Optical device, projection optical system, exposure device, and method for manufacturing article

Abstract

The present invention relates to an optical device, a projection optical system, an exposure device, and a method for manufacturing an article. An optical device having a gas supply mechanism that reduces the risk of light reaching an optical element being shielded is provided. The optical device comprises: a first optical element and a second optical element; a holding portion that holds the first optical element and the second optical element; a gas supply portion that supplies temperature-controlled gas toward a flow path provided in the holding portion; and a gas exhaust portion that exhausts the gas supplied by the gas supply portion, wherein the gas exhaust portion is arranged side by side in the arrangement direction of the first optical element and the second optical element.

Description

Technical Field

[0001] The present invention relates to an optical device, a projection optical system, an exposure device and a method for manufacturing an article. Background Art

[0002] It is known that in an optical device using optical elements such as lenses and reflectors, the optical performance of the optical device may be affected by temperature changes in the optical element or in the space in the optical path. This may be caused by changes in the surface shape of the optical element, thermal deformation in the holding portion of the optical element, or changes in the refractive index of air.

[0003] One of the main causes of temperature changes in the optical elements and spaces in the optical path described above is light incident on the optical element. When light passes through the optical element or is reflected in the optical element, part of the light is absorbed by the optical element, thereby generating heat. Part of the generated heat is transferred to the holder of the optical element or the space around the optical element. In particular, when there is an optical path near the holder, natural convection occurs as the temperature of the holder rises, and sometimes heat is transferred from the holder to the space including the optical path. As a result, the refractive index of the gas in the optical path changes, which may lead to a reduction in the optical performance of the optical device.

[0004] In order to suppress the reduction of optical performance in an optical device, a cooling mechanism for cooling an optical element and a space near the optical element is known. Japanese Patent Publication No. 2018-91919 discloses a gas supply mechanism for supplying and exhausting a gas for temperature regulation to a space between two optical elements.

[0005] In the gas supply mechanism of Japanese Patent Publication No. 2018-91919, the gas supply mechanism is arranged in the upper and lower directions of the two optical elements, so there is a possibility that the light is blocked by the gas supply mechanism according to the optical path of the light reaching each optical element. By studying the configuration of the gas supply mechanism, the risk of light reaching the optical element being blocked can be reduced.

[0006] An object of the present invention is to provide an optical device including a gas supply mechanism that reduces the risk of light reaching an optical element being blocked. Summary of the invention

[0007] The optical device of the present invention is characterized in that it comprises: a first optical element and a second optical element; a holding portion that holds the first optical element and the second optical element; a gas supply portion that supplies temperature-controlled gas toward a flow path provided in the holding portion; and a gas exhaust portion that exhausts the gas supplied by the gas supply portion, wherein the gas exhaust portion is arranged side by side in the arrangement direction of the first optical element and the second optical element. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram showing the overall structure of the exposure device.

[0009] Figure 2 This is a diagram showing the structure of the optical device of Example 1.

[0010] Figure 3 This is a diagram of the optical device viewed from the Y-axis direction.

[0011] Figure 4 This is a diagram showing the structure of the optical device of Example 2.

[0012] Figure 5 This is a diagram showing the structure of an optical device according to Example 3.

[0013] Figure 6 It is a diagram showing the structure of an optical device as a comparative example. DETAILED DESCRIPTION

[0014] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are attached to the same components, and repeated descriptions are omitted.

[0015] Figure 1 1 is a schematic diagram showing the structure of an exposure device 1 including a projection optical system PO equipped with an optical device of the present invention. The exposure device 1 is used in a photolithography process as a manufacturing process of devices such as semiconductor devices and liquid crystal display devices. In the exposure device 1, a pattern of a mask M is projected onto a photosensitive material on a substrate using exposure light L with a strong light intensity, so optical elements such as lenses and reflectors included in the exposure device 1 are easily heated due to absorption of the exposure light L.

[0016] The exposure device 1 includes an illumination optical system IL, a projection optical system PO, a mask stage MS capable of holding and moving a mask M, and a substrate stage WS capable of holding and moving a substrate W. In addition, the exposure device 1 includes a control unit C for controlling an exposure process for the substrate W, and performs an exposure process for forming a latent image (latent image pattern) by projecting a pattern of the mask M onto a resist film (photosensitive agent) on the substrate via the projection optical system PO.

