Optical device, exposure apparatus and exposure method

Abstract

To provide a technique of shifting a route of light by using a prism in which an increase of an astigmatic difference is suppressed despite a simple configuration, and an effect of chromatic aberration caused by a wavelength dependence of the refraction index of a prism material is also suppressed.SOLUTION: An optical device that shifts a route of input light, and outputs output light along an optical path which is parallel with but not the same as an optical path of input light, and the device comprises: a first prism body and a second prism body each of which has an incident surface and an exiting surface non-parallel with each other; and a shift amount adjustment mechanism which changes a distance between the prisms to adjust a shift amount of light. Each of the first prism body and the second prism body is arranged in a state where end faces of a first member whose one end face constitutes an incident surface and a second member whose one end face constitutes an exiting surface and which has Abbe number different from the first member are abutted to each other.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an optical device that can be applied to a technique for exposing a substrate, such as a printed wiring board or a glass substrate, to form a pattern on the substrate. [Background technology]

[0002] One technique for forming patterns such as wiring patterns on various substrates such as semiconductor substrates, printed wiring substrates, and glass substrates is to expose a photosensitive layer formed on the substrate surface to a light beam modulated according to drawing data. In this type of technique, a means for shifting the incidence position of the light beam on the substrate is provided on the optical path in order to draw at an appropriate position while adapting to distortion or deformation of the substrate.

[0003] For example, in the technology described in Patent Document 1, a pair of wedge prisms facing each other in opposite directions are arranged on the optical path. The distance between the wedge prisms is changed to shift the position of the image formed on the image plane by the passing light beam. In this technology, the angle of incidence of light with respect to the prism is set so that the astigmatic difference is approximately zero when the distance between the prisms is a reference value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-244446 A Summary of the Invention [Problem to be solved by the invention]

[0005] In this technology of shifting a light beam by an optical device using a prism, deviation in the shift amount due to the optical characteristics of the prism material can be a problem. Specifically, due to the wavelength dependency of the refractive index of the material, the emission angle of the light beam differs depending on the wavelength, and the shift amount varies accordingly. When the light beam has a significant bandwidth, the shift amount differs depending on the wavelength component, causing the beam spot to widen, and the clarity of the image formed by exposure in the exposure device decreases. Even when a light source with a sufficiently narrow bandwidth is used, if the central wavelength changes due to variable factors such as changes in temperature and driving current, the obtained shift amount will deviate from the design value. All of these phenomena will reduce the quality of the image formed by exposure.

[0006] In this specification, the phenomenon in which the refractive index of a prism material varies with wavelength is referred to as "dispersion."Furthermore, the phenomenon in which the position of a light beam fluctuates or the beam spot size changes due to the wavelength dependency of the refractive index, which reduces the quality of an image formed by exposure, is referred to as "chromatic aberration," following the terminology used in lenses.

[0007] Furthermore, in this type of optical device, it is necessary to change the shift amount as necessary, but if the setting of the shift amount is changed, the magnitude of the above-mentioned chromatic aberration also changes accordingly. Therefore, it is practically impossible to suppress the chromatic aberration, for example, by optimizing the design of not only the optical device but also the entire optical system including the optical device. For this reason, it is necessary to establish a technology that can obtain the effect of suppressing the chromatic aberration caused by the wavelength dependency of the refractive index of the prism material while maintaining the function of suppressing the astigmatic difference. In this respect, there is still room for improvement in the above-mentioned conventional technology.

[0008] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a technology for shifting the path of light using a prism, which has a simple configuration, yet is capable of suppressing an increase in astigmatic difference and also suppressing the effects of chromatic aberration caused by the wavelength dependence of the refractive index of the prism material. [Means for solving the problem]

[0009] One aspect of the present invention is an optical device that shifts a path of input light and outputs output light along an optical path that is parallel to but not identical to the optical path of the input light, and includes a first prism body having an entrance surface and an exit surface that are non-parallel to each other, a second prism body having an entrance surface and an exit surface that are non-parallel to each other and having an apex angle that is approximately the same as that of the first prism body, and a shift amount adjustment mechanism that supports the first prism body and the second prism body in opposite directions to each other and so that the exit surface of the first prism body faces the entrance surface of the second prism body, and changes the distance between them to adjust the shift amount of light that enters the entrance surface of the first prism body and exits from the exit surface of the second prism body.

[0010] Here, each of the first prism body and the second prism body has a first member having one end face forming the entrance surface and a second member having one end face forming the exit surface, the first member and the second member being prisms formed of materials having different Abbe numbers, and are arranged with one end face of the first member different from the entrance surface and one end face of the second member different from the exit surface butted against each other. Hereinafter, when there is no need to particularly distinguish between the first prism body and the second prism body, they may be simply referred to as "prism bodies".

[0011] In the following, when there is no need to particularly distinguish between the first prism body and the second prism body, they may be collectively referred to simply as "prism body."

[0012] In the invention configured as described above, similar to the technology described in Patent Document 1, the shift of the optical path is realized by a prism pair combining two prism bodies, and the amount of shift can be adjusted by changing the distance between the prism bodies. Also, as described in Patent Document 1, it is possible to reduce the astigmatic difference in the output light by appropriately setting the incident angle of the input light to the first prism body, one of the prism bodies that constitutes the prism pair.

[0013] On the other hand, chromatic aberration caused by the wavelength dependency (dispersion) of the refractive index of the prism material is dealt with by making each of the two prism bodies that make up the prism pair into a composite structure combining materials with different Abbe numbers. Specifically, a first member, one end face of which constitutes the entrance surface of the prism body, and a second member, one end face of which constitutes the exit surface, are made of different materials, and the other end faces of each are butted together to form one prism body as a whole.

[0014] In this invention, the Abbe number is used as an index that quantitatively expresses the wavelength dependency of the refractive index of a material, and the prism body is constructed by combining two types of materials with different Abbe numbers. In each prism body, the dispersions that occur in the two materials with different wavelength dependencies of the refractive index act complementary to each other, that is, cancel each other out, making it possible to suppress the overall dispersion to a low level. The detailed design concept will be described later, but a particularly remarkable effect can be obtained by optimizing the combination of materials and dimensions based on the optical properties of each material.

[0015] As described later, according to the knowledge of the inventors of the present application, the optimal conditions for reducing astigmatic difference and the optimal conditions for reducing chromatic aberration are not mutually exclusive, and it is possible to design a system that achieves both. Therefore, in an optical device to which the present invention is applied, it is possible to realize a light shift while suppressing an increase in astigmatic difference and the influence of dispersion caused by the optical properties of the prism material.

[0016] Another aspect of the present invention is an exposure apparatus comprising a stage that supports a substrate to be processed, an exposure section that modulates a light beam based on predetermined exposure data and causes the modulated light beam to be incident on a surface of the substrate via the optical device described above, and a moving mechanism that moves the stage and the exposure section relative to one another.

[0017] Another aspect of the present invention is an exposure method for exposing a substrate by irradiating a light beam modulated based on predetermined exposure data onto a surface of the substrate, the exposure method comprising: arranging an optical device having the above-described configuration on an optical path of the light beam; and exposing the substrate with the light beam while adjusting the shift amount of the light beam using the shift amount adjustment mechanism.

[0018] In the invention thus configured, when the substrate surface is exposed with a modulated light beam, the optical device described above is provided in the optical path of the light beam. Therefore, when it is necessary to adjust the incident position of the light beam in response to, for example, deformation of the substrate or positional deviation on the stage, the shift of light by the optical device can be utilized. The optical device of the present invention is particularly suitable for such applications, since it can reduce the astigmatic difference and can suppress positional deviation of the light beam and expansion of the beam spot due to dispersion.

