Illumination optical system, exposure device, and article manufacturing method

Abstract

The present invention relates to an illumination optical system, an exposure device, and an article manufacturing method. The illumination optical system for illuminating an illuminated surface comprises: a first rod integrator having a first incident surface and a first exit surface; a second rod integrator having a second incident surface and a second exit surface, and light emitted from the first exit surface is incident on the second incident surface; a spacer sandwiched by the first exit surface and the second incident surface; and an optical system disposed between the second exit surface and the illuminated surface to reduce the unevenness of the intensity distribution of the light emitted from the second exit surface.

Description

Technical Field

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

[0002] An exposure device can be used in a photolithography process for manufacturing articles such as semiconductor devices. The exposure device can include an illumination optical system for illuminating an original plate and a projection optical system for projecting a pattern of the original plate illuminated by the illumination optical system onto a substrate. The substrate provided to the exposure device is coated with a photosensitive material on the surface, and the pattern of the original plate is projected onto the substrate, thereby transferring the pattern to the photosensitive material. If the illumination optical system illuminates the original plate unevenly, there is a possibility that the transfer of the pattern to the photosensitive material cannot be performed well. Therefore, the illumination optical system can have a reflective optical integrator for illuminating the original plate with uniform illumination.

[0003] In order to improve the uniformity of illumination, a reflective optical integrator with a longer total length is advantageous, but it is difficult to manufacture a reflective optical integrator (rod integrator) with a longer total length at a low cost. Japanese Patent Publication No. 2005-32909 describes a structure in which a plurality of optical integrators (rod integrators) are arranged in series along the direction in which illumination light passes. According to this structure, the same effect as the case of using a single optical integrator having a length obtained by summing the length of the plurality of optical integrators can be obtained.

[0004] However, if multiple optical integrators are arranged separately from each other, loss may occur between the optical integrator on the upstream side and the optical integrator on the downstream side, or the illumination of the peripheral part may be reduced. Therefore, if multiple optical integrators are arranged in contact with each other, it is easy to cause damage, defects and other degradation on the contact surface, which will also become the main reason for reducing the illumination. Alternatively, a method of bonding multiple optical integrators with an adhesive is also considered, but in such a method, the adhesive deteriorates during long-term use and the transmittance may be reduced. Summary of the invention

[0005] The present invention provides a technique that is advantageous for suppressing a decrease in illumination while suppressing degradation such as damage and defect caused by contact between optical integrators.

[0006] The first aspect of the present invention relates to an illumination optical system for illuminating an illuminated surface, the illumination optical system comprising: a first rod integrator having a first incident surface and a first exit surface; a second rod integrator having a second incident surface and a second exit surface, light emitted from the first exit surface being incident on the second incident surface; a spacer clamped by the first exit surface and the second incident surface; and an optical system arranged between the second exit surface and the illuminated surface to reduce the unevenness of the intensity distribution of the light emitted from the second exit surface.

[0007] A second aspect of the present invention relates to an exposure device including the illumination optical system and a projection optical system according to the first aspect, and configured to project a pattern of an original plate illuminated by the illumination optical system onto a substrate using the projection optical system.

[0008] The third aspect of the present invention relates to a method for manufacturing an article, which comprises: an exposure process, in which a photosensitive material applied to a substrate is exposed using the exposure device involved in the second aspect; and a development process, in which the photosensitive material is developed to manufacture an article from the substrate that has undergone the development process. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a figure which shows the structure of the exposure apparatus of a comparative example.

[0010] Figure 2 It is a diagram showing the structure of an optical integrator in an exposure device of a comparative example.

[0011] Figure 3 It is a figure which shows the structure of the exposure apparatus which concerns on 1st Embodiment.

[0012] Figure 4 It is a diagram schematically showing the structure of the optical integrator of the exposure apparatus according to the first embodiment.

[0013] Figure 5 It is a diagram schematically showing the light intensity distribution of the optical integrator of the exposure apparatus according to the first embodiment.

[0014] Figure 6 It is a diagram schematically showing the structure of an optical integrator of an exposure apparatus according to a second embodiment.

[0015] Figure 7 It is a diagram schematically showing the light intensity distribution of the optical integrator of the exposure apparatus according to the second embodiment.

