 3a 'formed as a part with the silicon-based adhesive 1.
An annular stainless steel cover 7 with a gas introduction pipe 7 'and a gas exhaust pipe 7 "covering the lens support cover 3' is fixed to the lens support cover 3 'with screws 6.

The cover 7 is fastened to the support member 3 'by screws 6 so as to press the end surface of the optical member 2 outside the optically effective diameter from above. The annular cover 7 is provided so as to be in contact with the shape of the optical member 2, but a slight gap may occur. Therefore, when the optical structure is optically cleaned by the above-described structure, a gas having a pressure slightly higher than the pressure outside the cover 7 is introduced from the gas introduction pipe 7 ′ into the sealed space 7 a of the cover 7, whereby the optical cleaning is performed. Ozone and active oxygen generated at that time can be prevented from entering the sealed space 7a.

As a gas introduced into the sealed space 7a,
An inert gas such as N ₂ , He, or Ar, or H ₂ diluted with He or the like can be used, but is not limited thereto. Also in the case of the present embodiment, the cover 7 has a light-shielding property for preventing ultraviolet rays from being irradiated on the adhesive 1, and can seal the scattering of outgas generated from the adhesive 1 to some extent.

A plurality of optical structures manufactured in the first to third embodiments were assembled in the lens barrel 8 to manufacture an optical system. FIG. 4 is a schematic cross-sectional view of an optical system for a projection exposure apparatus in which one of the optical structures according to the first to third embodiments or a combination of two or more of them is incorporated in a lens barrel 8. FIG. 7 is a schematic sectional view enlarging a part of an optical system (projection optical system) in which the optical structure manufactured in the third embodiment is incorporated in a lens barrel.

Although the projection optical system shown in FIG. 4 comprises only a plurality of refractive elements (lens elements), the projection optical system comprises only a plurality of reflective elements (mirrors and the like), and a plurality of refractive elements and a reflective element. The optical structure of any of the first to third embodiments can be applied to a projection optical system configured by combining elements. Further, the projection optical system does not need to have a single lens barrel, and a plurality of lens barrels may be combined.

In the lens barrel 8 of the projection optical system, a plurality of optical members 2 are stacked at predetermined intervals along the optical axis, and the intervals of the plurality of optical members 2 are adjacent to each other. It is adjusted by inserting a lens spacing ring 9 (washer) having a predetermined thickness between the two optical structures. In addition, the optical structure shown in the first to third embodiments according to the present invention is such that a mask (reticle) is formed on a wafer coated with a photoresist.
In addition to the projection optical system for projecting the image of the pattern,
It has multiple optical elements such as a beam expander, an optical integrator (fly-eye lens), an aperture stop (σ stop), a field stop, and a condenser lens, and is masked with exposure illumination light (exposure light) emitted from a light source. An illumination optical system for irradiating (reticle), an illumination light emitted from a light source arranged under the floor of a clean room and separated from the projection exposure apparatus main body to the illumination optical system in the main body, and a light of the illumination optical system. Irradiation light (alignment light) in the ultraviolet wavelength range is applied to an alignment mark on a light transmission system, mask or substrate having at least one optical element (movable mirror or the like) for adjusting the positional relationship between the axis and the illumination light. And the optical characteristics of the projection optical system (for example, focus position, projection magnification, Seidel's five aberrations, etc.). For this purpose, a reference mark on a stage on which a mask or a substrate is mounted, or a measurement mark on the mask is irradiated with exposure light or illumination light having substantially the same wavelength as the exposure light, and the projection optical system is generated from the mark. The present invention is also applied to a measurement optical system that receives passing light.

For the projection optical system shown in FIG. 4, light cleaning was performed using a light cleaning device whose light source was a low-pressure mercury lamp. In a light cleaning device whose light source is a low-pressure mercury lamp, the above optical system is installed so as not to be irradiated with light to the other,
Light washing was performed. At this time, the inside of the lens barrel 8 of the projection optical system is filled with air.