[0019] In addition, here, of the two members constituting the first and second prism bodies, the one that becomes the entrance surface of the prism body is called the "first member" and the one that becomes the exit surface is called the "second member". In other words, the "first member" and the "second member" are defined in relation to the path of light, regardless of the type of material. Therefore, the first member in the first prism body and the first member in the second prism body may be made of the same material or may be made of different materials. Similarly, the second member in the first prism body and the second member in the second prism body may be made of the same material or may be made of different materials. For example, there may be a case where the first member in the first prism body and the second member in the second prism body are made of the same material, and the second member in the first prism body and the first member in the second prism body are made of the same material. Effect of the Invention

[0020] As described above, in the optical device of the present invention, when shifting light using a prism pair having two prism bodies, each prism body is structured by combining materials with different Abbe numbers. This makes it possible to reduce the astigmatic difference while also suppressing the effects of dispersion caused by the optical properties of the materials. In addition, in the exposure device and exposure method using this, it is possible to form an image by exposure with good image quality by suppressing the positional deviation and dispersion of the light beam. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram illustrating a first configuration example of an exposure apparatus. [Diagram 2] FIG. 2 is a diagram illustrating a second configuration example of an exposure apparatus. [Diagram 3] FIG. 2 is a diagram showing a configuration of an image position adjusting device. [Figure 4] FIG. 13 is a diagram showing the relationship between the shift amount and the astigmatic difference. [Diagram 5] FIG. 13 is a diagram showing the configuration of a device for adjusting the amount of astigmatic difference correction. [Figure 6] 10 is a flowchart showing a process for adjusting a correction amount. [Figure 7] 4 is a flowchart showing an exposure operation. [Figure 8] FIG. 2 is a diagram showing a detailed structure of a wedge prism. [Figure 9] FIG. 2 is a diagram showing definitions of each part for explaining the design concept of the present embodiment. [Figure 10] FIG. 2 illustrates examples of light source spectra and refractive indices of prism materials. [Figure 11] FIG. 13 is a diagram showing a modified example of the correction optical element. [Figure 12] FIG. 2 is a diagram showing a modified example of the exposure apparatus in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Specific aspects of the optical device according to the present invention will be described below with reference to several embodiments. Here, an embodiment will be described in which the optical device according to the present invention is applied to an exposure device that exposes and draws on a substrate with a modulated light beam. This exposure device draws a pattern on the photosensitive material by irradiating a substrate on which a layer of photosensitive material such as resist has been formed with a laser beam of a predetermined pattern. As the substrate to be exposed, various substrates such as a printed wiring board, a glass substrate for various display devices, and a semiconductor substrate can be used.

[0023] First, two configuration examples of an exposure apparatus to which the optical apparatus according to the present invention can be applied will be described, and then the optical apparatus applied to these exposure apparatus will be described in detail.

[0024] <Exposure Apparatus of First Configuration Example> 1 is a diagram showing a first example of the configuration of an exposure apparatus including an optical device according to the present invention. The basic configuration of this exposure apparatus 2 is the same as that described as "optical apparatus 2" in Patent Document 1. Therefore, explanations of the principles and basic configurations that can be understood by referring to Patent Document 1 will be omitted, and common reference numerals will be used as much as possible, and an outline of the apparatus configuration will be briefly described here.

[0025] For the following explanation, an XYZ Cartesian coordinate system is defined as shown in Fig. 1. Fig. 1 is a side view of an exposure apparatus 2, with the direction that is horizontal and perpendicular to the paper surface of Fig. 1 being the X direction, and the direction that is horizontal and perpendicular to the paper surface of Fig. 1 being the Y direction. The downward vertical direction is the Z direction.

[0026] The exposure apparatus 2 includes a movable stage 20, an exposure head 21, and a control unit 22. The movable stage 20 holds the substrate 9 to be exposed in a horizontal position, and the exposure head 21 irradiates a modulated light beam onto the substrate 9, thereby drawing a fine pattern on the substrate 9. The control unit 22 executes a control program prepared in advance to control each part of the apparatus, thereby achieving a predetermined operation.

[0027] Although not shown in the figure, a stage driving mechanism 201 is connected to the movable stage 20. The stage driving mechanism 201 includes a main scanning driving mechanism that moves the movable stage 20 in the Y direction, a sub-scanning driving mechanism that moves it in the X direction, and an elevation mechanism that moves it in the Z direction. A linear motor, for example, can be used as a driving source for such mechanisms. This allows the exposure device 2 to perform drawing by making the exposure beam emitted from the exposure head 21 incident on any position on the substrate 9.

[0028] The exposure head 21 includes a light source 23, an illumination optical system 24, a spatial light modulation device 25, and an imaging optical system 26. The light source 23 is, for example, a lamp that irradiates light that becomes an exposure beam. The illumination optical system 24 guides the light emitted from the light source 23 to the spatial light modulation device 25. The spatial light modulation device 25 modulates the light guided by the illumination optical system 24 based on predetermined drawing data to generate a modulated light beam.

[0029] The illumination optical system 24 includes optical elements such as a mirror 240, a lens 241, an optical filter 242, a rod integrator 243, a lens 244, and mirrors 245 and 246. Due to the action of these optical elements, the light from the light source 23 is shaped into a beam and guided to the spatial light modulation device 25 at a predetermined angle of incidence.

[0030] As the spatial light modulation device 25, for example, a DMD (digital micromirror device), a diffraction grating type spatial light modulation element, etc. can be used. The spatial light modulation device 25 modulates the incident light beam based on drawing data. As a result, the light beam is modulated according to the shape of the pattern to be drawn. The modulated light beam is incident on the surface of the substrate 9 via an imaging optical system 26.

[0031] The imaging optical system 26 includes optical elements such as a first imaging lens 260, a mirror 261, an image position adjustment position 1, and a second imaging lens 262, and constitutes a reduction optical system. By the action of these optical elements, an optical image corresponding to the shape of the pattern to be drawn is formed on the surface of the substrate 9. Specifically, the modulated light beam forms a primary image (intermediate image) by the first imaging lens 260, and the primary image is formed by the second imaging lens 262 on the surface of the substrate 9, which is the image plane, to become a final image.

[0032] A focus drive mechanism (not shown) that moves the second imaging lens 262 in the Z direction is coupled to the imaging optical system 26. The control unit 42 operates the focus drive mechanism, whereby the second imaging lens 262 moves toward and away from the substrate 9 as indicated by the dotted arrows. This adjusts the focus of the imaging optical system 26 so that the light beam emitted from the second imaging lens 262 converges on the surface of the substrate 9.

[0033] The image position adjustment device 1 corresponds to one embodiment of the "optical device" according to the present invention, and has a function of shifting incident light by an arbitrary distance in the X-axis direction. When the optical device according to the present invention is applied to the exposure device 2, it has a function of shifting the position of the image formed on the image plane, and in this sense functions as an image position adjustment device. In this embodiment, the image position adjustment device 1 is disposed between the primary image and the second imaging lens 262. The structure and operation will be described later.

[0034] <Exposure Apparatus of Second Configuration Example> Fig. 2 is a diagram showing a schematic diagram of a second configuration example of an exposure apparatus including an optical device according to the present invention. In Fig. 2, an XYZ Cartesian coordinate system is defined similarly to Fig. 1. That is, Fig. 2 is a diagram showing a side view of an exposure apparatus 4, and the direction that is horizontal and perpendicular to the paper surface of Fig. 2 is defined as the X direction, and the direction that is horizontal and perpendicular to the paper surface of Fig. 2 is defined as the Y direction. The vertical downward direction is defined as the Z direction.