[0017] The light emitted from the light source (not shown) is shaped into, for example, an arc-shaped light long in the X direction by the slit (not shown) included in the illumination optical system IL. The mask M and the substrate W are respectively held by the mask stage MS and the substrate stage WS, and are arranged at substantially optically conjugate positions across the projection optical system PO. The mask M is located on the object plane of the projection optical system PO, and the substrate W is located on the image plane of the projection optical system PO.

[0018] The projection optical system PO projects the pattern formed on the mask M onto the substrate W at a predetermined projection magnification. The pattern formed on the mask M can be sequentially transferred onto the substrate W by performing exposure processing while scanning the mask stage MS and the substrate stage WS in a direction parallel to the object plane of the projection optical system PO at a speed ratio corresponding to the projection magnification of the projection optical system PO.

[0019] The projection optical system PO includes a trapezoidal reflector G1, a concave reflector G2, a convex meniscus lens G3, and a convex reflector G4. The exposure light L emitted from the illumination optical system IL and transmitted through the mask M is bent by the first surface G1a of the trapezoidal reflector G1 and is incident on the first concave reflection surface G2a of the concave reflector G2. The exposure light L reflected on the first concave reflection surface G2a is reflected on the convex reflection surface of the convex reflector G4 after passing through the meniscus lens G3, and is incident on the second concave reflection surface G2b of the concave reflector G2. The exposure light L reflected on the second concave reflection surface G2b is bent by the second surface G1b of the trapezoidal reflector G1 and forms an image on the substrate W.

[0020] exist Figure 1 In the embodiment, the concave reflecting mirror G2 is set as one reflecting mirror, and the first concave reflecting surface G2a and the second concave reflecting surface G2b are set as the same surface. As another structural example, the concave reflecting mirror G2 can also be divided into a first concave reflecting mirror having the first concave reflecting surface G2a and a second concave reflecting mirror having the second concave reflecting surface G2b.

[0021] exist Figure 1 In the projection optical system PO in FIG. 1 , the reflection surface of the convex reflection mirror G4 becomes an optical pupil. The optical path of the exposure light L becomes smaller near the meniscus lens G3 and the convex reflection mirror G4, so the light intensity of the light passing through the meniscus lens G3 and the light reflected by the convex reflection mirror G4 becomes stronger. Therefore, the meniscus lens G3 and the convex reflection mirror G4 are easily heated, and the lens barrel as a holding part holding them is also easily heated.

[0022] When heat is conducted to the lens barrel, natural convection occurs, and the heat is easily diffused to the vicinity of the lens barrels 103 and 104. Here, near the lens barrels 103 and 104, there are an optical path of the exposure light L from the trapezoidal reflector G1 toward the concave reflector G2, and an optical path of the exposure light L from the concave reflector G2 toward the trapezoidal reflector G1. When heat diffuses to the vicinity of the lens barrel, the refractive index of the space in the optical path of the exposure light L changes, which is likely to cause a reduction in the imaging performance of the projection optical system PO.

[0023] The present invention relates to an optical device capable of reducing the diffusion of heat around the lens barrel by efficiently cooling a lens barrel as a holding portion for optical elements such as lenses and reflectors and the optical elements.

[0024] (Example 1)

[0025] use Figure 2 The optical device 100 of Example 1 is described. The optical device 100 includes a meniscus lens 101 as a first optical element, a convex mirror 102 as a second optical element, a lens barrel 103 as a holding portion for holding the meniscus lens 101, and a lens barrel 104 as a holding portion for holding the convex mirror 102. Figure 2 In the embodiment, the lens barrel 103 and the lens barrel 104 are configured as independent structures, but the lens barrel 103 and the lens barrel 104 may be integrated to constitute one lens barrel.

[0026] In addition, the first optical element is not limited to the meniscus lens 101, and may be a lens of other shapes or a reflector. Similarly, the second optical element is not limited to the convex reflector 102, and may be a reflector of other shapes or a lens. In addition, the number of optical elements is not limited to two, and the optical device 100 may include more than three optical elements.

[0027] Figure 2 The optical device 100 is shown Figure 1 The example of the specific structure near the meniscus lens G3 and the convex reflector G4 in the figure shows that the exposure light L passes through the vicinity of the lens barrels 103 and 104, the exposure light L after passing through the meniscus lens 101 is reflected by the reflection surface 102a of the convex reflector 102, and the exposure light L reflected by the reflection surface 102a passes through the meniscus lens 101 again.

