JP3514439B2 - Support structure for optical element, exposure apparatus configured using the support structure, and method for manufacturing devices and the like using the apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for an optical element, and an exposure apparatus constructed using the support structure,
The present invention relates to a method of manufacturing a device or the like by the apparatus.

[0002]

2. Description of the Related Art In order to improve the degree of integration and operation speed of solid-state elements such as LSIs, miniaturization of circuit patterns is in progress. At present, lithography using a reduction projection exposure method, which is excellent in mass productivity and resolution performance, is widely used for forming these patterns. In this method, a circuit pattern on a mask, which is an original plate on which a transfer pattern is drawn, is collectively transferred onto a wafer, which is an exposed substrate, through a projection lens. Its limiting resolution performance is proportional to the exposure wavelength and inversely proportional to the numerical aperture (NA) of the projection lens. Therefore, conventionally, the resolution has been improved by increasing the NA of the projection lens. However, it has become necessary to shorten the wavelength of exposure light in order to further advance the miniaturization of semiconductor devices.

Even if a projection lens having a high resolution and a light source having a short wavelength and a high illuminance are used, if the illuminance (light intensity) distribution of the light illuminating the mask is not uniform, the circuit pattern image exposed on the wafer is exposed. However, a uniform resolution cannot be obtained over the entire surface, and a problem arises in that good printing cannot be performed. Therefore, the illumination optical system in the projection exposure apparatus is required to have a uniform illuminance in the illumination light flux to the mask surface for uniform exposure over the entire printing surface.

However, in an exposure apparatus that uses i-line (wavelength λ = 365 nm) as exposure light and an exposure apparatus that uses exposure light having a shorter wavelength than the i-line, the exposure light photochemically removes impurities in the air due to the shorter wavelength. Known to react,
The product of such a reaction adheres to the glass member, resulting in uneven transmittance due to deterioration of transmittance and deterioration of optical characteristics.
Here, as the product, for example, ammonium sulfate (NH ₄ ) ₂ SO _{4 which} is generated by reacting (oxidizing) oxygen in the air when SO ₂ absorbs light energy and becomes excited is typical. Can be mentioned. This ammonium sulfate has a white color, and if it adheres to the surface of an optical member such as a lens or a mirror, the above-mentioned optical characteristics deteriorate. Then, the exposure light is scattered and absorbed by ammonium sulfate, so that the transmittance of the optical system is reduced. Particularly, in the short wavelength region where the exposure light has a wavelength shorter than 248 nm, which is shorter than the i-line, such as a KrF excimer laser (wavelength λ = 248 nm), the wavelength energy of the light increases and the exposure light causes a stronger photochemical reaction. In addition to the deterioration of the optical characteristics, the ArF excimer laser (wavelength λ =
In the case of (193 nm), there is a phenomenon that exposure light reacts with a small amount of oxygen in the purge gas to generate ozone, and residual oxygen and generated ozone both absorb the exposure light. As a result, the amount of exposure light until it reaches the photosensitive substrate (transmittance) is reduced, and the throughput is reduced.

Conventionally, as a method of blocking impurities from the outside and sealing the inside of a lens or a lens barrel, which is an optical element of a projection optical system, a method of sealing a gap at the boundary with the outside with a sealing material such as a silicone resin. Has been proposed (JP-A-11-0.
67651). This method is shown in FIG. In FIG. 4, 31 is a lens, 32 is a holding member that holds the lens 31, 33 is a lens unit that holds a plurality of holding members 32, 34 is an interval between the holding members 32, and each is supported at three points 3 Point support screws, 35 is a sealing material that seals the gap between the holding member 32 and the lens unit 33, and 36 is a tube joint that supplies and discharges a purging gas into the sealed lens unit 33. By sealing the gap between the holding member 32 and the lens unit 33 with the seal material 35, it is possible to block impurities from the outside and to seal the purging gas with high purity inside the lens unit 33. Further, by sealing the purging gas inside the lens unit 33, the oxygen concentration inside can be suppressed.