Here, in particular, a procedure for optically cleaning the optical system in which the optical member 2 of the third embodiment is incorporated in the lens barrel (before the optical system is incorporated in the projection exposure apparatus) is shown below. . First, as shown in FIG. 7, the gas introduction pipe 7 'of the cover 7 of the optical structure is connected to the gas supply pipe 12 provided in the gas supply source 14, and the gas exhaust pipe 7 "is connected to the gas exhaust mechanism 1
6 was connected to a gas exhaust pipe 15. Control of gas introduction and discharge is performed by the gas supply pipe 12 and the gas discharge pipe 15.
The opening and closing of the valves 13 and 13 'respectively provided in the above.

A light cleaning device whose light source is a low-pressure mercury lamp is installed so as not to be irradiated with light other than the above optical system.
Light washing was performed using light of nm. At this time, the inside of the lens barrel of the optical system is filled with air. As described in the problem to be solved by the invention, not only is it possible to prevent ultraviolet rays from being directly irradiated to the adhesive, but also ozone and active oxygen are generated during light cleaning, and the ozone and active oxygen are It is necessary to protect the adhesive from ozone and active oxygen, since it has a bad effect on the adhesive, and it is necessary to prevent the gas from being scattered even if outgassing occurs when the adhesive is irradiated with ultraviolet rays. because, the sealed space 7a of the cover 7, while introducing a gas supply source 14 by opening the valve 13 the N ₂ gas at a slightly higher pressure than the pressure (air) in the barrel, the valve 13 '
Is opened and the gas is discharged by the gas discharge mechanism 16 to create a flow of N ₂ in the sealed space 7a. Ozone and active oxygen do not enter the sealed space 7a of the cover 7, and the outgas is discharged using the flow of N _2. I did it.

The optical system in which the optical structures of the first to third embodiments are incorporated in a lens barrel is a silicon-based optical system which has been a problem in the conventional optical structure even after the above-described light cleaning. Deterioration of the adhesive, and a decrease in the transmittance caused by deposits on the optical member due to outgas from the silicon-based adhesive do not occur, a decrease in laser durability does not occur, and a good optical member The supporting state and the optical characteristics could be maintained.

FIG. 5 is a view showing the basic structure of a projection exposure apparatus according to the present invention. As shown in FIG. 5, the projection exposure apparatus according to the present invention includes at least a wafer stage 23 on which a substrate W (wafer) coated with a photosensitive material is placed, and an illumination optical system that irradiates exposure light onto a mask (reticle R). 21,
A light source 100 such as an excimer laser for supplying exposure light to the illumination optical system 21 and a projection optical system 25 disposed between the wafer W and the reticle R are provided. Projection optical system 25
Is arranged such that the surface (pattern forming surface) of the reticle R comes to the object plane (P1), and the surface of the wafer W comes to the image plane (P2) of the projection optical system 25. .

The reticle R is a reticle stage 2
2 and is configured to project and expose a pattern on a reticle R to a wafer W placed on a wafer stage 23 via a projection optical system 25. The reticle R exchange system 200 has a function of inserting and removing the reticle R set on the reticle stage 22, exchanging the reticle R, and transferring the reticle R between the reticle stage 22 and the reticle cassette.

Further, in the projection optical system, as shown in FIG.
As shown in FIG. _TwoFrom the source 11
N through feed pipe 10_TwoIs supplied, and the support members 3, 3 '
N through the through holes provided in each_TwoSpread throughout
That is, the lens element is sandwiched between two adjacent lens elements.
Configuration supplied to each of the substantially enclosed spaces
Has become.

Although not shown, the illumination optical system 21 disposed between the light source 100 and the reticle R is housed in one or a plurality of lens barrels 8 and has the same structure as that of FIG. 8 is configured to supply N ₂ . A projection exposure apparatus in which the optical system shown in FIG. 4 incorporating the optical structure of the first embodiment and / or the second embodiment is an ArF excimer laser (wavelength λ = 193 nm) as a light source as shown in FIG. (In the lens barrel 8, FIG. 6)
N ₂ supply source 11 provided in the projection exposure apparatus as shown in FIG.
N ₂ is introduced, N ₂ through the through hole provided in the lens support member 3 and 3 'are pervasive throughout through the supply pipe 10 from. ), And similarly good results were obtained.

