Direct drawing type exposure apparatus

Abstract

To provide a direct drawing type exposure apparatus that realizes autofocusing in projecting an exposure pattern onto a substrate.SOLUTION: An exposure pattern formed by a spatial light modulator 3 provided inside each exposure head 1A,1B is projected in an irradiation area by a projection optical system 4 in each exposure head 1A,1B, and a stage 6 mounting a substrate W is moved by a stage moving mechanism 61 to perform exposure such that the substrate W passes the irradiation area. An AF-use range finder 3 which measures a distance from the substrate W perform measurement, and a controller 7 controls an optical path length changer 91 or a mirror 82A provided between the exposure head 1A,1B and the irradiation area according to measurement data of the AF-use range finder 3 to achieve a focused state.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The invention of this application relates to a direct imaging type exposure apparatus which forms an exposure pattern by a spatial light modulator and performs exposure. [Background technology]

[0002] Direct imaging exposure equipment is known as an exposure equipment used in photolithography processes, etc. A direct imaging exposure equipment is a type of maskless exposure equipment that forms an exposure pattern using a spatial light modulator such as a DMD (Digital Mirror Device) and directly draws and exposes the pattern without a mask. Direct imaging exposure equipment is extremely easy to change the exposure pattern as needed, making it suitable for high-mix low-volume production. For this reason, it is widely used for manufacturing circuit boards for various products and for manufacturing various fine parts (MEMS). The object to be exposed is often plate-shaped (substrate), but it may not be plate-shaped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-300543 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the invention of this application is to realize autofocus when projecting an exposure pattern onto a substrate in the above-mentioned direct imaging exposure apparatus. [Means for solving the problem]

[0005] In order to solve the above problems, the direct imaging exposure apparatus of the invention disclosed in this specification is a direct imaging exposure apparatus that includes a stage on which a substrate is placed, a stage movement mechanism that moves the stage on which the substrate is placed from a standby position so that the substrate passes through an irradiation area, and an exposure head that houses a spatial light modulator that spatially modulates light from a light source and a projection optical system that projects the light pattern formed by the spatial light modulator onto the irradiation area, and exposes the substrate to the light pattern formed by the spatial light modulator as the substrate passes through the irradiation area. This direct imaging exposure apparatus is equipped with a rangefinder that measures the distance to the substrate at a position between when the stage is moved from a standby position and when the substrate reaches the irradiation area, an optical path length changer that is provided on the optical path between the exposure head and the irradiation area, and a controller that controls the optical path length changer in accordance with measurement data from the rangefinder to change the optical path length, thereby achieving a focused state using the projection optical system. In addition, in order to solve the above-mentioned problems, a direct imaging exposure apparatus according to another invention disclosed in this specification is a direct imaging exposure apparatus that includes a stage on which a substrate is placed, a stage moving mechanism that moves the stage on which the substrate is placed from a standby position so that the substrate passes through an irradiation area, and an exposure head that houses a spatial light modulator that spatially modulates light from a light source and a projection optical system that projects the light pattern formed by the spatial light modulator onto the irradiation area, and exposes the substrate to the light pattern formed by the spatial light modulator as the substrate passes through the irradiation area. This direct imaging exposure apparatus is equipped with a rangefinder that measures the distance to the substrate at a position between when the stage is moved from a standby position and when the substrate reaches the irradiation area, a mirror that bends the optical path between the exposure head and the irradiation area, an actuator that moves the mirror to change the optical path length from the exposure head to the irradiation area, and a controller that controls the actuator in accordance with measurement data from the rangefinder to change the optical path length, thereby achieving a focused state with the projection optical system. Effect of the Invention

