JP7631159B2 - Drawing device - Google Patents

Description

The present invention relates to a drawing device that draws on a substrate.

Conventionally, a drawing device has been used that draws a pattern by irradiating light onto a photosensitive material formed on a semiconductor substrate, a printed circuit board, or a glass substrate for an organic electroluminescence display device or a liquid crystal display device (hereinafter referred to as a "substrate").

For example, in the pattern exposure device of Patent Document 1, light output from a light source is spatially modulated by a DMD (Digital Micromirror Device) to form a pattern light, and the pattern light is imaged on a photosensitive material by an optical system. The optical system includes a first imaging optical system that images the pattern light formed by the DMD, a microlens array arranged on the imaging surface of the first imaging optical system, and a second imaging optical system that images the light that has passed through the microlens array on the photosensitive material. The microlens array has a plurality of microlenses that are two-dimensionally arranged to correspond to the plurality of micromirrors of the DMD. In the pattern exposure device, the microlens array is moved in the optical axis direction by a focus control unit, thereby adjusting the imaging position of the pattern light on the substrate.

JP 2018-41025 A

However, in a pattern exposure apparatus such as that described in Patent Document 1, if the amount of light is increased to improve throughput, there is a risk that the lens temperature in the first imaging optical system will rise while the pattern is being drawn. In this case, the focal length of the first imaging optical system will fluctuate due to the thermal lens effect, and the imaging position of the image of the DMD micromirror that should be imaged on each microlens of the microlens array will shift in the optical axis direction (i.e., the image will be out of focus). As a result, the image of the micromirror that is imaged on one microlens will spread to adjacent microlenses, and light may be irradiated onto spots on the substrate that should not be drawn, reducing the drawing accuracy.

In addition, since the amount of change in focal length due to the thermal lens effect differs between the center and periphery of the lens, it is difficult to appropriately adjust both the shift in the image formation position on the microlens located in the center of the microlens array and the shift in the image formation position on the microlens located in the periphery of the microlens array by simply moving the microlens array in the optical axis direction. It is also possible to reduce the thermal lens effect by using lenses made of a material with high transmittance, but this increases the cost of the lenses.

The present invention has been developed in consideration of the above problems, and aims to suppress the deterioration of drawing accuracy due to the thermal lens effect.

The invention described in claim 1 is a drawing device that draws on a substrate, comprising: a substrate holding unit that holds the substrate; a drawing head that irradiates light onto the substrate to draw a pattern; a substrate moving mechanism that moves the substrate holding unit relative to the drawing head; and a focus control unit that adjusts the imaging position of the light irradiated from the drawing head onto the substrate. The drawing head comprises a spatial light modulation unit that spatially modulates light from a light source; an imaging optical system that is arranged on the optical path of the light from the spatial light modulation unit; a microlens array that has a plurality of microlenses and focuses the light from the imaging optical system; a temperature sensor that measures the temperature of the imaging optical system; and an array deformation mechanism that bends the microlens array. The focus control unit controls the array deformation mechanism based on the temperature of the imaging optical system measured by the temperature sensor to bring the positions of each of the plurality of microlenses in the optical axis direction closer to the imaging position of the light from the imaging optical system.

The invention described in claim 2 is the drawing device described in claim 1, in which the temperature sensor acquires a first measured temperature, which is the temperature at the center of one optical element included in the imaging optical system, and the focus control unit controls the array deformation mechanism based on the first measured temperature.

The invention described in claim 3 is the drawing device described in claim 2, in which the temperature sensor also acquires a second measured temperature, which is the temperature at another portion of the one optical element that is spaced apart from the central portion, and the focus control unit controls the array deformation mechanism based on the first measured temperature and the second measured temperature.

The invention described in claim 4 is the drawing device described in claim 2 or 3, in which the one optical element is the optical element with the largest refractive index temperature coefficient among the multiple optical elements included in the imaging optical system.

The invention described in claim 5 is the drawing device described in any one of claims 2 to 4, in which the one optical element is the optical element having the largest linear expansion coefficient among the multiple optical elements included in the imaging optical system.

The invention described in claim 6 is the drawing device described in any one of claims 1 to 5, in which the shape of the microlens array perpendicular to the optical axis direction is a rectangle having one set of long sides and one set of short sides, and the array deformation mechanism includes a displacement unit that displaces the center portion of the microlens array in the longitudinal direction parallel to the set of long sides in the optical axis direction relative to both ends of the microlens array in the longitudinal direction.

The present invention can suppress the deterioration of drawing accuracy due to the thermal lens effect.

1 is a perspective view showing a drawing device according to an embodiment; FIG. 2 is a diagram showing a configuration of a computer provided in the control unit. FIG. 4 is a block diagram showing the functions of a control unit. FIG. FIG. 2 is an enlarged view of a portion of the drawing head. FIG. FIG. 2 is a diagram showing a microlens array. FIG. 2 is a diagram showing a microlens array. FIG. 2 is a diagram showing a microlens array. 1A to 1C are diagrams illustrating a flow of deformation of a microlens array.