As described above, the optical system in which the optical structures manufactured in the first and second embodiments are incorporated in a lens barrel is as follows.
Light cleaning can be performed immediately before the optical system is finally incorporated in the projection exposure apparatus, and optical cleaning can be performed even after the optical system is assembled in the projection exposure apparatus. Therefore, the original transmittance of the optical member can be maintained, so that the transmittance does not decrease even when irradiated with ultraviolet rays when the optical member is incorporated in the projection exposure apparatus.

The optical system shown in FIG. 4 incorporating the optical structure of the third embodiment is different from the optical system shown in FIG.
It was used as a projection optical system 25 of a projection exposure apparatus which was an rF excimer laser (wavelength λ = 193 nm). As shown in FIG. 7, the projection exposure apparatus includes a gas supply pipe 12 with a valve 13 for supplying gas to a sealed space 7a of a cover 7 of an optical structure in an optical system 25, a gas supply source 14, and a valve 13 '. A gas discharge pipe 15 and a gas discharge mechanism 16 are provided.

As shown in FIG. 6, inside the lens barrel 8 of the projection optical system
Has an N provided in the projection exposure apparatus. _TwoFrom the source 11
N through feed pipe 10_TwoIs introduced, and the lens support member 3 ′
N through the through holes provided in each of the_TwoIs all over
ArF laser irradiation, N_Twoatmosphere
And absorption (attenuation) of ArF laser is minimized
Can be suppressed. Therefore, in this state, light (ArF laser
ー) When cleaning, the N introduced into the lens barrel 8_Two
N at a pressure higher than the pressure of_TwoOpen the valve 13 with gas
And introduced into the sealed space 7a of the cover 7 from the gas supply source 14.
While the valve 13 ′ is opened and the gas exhaust mechanism 16
After discharging, N is contained in the sealed space 7a._TwoMake the flow of the lens barrel
8 and ozone and active oxygen generated during light cleaning
Discharges ozone and active oxygen entering the enclosed space 7a
Or enters the above-mentioned sealed space 7a.
Ozone and active oxygen are released by opening the valve 13 '
16 and the ozone and active oxygen react with the adhesive
Prevent responding.

The above optical system was subjected to light cleaning using an ArF excimer laser. As above, good results were obtained. In addition to the ArF excimer laser, a light cleaning low-pressure mercury lamp that can be switched to an ArF excimer laser may be provided to perform light cleaning. The optical system in which the optical structure manufactured in the third embodiment is incorporated in the lens barrel 8 can be optically cleaned immediately before being finally incorporated in the projection exposure apparatus. Even after being incorporated in the apparatus, it is possible to perform light cleaning.

However, in the latter case, the gas supply pipe 12 and the gas supply source 14 with the valve 13 for supplying gas to the sealed space 7a of the cover 7 of the optical structure, the gas discharge pipe 15 with the valve 13 'and the gas It is desirable that the discharge mechanism 16 be provided in the projection exposure apparatus. When a part of the exposure light is branched by an optical element disposed in the illumination optical system and received by a photoelectric detector, an optical member disposed between the optical element in the illumination optical system and the photoelectric detector And / or an adhesive or a filler for fixing the photoelectric detector to the support member may be provided with the protective member or the shielding member of the present invention. Also in this case, the exposure light is not irradiated to the adhesive or the filler, and generation of outgas from the adhesive or the filler can be prevented. Therefore, foreign substances such as organic substances caused by the adhesive or the filler do not adhere to the optical member or the photoelectric detector (light receiving surface) and do not enter (float) in the optical path. Intensity) can be detected.

Further, in the illumination optical system, the present invention can be applied to optical members other than lens elements and mirrors, for example, interference filters. Therefore, since the original transmittance of the optical member can be maintained, the transmittance or the reflectance does not decrease even if the optical member is irradiated with ultraviolet rays when the optical member is incorporated in the projection exposure apparatus.