[0006] As described below, the direct imaging exposure apparatus according to each of the disclosed inventions realizes autofocus when the exposure pattern is projected onto the substrate by the projection optical system. The structure in the exposure head is simplified by providing an optical path length changer on the optical path between the exposure head and the irradiation area. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic front view of a direct imaging exposure device according to a reference example. [Diagram 2] FIG. 1 is a schematic side view of a direct imaging exposure apparatus according to a reference example. [Diagram 3] FIG. 1 is a schematic plan view of a direct imaging exposure apparatus according to a reference example. [Figure 4] FIG. 2 is a schematic diagram showing the internal structure of the exposure head. [Diagram 5] FIG. 11 is a schematic front view showing an offset optical system in a reference example. [Figure 6] FIG. 2 is a perspective schematic diagram showing one offset optical system. [Figure 7] 5 is a schematic plan view showing the action of each offset optical system. FIG. [Figure 8] 11 is a schematic plan view showing the operation of a direct imaging exposure apparatus according to a reference example. FIG. [Figure 9] 1A to 1C are schematic diagrams showing the effect of improving productivity by each offset optical system. [Figure 10] 1 is a schematic front view showing a main part of a direct imaging exposure apparatus according to a first embodiment. [Figure 11] FIG. 11 is a schematic front view showing a main part of a direct imaging exposure device according to a second embodiment. [Figure 12] FIG. 11 is a schematic front view showing a main part of a direct imaging exposure device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a mode (embodiment) for carrying out the invention of this application will be described. Prior to the description of the direct imaging exposure apparatus of the embodiment, a direct imaging exposure apparatus of a reference example will be described. Figures 1 to 3 are schematic diagrams of the direct imaging exposure apparatus of the reference example, where Figure 1 is a schematic front view, Figure 2 is a schematic side view, and Figure 3 is a schematic plan view. The direct imaging exposure apparatus shown in FIGS. 1 to 3 includes a plurality of exposure heads 1A and 1B, a stage 6 on which a substrate W is placed, and a stage movement mechanism 61. The direct imaging exposure apparatus shown in FIGS.

[0009] Each of the exposure heads 1A and 1B is cylindrical overall, arranged vertically, and emits light downward. Fig. 4 is a schematic diagram showing the internal structure of the exposure head. As shown in Fig. 4, the exposure heads 1A and 1B are structured to accommodate a light source 2, a spatial light modulator 3 that spatially modulates the light from the light source 2, and an optical system (hereinafter, a projection optical system) 4 that projects an image formed by the light modulated by the spatial light modulator 3, etc., in a housing (not shown).

[0010] The light source 2 used is one that outputs light of an optimum wavelength according to the photosensitive wavelength of the photosensitive layer on the substrate W. The photosensitive wavelength of the resist film is often in the visible short wavelength range to the ultraviolet range, and the light source 2 used is one that outputs light in the visible short wavelength range to the ultraviolet range, such as 405 nm or 365 nm. In order to make the most of the performance of the spatial light modulator 3, it is preferable that the light source outputs coherent light, and for this reason a laser light source is preferably used. For example, a gallium nitride (GaN)-based semiconductor laser is used.

[0011] In this reference example, a DMD is used as the spatial light modulator 3. As shown enlarged in Fig. 4, in the DMD, each pixel is a tiny mirror 31. The mirror (hereinafter referred to as pixel mirror) 31 is, for example, a square mirror with a side length of about 13.68 µm, and a large number of pixel mirrors 31 are arranged in a rectangular lattice pattern. The number of pixels arranged is, for example, 1024 x 768.

[0012] The spatial light modulator 3 includes a modulator controller 32 that controls each pixel mirror 31. The exposure apparatus of the reference example includes a main controller 7 that controls the entire apparatus. The modulator controller 32 controls each pixel mirror 31 according to a signal from the main controller 7. Each pixel mirror 31 has a plane on which the pixel mirrors 31 are arranged as a reference plane, and can take a first attitude along this reference plane and a second attitude inclined, for example, at about 11 to 13 degrees with respect to this reference plane. The first attitude is an OFF state, and the second attitude is an ON state. The spatial light modulator 3 includes a driving mechanism for driving each pixel mirror 31, and the modulator controller 32 is capable of independently controlling whether each pixel mirror 31 takes the first position or the second position. Such a spatial light modulator 3 is available from Texas Instruments.