[0028] The optical device 100 includes a gas supply unit 105 that supplies temperature-controlled gas to the internal spaces of the lens barrels 103 and 104. The gas supply unit 105 supplies gas toward a flow path 106 provided in the lens barrel 104 as a holding portion of the convex reflecting mirror 102. That is, the gas supply unit 105 supplies gas toward the Y direction, which is the arrangement direction of the meniscus lens 101 and the convex reflecting mirror 102. By directly supplying the temperature-controlled gas toward the flow path 106, the gas can be efficiently supplied to the internal spaces of the lens barrels 103 and 104, and as a result, the meniscus lens 101, the convex reflecting mirror 102, etc. can be efficiently cooled.

[0029] In order not to block the optical path of the exposure light L, the gas supply unit 105 is arranged outside the optical path of the exposure light L. Figure 2 In the embodiment, the gas supply unit 105 is arranged on the side opposite to the meniscus lens 101 with respect to the convex reflecting mirror 102 .

[0030] The optical device 100 includes a gas exhaust unit 107 for exhausting gas from the internal space of the lens barrels 103 and 104. The gas exhaust unit 107 exhausts gas through an opening provided in a plate-shaped member 108. The plate-shaped member 108 is made of aluminum or the like and is fixed to the lens barrel 104. The internal space of the lens barrels 103 and 104 and the external space thereof are separated by the plate-shaped member 108, and the opening provided in the plate-shaped member 108 connects the internal space of the lens barrels 103 and 104 with the external space. The gas exhaust unit 107 includes a connection unit 107a connected to the plate-shaped member 108, a pipe 107b, and an exhaust mechanism 107c. Through the exhaust action of the exhaust mechanism 107c, gas is exhausted from the internal space of the lens barrels 103 and 104 through the pipe 107b.

[0031] Figure 3 (a) is viewed from the negative direction of the Y axis Figure 2 The optical device 100 shown in FIG. A plurality of gas supply units 105 are provided for the lens barrel 104, and temperature-controlled gas is supplied from each gas supply unit 105 to the internal space of the lens barrels 103 and 104. Figure 3 In (a), five gas supply units 105 are provided, but the number of gas supply units 105 is not limited thereto, and at least one gas supply unit 105 may be provided. In addition, two gas exhaust units 107 are provided for the plate-like member 108. As for the number of gas exhaust units 107, at least one gas exhaust unit 107 may be provided.

[0032] The barrel 104 is provided with a plurality of protrusions, and the convex mirror 102 is held by the barrel 104 by making it contact with these protrusions. In the region where no protrusions are present, a gap is formed between the barrel 104 and the convex mirror 102. This gap functions as a flow path for gas.

[0033] The gas supplied from the gas supply unit 105 moves to the internal space of the lens barrels 103 and 104 via the flow path 106. Then, the supplied gas is exhausted by the gas exhaust unit 107, passes through the space between the meniscus lens 101 and the convex reflector 102, and the gap between the lens barrel 104 and the convex reflector 102, and is then exhausted to the outside space from the opening provided in the plate-like member 108.

[0034] Figure 3 (b) is observed from the positive direction of the Y axis Figure 2 In the diagram of the optical device 100 shown, the meniscus lens 101 is not shown. Figure 2 The three protrusions 110 formed on the surface 103 a protrude in the positive direction of the Y axis to position the surface 101 a provided on the meniscus lens 101 . Figure 3The protrusion 111 in (b) is fixed to the surface 103b of the lens barrel 103, and the protrusion 111 supports the meniscus lens 101. In addition, gaps are formed between the surface 103a of the lens barrel 103 and the surface 101a of the meniscus lens 101, and between the surface 103b of the lens barrel 103 and the surface 101b of the meniscus lens 101, respectively.

[0035] Next, the effects of the optical device 100 of the present embodiment will be described in comparison with a comparative example. Figure 6 An optical device 600 is shown as a comparative example. Figure 2 The common structures of the optical device 100 are given the same reference numerals. Figure 6 , the heat generated in the meniscus lens 101 and the convex reflector 102 by the exposure light L is transferred to the lens barrels 103 and 104 and diffused to the periphery of the lens barrels 103 and 104 as natural convection. In the optical device 600, a cover 601 is provided on the upper part of the lens barrels 103 and 104 to reduce the diffusion of heat to the periphery of the lens barrels 103 and 104.

