JP7623915B2 - Direct imaging exposure device - Google Patents

Description

The invention of this application relates to a direct imaging exposure device that uses a spatial light modulator to form an exposure pattern and then expose the pattern.

A direct imaging exposure apparatus is known as an exposure apparatus used in photolithography processes, etc. The direct imaging exposure apparatus is a type of maskless exposure apparatus, which 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 devices are extremely easy to change the exposure pattern as needed, and are suitable for high-mix low-volume production. For this reason, they are widely used for manufacturing circuit boards for various products and for manufacturing various fine parts (MEMS). In most cases, the object to be exposed is plate-shaped (substrate), but there are also cases where it is not plate-shaped.

JP 2009-300543 A

As products become more sophisticated and multifunctional, there is a growing demand for higher definition and resolution in direct imaging exposure devices. This has led to problems with reduced productivity. This will be described below with reference to Figs. 13 and 14.
13 and 14 are diagrams for explaining the problem to be solved by the present invention, and are schematic perspective views showing an irradiation area in a direct imaging exposure apparatus.

A direct imaging exposure apparatus usually includes a plurality of exposure heads 1 each containing a light source and a spatial light modulator. The region that can be irradiated with light by one exposure head 1 is an irradiation area, which is indicated by a rectangular line E in Figs. 13 and 14.
As shown enlarged in Figures 13 and 14, each irradiation area E is actually a collection of minute irradiation patterns (hereinafter referred to as "micropatterns") M. The squares showing each irradiation area E are imaginary lines, and indicate an area onto which a large number of micropatterns M can be irradiated. One micropattern M corresponds to each pixel of the spatial light modulator, and in the case of a DMD, one micropattern M is a pattern formed by one pixel mirror. Although each pixel is square, the image is converted into a circle during projection by the lens system in the exposure head 1.

The substrate W, which is the object to be exposed, is placed on a stage and moves horizontally. Hereinafter, this direction of movement is referred to as the X direction. As it moves, it passes through each irradiation area E, during which exposure is performed by each micropattern M. Each micropattern M is controlled by turning each pixel on and off in the spatial light modulator. Therefore, the pattern formed by turning each micropattern M on and off is the exposure pattern.

As shown in Figure 13, although each micropattern M is spaced apart from the others, they are arranged so that they are exposed without gaps as the substrate W moves in the X direction. That is, the rows of each micropattern M in the horizontal direction perpendicular to the X direction (hereinafter referred to as the Y direction) are arranged offset from adjacent rows in the Y direction, resulting in a so-called staggered arrangement. The arrangement interval L of each micropattern in the Y direction is smaller than the diameter φ of each micropattern M. Therefore, when the substrate moves in the X direction and exposure is performed by each micropattern M, exposure is performed without gaps.

Note that "exposure without gaps" means that there are no gaps in the exposure pattern. For example, if the exposure pattern is one in which all pixels are on, then "exposure without gaps" means that the entire illuminated area is exposed to light. The exposure pattern is determined according to the circuitry to be formed, and accordingly there will be some parts that are not exposed to light. In other words, "exposure without gaps" means that the exposure pattern is transferred without any gaps.

Conventional direct imaging exposure devices generally have the configuration shown in Figure 13, but in order to achieve higher definition exposure, the configuration shown in Figure 14 is being considered. Higher definition means making the exposure pattern finer, which inevitably means that each micropattern M becomes smaller. Specifically, the reduction ratio of the projection magnification by the lens system in each exposure head 1 becomes smaller. Also, in order to achieve higher resolution, the NA of the projection lens included in the lens system becomes larger, and a high-resolution type spatial light modulator with a large number of pixels is used.