[0016] Figure 8 It is a diagram for explaining the function of the illumination optical system of the exposure apparatus according to the second embodiment.

[0017] Fig. 9 It is a diagram for explaining the function of the illumination optical system of the exposure apparatus according to the second embodiment.

[0018] Description of Reference Numerals

[0019] 4a: 1st rod integrator, 4b: 2nd rod integrator, 6: original plate (illuminated surface), 13: optical system, EX: exposure device, IL: illumination optical system, 7: projection optical system, 12: spacer. DETAILED DESCRIPTION

[0020] The following is a detailed description of the embodiments with reference to the attached drawings. It should be noted that the invention of the claims is not limited to the following embodiments. A plurality of features are described in the embodiments, but all of these plurality of features are not necessarily required features of the invention, and a plurality of features may be combined arbitrarily. Moreover, in the attached drawings, the same reference figure numerals are marked for the same or identical structures, and repeated descriptions are omitted.

[0021] First, refer to Figure 1 , Figure 2 A comparative example is described. Figure 1 The structure of the exposure device EX' of the comparative example is shown in FIG. Figure 2 (a) shows the structure of the optical integrator 4. The exposure device EX' can include an illumination optical system IL and a projection optical system 7. The illumination optical system IL can include, for example, a light source 1, an elliptical mirror 2, a focusing optical system 3, an optical integrator 4 and a focusing optical system 5. The light source 1 can be composed of, for example, an ultra-high pressure mercury lamp, an excimer laser or an LED, but can also be composed of other light-emitting devices. The elliptical mirror 2 can be configured so that its first focus coincides with the position of the light source 1. The light reflected by the elliptical mirror 2 is guided to the optical integrator 4 via the focusing optical system 3.

[0022] The optical integrator 4 may include a first rod integrator 4a and a second rod integrator 4b arranged along the optical axis. The first rod integrator 4a has a first incident surface 42 and a first exit surface 44, and the second rod integrator 4b has a second incident surface 52 and a second exit surface 54. The light emitted from the focusing optical system 3 first enters the first incident surface 42 of the first rod integrator 4a, is uniformized by repeated reflection in the first rod integrator 4a, and is emitted from the first exit surface 44 of the first rod integrator 4a. The light emitted from the first exit surface 44 of the first rod integrator 4a enters the second incident surface 52 of the second rod integrator 4b arranged separately from the first exit surface 44. The light incident on the second incident surface 52 is uniformized by repeated reflection in the second rod integrator 4b, and is emitted from the second exit surface 54 of the second rod integrator 4b.

[0023] The light emitted from the second emission surface 54 of the second rod integrator 4b illuminates the original plate 6 via the focusing optical system 5. In this way, the original plate 6 arranged on the illuminated surface is illuminated by the illumination optical system IL. The pattern of the original plate 6 illuminated by the illumination optical system IL is projected relative to the substrate 8 arranged on the substrate mounting table 9 by the projection optical system 7. As a result, the photosensitive material (photoresist) coated on the substrate 8 is exposed to form a latent image. In order to transfer the fine pattern of the original plate 6 to the photosensitive material on the substrate 8 with high precision, it is important to illuminate the illuminated surface (original plate 6) with uniform illumination by the illumination optical system IL.

[0024] In order to illuminate the illuminated surface with more uniform illumination, it is effective to lengthen the optical integrator 4, but it is difficult to form the optical integrator 4 with a single long rod integrator. Therefore, the optical integrator 4 can be formed by arranging at least two rod integrators 4a and 4b in series.

[0025] exist Figure 2 In (b), the distribution of the light intensity I of the second incident surface 52 of the second rod integrator 4b is represented by a solid line. Figure 2 In (b), the horizontal axis is the position in the Y direction on the second incident surface 52, and the vertical axis is the light intensity I. Since light leaks from the gap between the first emission surface 44 and the second incident surface 52, a part of the light emitted from the first emission surface 44 does not enter the second incident surface 52. Therefore, the light intensity I of the peripheral portion of the second incident surface 52 may be reduced. It should be noted that Figure 2 In (b), the dotted line represents the distribution of light intensity at the contact surface when the first emission surface 44 contacts the second incident surface 52. When there is a gap between the first integrator 4a and the second integrator 4b, the illumination of the illuminated surface is reduced compared to the case where the optical integrator 4 is composed of one rod-shaped integrator having the total length of the rod-shaped integrators, and the uniformity of the illumination is reduced.