[0036] The heat diffusion around the lens barrels 103 and 104 can be more effectively reduced by providing the gas exhaust unit 602 in the cover 601. The gas exhaust unit 602 is connected to the exhaust mechanism via a pipe. The gas is exhausted from the internal space of the cover 601 by the exhaust action of the exhaust mechanism.

[0037] like Figure 6 As shown in FIG. 1 , by configuring a cover 601 around the lens barrels 103 and 104, the diffusion of heat around the lens barrels 103 and 104 can be reduced. However, there are often spatial restrictions around the lens barrels. Figure 1 As shown, there is an optical path of the exposure light L around the lens barrel, and there is a possibility that at least a part of the exposure light L is blocked due to the arrangement of the cover 601.

[0038] In this embodiment, the gas exhaust unit 107 is not disposed on the upper part of the barrels 103 and 104, but is disposed in the arrangement direction of the optical elements held by the barrels. Therefore, the exposure light L is not blocked and the radial size of the optical elements can be avoided.

[0039] Return to Figure 2 , other structures of the optical device 100 are described. The lens barrel 103 is provided with an opening for sucking gas from the external space of the lens barrel 103. As described above, the gas discharge section 107 is connected to the exhaust mechanism 107c via the pipe 107b, and the gas is discharged from the internal space of the lens barrels 103 and 104 by the exhaust action of the exhaust mechanism 107c. At this time, the internal space of the lens barrel becomes a negative pressure state relative to the external space. Therefore, as in Figure 2As indicated by the middle arrow, the gas in the external space of the barrel 103 is sucked into the internal space of the barrel 103 through the opening provided in the barrel 103 .

[0040] The gas attracted to the inner space of the lens barrel 103 moves toward the gas discharge portion 107 through the gap provided between the lens barrel 103 and the meniscus lens 101. Thus, the cooling force of the lens barrel 103 and the meniscus lens 101 can be strengthened. In addition, the gas in the outer space of the lens barrel 103 is preferably a gas whose temperature is controlled by a temperature adjustment mechanism not shown. The gas in the outer space of the lens barrel 103 is preferably a gas controlled in such a way that the temperature is the same as the temperature of the gas supplied from the gas supply portion 105.

[0041] In addition, the exhaust force in each exhaust mechanism 107c and the supply amount of gas in each gas supply unit 105 are controlled so that the sum of the flow rates of gas exhausted from each gas exhaust unit 107 is greater than the sum of the flow rates of gas supplied from each gas supply unit 105. An amount of gas corresponding to the difference between the sum of the flow rates of gas exhausted from each gas exhaust unit 107 and the sum of the flow rates of gas supplied from each gas supply unit 105 is sucked into the internal space of the lens barrel 103 from the opening provided in the lens barrel 103.

[0042] Thermal fluid analysis confirmed that the temperature rise of the barrels 103 and 104 can be reduced by supplying gas into the barrel from an opening provided in the barrel. Our analysis results showed that the temperature rise can be suppressed to about 50% compared to the case where the opening is not provided.

[0043] (Example 2)

[0044] Next, use Figure 4 The structure of the optical device 400 of the second embodiment is described. In the optical device 400 of the second embodiment, the number of openings provided in the lens barrel 103 is increased compared to the optical device 100 of the first embodiment. Specifically, an opening 115 is also provided in the vertical direction (Z-axis direction) of the lens barrel 103. As a result, the amount of gas sucked from the external space of the lens barrels 103 and 104 to the internal space increases, so the cooling power of the lens barrels 103 and 104, the meniscus lens 101, and the convex reflector 102 can be further enhanced.

[0045] (Example 3)

[0046] Next, use Figure 5 The structure of the optical device 500 of Example 3 is described. The optical device 500 of Example 3 is different from the arrangement of the gas exhaust part 107 of the optical device 100 of Example 1. Specifically, the gas exhaust part 501 is arranged on the upper part of the convex reflection mirror 102.

[0047] The gas exhaust unit 501 is arranged at a position in the negative direction of the Y axis relative to the lens barrel 104, and exhausts gas through an opening provided in the lens barrel 104. The gas exhaust unit 501 includes a connection unit 501a connected to the lens barrel 104, a pipe 501b, and an exhaust mechanism 501c. Through the exhaust action of the exhaust mechanism 501c, the gas is exhausted from the internal space of the lens barrels 103 and 104 through the pipe 501b. By arranging the gas exhaust unit 501 in the Y axis direction rather than the Z axis direction relative to the lens barrel 104, the enlargement of the optical device 500 in the Z axis direction can be alleviated.