[0035] 2, the exposure apparatus 4 includes a movable stage 40, an exposure head 41, a control unit 42, and a light source unit 43. The movable stage 40 holds the substrate 9 to be exposed in a horizontal position, and is moved in the X, Y, and Z directions by a stage driving mechanism 401. The exposure head 41 irradiates a modulated light beam onto the substrate 9, thereby drawing a fine pattern on the substrate 9. The control unit 42 executes a control program prepared in advance to control each part of the apparatus, thereby achieving a predetermined operation.

[0036] The light source unit 43 includes, for example, a laser diode 431 as a laser light source, and an illumination optical system 432 including a collimator lens that shapes the emitted light into parallel light, and causes a laser light beam to be incident on the exposure head 41 as an exposure beam.

[0037] The exposure head 41 is provided with a spatial light modulator 410 having a diffractive optical element 411. Specifically, the spatial light modulator 410 is attached to the upper part of a support 400 that extends in the vertical direction (Z direction) on the exposure head 41, and is supported by the support 400 via a movable stage 412 with the reflection surface of the diffractive optical element 411 facing downward.

[0038] In the exposure head 41, the diffractive optical element 411 is disposed with the normal to its reflecting surface inclined with respect to the optical axis of the incident light beam, and the light emitted from the light source unit 43 enters the mirror 413 through an opening in the support 400 and is reflected by the mirror 413 before being irradiated onto the diffractive optical element 411. Then, the state of each channel of the diffractive optical element 411 is switched by the control unit 42 in accordance with the exposure data, and the laser light beam incident on the diffractive optical element 411 is modulated.

[0039] Then, the laser light reflected from the diffractive optical element 411 as zero-order diffracted light enters the lens of the imaging optical system 414, whereas the laser light reflected from the diffractive optical element 411 as first-order or higher diffracted light does not enter the lens of the imaging optical system 414. In other words, the configuration is such that basically only the zero-order diffracted light reflected by the diffractive optical element 411 enters the imaging optical system 414.

[0040] The light passing through the lenses of the imaging optical system 414 is converged by the focusing lens 415 and directed onto the substrate 9 at a predetermined magnification as an exposure beam. The imaging optical system 414 constitutes a reduction optical system. This focusing lens 415 is attached to a focus driving mechanism 416. Then, in response to a control command from the control unit 42, the focus driving mechanism 416 raises and lowers the focusing lens 415 in the vertical direction (Z-axis direction), thereby adjusting the convergence position of the exposure beam emitted from the focusing lens 415 on the upper surface of the substrate 9.

[0041] In this way, the light beam is modulated according to the shape of the pattern to be drawn, and the modulated light beam is incident on the surface of the substrate 9 via the imaging optical system 414, thereby drawing a predetermined pattern on the surface of the substrate 9.

[0042] An image position adjusting device 1 is disposed on the optical path from the diffractive optical element 411 to the imaging optical system 414. The configuration and function of the image position adjusting device 1 are the same as those provided in the exposure apparatus 2 of the first configuration example.

[0043] 3 is a diagram showing the configuration of an image position adjusting device. This image position adjusting device 1 shifts a light beam in the X direction by combining a pair of wedge prisms, that is, a first wedge prism 13 and a second wedge prism 14. Its basic principle and specific design method are described in Patent Document 1, and the same idea can be adopted in this embodiment. Therefore, here, the principle of light shifting by the wedge prism pair 10 and its configuration will be briefly described.

[0044] The first wedge prism 13 and the second wedge prism 14, which are one of the wedge prisms constituting the wedge prism pair 10, have approximately the same structure and shape (for example, the same apex angle α) and are arranged in opposite directions with a predetermined gap between them so that their opposing faces are parallel to each other. As will be described later, the gap is variable and is used to adjust the shift amount.

[0045] The first wedge prism 13 has two end faces 13a and 13b that are not parallel to each other, and when placed on the optical path of a light beam, the light beam is incident on one end face 13a, and the light beam that has passed through the inside is emitted from the other end face 13b. That is, in the first wedge prism 13, one end face 13a functions as the light entrance face, and the other end face 13b functions as the light exit face. Since the entrance face and exit face are not parallel, the direction of the light beam that exits from the exit face is different from the direction of the incident light. That is, the first wedge prism 13 causes the light beam to be deflected.

[0046] The same is true for the second wedge prism 14. That is, the second wedge prism 14 has two end faces 14a and 14b that are not parallel to each other, and when placed on the optical path of a light beam, the light beam is incident on one end face 14a, and the light beam that has passed through the inside is emitted from the other end face 14b. That is, in the second wedge prism 14, one end face 14a functions as the light entrance surface, and the other end face 14b functions as the light exit surface.

[0047] The first wedge prism 13 and the second wedge prism 14 are disposed facing each other such that the end face 13b, which is the exit face of the first wedge prism 13, and the end face 14a, which is the entrance face of the second wedge prism 14, are parallel to each other. Therefore, in terms of structure, the end face 13b of the first wedge prism 13 and the end face 14a of the second wedge prism 14 can also be said to be "opposing surfaces" that face each other. On the other hand, the end face 13a, which is the entrance face of the first wedge prism 13, and the end face 14b, which is the exit face of the second wedge prism 14, can also be said to be "non-opposing surfaces" that do not face each other.

[0048] The first wedge prism 13 is fixed to and supported by a suitable housing via a support 130. Meanwhile, the second wedge prism 14 is supported via a support 140 having a linear motion mechanism 141. As the linear motion mechanism 140, for example, a combination of a rotary motor and a ball screw mechanism controlled by the control unit 42, or a linear motor, etc., can be used.

[0049] The linear motion mechanism 141 moves the second wedge prism 14 in the vertical direction (Z direction) in response to a control command from the control unit 42. This causes the second wedge prism 14 to move within a predetermined movable range in the approaching and separating directions as indicated by the dotted arrows relative to the first wedge prism 13. As a result, the relative distance D1 between them changes.

[0050] An input light Li traveling in the (+Z) direction is incident on the wedge prism pair 10. Specifically, the input light Li is incident on the upper surface (non-facing surface 13a opposite to the facing surface 13b facing the second wedge prism 14) of the first wedge prism 13 which is the upper one of the two wedge prisms, that is, on the (-Z) side. The angle of incidence on the first wedge prism 13 at this time is represented by the symbol φi.

[0051] The light incident on the first wedge prism 13 is refracted at the non-facing surface 13a and the facing surface 13b of the first wedge prism 13, and is emitted from the facing surface 13b at a deviation angle θ with respect to the straight direction of the light indicated by the dotted line. The light is further refracted at the facing surface 14a and the non-facing surface 14b of the second wedge prism 14, and is emitted downward as output light Lo.

[0052] The traveling direction of this output light Lo is the same (+Z) direction as the input light Li. Therefore, it is parallel to the light Loa that would be output if the input light Li were not refracted and traveled straight ahead, and its optical path is shifted in the (-X) direction by a distance D2 from the optical path of the light Loa. In other words, this wedge prism pair 10 has the function of outputting output light Lo that is the input light Li shifted in the (-X) direction. As a result, the position of the image finally projected onto the substrate 9 changes in the X direction.

[0053] In the wedge prism pair 10, light is incident on and exits from each of the two wedge prisms. Therefore, to avoid confusion, in this specification, the light that is primarily incident on the wedge prism pair 10 from the outside is referred to as "input light," and the light that is finally exited from the wedge prism pair 10 is referred to as "output light."

[0054] 3, the greater the distance D1 between the first wedge prism 13 and the second wedge prism 14, the greater the shift amount D2. In other words, the shift amount D2 can be changed by moving the second wedge prism 14 to change the distance D1. The controller 42 controls the amount of movement of the second wedge prism 14 by the linear motion mechanism 141, so that an arbitrary shift amount can be realized.