[0006]

However, although the above-mentioned conventional example is an effective means for sealing a narrow gap,
Disadvantages occur in the following cases. First, in the conventional sealing material, since the object to be sealed is completely fixed to the lens barrel, when the object to be sealed is a driven object, the driving function of the object is disturbed and the driving performance is deteriorated. However, the conventional sealing material cannot be used. In addition, when stress is applied to the object to be sealed (particularly, a lens that is an optical element of a projection optical system) due to the close contact of the sealing material, lens deformation or birefringence occurs due to the influence of the lens or the like, Since the exposure performance is reduced due to the deterioration of the optical characteristics, the conventional sealing material cannot be used. Further, when a sealant is used at the bottom of the lens barrel,
At the bottom of the lens barrel, the diameter of the lens barrel is reduced by narrowing the exposure light path, and the space is also narrowed. It is difficult to enlarge the lens barrel diameter because there are wafers, alignment systems, etc. in the periphery, which causes congestion. Therefore, it becomes difficult to secure a space for inserting the sealing material as in the conventional example. Therefore, it is not possible to reliably perform the function of blocking impurities from the outside, simultaneously suppressing the oxygen concentration inside, and reliably sealing the inside of the lens barrel, resulting in a decrease in the transmittance of the lens and a decrease in the transmittance. The problem of unevenness arises. Therefore, there is a demand for a method of blocking impurities from the outside into the lens barrel, suppressing the oxygen concentration in the lens barrel, and reliably sealing the lens barrel.

Therefore, an object of the present invention is to provide a support structure for an optical element which can meet the demand, an exposure apparatus constituted by using the support structure, and a method for manufacturing a device and the like by the apparatus. Is.

[0008]