[0013] As shown in Fig. 4, the exposure heads 1A, 1B are equipped with an irradiation optical system 5 that irradiates the spatial light modulator 3 with light from the light source 2. In this reference example, the irradiation optical system 5 includes an optical fiber 51. In order to form an image with higher illuminance, each exposure head 1A, 1B is equipped with a plurality of light sources 2, and an optical fiber 51 is provided for each light source 2. As the optical fiber 51, for example, a quartz-based multimode fiber is used.

[0014] In order to form an image with high accuracy using the spatial light modulator 3, which is a DMD, it is desirable to make parallel light incident and reflected by each pixel mirror 31, and it is also desirable to make light incident obliquely on each pixel mirror 31. For this reason, the irradiation optical system 5 includes a collimator lens 52 that converts the light emitted from each optical fiber 51 and diverging into parallel light, as shown in Fig. 4.

[0015] The projection optical system 4 is composed of two projection lens groups 41, 42, and a microlens array (hereinafter abbreviated as MLA) 43 arranged between the projection lens groups 41, 42. The MLA 43 is arranged as an auxiliary to perform exposure with higher shape accuracy. The MLA 43 is an optical component in which a large number of minute lens elements are arranged in a rectangular lattice pattern. Each lens element has a one-to-one correspondence with each pixel mirror 31 of the spatial light modulator 3.

[0016] In the above-mentioned exposure heads 1A and 1B, the light from the light source 2 is guided by the optical fiber 61 and then enters the spatial light modulator 3 through the irradiation optical system 5. At this time, each pixel mirror 31 of the spatial light modulator 3 is controlled by the modulator controller 32 and selectively tilted according to the exposure pattern. That is, according to the exposure pattern to be formed, the pixel mirror 31 located at the position where the light should reach the irradiation area is turned on, and the other pixel mirrors 31 are turned off. The light reflected by the pixel mirror 31 in the off state does not reach the irradiation area, and only the light reflected by the pixel mirror 31 in the on state reaches the irradiation area. Therefore, the light of the predetermined exposure pattern is irradiated onto the irradiation area.

[0017] The stage 6 is a member on which the substrate W is placed on a horizontal upper surface. The upper surface is provided with vacuum suction holes (not shown) for vacuum-suctioning the substrate W. The stage moving mechanism 61 is a mechanism for moving the stage 6 on which the substrate W is placed, through the irradiation area. In this reference example, the stage moving mechanism 61 is a mechanism that not only moves the stage 6 in the X direction for exposure to pass through the irradiation area, but also moves the stage in the X direction. Specifically, the stage moving mechanism 61 includes an X-direction linear guide 611 arranged through the irradiation areas EA and EB along the X direction, a base 612 provided on the X-direction linear guide 611, an X-direction drive source (not shown) that moves the base 612 along the X-direction linear guide 611, and a Y-direction linear guide 613 provided on the base 612. The stage 6 is mounted on the Y-direction linear guide 613, and a Y-direction drive source (not shown) that moves the stage 6 along the Y-direction linear guide 613 is provided. For example, a linear motor is used as the X-direction drive source and the Y-direction drive source, and a linear motor stage configuration may be adopted. In addition, in the X direction, a standby position for the stage 6 is set on one side away from the irradiation areas EA and EB. A transfer mechanism (not shown) is disposed at the standby position.

[0018] As shown in Fig. 1, the main controller 7 includes a storage unit 71, which stores a main sequence program 72 for sequence control of the entire apparatus, and pixel sequence programs 731, 732 for sequence control of each pixel mirror 31 of the spatial light modulator 3 in each exposure head 1A, 1B when exposing one substrate W. In this reference example, exposure is performed in an outward path and a return path, so a pixel sequence program 731 for the outward path and a pixel sequence program 732 for the return path are stored. The main sequence program 72 sequentially calls and executes the pixel sequence programs 731, 732 when exposing each substrate W. Since it is the modulator controller 32 that actually controls each pixel mirror 31, the pixel sequence programs 731, 732 are programs that provide a sequence to the modulator controller 32 so that each pixel mirror 31 is driven by that sequence.