However, when a configuration such as that shown in FIG. 14 is adopted for higher resolution, the diameter φ of each micropattern M is smaller than the arrangement interval L of the micropatterns M in the Y direction (φ<L), so moving the substrate W in the X direction once will not allow for gap-free exposure. Therefore, it is necessary to pass each irradiation area E two or more times while shifting (changing position) in the Y direction. For example, in a configuration in which the stage makes one round trip through each irradiation area E, after passing each irradiation area on the outbound trip, a configuration can be considered in which the stage is shifted in the Y direction and passes each irradiation area again on the return trip.

In this way, even smaller micropatterns M can be exposed without gaps, but there is a problem of reduced productivity. That is, when passing through each irradiation area E, the stage movement speed must be reduced in order to ensure the necessary amount of exposure. If exposure is completed in one pass, the stage can be moved at high speed on the return trip, so there is no reduction in productivity, but if exposure is also required on the return trip, the movement speed will be reduced, and productivity will decrease.

The problem of reduced productivity due to higher resolution is also caused by the larger exposure head. Lenses with higher NA tend to be larger, which in turn leads to larger exposure heads. High-resolution spatial light modulators also tend to be larger due to the large number of pixels, which also contributes to the larger exposure heads.
The increase in size of the exposure head is reflected in an increase in its cross-sectional area (larger diameter), which results in a larger distance between each irradiation area. In particular, if the distance between the irradiation areas in the X direction increases, this means that the travel distance to pass through all the irradiation areas E becomes longer, which means that the time required for this becomes longer. This results in a decrease in productivity.

In this way, in a configuration that satisfies the demand for higher definition, the miniaturization of each minute pattern and the increase in size of each exposure head combine to reduce productivity.
The invention of this application has been made to solve the above-mentioned problems, and has an object to provide a direct imaging exposure apparatus that effectively solves the problem of reduced productivity that arises from the demand for higher resolution.

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 forms a light pattern using a spatial light modulator to expose a substrate, and is equipped with a plurality of exposure heads having a light source and a spatial light modulator, a stage on which the substrate is placed, and a stage movement mechanism that moves the stage so that the substrate passes through an irradiation area, which is an area irradiated with the light of the pattern formed by the spatial light modulator.
In this direct imaging exposure device, multiple exposure heads are arranged in two rows along a direction perpendicular to the movement direction of the stage, and an offset optical system is provided for each exposure head in at least one of the rows between each exposure head and each irradiation area, and each offset optical system is an optical system that offsets the optical axis in a direction such that each irradiation area by each exposure head in one row approaches each irradiation area by each exposure head in the other row.
In order to solve the above problems, the direct imaging exposure apparatus comprises:
An offset optical system may be provided for each of the two rows of exposure heads, and each offset optical system provided for each exposure head in the other row may be an optical system that offsets the optical axis so that each illumination area by each exposure head in the other row approaches each illumination area by each exposure head in one row.
In order to solve the above problem, in this direct imaging exposure device, each irradiation area by each exposure head in one row and each irradiation area by each exposure head in the other row can overlap in a direction perpendicular to the movement direction of the stage.
In order to solve the above problem, in this direct imaging exposure device, each irradiation area by each exposure head in one row and each irradiation area by each exposure head in the other row can be on a straight line.
In addition, in order to solve the above-mentioned problems, in this direct imaging exposure apparatus, the offset optical system can include a first reflective element whose reflective surface bends the optical axis from the exposure head at a right angle, and a second reflective element having a reflective surface that bends the optical axis bent at a right angle by the first reflective element toward the substrate.
In order to solve the above problem, in the direct imaging exposure apparatus, an optical path length changer for changing the optical path length to the irradiation area can be provided between the first reflecting element and the second reflecting element.
In addition, in order to solve the above problem, in this direct imaging exposure apparatus, the second reflective element can be made movable along the optical axis from the first reflective element so that the optical path length to the irradiation area can be changed.