In order to achieve the above-mentioned object, the present invention is constituted by using a supporting structure for an optical element constructed as described in (1) to ( 13 ) below, and the supporting structure. And an exposure apparatus and a method for manufacturing a semiconductor device and the like using the exposure apparatus. (1) A support structure for an optical element including a support member for supporting the optical element and a lens barrel for holding the support member, wherein the mirror
A thin film member that seals a purge gas in the cylinder and closes the gap between the optical element and the support member and / or the gap between the support member and the lens barrel is used. It is composed of a thin film sealing material having flexibility and hermeticity and having sufficient strength, and the thin film sealing material prevents mutual gas exchange in a space separated by the optical element in the support structure. A support structure for an optical element, characterized in that it is configured to block. (2) A support structure for an optical element including a support member for supporting the optical element and a lens barrel for holding the support member, wherein a gap between the optical element and the support member and / or the support member and the A thin film member for closing a gap between the lens barrel and the lens barrel, wherein the thin film member has a gap between at least one surface of the optical element and a surface of the support member on the same surface as at least one surface of the optical element. The thin film shape is adhered over the entire circumference and / or the entire circumference between at least one surface of the supporting member and the surface of the lens barrel on the same surface as at least one surface of the supporting member. A support structure for optical elements, characterized in that the member is arranged to block mutual gas exchange in a space separated by the optical elements in the support structure. (3) The support structure for an optical element according to the above (2), wherein the close contact is bonded by an adhesive. (4) In the above-mentioned close contact bonding, an annular holding member for fastening the entire circumference of a contact surface with the thin film member through a through hole formed in the thin film member is provided. (3) The optical element support structure according to (3). (5) In any one of the above (2) to (4), the thin film member is a thin film sealing material that is flexible, has an airtight property, and has sufficient strength. A support structure for the described optical element. (6) The support structure for an optical element according to (5), wherein the thin film sealing material has a groove for preventing the adhesive from flowing toward the center of the optical element. (7) The adhesive, and / or the annular pressing member, and / or the thin film member is an organic silicon compound,
The optical element according to any one of (3) to (6) above, which is a material that does not generate or degas a gas that does not contain at least one or more of ammonia, sulfate ions and organic gas. Support structure. (8) The adhesive, and / or the annular pressing member, and / or the thin film member is an organic silicon compound,
Any of the above (3) to (6), characterized in that the material is coated with a material that does not generate or degasses at least one of ammonia, sulfate ions and organic gas. A support structure for an optical element according to. (9) The contact surface between the optical element and the support member and / or the contact surface between the support member and the lens barrel is
The optical element support structure according to any one of (1) to (8) above, which is supported by three-point support. (10) The optical element support structure according to any one of (1) to (9), wherein the support member is a movable member that moves in the same direction as the optical element. (11) A support member that supports the optical element and a support member
The lens barrel holding the optical element and the support member
A support for an optical element having a driving element that drives the lens barrel.
It has a holding structure, and the purging gas is sealed in the lens barrel.
Flexibility to close the gap between the support member and the lens barrel
It is a thin film that has a tight seal and has sufficient strength.
A sealing material is provided, and the support structure is formed by the thin film sealing material.
In the space separated by the optical elements in the structure
Configured to block mutual gas exchange,
The thin film member surrounds the space surrounding the drive element and the mirror.
Support for optical elements characterized by being cut off from the inside of the cylinder
Holding structure. ( 12 ) An exposure apparatus, wherein a part of an optical system is configured by using the optical element support structure according to any one of (1) to ( 11 ). ( 13 ) A method of manufacturing a device or the like, which comprises a step of exposing a wafer with a device pattern by the exposure apparatus according to ( 12 ) above and a step of developing the exposed wafer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiments of the present invention,
By applying the above configuration, a structurally simple sealing mechanism using a sealing material can be configured, and the lens barrel structure including this sealing mechanism, the projection optical system, and the like can be easily designed. A mechanism is used to block the inflow of impurities into the lens barrel, prevent impurities from adhering to the optical element, maintain and guarantee the gas purity inside the lens barrel, and when using an ArF excimer laser or the like as the light source, By suppressing the leak gas such as oxygen, it becomes possible to maintain and guarantee the optical characteristics and the uniformity of the illumination light, and suppress the decrease of the exposure amount. Furthermore, it becomes possible to realize a lens barrel structure that protects the environmental conditions outside the lens barrel and has a space-saving sealing mechanism. Therefore,
According to this, maintaining and improving the reliability of the exposure apparatus by maintaining and guaranteeing the optical characteristics and the uniformity of the illumination light, reducing the cost of the exposure apparatus with a simple structure and space-saving sealing mechanism, and suppressing the reduction of the exposure amount It is possible to maintain and improve the reliability of the throughput of the exposure apparatus. More specifically, for example, by applying the configurations of (1) to (4) above, mutual gas exchange in the space separated by the optical element in the lens barrel can be reliably blocked. It will be possible. Further, by applying the configuration of the above (5), by using the thin film-like sealing material having good flexibility and hermeticity and having sufficient strength, gas exchange in the space separated by the optical element is performed. It is possible to increase the reliability of the cutoff of. In addition, (7) above
By applying the configuration of (1), it becomes possible to reliably block gas exchange in the space separated by the optical element without generating a substance that deteriorates optical characteristics due to the exposure light in the lens barrel. . Further, by applying the configuration of the above (8), it can be applied to a material that generates a substance that deteriorates optical characteristics due to exposure light in the lens barrel, and it is possible to cope with a wide range of environmental conditions. . Further, by applying the configuration of the above (10), by moving the holding member, without impairing the blocking function of the gas exchange, and at the same time without disturbing the movement of the holding member, The holding member can be moved in the same direction.

[0010]

EXAMPLES Examples of the present invention will be described below. [Embodiment 1] FIG. 1 shows a partial configuration of a projection optical system unit of a semiconductor exposure apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a lens barrel including a projection optical system in a semiconductor exposure apparatus of the present embodiment, 2 is a main body surface plate that supports the lens barrel 1, 3 is a wafer having a surface coated with a photosensitive agent, and 4 is a wafer. 3 is a wafer stage that supports 3. Further, 5 is a reticle (original plate) that depicts a pattern to be transferred to the wafer 3, 6 is a reticle stage that holds the reticle 5, and 7 is a reticle stage.
Is a part of an illumination system optical unit that illuminates the reticle 5 with exposure light, 8 is located on the main body surface plate 2, and the reticle stage 6
Is an outer cylinder for holding. Further, 9 is a part of the lens barrel 1 including the projection optical system, and the lens lowermost part is located at the lowest part, and 10 is a lens driving unit driven by a part of the projection optical system. The reticle 5 is exposed by the illumination system optical unit 7,
The pattern of the reticle 5 is transferred onto the wafer 4 via the projection optical system lens (inside the lens barrel 1).