[0019] Between the standby position and the irradiation area, a camera (not shown) is provided for capturing an image of an alignment mark on the substrate W in order to control (align) the formation position of the exposure pattern on the substrate W. The captured image data of the camera is sent to the main controller 7. The main controller 7 executes pixel sequence programs 731 and 732 using the captured image data as an argument, thereby controlling the formation position of the exposure pattern.

[0020] In addition, a rangefinder for autofocus during exposure (hereinafter referred to as AF rangefinder) 10 is provided between the standby position and the location where each irradiation area is lined up. The AF rangefinder 10 measures the distance to the substrate W when it passes directly underneath, and a laser displacement meter is used, for example. The AF rangefinder 10 is connected to the main controller 7, and sends the measured value to the main controller 7. The main controller 7 feeds back this value to the projection optical system 4 in each exposure head 1A, 1B, and uses it for focus control of the projection lenses 41, 42.

[0021] In order to deal with the problem of reduced productivity due to higher resolution, the direct imaging exposure apparatus of this reference example has a different formation position of the irradiation area from that of the conventional apparatus, and is provided with offset optical systems 8A and 8B as a configuration for this purpose. These points will be described with reference to Figures 5 to 7. Figure 5 is a front schematic diagram showing the offset optical systems in the reference example, Figure 6 is a perspective schematic diagram of one offset optical system, and Figure 7 is a plan schematic diagram showing the action of each offset optical system.

[0022] The offset optical systems 8A and 8B are optical systems that make the irradiation areas EA and EB by the exposure heads 1A and 1B not directly below the exposure heads but shifted (offset) in the X direction. The offset optical system 8 is provided for each of the exposure heads 1A and 1B. For convenience of explanation, the exposure heads 1A in the row closer to the standby position (left side in FIG. 1) of the two rows of exposure heads 1A and 1B in the Y direction are referred to as the first row, and the exposure heads 1B farther from the standby position are referred to as the second row. The offset optical system 8A provided in each exposure head 1A in the first row is referred to as the first row offset optical system, and the offset optical system 8B provided in each exposure head 1B in the second row is referred to as the second row offset optical system.

[0023] Each offset optical system 8A, 8B is composed of two mirrors (total reflection mirrors) 81A, 82A, 81B, 82B. Of the two mirrors 81A, 82A, 81B, 82B, the mirrors 81A, 81B arranged on the optical axis close to the exposure heads 1A, 1B are oriented at 45 degrees to the optical axis and are mirrors that bend the optical axis horizontally toward the exposure heads 1A, 1B in the adjacent row (hereinafter referred to as the first mirror). The other mirrors 82A, 82B are also oriented at 45 degrees to the optical axis and are mirrors that return the optical axis bent horizontally to the vertical direction (hereinafter referred to as the second mirror).

[0024] 5 and 6, each first mirror 81A in the first row offset optical system 8A is a mirror that bends the optical axis toward the second row, and conversely, each first mirror 81B in the second row offset optical system 8B is a mirror that bends the optical axis toward the first row. The first mirrors 81A in the first row offset optical system 8A are arranged along the Y direction and are located at the same height. The first mirrors 81B in the second row offset optical system 8B are also arranged along the Y direction and are located at the same height, which is the same as the height of each first mirror 81A in the first row offset optical system 8A.

[0025] 5, the second mirrors 82A in each first row offset optical system 8A are arranged along the Y direction, and are at the same height and in the same orientation as the first mirrors 81A. The second mirrors 82B in each second row offset optical system 8B are also arranged along the Y direction, and are at the same height and in the same orientation as the first mirrors 81B. Therefore, the second mirrors 82A in each first row offset optical system 8A and the second mirrors 82B in each second row offset optical system 8B are all arranged on the same straight line in the Y direction, and are oriented such that their angles differ by 180 degrees from each other.

[0026] 5 and 7, each irradiation area EA of light from each exposure head 1A in the first row is shifted toward the second row by each first row offset optical system 8A, and each irradiation area EB of light from each exposure head 1B in the second row is shifted toward the first row by each second row offset optical system 8B. In particular, in this reference example, each second mirror 82A in each first row offset optical system 8A and each second mirror 82B in each second row offset optical system 8B are aligned on the same straight line along the Y direction, so that each irradiation area EA by each exposure head 1A in the first row and each irradiation area EB by each exposure head 1B in the second row are aligned on the same straight line along the Y direction as shown in FIG.