[0026] However, if the first output surface 44 of the first rod integrator 4a and the second incident surface 52 of the second rod integrator 4b are arranged in contact with each other, the first output surface 44 and the second incident surface 52 may be damaged, defected, or otherwise degraded due to vibration of the exposure device, expansion due to light irradiation, or the like. As a result, the illumination of the illuminated surface may be reduced. In addition, if the first output surface 44 of the first rod integrator 4a and the second incident surface 52 of the second rod integrator 4b are bonded together using an adhesive, the light transmittance may be reduced due to degradation of the adhesive during long-term use, and the illumination of the illuminated surface may be reduced. Therefore, although it is desirable to arrange the rod integrators close to each other, it is not preferred to arrange the rod integrators in contact with each other.

[0027] Below, refer to Figure 3 , Figure 4 , Figure 5 The exposure apparatus EX according to the first embodiment of the present invention will be described. Figure 3 The structure of the exposure apparatus EX of the first embodiment is shown in FIG. Figure 4 The structure of the optical integrator 4 of the exposure apparatus EX of the first embodiment is schematically shown in FIG. Figure 5 Schematically shows the light intensity distribution of the optical integrator 4 of the exposure apparatus EX according to the first embodiment. Matters not mentioned in the first embodiment can be handled in accordance with the above-mentioned comparative example.

[0028] The exposure apparatus EX of the first embodiment has an improved structure of the optical integrator 4 of the exposure apparatus EX of the comparative example. In the first embodiment, the optical integrator 4 can include a first rod integrator 4a and a second rod integrator 4b arranged along the optical axis. The first rod integrator 4a has a first incident surface 42 and a first exit surface 44, and the second rod integrator 4b has a second incident surface 52 and a second exit surface 54. The light emitted from the focusing optical system 3 first enters the first incident surface 42 of the first rod integrator 4a, is uniformized by repeated reflection in the first rod integrator 4a, and is emitted from the first exit surface 44 of the first rod integrator 4a. The light emitted from the first exit surface 44 of the first rod integrator 4a enters the second incident surface 52 of the second rod integrator 4b arranged to be separated from the first exit surface 44. The light incident on the second incident surface 52 is uniformed by repeated reflection in the second rod integrator 4b and is emitted from the second emission surface 54 of the second rod integrator 4b. The cross-sectional shape of the first rod integrator 4a and the second rod integrator 4b can be a quadrilateral (for example, a square or a rectangular shape other than a square).

[0029] In the first embodiment, the optical integrator 4 may include a spacer 12 sandwiched between the first emission surface 44 of the first rod integrator 4a and the second incident surface 52 of the second rod integrator 4b. The spacer 12 may be configured to contact the first emission surface 44 and the second incident surface 52. The spacer 12 may maintain a gap between the first emission surface 44 and the second incident surface 52 so that the first emission surface 44 of the first rod integrator 4a and the second incident surface 52 of the second rod integrator 4b do not contact each other. By providing the spacer 12, the contact between the first emission surface 44 and the second incident surface 52 can be prevented while the gap between the first emission surface 44 and the second incident surface 52 is maintained small. Thus, it is possible to suppress the loss of light caused by the gap while suppressing the deterioration such as damage on the first emission surface 44 and the second incident surface 52.

[0030] In the first embodiment, the optical integrator 4 can include a supporting member B for supporting the first rod integrator 4a and the second rod integrator 4b. The supporting member B can also support the spacer 12. The optical integrator 4 can include a positioning member P1 and a holding member P2. The positioning member P1 and the holding member P2 can be supported by the supporting member B. The holding member P2 presses the first rod integrator 4a and the second rod integrator 4b relative to the positioning member P1, and can hold the first rod integrator 4a and the second rod integrator 4b by friction. The holding member P2 has a portion that contacts the first rod integrator 4a and the second rod integrator 4b, and the portion can be composed of an elastic member.