Figure 1 is a perspective view showing a drawing device 1 according to one embodiment of the present invention. The drawing device 1 is a direct drawing device that draws a pattern by irradiating a photosensitive material on a substrate 9 with spatially light-modulated, approximately beam-like light and scanning the irradiated area of the light on the substrate 9. In Figure 1, three mutually orthogonal directions are indicated by arrows as the X direction, the Y direction, and the Z direction. In the example shown in Figure 1, the X direction and the Y direction are horizontal directions perpendicular to each other, and the Z direction is a vertical direction. The same applies to the other figures.

The drawing device 1 includes a stage 21, a stage movement mechanism 22, an imaging unit 3, a drawing unit 4, and a control unit 10. The control unit 10 controls the stage movement mechanism 22, the imaging unit 3, the drawing unit 4, and the like. The stage 21 is a substantially flat board-shaped board holder that holds the board 9 in a horizontal state from below (i.e., on the (-Z) side) below the imaging unit 3 and the drawing unit 4. The board 9 is, for example, a printed wiring board. The stage 21 is, for example, a vacuum chuck that adsorbs and holds the bottom surface of the board 9. The stage 21 may have a structure other than a vacuum chuck. The top surface 90 of the board 9 placed on the stage 21 is substantially perpendicular to the Z direction and substantially parallel to the X and Y directions.

The stage moving mechanism 22 is a substrate moving mechanism that moves the stage 21 holding the substrate 9 in a horizontal direction (i.e., a direction approximately parallel to the upper surface 90 of the substrate 9) relative to the imaging unit 3 and the drawing unit 4. The stage moving mechanism 22 includes a first moving mechanism 23 and a second moving mechanism 24. The second moving mechanism 24 moves the stage 21 linearly in the X direction along the guide rail. The first moving mechanism 23 moves the stage 21 linearly in the Y direction together with the second moving mechanism 24 along the guide rail. The driving sources of the first moving mechanism 23 and the second moving mechanism 24 are, for example, a linear servo motor or a motor attached to a ball screw. The structures of the first moving mechanism 23 and the second moving mechanism 24 may be modified in various ways.

The drawing device 1 may be provided with a stage rotation mechanism that rotates the stage 21 around a rotation axis extending in the Z direction. The drawing device 1 may also be provided with a stage lifting mechanism that moves the stage 21 in the Z direction. For example, a servo motor can be used as the stage rotation mechanism. For example, a linear servo motor can be used as the stage lifting mechanism. The structures of the stage rotation mechanism and the stage lifting mechanism may be modified in various ways.

The imaging unit 3 has multiple imaging heads 31 (two in the example shown in FIG. 1) arranged in the X direction. Each imaging head 31 is supported above the stage 21 and the stage movement mechanism 22 by a head support part 30 that is provided across the stage 21 and the stage movement mechanism 22. Of the two imaging heads 31, one imaging head 31 is fixed to the head support part 30, and the other imaging head 31 is movable in the X direction on the head support part 30. This makes it possible to change the distance in the X direction between the two imaging heads 31. The number of imaging heads 31 in the imaging unit 3 may be one, or three or more.

Each imaging head 31 is a camera equipped with an imaging sensor and an optical system (not shown). Each imaging head 31 is, for example, an area camera that captures a two-dimensional image. The imaging sensor is equipped with, for example, a plurality of elements such as CCDs (Charge Coupled Devices) arranged in a matrix. In each imaging head 31, the reflected light of the illumination light guided from a light source (not shown) to the upper surface 90 of the substrate 9 is guided to the imaging sensor via the optical system. The imaging sensor receives the reflected light from the upper surface 90 of the substrate 9 and captures an image of the approximately rectangular imaging area. As the light source, various light sources such as LEDs (Light Emitting Diodes) can be used. Note that each imaging head 31 may be another type of camera, such as a line camera.

The drawing unit 4 has multiple drawing heads 41 (five in the example shown in FIG. 1) arranged in the X and Y directions. Each drawing head 41 is supported above the stage 21 and the stage movement mechanism 22 by a head support unit 40 that is provided across the stage 21 and the stage movement mechanism 22. The head support unit 40 is disposed on the (+Y) side of the head support unit 30 of the imaging unit 3. Each drawing head 41 has a light source, an optical system, a spatial light modulation unit, etc., which will be described later. The multiple drawing heads 41 have approximately the same structure. The number of drawing heads 41 in the drawing unit 4 may be one or more.

In the drawing device 1, modulated (i.e., spatially light modulated) light from the multiple drawing heads 41 of the drawing unit 4 is irradiated onto the upper surface 90 of the substrate 9, while the substrate 9 is moved in the Y direction by the stage movement mechanism 22. As a result, the irradiation area of the light from the multiple drawing heads 41 is scanned in the Y direction on the substrate 9, and a pattern is drawn on the substrate 9. In the following description, the Y direction is also referred to as the "scanning direction" and the X direction is also referred to as the "width direction". The stage movement mechanism 22 is a scanning mechanism that moves the irradiation area of the light from each drawing head 41 in the scanning direction on the substrate 9.