As will be described below, the direct imaging exposure apparatus according to the disclosed invention is provided with an offset optical system, so that the areas irradiated by the exposure heads in one row and the areas irradiated by the exposure heads in the other row are close to each other, shortening the travel distance of the substrate for the substrate to completely pass through these irradiation areas, thereby improving productivity.
Furthermore, in a configuration in which each exposure head in both rows is provided with an offset optical system, the design brings each irradiation area closer to each other from both sides, so the offset distances do not become long and the arrangement can be symmetrical, making the design easier.
If each offset optical system is an optical system that offsets the illumination areas by each exposure head in one row so that they overlap with the illumination areas by each exposure head in the other row, the effect of improving productivity will be greater, and if the optical systems are offset so that they are aligned in a straight line, the effect of improving productivity will be even greater.
In addition, in a configuration in which an optical path length changer for changing the optical path length to the irradiation area is provided between the first and second reflecting elements forming the offset optical system, there is no need to provide an optical path length changer in the exposure head, so the structure of the exposure head is simplified. Also, it is easy to adjust the positions of the first and second reflecting elements and the optical path length changer.
Furthermore, in a configuration in which the second reflective element, of the first reflective element and the second reflective element that form the offset optical system, is arranged to be movable along the optical axis from the first reflective element so that the optical path length to the irradiation area can be changed, there is no need to provide a separate optical path length changer, which results in a simpler structure and reduced costs due to the reduced number of parts.

1 is a schematic front view of a direct imaging exposure apparatus according to a first embodiment. 1 is a schematic side view of a direct imaging exposure apparatus according to a first embodiment. 1 is a schematic plan view of a direct imaging exposure apparatus according to a first embodiment. FIG. 2 is a schematic diagram showing the internal structure of the exposure head. FIG. 2 is a schematic front view showing the offset optical system according to the first embodiment. FIG. 2 is a perspective schematic diagram showing one offset optical system. 5 is a schematic plan view showing the action of each offset optical system. FIG. 4A to 4C are schematic plan views showing the operation of the direct imaging exposure apparatus according to the embodiment. 1A to 1C are schematic diagrams showing the effect of improving productivity by each offset optical system. FIG. 11 is a schematic front view showing a main part of a direct imaging exposure device according to a second embodiment. FIG. 11 is a schematic front view showing a main part of a direct imaging exposure device according to a third embodiment. FIG. 13 is a schematic front view showing a main part of a direct imaging exposure device according to a fourth embodiment. FIG. 1 is a schematic perspective view for explaining a problem to be solved by the present invention, showing an irradiation area in a direct imaging exposure apparatus. FIG. 1 is a schematic perspective view for explaining a problem to be solved by the present invention, showing an irradiation area in a direct imaging exposure apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given of a mode (embodiment) for carrying out the invention of this application.
1 to 3 are schematic diagrams of a direct imaging exposure apparatus according to a first embodiment, with FIG. 1 being a schematic front view, FIG. 2 being a schematic side view, and FIG. 3 being a schematic plan view.
The direct imaging exposure apparatus shown in FIGS. 1 to 3 comprises a plurality of exposure heads 1 A, 1 B, a stage 6 on which a substrate W is placed, and a stage moving mechanism 61 .

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

The light source 2 used is one that outputs light of an optimal wavelength depending on 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, so 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 for the light source 2 to output coherent light, and for this reason a laser light source 2 is preferably used. For example, a gallium nitride (GaN) semiconductor laser is used.

In this embodiment, 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 size of about 13.68 μm on each side, and a large number of pixel mirrors 31 are arranged in a rectangular lattice. The number of mirrors arranged is, for example, 1024 × 768.

The spatial light modulator 3 includes a modulator controller 32 that controls each pixel mirror 31. The exposure apparatus of the embodiment includes a main controller 7 that controls the entire apparatus. The modulator controller 32 controls each pixel mirror 31 in accordance with 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 can independently control whether each pixel mirror 31 takes the first position or the second position. Such a spatial light modulator 3 is available from Texas Instruments.