[0056]

As described above, the optical structure according to the present invention and the optical system incorporating the same maintain the optical performance even when used in the optical system of a projection exposure apparatus that uses ultraviolet light as exposure light. However, the optical member does not deteriorate. Further, the optical member according to the present invention has the optical member incorporated in the support member, the optical member in the state where the optical structure is incorporated in the lens barrel (optical system), and the optical system incorporated in the projection exposure apparatus. Optical cleaning of the optical member in the state is possible.

Therefore, the original transmittance of the optical member can be maintained, so that the transmittance does not decrease even when irradiated with ultraviolet rays when the optical member is incorporated in the projection exposure apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical structure according to a first embodiment.

FIG. 2A is an exploded perspective view of an optical structure according to a second embodiment, and FIG. 2B is a cross-sectional view taken along line XX ′ in a state where the optical structures are assembled.

FIG. 3 is a schematic sectional view of an optical structure according to a third embodiment.

FIG. 4 is a schematic sectional view of an optical system in which any one of the optical structures manufactured in the first embodiment and the second embodiment, or two or more of them are combined and incorporated into a lens barrel.

FIG. 5 is a schematic view showing a basic structure of a projection exposure apparatus according to the present invention.

FIG. 6 is a schematic sectional view when the optical system shown in FIG. 2 is used as an optical system of a projection exposure apparatus.

FIG. 7 is a schematic sectional view enlarging a part of an optical system (projection optical system) in which an optical structure manufactured in a third embodiment is incorporated in a lens barrel.

FIG. 8 is a schematic sectional view of a conventional optical structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Adhesive or filler 2 ... Optical member 3, 3 '... Support member (lens support member) 3a, 3a' ... Optical member fixing part (fixing part) 3b ... Support member Top surface of (lens support member) 4 Metal film 5 Cover 6 Screw 7 Cover with gas introduction pipe and gas discharge pipe 7a Sealed space 8 Lens barrel 9. ..Lens spacing ring (washer) 10 ... Nitrogen supply pipe 11 ... Nitrogen supply source 12 ... Gas supply pipe 13, 13 '... Valve 14 ... Gas supply source 15 ... Gas discharge Tube 16 Gas exhaust mechanism 21 Illumination optical system 22 Reticle stage 23 Wafer stage 25 Projection optical system 100 Light source 200 Reticle exchange system 300 Stage control system 400: Main control unit W: Substrate ( Fine Art) R ··· mask (reticle)

Claims (8)

[Claims] 1. An optical structure comprising at least one optical member fixed to a support member with an adhesive or a filler, wherein a protective member is provided on a surface of the adhesive or the filler. Optical structure. 2. An optical structure in which an optical member irradiated with a light beam is fixed to a support member with an adhesive or a filler, wherein the light beam is applied to the adhesive or the filler, or the irradiation is performed. An optical structure, comprising a shielding member for preventing generation of gas from the adhesive or filler due to the above. 3. The optical structure according to claim 1, wherein the protection member or the shielding member is a thin film. 4. The thin film is made of Ni, Si, Au, Pt, W, Mo, Cr, Ti, Al
The optical structure according to claim 3, wherein the optical structure is a metal film containing one or more components selected from the group consisting of an alloy or a compound thereof. 5. The protective member or the shielding member covers the adhesive or filler to form a substantially sealed space, a gas introduction pipe for introducing gas into the sealed space, and the sealed space. The optical structure according to claim 1, further comprising: a gas discharge pipe configured to discharge gas from the gas outlet. 6. The gas introduced into the sealed space is a gas selected from N ₂ , Ar, He, and H ₂ , or a mixed gas containing two or more gases selected from these gases. The optical structure according to claim 5, wherein: 7. An optical system for a projection exposure apparatus, into which the optical structure according to claim 1 is incorporated. 8. A projection exposure apparatus comprising: an illumination optical system for illuminating a mask; and a projection optical system for projecting and exposing a pattern formed on the mask onto a substrate. A projection exposure apparatus using the optical system for a projection exposure apparatus according to claim 7 as an optical system.