[0055] Here, the light passing through the wedge prism pair 10 is bent in the X direction by refraction, while the traveling direction in the Y direction does not change. Due to such anisotropy, an astigmatic difference appears in the output light Lo. Therefore, as will be described next, when the light beam is finally converged on the surface of the substrate 9, a difference occurs in the focal position with respect to the image plane between the X direction and the Y direction, which may result in a deterioration in drawing quality.

[0056] Fig. 4 is a diagram showing the relationship between the shift amount and the astigmatic difference. More specifically, Fig. 4(a) is a graph showing a schematic diagram of the change in astigmatic difference when the shift amount is changed. As described in Patent Document 1 and as plotted by multiple dashed lines in Fig. 4(a), the behavior of the astigmatic difference when the shift amount D2 is changed by changing the distance D1 between the wedge prisms differs depending on the incidence angle φi.

[0057] In the technology described in Patent Document 1, the center of the variable range of the shift amount is set as a reference value (a shift amount of zero), and a plot Pb is adopted in which the astigmatic difference is zero when the shift amount is set to the reference value. In this case, the astigmatic difference becomes larger as the shift amount deviates from the reference value, and in order to avoid this, it has been proposed to rotate the wedge prism pair as a method of changing the incident angle φi according to the shift amount.

[0058] On the other hand, in this embodiment, a plot Pa is used in which the astigmatic difference does not change even if the shift amount is changed. It is known that when the incident angle is set so that the deviation angle θ is minimized in the relationship between the incident angle φi and the deviation angle θ, no variation in the astigmatic difference occurs. However, in this case, regardless of the setting of the shift amount S, an astigmatic difference Da that is not necessarily small remains. In this embodiment, the following idea is used to make the astigmatic difference zero regardless of the shift amount S.

[0059] 4(b) is a diagram showing a schematic diagram of the change in the focal position of the imaging optical system when the distance D1 between the wedge prisms is changed. When the distance D1 between the wedge prisms changes, the effective optical path length changes, and therefore the focal position of the imaging optical system (imaging optical system 26 in the first configuration example, imaging optical system 414 in the second configuration example) with respect to the image plane fluctuates. In addition, when there is an astigmatic difference, the focal position differs between the X direction and the Y direction.

[0060] However, when the incident angle φi is set so that the deviation angle θ is minimum, the distance between the in-focus position in the X direction and the in-focus position in the Y direction, i.e., the astigmatic difference, is a constant value Da regardless of the distance D1 between the wedge prisms. Therefore, it is conceivable to eliminate the astigmatic difference by arranging an optical element that cancels this astigmatic difference on the optical path as a "correction optical element" separate from the wedge prism pair 10.

[0061] Specifically, for example, in the case of an astigmatic difference in which the focal position in the X direction is farther away than in the Y direction, by placing an optical element on the optical path that generates astigmatism such that the focal position in the Y direction is farther away than in the X direction, it is possible to correct the astigmatic difference by canceling each other out. If the astigmatic difference generated by such an optical element has the same absolute value but the opposite sign to the astigmatic difference generated by the wedge prism pair 10, it is possible to ultimately make the astigmatic difference on the image plane zero.

[0062] Such a correction optical element can be, for example, an asymmetric lens with different focal lengths in the X and Y directions. For example, a cylindrical lens arranged with its axial direction in the X or Y direction has power only in the direction perpendicular to the axial direction, and is suitable for such a purpose.

[0063] In this embodiment, as shown in Fig. 3, a correction lens 15 serving as a correction optical element for correcting such astigmatic difference is provided above the first wedge prism 13. In this example, the correction lens 15 is a cylindrical lens with its axial direction in the Y direction. With this configuration, the focal position of the imaging optical system with respect to the image surface can be moved closer to the imaging optical system in the X direction while maintaining the focal position in the Y direction.

[0064] In order to make it possible to reduce the astigmatic difference to zero, the correction lens 15 is supported so as to be movable up and down. Specifically, the correction lens 15 is supported by a support unit 150 having a linear motion mechanism 151. The linear motion mechanism 151 can be realized, for example, by a combination of a rotary motor and a ball screw mechanism, or by a linear motor. The linear motion mechanism 151 operates in response to a control command from the control unit 42, and moves the correction lens 15 in the vertical direction (Z direction). This makes it possible to adjust the amount of correction for the astigmatic difference and realize a condition in which the astigmatic difference caused by the wedge prism pair 10 is completely canceled.

[0065] The astigmatic difference correction effect of this embodiment is obtained as follows. First, at the design stage of the device, the specifications of the first wedge prism 13 and the second wedge prism 14 are determined, and the incident angle φi of the input light Li to the wedge prism pair 10 is determined accordingly. Specifically, by the method described in Patent Document 1, the apex angle α, the refractive index n, the maximum actual shift amount S required on the image plane, the movable range width d of the second wedge prism 14, and the magnification M of the lens subsequent to the image position adjustment device 1 are calculated using the following equation:

number

number

[0066] In this embodiment, once the specifications of the wedge prism pair 10 are determined, the incident angle φi of the input light is also determined at the design stage. Therefore, if the incident angle φi is set with sufficient accuracy during the assembly of the device or during initial adjustment, there is basically no need to change it thereafter.

[0067] On the other hand, in order to maximize the effect of correcting the astigmatic difference (ideally to make the astigmatic difference zero), it is necessary to appropriately set the radius of curvature of the cylindrical lens, which is the correction lens 15, and its position on the optical path. More simply, it is possible to optimize the amount of correction of the astigmatic difference by adjusting the position of the correction lens 15 as follows. Note that, although the adjustment process using the exposure apparatus 2 of the first configuration example will be described here, the same idea can also be applied to the second exposure apparatus 4.

[0068] Fig. 5 is a diagram showing the configuration of a device for adjusting the amount of astigmatic difference correction. Fig. 6 is a flowchart showing the process for this adjustment. The process for optimizing the amount of astigmatic difference correction by the cylindrical lens 15 is performed by placing a dummy substrate 52 in place of the substrate 9 at a position corresponding to the image plane, as shown in Fig. 5, and capturing an image projected onto the dummy substrate 52 by an observation camera 51. The observation camera 51 and the dummy substrate 52 may be provided for this purpose, but may also be provided in advance for the purpose of calibrating an autofocus mechanism in an exposure head, for example.

[0069] The observation camera 51 and the dummy substrate 52 are required to move in the horizontal direction in order to be selectively positioned directly below the movable stage 20 and the exposure head 21. They are also required to move in the Z direction in order to search for the focusing position, which will be described later. For example, such mechanisms can be attached to the side of the movable stage 20 that is provided with mechanisms for moving in these directions.

[0070] The specific process is as follows. First, a dummy substrate 52 and an observation camera 51 are placed in place of the movable stage 20 at a position where the image plane of the exposure beam hits (step S101). The correction lens 15 is provisionally set to an appropriate reference position (step S102). The position of the second wedge prism 14 at this time is arbitrary, but can be set to, for example, the reference position.

[0071] In this state, the exposure head 21 projects a predetermined reference pattern onto the surface of the dummy substrate 52 on the image plane (step S103). This reference pattern is for measuring the focal positions in the X and Y directions individually, and may be, for example, a combination of lines in the X and Y directions. The projection of the reference pattern may be performed by modulating the exposure beam with the spatial light modulation device 25, or may be performed by placing an adjustment mask on the optical path.

[0072] In this way, the astigmatic difference is obtained using the reference pattern projected on the surface of dummy substrate 52. Specifically, observation camera 51 captures the reference pattern, and the image data is provided to control unit 22. While integrally moving observation camera 51 and dummy substrate 52 in the Z direction, control unit 22 obtains the position where the reference pattern in the X direction is most clearly projected onto the image plane, that is, the position where the reference pattern in the Y direction is focused on the image plane (step S104), and calculates the difference therebetween to obtain the astigmatic difference (step S105).