As shown in FIG. 4, the exposure heads 1A and 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 embodiment, the irradiation optical system 5 includes an optical fiber 51. To form an image with higher illuminance, each exposure head 1A and 1B is equipped with multiple 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.

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 reflect it on each pixel mirror 31, and it is also desirable to make the 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.

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 many tiny lenses 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.

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 is 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 it. As a result, the light of the specified exposure pattern is irradiated onto the irradiation area.

The stage 6 is a member on whose horizontal upper surface the substrate W is placed. 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 embodiment, the stage moving mechanism 61 is a mechanism that can move the stage 6 in the X direction for exposure to pass through the irradiation area, and also move the stage in the Y 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 can 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.

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 device, and pixel sequence programs 731 and 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 embodiment, exposure is performed in the forward and return passes, so a pixel sequence program 731 for the forward pass and a pixel sequence program 732 for the return pass are stored. The main sequence program 72 sequentially calls and executes the pixel sequence programs 731 and 732 when exposing each substrate W. Note that since it is the modulator controller 32 that actually controls each pixel mirror 31, the pixel sequence programs 731 and 732 are programs that provide a sequence to the modulator controller 32 so that each pixel mirror 31 is driven by that sequence.

Between the waiting position and the irradiation area, a camera (not shown) is provided to capture 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 from the camera is sent to the main controller 7. The main controller 7 controls the formation position of the exposure pattern by executing pixel sequence programs 731 and 732 using the captured image data as an argument.

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 for example a laser displacement meter is used. 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.

In this embodiment of the direct imaging exposure apparatus, the position at which the irradiation area is formed is different from that of the conventional apparatus in order to address the problem of reduced productivity that accompanies higher resolution, and offset optical systems 8A and 8B are provided as a configuration for this purpose. These points will be explained with reference to Figures 5 to 7. Figure 5 is a front schematic diagram showing the offset optical system in the first embodiment, 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.

The offset optical system 8A, 8B is an optical system that causes the irradiation areas EA, EB of the exposure heads 1A, 1B to be shifted (offset) in the X direction rather than directly below. An offset optical system 8 is provided for each exposure head 1A, 1B. For convenience of explanation, of the two rows of exposure heads 1A, 1B in the Y direction, the exposure heads 1A in the row closer to the standby position (left side in FIG. 1) 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 for 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 for each exposure head 1B in the second row is referred to as the second row offset optical system.

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 mirror 81A, 81B arranged on the optical axis close to the exposure heads 1A, 1B is oriented at 45 degrees to the optical axis and is a mirror that bends the optical axis horizontally toward the exposure heads 1A, 1B in the adjacent row (hereinafter referred to as the first mirror). The other mirror 82A, 82B is also oriented at 45 degrees to the optical axis and is a mirror that returns the optical axis bent horizontally to the vertical direction (hereinafter referred to as the second mirror).

In other words, as can be seen from Figures 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. Note that each first mirror 81A in the first row offset optical system 8A is arranged along the Y direction and is located at the same height. Each first mirror 81B in the second row offset optical system 8B is also arranged along the Y direction and is located at the same height, which is the same height as each first mirror 81A in the first row offset optical system 8A.

As shown in FIG. 5, each second mirror 82A in each first row offset optical system 8A is arranged along the Y direction, and has the same posture and height as each first mirror 81A. Each second mirror 82B in each second row offset optical system 8B is also arranged along the Y direction, and has the same posture and height as each first mirror 81B. Therefore, 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 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.

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 embodiment, 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 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 line along the Y direction as shown in FIG. 7.

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 by a single pass.
In this embodiment, each of the irradiation areas EA, EB is rectangular as shown in Fig. 7 and other figures. This is due to the arrangement of the pixel mirrors 31 in the spatial light modulator 3. In Fig. 7 and other figures, the longitudinal direction of each of the irradiation areas EA, EB coincides with the Y direction, but in many cases, the longitudinal direction is slightly tilted (by a few degrees) relative to the Y direction. This is also achieved by disposing the spatial light modulator 3 at a slight tilt.