[0027] Each micropattern M in each irradiation area EA, EB is similar to that in Fig. 14. That is, as shown in Fig. 6, although they are arranged in a staggered pattern, the distance between each micropattern M in the Y direction is longer than the diameter φ of the micropattern M, and exposure without gaps cannot be performed in a single pass. In this reference example, each of the irradiation areas EA, EB is rectangular as shown in Fig. 7 etc. This is due to the arrangement of each pixel mirror 31 in the spatial light modulator 3. Also, in Fig. 7 etc., the longitudinal direction of each of the irradiation areas EA, EB coincides with the Y direction, but in many cases, it is slightly tilted (by a few degrees) with respect to the Y direction. This is also achieved by arranging the spatial light modulator 3 at a slight tilt.

[0028] Next, the operation of such a direct imaging type exposure apparatus of the reference example will be described with reference to Fig. 8. Fig. 8 is a schematic plan view showing the operation of the direct imaging type exposure apparatus of the reference example. 8(1), when exposure is performed by the direct imaging exposure apparatus of the reference example, the substrate W is placed on the stage 6 at the standby position by a transfer mechanism (not shown). The stage 6 vacuum-adsorbs the substrate W, and moves the substrate W in the X direction toward each of the irradiation areas EA and EB by a stage movement mechanism 61.

[0029] When the stage 6 passes directly below a camera (not shown), the camera captures an image of the alignment mark on the substrate W and sends the image to the main controller 7. When the stage 6 passes directly below an AF rangefinder, the AF rangefinder 10 measures the distance to the substrate W on the stage 6, and the measurement data is sent to the main controller 7.

[0030] Then, when the substrate W on the stage 6 passes through each of the irradiation areas EA, EB on the outward journey, the main controller 7 executes the pixel sequence program 731 for the outward journey, so that the light of the exposure pattern is irradiated onto each of the irradiation areas EA, EB by each of the exposure heads 11. At this time, in addition to receiving image data of the alignment mark captured by the camera and irradiating the light of the exposure pattern onto a predetermined position, the projection lenses 41, 42 are controlled by the measurement data from the AF rangefinder 10, and exposure is performed in an optimally focused state.

[0031] In this manner, exposure is performed on the outward journey, and the substrate W on the stage 6 passes through each of the irradiation areas EA and EB. Then, the stage 6 performs an inversion operation at the inversion position. As shown in FIG. 8(2), the inversion position is a position where the substrate W has completely passed through each of the irradiation areas EA and EB (where the rear end of the substrate W has passed through each of the irradiation areas EA and EB) and is slightly further ahead.

[0032] As shown in Fig. 8(3), at the inversion position, the stage movement mechanism 61 moves (shifts) the stage 6 in the Y direction. The movement distance (hereinafter referred to as the shift distance) at this time is a distance for exposing the substrate W without gaps by combining the outward and return passes by exposure on the return pass, and is set in advance. The shift distance is indicated by S in Fig. 8(3). In addition to the shift distance S, the movement direction of the shift distance S is also set in advance so that exposure is performed without gaps.

[0033] After the stage 6 has been moved by the shift distance S at the reversal position, it starts moving in the opposite direction toward each of the irradiation areas EA and EB. Then, when passing through each of the irradiation areas EA and EB, the pixel sequence program 732 for the return pass is executed, and exposure on the return pass is performed by each exposure head 11. After the substrate W passes through each of the irradiation areas EA and EB on the return path, the stage 6 returns to the standby position as shown in Fig. 8(4). Then, the substrate W is carried out from the stage 6 by a transfer mechanism (not shown). Then, the unexposed substrate W is placed on the stage 6 again, and the same process is repeated.