[0073] If the calculated astigmatic difference is equal to or less than a predetermined allowable value (YES in step S106), the astigmatic difference correction is functioning effectively, and the adjustment process can be terminated. On the other hand, if the astigmatic difference exceeds a predetermined allowable value (NO in step S106), the amount of movement of the correction lens 15 is calculated based on the magnitude and sign of the astigmatic difference, and the correction lens 15 is moved in the Z direction according to the amount of movement (step S107). As the amount of movement of the correction lens 15, for example, a value obtained by dividing the value of the astigmatic difference calculated at the image plane by the square of the magnification of the optical system between the image position adjustment device 1 and the image plane can be used.

[0074] Then, the evaluation of the astigmatic difference is performed again in steps S104 to S106. By repeating this process, the position of the correction lens 15 for minimizing the astigmatic difference (ideally to zero) can be optimized.

[0075] The correction of the astigmatic difference optimized in this manner functions effectively even if the position of the second wedge prism 14 is changed. In other words, to make this possible, the incident angle φi of the input light Li to the wedge prism pair 10 is selected to be a value that minimizes the deviation angle θ. Therefore, even if the position of the second wedge prism 14 is changed to change the shift amount in a subsequent exposure operation, there is no need to change the position of the correction lens 15.

[0076] It is sufficient for this adjustment process to be performed at timings such as when the apparatus is started up, when regular maintenance is performed, when the operating time of the apparatus or the number of processed substrates reaches a predetermined value, etc. In addition, for example, if the apparatus is placed in a stable environment with little temperature change, the adjustment may be performed only at the time of installation. In any case, the frequency of execution is not very high, and there is no particular need to perform it during the execution of the exposure operation described next.

[0077] 7 is a flow chart showing the exposure operation. After the above-mentioned adjustment process has been performed, the substrate 9 to be exposed is carried into the apparatus and placed on the movable stage 20 (step S201). Next, alignment adjustment is performed to grasp the positional relationship between the substrate 9 on the movable stage 20 and the exposure head 21, and adjust the position as necessary (step S202). Since known techniques can be applied for alignment adjustment, a description thereof will be omitted.

[0078] Then, the movable stage 20 is moved to a predetermined exposure position (step S203), and a shift amount of the image required to correspond to the positional deviation of the substrate 9 identified by the alignment adjustment is calculated (step S204). A required movement amount of the second wedge prism 14 is calculated according to the required shift amount on the image plane (step S205). Specifically, the movement amount of the second wedge prism 14 is calculated from the required shift amount on the image plane and the magnification of the imaging optical system. Based on the result, the second wedge prism 14 is moved to a new position and positioned (step S206). At this time, no change in astigmatic difference occurs due to the second wedge prism 14. Therefore, it is not necessary to move the correction lens 15.

[0079] 4(b), the change in the distance D1 in the wedge prism pair 10 causes a change in the focal position of the imaging optical system 26. Therefore, in accordance with the new position of the second wedge prism 14, the Z-direction position of the imaging lens, specifically, the second imaging lens 262, is changed by the focus drive mechanism (step S207).

[0080] In this state, the exposure head 21 irradiates the surface of the substrate 9 with an exposure beam modulated according to the drawing data (step S208), thereby exposing the surface of the substrate 9 and drawing a predetermined pattern. The processes of steps S203 to S208 are continuously executed until drawing on the substrate 9 is completed (step S209). This completes the exposure operation for one substrate 9.

[0081] As described above, in the image position adjusting device 1 of this embodiment provided in the exposure devices 2 and 4, the image position is shifted in the X direction by the wedge prism pair 10. The astigmatic difference caused by the wedge prism pair 10 is corrected by providing a correction lens 15 having different powers in the X and Y directions. Since the incident angle φi of light on the wedge prism pair 10 is set so that the deviation angle θ is minimized, the astigmatic difference does not vary even if the distance between the wedge prisms is changed. Therefore, the astigmatic difference correction effect by the correction lens 15 is effective regardless of the distance between the wedge prisms, and the shift amount can be changed only by the linear movement of the wedge prisms, and no increase in the astigmatic difference occurs.

[0082] Next, we will explain in more detail the structure of the two wedge prisms 13, 14 that make up the wedge prism pair 10. Up to this point, these wedge prisms 13, 14 have been explained as an integrated optical element, but as will be explained below, each of the wedge prisms 13, 14 actually has a structure in which two members are combined.

[0083] Fig. 8 is a diagram showing the detailed structure of the wedge prism. More specifically, Fig. 8(a) is a diagram showing the structures of two wedge prisms 13 and 14 constituting the wedge prism pair 10, and Fig. 8(b) is a diagram showing the structure of the first wedge prism 13. As shown in Fig. 8(a), the first wedge prism 13 and the second wedge prism 14 are arranged in a rotationally symmetric relationship with respect to an axis Y1 that is parallel to the Y axis and is virtually set in the gap between them.

[0084] The first wedge prism 13 has a structure in which two prism members 131, 132 are combined. Similarly, the second wedge prism 14 has a structure in which two prism members 141, 142 are combined. Since these basically have the same structure, the detailed structure will be described below using the first wedge prism 13 as an example.

[0085] 8(b), the first wedge prism 13 has a first prism member 131 and a second prism member 132. More specifically, each of the first prism member 131 and the second prism member 132 is a single wedge prism. That is, the first prism member 131 has two end faces 131a and 131b that are not parallel to each other, and one of these end faces 131a serves as the entrance face 13a of the first wedge prism 13. The second prism member 132 has two end faces 132a and 132b that are not parallel to each other, and one of these end faces 132b serves as the exit face 13b of the first wedge prism 13.

[0086] The other end face 131b of the first prism member 131 and the other end face 132a of the second prism member 132 are arranged in a state of being butted against each other. The first prism member 131 and the second prism member 132 may be butted against each other so that their mirror-polished end faces are in direct contact with each other, or the two members 131, 132 may be joined via a layer of optical adhesive. Alternatively, the end face 131b of the first prism member 131 and the end face 132a of the second prism member 132 may be structured so that they face each other with a minute air gap therebetween. With this structure, the first prism member 131 and the second prism member 132 are integrated to form one prism, that is, the first wedge prism 13. The same applies to the second wedge prism 14.

[0087] In the first wedge prism 13, the first member 131 and the second member 132 are formed of different optical materials. Specifically, the first member 131 and the second member 132 are formed of materials with different wavelength dependency of the refractive index. For example, the Abbe number can be used as an index to quantitatively express the wavelength dependency of the refractive index of a material. In other words, it can be said that the larger the Abbe number of a material, the smaller the wavelength dependency of the refractive index. However, strictly speaking, it is necessary to compare the wavelength dependency in the wavelength range used, that is, the wavelength range of the light emitted by the light source. As an example of such a material, for example, a combination of crown glass with a relatively large Abbe number (small wavelength dependency) and flint glass with a smaller Abbe number (large wavelength dependency) can be used.

[0088] In the image position adjustment device 1 that uses deflection by a prism, the refractive index of the prism material has wavelength dependency, which causes degradation of image quality. For example, if the spectrum of the light source that generates the light beam has a certain degree of spread and the refractive index of the prism material differs depending on the wavelength, the magnitude of deflection by the prism differs depending on the wavelength, so that the beam spot after passing through the prism is expanded in the deflection direction. This causes degradation of the resolution and clarity of the image.