FIG. 2 is a drawing that best represents the features of the configuration of this embodiment. In FIG. 2, 11 is a lens that is a part of the projection optical system, 12 is a holding member that supports the lens, and 13 is a lens.
Is a lens barrel that supports the holding member 12, and 14 is a three-point support pin that is inserted when supporting the lens 11 and the holding member 12 at three points on the circumference at equal intervals (only two points are shown because FIG. 2 is a sectional view). Not). Further, 15 is a holding spring for fixing the lens 11 from the opposite side of the three-point support pin 14, 16 is a holding spring support rod for fixing the holding spring 15, and 17 is a thin film-like member for blocking the inside and the outside of the lens 11. It is a sealing material that is flexible and has a good sealing property and has sufficient strength (hereinafter referred to as a film seal). 18 is a film seal 1
An annular seal retainer for fixing 7 and 19 a seal retainer 1
8 is a screw for fixing the pressing spring support rod 16.

In the above structure, in consideration of the holding deformation of the lens 11, the lens 11 and the holding member 12 are held at three points by the three-point support pins 14, and the pressing spring 15 is provided from the opposite side.
By fixing the lens 11 and the holding member 12 at three points, a gap is created between the lens 11 and the holding member 12, so that the lens 11 and the holding member 12 are closed as shown in FIG. The gap between the holding members is closed with a film seal to prevent gas from flowing from the B surface to the A surface. Figure 2
As described above, when closing the gap between the lens 11 and the holding member 12, the lens 11 and the film seal 17 are fixed by adhesion, and the holding member 12 and the film seal 17 are fastened by the seal retainer 18 through the through hole of the film seal 17. ,
When the lens 11 and the film seal 17 are bonded together, a groove is provided in the center direction of the lens 11 from the bonding portion in order to prevent the bonding liquid from flowing in the center direction of the lens 11.

For adhesion, an organic silicon compound, ammonia,
A UV-resistant adhesive that does not generate or degas a gas that does not contain at least one of sulfate ions and organic gas is used. Further, also for the seal retainer 18, the same material as the above adhesive is used. The film seal 17 is a polyimide (polycondensation of aromatic tetrabasic acid and aromatic diamine) film seal [Product name: Kapton,
Toray Co., Ltd.] with a thickness of 25 μm, but flexible with a sealing material of a material that does not generate or degas a gas that does not contain at least one or more of organic silicon compounds, ammonia, sulfate ions and organic gas. Other materials may be used as long as they have no problem in strength, etc. and are resistant to ultraviolet rays.

Also, the thickness of the film seal 17 varies depending on the adhesion or fixation, or the stress strength or material of the object to be adhered or fixed.
It may be selected so that there is no problem in the performance of the object due to the influence of the film seal 17
The thickness may be such that the stress applied to the object (in the example, the lens 11) does not cause the performance of the object to deteriorate.

A coating that does not generate or degas a gas that does not contain at least one of an organic silicon compound, ammonia, sulfate ions and an organic gas even when a gas that deteriorates optical properties is generated from the film seal 17 by exposure. It may be processed. The location is shown in Figure 1.
Like the lens lowermost part 9 of the above, it is arranged at the lowest part of the projection optical system (it can also be used at the uppermost part) at a position necessary for completely sealing the inside of the projection optical system, and There is no problem if it is a position that blocks the space and does not interfere with the function of the object to be sealed and its surroundings.