[0031] The spacer 12 has an attenuation portion BP for attenuating a portion of the light emitted from the first emission surface 44 (a portion of the cross section perpendicular to the optical axis). Figure 4 As shown in (b) of FIG. 5 , the attenuation portion BP can be configured so that a light intensity distribution having rotational symmetry is formed on the second incident surface 52. Figure 4 In the example shown in (b) of FIG. 1 , the spacer 12 can be configured so that a light intensity distribution having a two-fold symmetry is formed on the second incident surface 52 .

[0032] The optical integrator 4 can include at least one other rod integrator arranged in series with the first rod integrator 4a and the second rod integrator 4b along the optical axis. In other words, the optical integrator 4 can include at least three rod integrators arranged in series along the optical axis, and a spacer 12 can be arranged between adjacent rod integrators.

[0033] exist Figure 5 (a) schematically shows the light intensity distribution of the second incident surface 52 of the second rod integrator 4b. Figure 5 (b) schematically shows the light intensity distribution of the imaginary surface 53 between the second incident surface 52 and the second emitting surface 54 of the second rod integrator 4b. Figure 5 (c) schematically shows the light intensity distribution of the second emission surface 54 of the second rod integrator 4b. Figure 5 As schematically shown in (a), (b), and (c) of FIG. 1 , the non-uniform light intensity distribution having rotational symmetry formed by the attenuation portion BP is gradually made uniform by repeated reflection by the second rod integrator 4 b.

[0034] The illumination optical system IL can include the optical system 13. The optical system 13 is disposed between the second emission surface 54 and the illuminated surface (the original plate 6), and can be configured to reduce the non-uniformity of the intensity distribution of the light emitted from the second emission surface 54. Figure 3Reference numerals 13a, 13b, and 13c in the figure schematically indicate the movement of the optical system 13. The optical system 13 can be, for example, a zoom optical system. By providing the optical system 13, the non-uniformity of the light intensity distribution that may be generated by the attenuation portion BP of the spacer 12 can be reduced.

[0035] Below, refer to Figure 6 , Figure 7 , Figure 8 An exposure apparatus EX according to a second embodiment of the present invention will be described. Figure 6 The structure of the optical integrator 4 of the exposure apparatus EX of the second embodiment is schematically shown in FIG. Figure 7 Schematically shows the light intensity distribution of the optical integrator 4 of the exposure device EX of the second embodiment. Matters not mentioned in the second embodiment can be in accordance with the exposure device EX of the first embodiment. In the second embodiment, the optical integrator 4 can include a spacer 12 clamped by the first emission surface 44 of the first rod integrator 4a and the second incident surface 52 of the second rod integrator 4b. The spacer 12 can be configured to contact the first emission surface 44 and the second incident surface 52. The spacer 12 can maintain a gap between the first emission surface 44 and the second incident surface 52 so that the first emission surface 44 of the first rod integrator 4a and the second incident surface 52 of the second rod integrator 4b do not contact. The cross-sectional shape of the first rod integrator 4a and the second rod integrator 4b can be a quadrilateral (for example, a square or a rectangle other than a square).

[0036] In the second embodiment, the spacer 12 has an attenuation portion BP for attenuating a portion of the light emitted from the first emission surface 44. Figure 6 As shown in (b) of FIG. 5 , the attenuation portion BP can be configured so that a light intensity distribution having rotational symmetry is formed on the second incident surface 52. Figure 6 In the example shown in (b), the spacer 12 can be configured so that a light intensity distribution having a four-fold symmetry is formed on the second incident surface 52. The attenuation portion BP can be configured to contact the first emission surface 44 and the four corners of the second incident surface 52. The spacer 12 can have a circular opening, for example, but may also have an opening of another shape (for example, an elliptical shape).

[0037] exist Figure 7 (a) schematically shows the light intensity distribution of the second incident surface 52 of the second rod integrator 4b. Figure 7 (b) schematically shows the light intensity distribution of the imaginary surface 53 between the second incident surface 52 and the second emitting surface 54 of the second rod integrator 4b. Figure 7 (c) schematically shows the light intensity distribution of the second emission surface 54 of the second rod integrator 4b. Figure 7As schematically shown in (a), (b), and (c) of FIG. 1 , the non-uniform light intensity distribution having rotational symmetry formed by the attenuation portion BP is gradually uniformized by repeated reflections by the second rod integrator 4b. However, there may be a case where the uniformization of the light intensity distribution by the optical integrator 4 is insufficient.