[0089] Even if the light source spectrum is sufficiently narrow, the central wavelength may fluctuate due to fluctuations in the ambient temperature, driving current, etc. This causes the designed shift amount to differ from the actual shift amount, resulting in image position shift. This type of beam spot size fluctuation and position shift caused by the refractive index differing depending on the wavelength is referred to as "dispersion" in this specification.

[0090] In this embodiment, this problem is addressed by configuring the wedge prism with a combination of different materials as described above. Below, the design concept for achieving image position adjustment while suppressing the effects of dispersion will be explained with reference to Figures 9 and 10. Note that, although the first wedge prism 13 will be explained as an example here, the same can be done for the second wedge prism 14.

[0091] Fig. 9 is a diagram showing the definition of each part to explain the design concept of this embodiment. As shown in Fig. 9, the first wedge prism 13 has a structure in which two prism members 131 and 132 are combined, and the apex angle is α. In addition, each of the two prism members 131 and 132 is a wedge prism, and each of the apex angles is α. A ,α B As shown in Fig. 9, two prism members 131 and 132 are combined so that their apex angles are opposite to each other.

[0092] The two prism members 131 and 132 are made of different materials. Here, they are called material A and material B, and their respective refractive indices are n A ,n B In addition, the angle between the direction of the input light Li and the direction of the output light, that is, the deflection angle, is represented by the symbol θ.

[0093] Figure 10 shows an example of the light source spectrum and the refractive index of the prism material. As shown in Figure 10(a), the central wavelength of the spectrum of the light source that is the source of the light beam is λ0, the lower limit of the effective wavelength is λ1, and the upper limit is λ2. In other words, the design wavelengths of the optical system can be considered to be λ1 to λ2. There is a relationship between these wavelengths: λ1<λ0<λ2.

[0094] The refractive indexes of materials A and B have wavelength dependence. The refractive indexes of material A at wavelengths λ0, λ1, and λ2 are n A0 ,n A1 ,n A2 Generally, the longer the wavelength, the smaller the refractive index, so n A1 >n A0 >n A2 It is considered that the refractive index of material B at wavelengths λ0, λ1, and λ2 is n B0 ,n B1 ,n B2 Expressed by (n B1 >n B0 >n B2 ) Here, material A has a larger Abbe number than material B, in other words, the wavelength dependency of the refractive index is smaller. Also, the difference between the refractive index at wavelength λ1 and the refractive index at wavelength λ2 is represented by Δn.

[0095] Figure 10(b) shows an example of the physical properties of materials. Here, the physical properties are shown when BK7 glass, an example of crown glass, is used as material A, and F2 glass, an example of flint glass, is used as material B. The design wavelengths are λ1 = 401 nm, λ2 = 405 nm (center wavelength λ0 = 403 nm).

[0096] A specific design method is as follows. First, for the apex angle α of the first prism 13, the optimal value at which the deviation angle θ is minimized can be determined using, for example, the ideas of Patent Document 1 and the above-mentioned (Equation 1) and (Equation 2). The refractive index n in these methods is that of a single material, but in this embodiment, it is a value derived from the two prism materials. When the refractive indexes of the two materials are different, for example, the average value of those refractive indices can be used. Also, a weighted average value according to the thickness (more strictly speaking, the optical path length) of each material may be used.

[0097] The deflection angle θ at this time is calculated from the following formula (10) described in Patent Document 1: θ=(n-1)α … (Equation 3) The materials and dimensions of the first wedge prism 13 made of a combination of two types of materials should be determined so that this deviation angle θ can be realized.

[0098] Here, as one prism material A, a material is selected that has high transmittance for light of design wavelengths λ1 to λ2 and a relatively small wavelength dependency of the refractive index. For example, the above-mentioned BK7 glass can be used. As the other prism material B, a material with a larger wavelength dependency of the refractive index is preferable in order to effectively cancel out the dispersion caused by material A. For example, the above-mentioned F2 glass can be used.

[0099] The difference between the angle of deviation that a prism (first member 131) made of material A imparts to light of wavelength λ1 and the angle of deviation that it imparts to light of wavelength λ2 is (n A1 -n A2 )·α A The difference between the angle of deviation that the prism (second member 132) made of material B imparts to the light of wavelength λ1 and the angle of deviation that the prism imparts to the light of wavelength λ2 is expressed as (n B1 -n B2 )·α B When the dispersion is completely cancelled, these become equal, so the following equation can be expressed: (n A1 -n A2 )α A=(n B1 -n B2 )α B … (Formula 4) The following relationship holds.

[0100] In addition, when a light ray with a central wavelength λ0 passes through a prism, the exit angle of the light ray must be equal to the deviation angle θ, so from the relationship in (Equation 3), the following equation is obtained: (n A0 -1)α A -(n B0 -1)α B =θ … (Formula 5) By simultaneously solving (Equation 4) and (Equation 5), the following equation is obtained:

number

[0101] For example, assuming that a wedge prism is fabricated using only BK7 glass as shown in FIG. 10(b), when desired image shift characteristics are set and (Equation 1) and (Equation 2) are applied, the design values ​​obtained are, for example, apex angle α=10°, incidence angle φi=7.66°, and deviation angle θ=5.30°. In order to achieve an equivalent deviation angle θ in a combination of BK7 glass and F2 glass, the apex angle α of the first member 131 is, according to (Equation 6), A , the apex angle α of the second member 132 B can be determined to be 19.80° and 7.98°, respectively.

[0102] Here, the refractive index value n corresponding to the central wavelength λ0 of the light source spectrum is A0 ,n B0 Instead of these, for example, the average value of the refractive index corresponding to the design wavelength range, i.e., (n A1 -n A2 ) / 2,(n B1 -n B2) / 2 may be used for the calculation. Alternatively, a weighted average value obtained by appropriately weighting the refractive index values ​​at each wavelength may be used.

[0103] <Modification> FIG. 11 is a diagram showing a modified example of the correction optical element. FIG. 11(a) shows a modified example in which a parallel plane plate 16 (a pair of parallel plane plates 16a, 16b) is used as a correction optical element instead of a cylindrical lens. It is known that astigmatism occurs when a parallel plane plate is arranged tilted with respect to the optical path, and this fact can be used to correct the astigmatic difference caused by the wedge prism pair 10. In this case, whether the parallel plane plate 16a is tilted around the X axis or the Y axis is determined depending on whether the focal position in the X direction or the Y direction is farther. On the other hand, the parallel plane plate 16b is tilted in a counterclockwise direction coaxially with the parallel plane plate 16a. As a result, the parallel plane plates 16a, 16b are tilted by the same amount in opposite directions from the parallel state, so that they assume a so-called V-shaped posture, and the parallel plane plate 16b cancels the parallel shift of the input light Li caused by the parallel plane plate 16a. Here, tilting around the X-axis means tilting so that the normal vector of the main surface of the plane-parallel plate 16a has a Y-direction component but does not have an X-direction component, and tilting around the Y-axis means the opposite. Also, by providing a drive mechanism 161 for changing the magnitude of the tilt, it becomes possible to adjust the amount of correction for the astigmatic difference.

[0104] 11(b) shows a modified example in which a variable curvature mirror 17 is used as a correction optical element in place of the cylindrical lens. A folding mirror 171 may be provided as appropriate to fold back the optical path of the input light. Even in this embodiment, it is possible to correct the astigmatic difference caused by the wedge prism pair 10 by using the variable curvature mirror 17, which can change the curvature (power) without moving the position.

[0105] In this sense, by making the mirror 246 in the exposure apparatus 2 in Fig. 1 a variable curvature mirror as described above, it is possible to make it function as a correction optical element. In this case, it is not necessary to provide a correction optical element in the image position adjustment apparatus 1. In other words, the correction optical element constituting the image position adjustment apparatus 1 is provided inside the illumination optical system 24.