Next, the operation of the direct imaging exposure apparatus of this embodiment will be described with reference to Fig. 8. Fig. 8 is a schematic plan view showing the operation of the direct imaging exposure apparatus of the embodiment.
8A, a substrate W is placed on a stage 6 at a standby position by a transfer mechanism (not shown). The stage 6 holds the substrate W by vacuum suction, and moves the substrate W in the X direction toward each of the irradiation areas EA and EB by a stage moving mechanism 61.

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. Also, when the stage 6 passes directly below the AF rangefinder 10, 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.

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 each of the exposure heads 11 irradiates each of the irradiation areas EA, EB with light of an exposure pattern. 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 at a predetermined position, each of the projection lenses 41, 42 is controlled by measurement data from the AF rangefinder 10, and exposure is performed in an optimally focused state.

In this way, 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 (the rear end of the substrate W has passed through each of the irradiation areas EA and EB) and is slightly further ahead.

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.

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, an unexposed substrate W is placed on the stage 6 again, and the same process is repeated.

According to the direct imaging exposure apparatus of this embodiment, the offset optical systems 8A and 8B are provided, so 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 approach each other, and the movement 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 movement distance required for the substrate W to completely pass through the irradiation areas EA and EB when there is no offset is indicated by D, and the distance required for the substrate W to completely pass through the irradiation areas EA and EB when there is an offset is indicated by D' (note that 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 reduction in the movement distance, productivity is greatly improved. This effect is particularly advantageous in cases where the micropattern M becomes small to meet the demand for high resolution and exposure on the outward and return paths is required, and it is possible to suppress a decrease in productivity while achieving high resolution exposure.

In this embodiment, 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.

Figure 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 in a perfect straight line, but overlap when viewed in the Y direction. Also, in Figure 9 (2), 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 closer to each other. Even with these configurations, there is an effect of improving productivity compared to conventional non-offset configurations, and they can be implemented.

In the above examples, the offset optical systems 8A and 8B are provided in each of the exposure heads 1A and 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 and 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 the arrangement can be made symmetrical, making the design easier.

In addition, the effect of improving productivity is obtained by shortening the distance required for the substrate W to pass completely through each irradiation area EA, EB, and is not necessarily limited to a configuration in which exposure is performed on the outbound and return journeys. For example, it is also effective if exposure is performed only on the return journey and not on the outbound journey. During exposure, the movement speed of the stage 6 is reduced to ensure a predetermined amount of exposure, so the movement distance at low speeds is shortened, shortening the takt time and improving productivity.

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

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. 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, which forms an acute angle with the inclined face, is perpendicular to the optical axis.

One of the two prisms 91, 92 is a fixed prism 91, and the other is a movable prism 92. The movable prism 92 is provided with an actuator 93 such as a piezoelectric element. 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, so that the optimal focusing state can be achieved by controlling the actuator 93 in accordance with the measurement data of the AF rangefinder 10.

In the second 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, and the structure within the exposure head 1 is simplified. In particular, in the second 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.

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

Next, a direct imaging exposure apparatus according to a third embodiment will be described with reference to Fig. 11, which is a schematic front view showing the main components of the direct imaging exposure apparatus according to the third embodiment.
In the direct imaging exposure apparatus of the third embodiment, each of the offset optical systems 8A and 8B has an autofocus function, similar to the second embodiment. The third embodiment differs from the second embodiment in that the autofocus function is realized by moving an offset mirror.

11, the second mirror 82A is a movable mirror and is provided with an actuator 83. The actuator 83 is similarly connected to the main controller 7 and is controlled according to measurement data from the AF rangefinder 10. As a result of the actuator 83 moving the second mirror 82A, the optical path length changes and an optimal focusing state is achieved. Although not shown in the figure, a similar configuration is also adopted in the second row offset optical system 8B.
According to the third 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.