[0038] Therefore, the illumination optical system IL can include the optical system 13. The optical system 13 is disposed between the second emission surface 54 and the illuminated surface (the original plate 6), and can be configured to reduce the non-uniformity of the intensity distribution of the light emitted from the second emission surface 54. Figure 3 Reference numerals 13a, 13b, 13c schematically show the movement of the optical system 13. The optical system 13 can be, for example, a zoom optical system. By providing the optical system 13, the non-uniformity of the light intensity distribution that may be generated by the attenuation portion BP of the spacer 12 can be reduced.

[0039] exist Figure 8 (a) shows an example of the light intensity distribution of the second incident surface 52, the imaginary surface 53, and the second emitting surface 54 of the second rod integrator 4b. Figure 8 In (a), the horizontal axis represents the position in the diagonal direction of the cross section (the cross section in the direction perpendicular to the optical axis) of the second rod integrator 4b, and the vertical axis represents the light intensity.

[0040] exist Figure 8 The function of the optical system 13 is schematically shown in (b). By moving the optical system 13, the distribution of the light intensity I of the illuminated surface where the original plate 6 is arranged can be changed. Figure 8 (b) schematically shows the distribution of light intensity I formed on the illuminated surface when light having a uniform light intensity distribution is incident on the optical system 13. Figure 8 In (b), the horizontal axis is the position in the diagonal direction of the cross section (cross section in the direction perpendicular to the optical axis) of the second rod integrator 4b, and the vertical axis is the light intensity. When the optical system 13 is arranged at the position 13a on the light source 1 side, the distribution of the light intensity I formed on the illuminated surface can be in a cross-sectional shape like a downward convex quadratic curve. When the optical system 13 is arranged at the position 13c on the illuminated surface side, the distribution of the light intensity I formed on the illuminated surface can be in a cross-sectional shape like a upward convex quadratic curve.

[0041] exist Fig. 9 The effects provided by the optical system 13 are schematically shown in (a) and (b). Fig. 9 In (a), reference numeral 53 schematically shows that the length of the second rod integrator 4b only reaches Figure 6 The distribution of light intensity I formed on the illuminated surface where the original plate 6 is arranged when the optical system 13 is not provided on the imaginary surface 53 of (a). Fig. 9 In (a), reference numeral 13a shows the correction effect of the light intensity I achieved by the optical system 13 disposed at the position 13a. Fig. 9 In (a), reference numeral 6 schematically shows that the length of the second rod integrator 4b only reaches Figure 6 The distribution of light intensity I formed on the illuminated surface where the original plate 6 is arranged when the optical system 13 is arranged at the position 13a and the imaginary plane 53 of (a) is shown. It can be seen that the non-uniformity of the distribution of light intensity I formed on the illuminated surface can be reduced by adjusting the position of the optical system 13.

[0042] exist Fig. 9 In (b), reference numeral 54 schematically shows that when the length of the second rod integrator 4b reaches Figure 6 The distribution of light intensity I formed on the illuminated surface where the original plate 6 is arranged when the second emission surface 54 of (a) is not provided and the optical system 13 is not provided. Fig. 9 In (b), reference numeral 13c indicates the correction effect of the light intensity I achieved by the optical system 13 disposed at the position 13c. Fig. 9 In (b), reference numeral 6 schematically shows that when the length of the second rod integrator 4b reaches Figure 6 The distribution of light intensity I formed on the illuminated surface where the original plate 6 is arranged when the second emission surface 54 of (a) is set and the optical system 13 is arranged at the position 13c. It can be seen that the non-uniformity of the distribution of light intensity I formed on the illuminated surface can be reduced by adjusting the position of the optical system 13.

[0043] In each of the above embodiments, the opening of the spacer 12 can be in a shape such that a light intensity distribution having rotational symmetry is formed on the second incident surface 52. The opening that can be provided in the spacer 12 can be, for example, circular or elliptical, or can be other shapes that block light at the four corners of the second rod integrator 4b. Alternatively, the spacer 12 can also be composed of a plurality of separate parts. The number of attenuation parts BP can be determined arbitrarily, but it is preferably determined in a manner such that a light intensity distribution having rotational symmetry is formed on the second incident surface 52. The area of ​​each of the plurality of attenuation parts BP can be determined arbitrarily, but it is preferably determined in a manner such that a light intensity distribution having rotational symmetry is formed on the second incident surface 52.