In the first embodiment, by inserting the film seal 17 between the lens 11 and the holding member 12, the inside and the outside of the lens 11 are reliably shielded, the inflow of impurities from the outside is prevented, and the photochemical reaction by the exposure light is performed. By suppressing the adherence of impurities to the lens 11, maintaining and guaranteeing the gas purging purity inside the lens barrel, and suppressing the oxygen concentration inside the lens barrel, it is possible to prevent deterioration of optical characteristics, illuminance uniformity, and exposure amount. it can. In addition, the film seal 17 is attached to the lens 11
It is possible to avoid the deformation and distortion of the lens due to the adhesive stress at the time of adhering to, and to prevent the deterioration of the exposure performance due to the deterioration of the optical characteristics.

[Embodiment 2] In FIG. 3, reference numeral 21 is a lens, 22 is a holding member for holding the lens 21 having a through hole, 23 is a movable portion for holding the holding member 22 and is movable up and down, and 24 is a bellows or the like. This is a driving element configured to generate a force for driving the movable portion 23 by the compressed air, and in this embodiment, three sets are arranged symmetrically on the circumference in an axially symmetrical manner. Reference numeral 25 denotes notches at equal intervals, one end of the drive element 24 is fixed to the notched portion, a fixed portion serving as a reference for the movable portion 23, and 26 a drive for transmitting the force of the drive moving element 24 to the movable portion 23. The action plates 27 are two or more pairs of plate springs, which are symmetrically arranged and fixed to the movable portion 23 and the fixed portion 25 to form a spring mechanism. Is located in.

Reference numeral 28 is a ring-shaped leaf spring retainer which is fastened to the fixed portion 25 and the movable portion 23 through a through hole provided in the leaf spring 27, 29 is a film seal for blocking the inside and outside of the lens barrel, and 30 is a projection optical system. A fixed part (lens barrel) which is a part of the fixed part of the device, 31 is a ring-shaped seal retainer that is fastened to the movable part 23 and the fixed part 30 through a through hole provided in the film seal 29, and 32 is compressed by the drive element 24. It is composed of a joint that serves as a connecting part for sending gas. The drive element 24 is a leaf spring 27.
When the film seal 29 is not attached, the external gas flows into the lens barrel from the cutout portion of the fixing portion 25 in order to fix the drive element 24.

In the above structure, the compressed gas is sent from the joint 32 to the drive element 24, and the force generated by the drive element 24 is passed through the drive action plate 26 to form a rectangular shape by the upper and lower leaf springs 27 symmetrically arranged. The movable portion 23 having the link spring mechanism is vertically moved and the lens 21 is moved to correct the aberration generated in the projection optical system and the exposure magnification. The film seal 29 is the same as that used in the first embodiment. Even when a gas that deteriorates the optical characteristics is generated from the film seal 29 by exposure, the same coating process as in Example 1 may be performed.

In the second embodiment, the movable part 23 and the fixed part 30 are fixed by the film seal 29. However, by using the flexible film seal 29, the film seal 29, the movable part 23 and the fixed part 30 are fixed. Even if friction occurs on the contact surface, it does not affect the driving and performance of the movable portion 23.
By blocking the space between the inside and the outside of the projection optical lens 21 and preventing the impurities from outside, it is possible to prevent the deterioration of the optical characteristics, the illuminance uniformity, and the exposure amount, as in the first embodiment.

[0021]

As described above, according to the present invention, the thin film member closes the gap between the optical element and the support member and / or the gap between the support member and the lens barrel, and the mirror By configuring to block the inflow of impurities into the barrel, it is possible to prevent impurities from adhering to the optical element, and to maintain the purity of the gas inside the lens barrel.
A support mechanism for an optical element, which can form a seal mechanism whose mechanism can be easily designed without changing the structure, and can realize a lens barrel structure, etc. in a space-saving manner, and a structure using the support structure The exposed exposure apparatus and the method of manufacturing a semiconductor device or the like by the apparatus can be realized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a lens barrel structure having a sealing function according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a lens barrel structure having a sealing function according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a lens barrel structure having a sealing function according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a conventional example.