[0034] According to the direct imaging exposure apparatus of the reference example, since the offset optical systems 8A and 8B are provided, each irradiation area EA by the first row of exposure heads 1A and each irradiation area EB by the second row of exposure heads 1B approach each other, and the moving distance of the stage 6 for the substrate W to completely pass through these irradiation areas EA and EB is shortened. In FIG. 7, the moving distance required for the substrate W to completely pass through the irradiation areas EA and EB in the case of no offset is indicated by D, and the distance required for the substrate W to completely pass through the irradiation areas EA and EB in the case of offset is indicated by D' (in reality, the length of the substrate W in the X direction is added to this, but since it is common, it is omitted). Due to such a shortening of the moving distance, the productivity is greatly improved. This effect is particularly advantageous in the case where the minute pattern M becomes small to meet the demand for high definition and exposure on the outward and return paths is required, and it is possible to suppress a decrease in productivity while achieving high definition exposure.

[0035] In this reference example, each offset optical system 8A, 8B is an optical system that offsets each irradiation area EA by the first row of exposure heads 1A and each irradiation area EB by the second row of exposure heads 1B so that they are aligned in a straight line, thereby maximizing the effect of improving productivity. However, even if the alignment is not perfectly straight, the effect of improving productivity can be expected. This point will be explained with reference to Fig. 9. Fig. 9 is a schematic diagram showing the effect of improving productivity by each offset optical system.

[0036] Fig. 9(1) shows an example in which each irradiation area EA by the first row of exposure heads 1A and each irradiation area EB by the second row of exposure heads 1B are not perfectly aligned, but overlap when viewed in the Y direction. Also, Fig. 9(2) shows that each irradiation area EA by the first row of exposure heads 1A and each irradiation area EB by the second row of exposure heads 1B do not overlap, but are offset from a position directly below to a position close to each other. Even with these configurations, there is an effect of improving productivity compared to conventional configurations that are not offset, and they can be implemented.

[0037] In the above examples, the offset optical system 8A, 8B is provided in each of the exposure heads 1A, 1B in both rows, but the offset optical system may be provided only in one row. For example, the offset optical system may be provided only in each of the exposure heads 1A in the first row, and the offset optical system may not be provided in each of the exposure heads 1B in the second row, and the position directly below the offset optical system may be each of the irradiation areas EB. In this case, the productivity is improved by offsetting each of the irradiation areas EA by each of the exposure heads 1A in the first row in a direction approaching each of the irradiation areas EB by each of the exposure heads 1B in the second row. In this case, the most effective method is to make each of the irradiation areas EA, EB completely aligned, but the effect of improving productivity can be obtained even if they overlap or are close to each other but not overlapping. However, in a configuration in which offset optical systems 8A, 8B are provided on each exposure head 1A, 1B in both rows, the design brings the irradiation areas EA, EB closer to each other from both sides, so even if the irradiation areas EA, EB are overlapped or aligned in a straight line, the offset distance does not become very long and they can be arranged symmetrically, making the design easier.

[0038] Furthermore, the effect of improving productivity is obtained by shortening the distance required for the substrate W to completely pass through each of the irradiation areas EA and EB, and is not necessarily limited to a configuration in which exposure is performed on the outbound and return passes. For example, the effect is also achieved in a case in which exposure is performed only on the return pass and not on the outbound pass. During exposure, the movement speed of the stage 6 is slowed down to ensure a predetermined amount of exposure, so the movement distance at a low speed is shortened, shortening the takt time and improving productivity.

[0039] Next, a direct imaging type exposure apparatus according to the first embodiment will be described below. Fig. 10 is a schematic front view showing the main part of the direct imaging type exposure apparatus according to the first embodiment. The direct imaging exposure apparatus of the first embodiment differs from the first embodiment in that each offset optical system 8A, 8B has an autofocus function. Specifically, as shown in Fig. 10, each offset optical system 8A, 8B is provided with an optical path length changer 9. In this example, the optical path length changer 9 is a prism pair unit.

[0040] The optical path length changer 9, which is a prism pair unit, is a combination of two prisms 91, 92 of the same size and shape, and in this example, the two prisms 91, 92, each with a right-angled triangular cross section, are arranged with their inclined faces facing each other. The other face that forms an acute angle with the inclined face is perpendicular to the optical axis.