[0044] The spacer 12 may also be composed of a light-transmitting member. In this case, a more uniform light intensity distribution can be formed on the illuminated surface. The optical system 13 may be a zoom optical system as in the above example, but may also be another optical system. The optical system 13 may also be an optical member that is arranged near the pupil of the focusing optical system 5 and changes the transmittance depending on the incident angle.

[0045] The following describes the adjustment method of the exposure device EX or the illumination optical system IL. First, the illumination distribution of the illuminated surface on which the original plate 6 is arranged or the exposure surface on which the substrate 8 is arranged can be measured. Then, based on the result of the measurement, the position of the optical system 13 is determined to reduce the unevenness of the illumination distribution, and the optical system 13 is adjusted or driven to the position. In this way, the preparation for exposing the substrate 8 can be completed.

[0046] Hereinafter, an article manufacturing method for manufacturing an article such as a semiconductor device by a photolithography process using the above-mentioned exposure apparatus EX will be described. The article manufacturing method includes an exposure process of exposing a photosensitive material applied to a substrate by the exposure apparatus EX and a development process of developing the photosensitive material, and an article is manufactured from the substrate that has undergone the development process.

[0047] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, in order to disclose the scope of the invention, the following claims are attached.

Claims

1. An illumination optical system for illuminating an illuminated surface, characterized in that: include: A first rod integrator having a first incident surface and a first exit surface, and making light incident on the first incident surface uniform and emitting light from the first exit surface; a second rod integrator having a second incident surface and a second exit surface, and making the light emitted from the first exit surface and incident on the second incident surface uniform and emitting from the second exit surface; a spacer configured to contact the first emitting surface and the second incident surface; as well as an optical system disposed between the second emission surface and the illuminated surface, and reducing the non-uniformity of the intensity distribution of the light emitted from the second emission surface, The spacer includes an attenuation portion that attenuates a portion of the light emitted from the first emission surface, and the attenuation portion is configured to form a light intensity distribution having rotational symmetry on the second incidence surface.

2. The illumination optical system according to claim 1, characterized in that: The spacer is configured so that a light intensity distribution having two-fold symmetry is formed on the second incident surface.

3. The illumination optical system according to claim 1, wherein: The spacer is configured so that a light intensity distribution having four-fold symmetry is formed on the second incident surface.

4. The illumination optical system according to claim 3, characterized in that: The cross-sectional shape of the first rod integrator and the second rod integrator is a quadrilateral, The attenuation portion is in contact with four corners of the first emission surface and the second incidence surface.

5. The illumination optical system according to claim 1, wherein: Also includes: The supporting member supports the first rod integrator and the second rod integrator.

6. The illumination optical system according to claim 1, characterized in that: The optical system includes a zoom optical system.

7. An illumination optical system for illuminating an illuminated surface, characterized in that: include: A first rod integrator having a first incident surface and a first exit surface, which makes light incident on the first incident surface uniform and emits the light from the first exit surface; a second rod integrator having a second incident surface and a second exit surface, and making the light emitted from the first exit surface and incident on the second incident surface uniform and emitting from the second exit surface; A spacer, sandwiched by the first emission surface and the second incident surface; as well as an optical system disposed between the second emission surface and the illuminated surface, and reducing the non-uniformity of the intensity distribution of the light emitted from the second emission surface, The spacer includes an attenuation portion that attenuates a portion of the light emitted from the first emission surface, and the attenuation portion is configured to form a light intensity distribution having rotational symmetry on the second incidence surface.

8. An exposure device, characterized in that: include: The illumination optical system according to any one of claims 1 to 7; as well as Projection optical system, The exposure device is configured to project the pattern of the original plate illuminated by the illumination optical system onto a substrate using the projection optical system.

9. A method for manufacturing an article, characterized in that: include: an exposure step of exposing the photosensitive material coated on the substrate using the exposure device according to claim 8; as well as A developing step to develop the photosensitive material. An article is manufactured from the substrate that has undergone the development step.

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