[0106] Figure 12 is a diagram showing a modification of the exposure apparatus of Figure 1. In exposure apparatus 2a of this modification, mirror 246 in exposure apparatus 2 of Figure 1 is replaced with a plane mirror 247, and further, a correction lens 15a is provided as a correction optical element in the optical path between the plane mirror 247 and spatial light modulation device 25. In this way, the correction optical element does not need to be provided immediately before the wedge prism pair 10, and can be placed at an appropriate position on the optical path.

[0107] In this case, since the correction lens 15a also functions as a focus lens for the spatial light modulation device 25, the “reference position” in step S102 in the adjustment process of FIG. 6 becomes the position where the light emitted from the correction lens 15a is focused on the spatial light modulation device 25.

[0108] As described above, in the image position adjusting device 1 of this embodiment, the shift amount of the light beam can be adjusted by changing the interval between the pair of wedge prisms 13 and 14. Therefore, the position of the image formed on the image plane can be adjusted.

[0109] Here, the problem of image quality being reduced by chromatic aberration caused by the wavelength dependency (dispersion) of the refractive index of the prism material is addressed by constructing each wedge prism from a combination of two materials. In other words, by combining two prism components made of materials with different wavelength dependencies of refractive index and making the whole function as a single wedge prism, the effects of dispersion caused by each material are cancelled out.

[0110] In addition, the effect of degradation of image quality due to the astigmatic difference of the prism is suppressed by optimizing the angle of incidence of the light beam on the wedge prism pair 10. In addition, the problem of the magnitude of the astigmatic difference changing when the distance between the prisms is changed to adjust the shift amount is addressed by providing a corrective optical element on the optical path.

[0111] By combining these, in this embodiment, image disturbance caused by both astigmatic difference and dispersion can be suppressed, and image position adjustment can be performed with good quality. And, in the exposure apparatuses 2 and 4 that employ this image position adjustment device 1, image formation on a substrate by exposure can be performed with good quality.

[0112] As described above, in the above embodiment, the image position adjusting device 1 functions as the "optical device" of the present invention, and the first wedge prism 13 and the second wedge prism 14 correspond to the "first prism body" and the "second prism body" of the present invention, respectively. The prism member 131 in the first wedge prism 13 and the prism member 141 in the second wedge prism 14 correspond to the "first member" of the present invention, while the prism member 132 in the first wedge prism 13 and the prism member 142 in the second wedge prism 14 correspond to the "second member" of the present invention.

[0113] In the above embodiment, the correction lens 15, the plane-parallel plate 16, the variable curvature mirror 17, etc. function as the "correction optical element" of the present invention. The support parts 130 and 140 function together as the "shift amount adjustment mechanism" of the present invention. On the other hand, the support part 150 and the drive mechanism 161 function as the "correction amount adjustment mechanism" of the present invention.

[0114] In the exposure apparatuses 2 and 4 of the above embodiments, the movable stages 20 and 40 function as the "stage" of the present invention, and the stage driving mechanisms 201 and 401 function as the "moving mechanisms" of the present invention. Also, the exposure heads 21 and 41 function as the "exposure units" of the present invention.

[0115] In the above embodiment, the X direction, which is the shift direction of the light, corresponds to the "first direction" of the present invention, and the Y direction perpendicular to the X direction corresponds to the "second direction" of the present invention. Here, in the above description, the final emission direction of the exposure beam is the Z direction, which is the vertical direction, and the shift direction of the image is the X direction, so the operation is described in the XYZ coordinate system. However, essentially, there is no need to relate it to the vertical direction, and the discussion should be based on the traveling direction of the input light (or output light). In that case, among the directions perpendicular to the incident direction of the input light, the direction parallel to the shift direction of the output light and the direction perpendicular to the same can be considered as the "first direction" and "second direction" of the present invention, respectively.

[0116] In the wedge prism pair 10 of the above embodiment, one prism member 131 constituting the first wedge prism 13, which is the "first prism body" of the present invention, corresponds to the "first member" of the present invention, and the prism member 131 is made of BK7 glass, which has a relatively large Abbe number. The other prism member 132 corresponds to the "second member" of the present invention, and is made of F2 glass, which has a relatively small Abbe number. On the other hand, in the second wedge prism 14, the prism member 141 made of F2 glass corresponds to the "first member" of the present invention, and the prism member 142 made of BK7 glass corresponds to the "second member" of the present invention.

[0117] In the present invention, the "first member" and "second member" are defined in terms of their relationship to the traveling direction of light, not in terms of materials, so the relationship between the material that becomes the "first member" and the material that becomes the "second member" is not necessarily the same between the two wedge prisms 13, 14, and may be reversed as described above. Of course, depending on the arrangement of these wedge prisms, the "first members" of the two wedge prisms may be made of the same material.

[0118] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-mentioned embodiment, the first wedge prism 13 and the second wedge prism 14 have the same structure. Specifically, they have the same shape, and the two prism members constituting each of them are also formed in the same shape and made of a common material between the two wedge prisms. However, the effect of the present invention can be obtained as long as each wedge prism has a structure for suppressing the influence of the above-mentioned dispersion, and in that sense, it is not necessary for the two wedge prisms to have a completely identical structure.

[0119] In reality, however, constructing the two wedge prisms from different materials and satisfying the above design conditions would make the design complicated, and there would be no particular advantage to doing so. For this reason, it is considered preferable to use the same combination of materials for the two wedge prisms.

[0120] For example, in the above embodiment, BK7 glass and F2 glass are used as the materials of the prism members constituting the wedge prism. However, this is only one example of material selection, and the combination of prism materials is not limited to the above. More generally, it is desirable to combine materials whose refractive indexes are relatively close to each other and whose wavelength dependence is relatively large on one side and small on the other side.

[0121] In this sense, among the materials used as optical materials, the crown glass containing BK7 has a relatively small wavelength dependency of the refractive index, while the flint glass containing F2 has a larger wavelength dependency. Therefore, a combination of materials selected from one each of the two groups can be suitable for the present invention. In addition, various other combinations of materials are possible.

[0122] In the above embodiment, a correction optical element (e.g., correction lens 15 in FIG. 3) is provided on the optical path of the exposure beam to suppress an increase in astigmatic difference accompanying a change in the distance between the prisms. However, in terms of simply suppressing the effects of dispersion, the technical idea of ​​the present invention of "forming each wedge prism from a combination of different materials" is effective regardless of the presence or absence of such a correction optical element.

[0123] Also, for example, in the above embodiment, the correction lens 15 or the like serving as a correction optical element is disposed in front of the wedge prism pair 10 in the light traveling direction, that is, on the optical path of the input light Li. However, the correction optical element may be disposed behind the wedge prism pair 10, that is, on the optical path of the output light Lo. However, by disposing the correction optical element on the optical path before the image shift is performed, as in the present embodiment, the range of incidence of light is limited, making it easier to design the optical element.

[0124] In the above embodiment, the correction lens 15 as the correction optical element is a single cylindrical lens, but the correction optical element may be configured by combining, for example, a cylindrical lens whose axial direction is in the X direction with a cylindrical lens whose focal length is different from that and whose axial direction is in the Y direction. The correction optical element may also have the functions of any of the lenses provided in the illumination optical system or the imaging optical system. For example, a concave lens, a convex mirror, or the like may be used as the correction optical element.

[0125] In the adjustment process of the above embodiment, the correction of the astigmatic difference by the correction optical element is aimed at making the astigmatic difference equal to or less than a predetermined tolerance. However, the aim may be for the astigmatic difference to be zero after correction, and naturally, a state in which the astigmatic difference is zero and does not fluctuate is the most ideal.