[0041] One of the two prisms 91, 92 is a fixed prism 91, and the other is a movable prism 92. An actuator 93 such as a piezoelectric element is provided on the movable prism 92. The actuator 93 is connected to the main controller 7, and the main controller 7 controls the actuator 93 in accordance with measurement data from the AF rangefinder 10. 10, the optical path length (optical distance) changes. Therefore, by controlling the actuator 93 according to the measurement data of the AF rangefinder 10, an optimal focusing state can be achieved.

[0042] In the first embodiment, the optical path length changer 9 is provided in the offset optical systems 8A and 8B, so there is no need to provide it within the exposure head 1, simplifying the structure within the exposure head 1. In particular, in the first embodiment, the optical path length changer 9 is provided between the first mirror 81 and the second mirror 82, so adjustments during placement are easy. After the first mirror 81, the second mirror 82, and the optical path length changer 9 are housed in a housing and aligned, the housing can be precisely positioned relative to the exposure head 1, making adjustments easy.

[0043] Incidentally, the optical path length changer 9 may be disposed on the optical path between the first mirror 81 and the exposure heads 1A, 1B, or may be disposed on the exit side (below) of the second mirror 82. Also, as the optical path length changer 9, it is possible to adopt a configuration other than a prism pair unit.

[0044] Next, a direct imaging type exposure apparatus according to a second embodiment will be described below. Fig. 11 is a schematic front view showing the main part of the direct imaging type exposure apparatus according to the second embodiment. In the direct imaging exposure apparatus of the second embodiment, each offset optical system 8A, 8B has an autofocus function, similar to the first embodiment. The second embodiment differs from the first embodiment in that the autofocus function is realized by moving an offset mirror.

[0045] 11, the second mirror 82A is a movable mirror and is provided with an actuator 83. The actuator 83 is also connected to the main controller 7 and is controlled according to measurement data from the AF rangefinder 10. As a result of the movement of the second mirror 82A by the actuator 83, the optical path length changes and an optimal focusing state is achieved. According to the second embodiment, the focusing state is achieved by moving the optical elements constituting the offset optical system 8, and no optical path length modulator is used. This simplifies the configuration and is expected to reduce costs by reducing the number of parts.

[0046] Next, a direct imaging type exposure apparatus according to a third embodiment will be described with reference to Fig. 12, which is a schematic front view showing the main part of the direct imaging type exposure apparatus according to the third embodiment. In the third embodiment, as in the second embodiment, an autofocus function is implemented using optical elements that configure the offset optical systems 8A and 8B. As shown in Fig. 12, in the third embodiment, two mirrors 84 and 85 are added to the exit side of the second mirror 82A. That is, a third mirror 84 is provided immediately below the second mirror 82A at an angle of 45 degrees to the optical axis. The third mirror 84 is oriented 180 degrees differently from the second mirror 82A, and bends the optical axis in the opposite direction to the horizontal direction (X direction).

[0047] A fourth mirror 85 is provided at the same height as the third mirror 84. The fourth mirror 85 is also oriented at 45 degrees with respect to the optical axis, and is disposed in the same orientation as the third mirror 84. 12, the optical axis is bent vertically downward by the fourth mirror 85 and reaches the irradiation area EA. The distance between the third mirror 84 and the fourth mirror 85 is shorter than the distance between the first mirror 81A and the second mirror 82A, and the distance between the first mirror 81A and the fourth mirror 85 as viewed in the X direction is the offset distance.

[0048] In the third embodiment, the second mirror 82A and the third mirror 84 are held together by a frame (not shown), and an actuator 86 is provided for this frame. The actuator 86 is connected to the frame (not shown) so as to move the second mirror 82A and the third mirror 84 together in the X direction.

[0049] In the third embodiment as well, the actuator 86 is controlled by a signal from the main controller 7, and the second mirror 82A and the third mirror 84 move together and change their positions in accordance with the measurement data of the AF rangefinder 10. As a result, the optical path length changes and an optimal focusing state is achieved.