Next, a direct imaging type exposure apparatus according to a fourth 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 fourth embodiment.
In the fourth embodiment, as in the third embodiment, an autofocus function is implemented using optical elements constituting the offset optical systems 8A and 8B. In the fourth 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 82, and bends the optical axis in the opposite direction to the horizontal direction (X direction).

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.

In the fourth 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.

In the fourth embodiment, the actuator 86 is also 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 according to the measurement data of the AF rangefinder 10. As a result, the optical path length changes and the optimal focusing state is achieved. Although not shown in the figure, a similar configuration is also adopted in the second row offset optical system 8B.

Compared to the third embodiment, the fourth embodiment has the advantage that the irradiation area EA does not move during autofocus. In the third embodiment, autofocus is achieved by moving only the second mirrors 82A and 81B, so the positions of the irradiation areas EA and EB also shift 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 fourth embodiment is superior in that it does not require this.

In the above-described embodiments, 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 each embodiment, exposure is 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.

Furthermore, it is not essential for the present invention that the substrate W passes through each irradiation area EA, 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, EB contributes to improved productivity.

In addition, in each of the above-mentioned embodiments, a so-called twin stage configuration may be adopted. A twin stage configuration is a configuration in which two stages are provided, with standby positions for the stages set on either side 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 are exposed alternately. In this case, too, the travel distance for the substrate W to pass completely through each irradiation area EA and EB is shortened by each offset optical system 8A and 8B, improving productivity.

Reference Signs List 1A Exposure head 1B Exposure head 10 AF range finder 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 81A First mirror 82A Second mirror 81B First mirror 82B Second mirror 9 Optical path length changer W Substrate

Claims (7)

A direct imaging exposure apparatus that forms a light pattern using a spatial light modulator to expose a substrate, comprising:
a plurality of exposure heads each having a light source and a spatial light modulator;
a stage on which a substrate is placed;
a stage moving mechanism for moving the stage so that the substrate passes through an irradiation area, which is an area onto which the light of the pattern formed by the spatial light modulator is irradiated;
The exposure heads are arranged in two rows in a direction perpendicular to the direction of movement of the stage,
an offset optical system is provided for each exposure head in at least one row between each exposure head and each irradiation area;
a direct imaging exposure device, wherein each offset optical system is an optical system that offsets each optical axis in a direction in which each illumination area by each exposure head in one row approaches each illumination area by each exposure head in the other row. The direct imaging exposure device according to claim 1, characterized in that the offset optical system is provided for each of the two rows of exposure heads, and the offset optical system provided for each exposure head of the other row is an optical system that offsets the optical axis so that each irradiation area by each exposure head of the other row approaches each irradiation area by each exposure head of the one row. The direct imaging exposure device according to claim 1 or 2, characterized in that each irradiation area by each exposure head in the one row and each irradiation area by each exposure head in the other row overlap in a direction perpendicular to the movement direction of the stage. The direct imaging exposure device according to claim 1 or 2, characterized in that each illumination area by each exposure head in the one row and each illumination area by each exposure head in the other row are on a straight line. A direct imaging exposure apparatus according to any one of claims 1 to 4, characterized in that each of the offset optical systems includes a first reflecting element whose reflecting surface bends the optical axis from the exposure head at a right angle, and a second reflecting element having a reflecting surface that bends the optical axis bent at a right angle by the first reflecting element toward the substrate at a right angle. The direct imaging exposure device according to claim 5, characterized in that an optical path length changer is provided between the first reflecting element and the second reflecting element, for changing the optical path length to the irradiation area by the exposure head provided with the offset optical system. The direct imaging exposure device according to claim 5, characterized in that the second reflecting element is movable along the optical axis from the first reflecting element so that the optical path length to the irradiation area can be changed.

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