[0126] In the above embodiment, the incident angle φi of the input light Li with respect to the wedge prism pair 10 is fixed. However, this may be variable. However, since there is no need to change the incident angle during operation in the present invention, a drive mechanism for changing the incident angle is not necessary, and a mechanism for manual adjustment, for example, may be used.

[0127] In the above embodiment, the optical device according to the present invention is applied to an exposure device that exposes a substrate to light and draws a pattern. However, the application of the optical device according to the present invention is not limited to this. For example, the present invention can also be applied to a projection device such as a projector.

[0128] As described above by way of example of specific embodiments, in the optical device according to the present invention, for example, in the first prism body, the angle of incidence of the input light with respect to the entrance surface may be set to an angle at which the deviation angle of the exit light from the exit surface is minimized. With such a configuration, it is possible to reduce the effect of astigmatic difference, which is another problem that occurs in prisms.

[0129] For example, each of the first prism body and the second prism body may be a wedge prism, and each of the first member and the second member may be a wedge prism. With such a configuration, it is possible to obtain the effects of the present invention by combining wedge prisms, for which manufacturing technology has already been established.

[0130] In this case, it is preferable that the first member and the second member are configured so that the one with the larger Abbe number has a larger apex angle. Generally, materials with small Abbe numbers have a large wavelength dependency of the refractive index, and the image is greatly distorted due to dispersion. For this reason, it is preferable to use a material with a large Abbe number and a low wavelength dependency of the refractive index as the main component, and to use other materials to compensate for the effect of dispersion caused by the material. To achieve this, it is effective to form a prism with a large apex angle using a material with a large Abbe number.

[0131] For example, one of the first member and the second member may be made of crown glass, and the other may be made of flint glass. Among materials widely used as optical materials, crown glass is a material whose refractive index has low wavelength dependency. In comparison, flint glass has a refractive index that is highly wavelength dependent. Therefore, the combination of these materials is suitable for achieving the effects of the present invention.

[0132] For example, the first prism body and the second prism body may have the same structure and shape, and in that case, they may be arranged symmetrically about a rotation axis perpendicular to the optical path. With this configuration, the first prism body and the second prism body can be manufactured with a common design, and adjustment during installation is also easy.

[0133] For example, the optical device may further include a correction optical element disposed in the optical path of the input light or the optical path of the output light to correct astigmatic difference appearing in the output light. With this configuration, it is possible to suppress both dispersion and astigmatic difference, which are unavoidable characteristics of prism materials.

[0134] Specifically, when a direction perpendicular to the incident direction of the input light and parallel to the shift direction of the output light relative to the input light is defined as a first direction, and a direction perpendicular to the incident direction and the first direction is defined as a second direction, the corrective optical element may be an optical element that generates astigmatism between the first direction and the second direction. By using an optical element having asymmetric characteristics, i.e., anisotropy, in two orthogonal directions in this way, correction can be made to cancel the astigmatic difference generated between the first direction and the second direction due to the wedge prism.

[0135] Here, the correction optical element may be, for example, a lens having different focal lengths in the first and second directions. Alternatively, the correction optical element may be a variable curvature mirror capable of changing the curvature between a cross section including the first direction and a cross section including the second direction. In any of these cases, by selecting and using an optical element having appropriate optical characteristics, it is possible to correct the astigmatic difference.

[0136] In addition, a correction amount adjustment mechanism may be provided that adjusts the amount of astigmatic difference correction by moving the lens as the correction optical element in a direction along the optical path. By making the amount of correction adjustable in this manner, the conditions required for the optical characteristics of the correction optical element are relaxed. [Industrial Applicability]

[0137] The present invention can be used to shift the position of a light beam or an image formed thereby by a predetermined amount in a predetermined direction, and is suitable for use in the technical field of exposing various substrates, such as printed wiring boards and glass substrates, to light in order to form patterns on the substrates. [Explanation of symbols]

[0138] 1 Image position adjustment device (optical device) 2,4 Exposure equipment 9 Substrate 10 Wedge Prism Pair 13 First wedge prism (first prism body) 14 Second wedge prism (second prism body) 15 Correction lenses (correction optical elements) 17 Variable curvature mirror (corrective optical element) 20,40 Movable stage (stage) 21, 41 Exposure head (exposure section) 130, 140 Support part (shift amount adjustment mechanism) 131,141 First member 132,142 Second member 150 Support part (correction amount adjustment mechanism) 161 Drive mechanism (correction amount adjustment mechanism) 201,401 Stage drive mechanism (movement mechanism) Li input light Lo output light X 1st direction Y Second direction

Claims

1. 1. An optical device for shifting a path of input light to output light along a path that is parallel to but not identical to the path of the input light, comprising: a first prism body having an entrance surface and an exit surface which are non-parallel to each other; a second prism body having an entrance surface and an exit surface which are not parallel to each other and an apex angle which is substantially the same as that of the first prism body; a shift amount adjustment mechanism that supports the first prism body and the second prism body in mutually opposite orientations and such that the exit surface of the first prism body and the entrance surface of the second prism body face each other, and adjusts the amount of shift between the input light that is incident on the entrance surface of the first prism body and the output light that is emitted from the exit surface of the second prism body by changing the distance therebetween; Equipped with Each of the first prism body and the second prism body is a first member having one end surface that constitutes the incident surface; a second member having one end surface constituting the light exit surface; having the first member and the second member are prisms each formed of a material having a different Abbe number, and one end face of the first member other than the entrance surface and one end face of the second member other than the exit surface are arranged abutting each other.

2. 2. The optical device according to claim 1, wherein the first prism body has an incident angle of the input light with respect to the entrance surface set to an angle at which a deviation angle of the exit light from the exit surface is minimized.

3. The optical device of claim 1 , wherein each of the first prism body and the second prism body is a wedge prism.

4. The optical device of claim 3 , wherein each of the first member and the second member is a wedge prism.

5. The optical device according to claim 4 , wherein the first member and the second member have a larger Abbe number and a larger apex angle between them.

6. 6. The optical device according to claim 1, wherein one of the first member and the second member is made of crown glass, and the other is made of flint glass.

7. 6. The optical device according to claim 1, wherein the first prism body and the second prism body have the same structure and shape.

8. The optical device according to claim 7 , wherein the first prism body and the second prism body are arranged symmetrically with respect to a rotation axis perpendicular to the optical path.

9. 6. The optical device according to claim 1, further comprising a correction optical element disposed in an optical path of the input light or an optical path of the output light for correcting an astigmatic difference appearing in the output light.

10. A direction perpendicular to the incident direction of the input light and parallel to the shift direction of the output light relative to the input light is defined as a first direction, and a direction perpendicular to the incident direction and the first direction is defined as a second direction. The optical device according to claim 9 , wherein the corrective optical element is an optical element that generates astigmatism between the first direction and the second direction.

11. The optical device according to claim 10 , wherein the corrective optical element is a lens having different focal lengths in the first direction and the second direction.

12. The optical device according to claim 11 , further comprising a correction amount adjustment mechanism that adjusts the amount of correction of the astigmatic difference by moving the correction optical element in a direction along the optical path.

13. a stage for supporting a substrate to be processed; an exposure section which modulates a light beam based on predetermined exposure data and makes the modulated light beam incident on a surface of the substrate via an optical device according to any one of claims 1 to 5 and 10 to 12; a moving mechanism for relatively moving the stage and the exposure unit; An exposure apparatus comprising:

14. 1. An exposure method for exposing a substrate by irradiating a light beam modulated based on predetermined exposure data onto a surface of the substrate, the method comprising the steps of: an optical device according to any one of claims 1 to 5 disposed on an optical path of the light beam; an exposure method in which the substrate is exposed to the light beam while the shift amount of the light beam is adjusted by the shift amount adjustment mechanism.

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