[0050] Compared to the second embodiment, the third embodiment has the advantage that the irradiation area EA does not move during autofocus. In the second embodiment, autofocus is achieved by moving only the second mirror 82A, so the position of the irradiation area EA also shifts in the X direction. For this reason, it is necessary to change the pixel sequence program 731 according to the drive amount (direction and distance) of the actuator 83 so that exposure is performed at a position that compensates for the shift. The configuration of the third embodiment is superior in that this is not necessary. Although only the exposure heads 1A in the first row are illustrated in FIG. 11 and FIG. 12, the same configuration is also adopted for the exposure heads 1B in the second row.

[0051] In the above-mentioned reference examples and each embodiment, the offset optical systems 8A and 8B are optical systems using mirrors, but prisms may be used instead of mirrors. Each prism is disposed in a position in which the optical axis is bent at a right angle, similar to the mirror. In the reference example and each embodiment, exposure was performed on the outbound and return journeys, but this is not essential, and when two round trips are made, exposure may be performed on two outbound journeys, or on two return journeys.

[0052] In addition, it is not essential for the present invention that the substrate W passes through each of the irradiation areas EA and EB twice, and the device may perform gap-free exposure in only one pass. That is, even if the separation distance L of the micropatterns M in the Y direction is smaller than the diameter φ of the micropatterns M as shown in Fig. 13 and gap-free exposure is performed in only one pass, a configuration that shortens the movement distance of the stage 6 required for the substrate W to completely pass through the irradiation areas EA and EB contributes to improving productivity.

[0053] In the above-mentioned reference examples and each embodiment, a so-called twin stage configuration may be adopted. The twin stage configuration is a configuration in which two stages are provided, and standby positions for the stages are set on both sides of the irradiation areas EA and EB. The stages on both sides alternately reciprocate through the irradiation areas, and the substrates W placed on each stage are alternately exposed. In this case, too, the movement distance for the substrate W to completely pass through each irradiation area EA and EB is shortened by each offset optical system 8A and 8B, improving productivity. [Explanation of symbols]

[0054] 1A Exposure head 1B Exposure head 10 AF rangefinder 6 Stage 61 Stage movement mechanism 611 X-direction linear guide 613 Y-direction linear guide 7 Main Controller 72 Main sequence program 731 pixel sequence program 732 pixel sequence program 8A Offset Optical System 8B Offset Optical System 81 First Mirror 82 Second Mirror 9. Optical path length changer W substrate

Claims

1. a stage on which a substrate is placed; a stage moving mechanism that moves a stage on which a substrate is placed from a standby position so that the substrate passes through an irradiation area; an exposure head that accommodates a spatial light modulator that spatially modulates light from a light source and a projection optical system that projects a light pattern formed by the spatial light modulator onto an irradiation area; A direct imaging exposure apparatus that exposes a substrate to a light pattern formed by a spatial light modulator when the substrate passes through an irradiation area, a range finder that measures the distance to the substrate at a position between the stage being moved from a standby position and the substrate reaching the irradiation area; an optical path length changer provided on an optical path between the exposure head and the irradiation area; a controller for controlling an optical path length changer in accordance with measurement data from a range finder to change the optical path length, thereby achieving a focused state by a projection optical system.

2. a stage on which a substrate is placed; a stage moving mechanism that moves a stage on which a substrate is placed from a standby position so that the substrate passes through an irradiation area; an exposure head that accommodates a spatial light modulator that spatially modulates light from a light source and a projection optical system that projects a light pattern formed by the spatial light modulator onto an irradiation area; A direct imaging exposure apparatus that exposes a substrate to a light pattern formed by a spatial light modulator when the substrate passes through an irradiation area, a range finder that measures the distance to the substrate at a position between the stage being moved from a standby position and the substrate reaching the irradiation area; a mirror for bending the optical path between the exposure head and the irradiation area; an actuator that moves a mirror to change the optical path length from the exposure head to the irradiation area; a controller for controlling an actuator in accordance with measurement data from a range finder to change an optical path length, thereby achieving a focused state by a projection optical system.

Images