[0048] In such a structure, for example, the meniscus lens 101 as the first optical element and the convex reflector 102 as the second optical element are both composed of lenses, such as Figure 5 As shown, it is suitable for the case where the exposure light L is transmitted from the right side of the first optical element (meniscus lens 101) to the left side of the second optical element (lens).

[0049] (How to make the item)

[0050] The manufacturing method of the article involved in the embodiment of the present invention is suitable for manufacturing micro devices such as semiconductor devices, components with fine structures, flat panel displays and other articles. The manufacturing method of the article of this embodiment includes a process of using the above-mentioned exposure device 1 to form a latent image pattern on a photosensitive agent applied to a substrate W (a process of exposing the substrate W), and a process of developing (processing) the substrate W after the latent image pattern is formed in the process. In addition, the manufacturing method includes other well-known processes (oxidation, film formation, evaporation, doping, flattening, etching, resist stripping, cutting, bonding, packaging, etc.). Compared with previous methods, the manufacturing method of the article of this embodiment is more advantageous in at least one of the performance, quality, productivity, and production cost of the article.

[0051] (Other embodiments)

[0052] As mentioned above, although the preferred embodiments of the present invention have been described, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist of the present invention.

[0053] According to the present invention, it is possible to provide an optical device including a gas supply mechanism that reduces the risk of light reaching an optical element being blocked.

Claims

1. An optical device, characterized in that: have: a first optical element and a second optical element; A holding portion, holding the first optical element and the second optical element; a gas supply unit for supplying gas to the interior of the holding unit through the first opening; as well as a gas exhaust portion for exhausting the gas inside the holding portion to the outside, The gas exhaust portion is arranged side by side in the arrangement direction of the first optical element and the second optical element. The gas exhaust portion exhausts the gas supplied to the inside of the holding portion by the gas supply portion through the first opening and the gas sucked into the inside of the holding portion from the outside of the holding portion through a second opening different from the first opening. The first optical element is supported by contacting with a protrusion provided on the holding portion. The second opening is a gap between a region of the holding portion where the protrusion is not provided and the first optical element. The flow rate of the gas discharged from the gas discharge portion is greater than the flow rate of the gas supplied from the gas supply portion.

2. The optical device according to claim 1, wherein: The gas exhaust unit includes an exhaust mechanism for exhausting gas from a space inside the holding unit.

3. The optical device according to claim 1, wherein: The gas supply unit is provided outside an optical path of light incident on the first optical element and the second optical element.

4. The optical device according to claim 1, wherein: A gas in an amount corresponding to a difference between a flow rate of the gas exhausted from the gas exhaust portion and a flow rate of the gas supplied from the gas supply portion is supplied from the second opening.

5. The optical device according to claim 1, wherein: The gas exhaust unit exhausts gas that has passed through a space between the first optical element and the second optical element, the gas being supplied by the gas supply unit.

6. The optical device according to claim 1, wherein: The gas supply unit and the gas exhaust unit are arranged closer to the second optical element than to the first optical element.

7. The optical device according to claim 1, wherein: The second optical element is held by the holding portion by abutting against a protrusion provided on the holding portion. The gas supplied by the gas supply unit passes through a gap between a region of the holding unit where the protrusion is not provided and the second optical element.

8. The optical device according to claim 1, wherein: The first optical element is a lens, and the second optical element is a reflector that reflects light that has passed through the first optical element.

9. The optical device according to claim 8, wherein: The gas supply portion is arranged on the side of the reflector opposite to the lens.

10. A projection optical system comprising a first concave reflecting surface and a second concave reflecting surface and the optical device according to any one of claims 1 to 9, wherein: Light from the object surface is reflected in the order of the first concave reflection surface, the convex reflection surface of the reflection mirror included in the optical device, and the second concave reflection surface, and is imaged on the image surface.

11. An exposure device, characterized in that: have: an illumination optical system that illuminates the mask with light from a light source; and The projection optical system according to claim 10 projects the image of the pattern of the mask onto the substrate.

12. A method for manufacturing an article, characterized in that: include: a forming step of forming a pattern on a substrate using the exposure apparatus according to claim 11; as well as a processing step of processing the substrate after the pattern is formed in the forming step, An article is manufactured using the substrate processed in the processing step.

Images