[Explanation of symbols]

1: lens barrel 2: Body surface plate 3: Wafer 4: Wafer stage 5: Reticle (original edition) 6: Reticle stage 7: Part of the illumination system optical unit 8: Outer cylinder 9: Bottom of lens 10: Lens drive unit 11: Lens 12: Holding member 13: lens barrel 14: 3 point support pin 15: Presser spring 16: Presser spring support rod 17: Film seal 18: Seal retainer 19: Screw 21: Lens 22: Holding member 23: Moving part 24: Drive element 25: Fixed part 26: Drive action plate 27: Leaf spring 28: Leaf spring retainer 29: Film seal 30: Fixed part (lens barrel) 31: Seal retainer 32: Joint 41: Lens 42: Holding member 43: Lens unit 44: 3 point support screw 45: Seal material 46: Tube fitting

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Claims (13)

(57) [Claims] 1. A support structure for an optical element, comprising a support member for supporting the optical element and a lens barrel for holding the support member,
The thin film member has a thin film member that seals a purge gas in the lens barrel and closes a gap between the optical element and the support member and / or a gap between the support member and the lens barrel. Is composed of a thin film sealing material having flexibility, hermeticity, and sufficient strength, and mutual gas in a space separated by the optical element in the support structure by the thin film sealing material. A support structure for an optical element, characterized in that it is arranged to block replacement. 2. A support structure for an optical element comprising a support member for supporting the optical element and a lens barrel for holding the support member,
A thin film member closing a gap between the optical element and the support member and / or a gap between the support member and the lens barrel, the thin film member and at least one surface of the optical element and the optical member. A lens barrel on the entire circumference of the gap between at least one surface of the element and the surface of the supporting member on the same surface side, and / or on the same surface side as at least one surface of the supporting member and at least one surface of the supporting member. Is closely bonded to the entire surface of the support structure and is configured to block mutual gas exchange in the space separated by the optical element in the support structure by the thin film member. Characteristic optical element support structure. 3. The support structure for an optical element according to claim 2, wherein the close-bonding is bonded by an adhesive. 4. The contact bonding method further includes an annular pressing member for fastening the entire circumference of a contact surface with the thin film member through a through hole formed in the thin film member. The support structure for an optical element according to claim 3. 5. The thin film-shaped member is a thin film-shaped sealing material which is flexible, has an airtight property, and has sufficient strength. A support structure for an optical element according to. 6. The support structure for an optical element according to claim 5, wherein the thin film sealing material has a groove for preventing the adhesive from flowing toward the center of the optical element. 7. The adhesive, and / or the annular pressing member, and / or the thin film-shaped member contains a gas containing at least one or more of an organic silicon compound, ammonia, sulfate ions and an organic gas. The support structure for an optical element according to any one of claims 3 to 6, which is a material that does not generate or degas. 8. The adhesive, and / or the annular pressing member, and / or the thin film-like member contains a gas containing at least one or more of an organic silicon compound, ammonia, sulfate ions and an organic gas. The optical element support structure according to any one of claims 3 to 6, which is coated with a material that does not generate or degas. 9. A contact surface between the optical element and the support member and / or a contact surface between the support member and the lens barrel is supported by three-point support. A support structure for an optical element according to claim 1. 10. The optical element support structure according to claim 1, wherein the support member is a movable member that moves in the same direction together with the optical element. 11. A support member for supporting an optical element, and a support portion.
A lens barrel for holding a material, the optical element and the support member
And an optical element for driving the lens barrel with respect to the lens barrel.
It is a basic support structure, and purge gas is introduced into the barrel.
It is hermetically sealed and closes the gap between the support member and the lens barrel.
Flexible, airtight, and strong enough to be thin
It has a film-shaped sealing material, and the thin-film sealing material
In the space separated by the optical element in the support structure
Are configured to block mutual gas exchange in
A space surrounding the drive element by the thin film member.
An optical system in which the inside of the lens barrel and the inside of the lens barrel are cut off from each other.
Element support structure. 12. An exposure apparatus, wherein a part of an optical system is constituted by using the optical element support structure according to any one of claims 1 to 11 . 13. A method of manufacturing a device or the like, which comprises the steps of exposing a wafer with a device pattern by the exposure apparatus according to claim 12 and developing the exposed wafer.