In the drawing device 1, drawing on the substrate 9 is performed by a so-called single-pass method. Specifically, the stage 21 is moved in the Y direction relative to the multiple drawing heads 41 by the stage moving mechanism 22, and the light irradiation area from the multiple drawing heads 41 is scanned only once in the Y direction (i.e., the scanning direction) on the upper surface 90 of the substrate 9. This completes drawing on the substrate 9. In addition, in the drawing device 1, drawing on the substrate 9 may be performed by a multi-pass method in which the movement of the stage 21 in the Y direction and the step movement in the X direction are repeated. In addition, when drawing is performed by the multi-pass method in the drawing device 1, the Y direction is the main scanning direction and the X direction is the sub-scanning direction. In addition, the first moving mechanism 23 of the stage moving mechanism 22 is a main scanning mechanism that moves the stage 21 in the main scanning direction, and the second moving mechanism 24 is a sub-scanning mechanism that moves the stage 21 in the sub-scanning direction.

Figure 2 is a diagram showing the configuration of the computer 100 provided in the control unit 10. The computer 100 is a normal computer that includes a processor 101, a memory 102, an input/output unit 103, and a bus 104. The bus 104 is a signal circuit that connects the processor 101, the memory 102, and the input/output unit 103. The memory 102 stores various information. The memory 102 reads and stores a program 109 that is pre-stored in, for example, a storage medium 108. The storage medium 108 is, for example, a USB memory, a CD-ROM, a hard disk drive (HDD), or a solid state disk (SSD).

The processor 101 executes various processes (e.g., numerical calculations and image processing) using the memory 102 and the like in accordance with the above-mentioned program 109 and the like stored in the memory 102. The input/output unit 103 includes a keyboard 105 and a mouse 106 for receiving input from an operator, and a display 107 for displaying output from the processor 101 and the like. The control unit 10 may be a programmable logic controller (PLC) or a circuit board, or the like, or may be a combination of these with one or more computers.

Figure 3 is a block diagram showing the functions of the control unit 10 that are realized by the computer 100 executing the program 109. Figure 3 also shows components other than the control unit 10. The control unit 10 includes a storage unit 111, an imaging control unit 112, a position detection unit 113, a drawing control unit 114, and a focus control unit 115.

The storage unit 111 is mainly realized by the memory 102, and stores various information related to drawing of a pattern in the drawing device 1 in advance. The information stored in the storage unit 111 includes, for example, CAD data of the pattern to be drawn on the substrate 9.

The imaging control unit 112, the position detection unit 113, the drawing control unit 114, and the focus control unit 115 are mainly realized by the processor 101. The imaging control unit 112 controls the imaging unit 3 and the stage movement mechanism 22 to cause the imaging unit 3 to capture an image of the upper surface 90 (see FIG. 1) of the substrate 9 and obtain an image including the alignment mark. The captured image is sent to the storage unit 111 and stored. The position detection unit 113 detects the position of the substrate 9 on the stage 21 (see FIG. 1) based on the captured image (i.e., the relative position of the substrate 9 with respect to the drawing unit 4). The drawing control unit 114 controls the drawing unit 4 and the stage movement mechanism 22 based on the position of the substrate 9 detected by the position detection unit 113, and causes the drawing unit 4 to draw a pattern on the substrate 9 while adjusting the drawing position on the substrate 9. The focus control unit 115 adjusts the imaging position of the light irradiated from the drawing head 41 of the drawing unit 4 to the substrate 9 when drawing a pattern on the substrate 9.

Figure 4 is a side view showing the configuration of the drawing head 41. Figure 5 is an enlarged view of a portion of the drawing head 41. In Figure 5, multiple components of the drawing head 41 are shown arranged in a straight line, which differs from the actual arrangement. Also, in Figure 5, the microlenses of the microlens array 43, which will be described later, are drawn larger than they actually are. Furthermore, in Figure 5, the temperature sensor 45 and the array deformation mechanism 46, which will be described later, are not shown.

The drawing head 41 includes a spatial light modulation unit 412 and a projection optical system 413. In the drawing head 41, light from a light source (not shown) is converted into light with a substantially uniform intensity distribution in an illumination optical system (not shown) and then guided to the spatial light modulation unit 412. As the light source, various light sources such as an LD (Laser Diode) can be used. The spatial light modulation unit 412 spatially modulates the light from the light source via the illumination optical system, and guides only the necessary light used to draw the pattern to the projection optical system 413. In this embodiment, the spatial light modulation unit 412 includes a DMD (Digital Micromirror Device) which is a spatial light modulation element. The DMD is configured by arranging, for example, 1920 x 1080 micromirrors (i.e., modulation elements) in a matrix on a memory cell. Each micromirror is a substantially square with one side of approximately 10 μm, and the DMD is a substantially rectangular shape of approximately 20 mm x 10 mm.

The projection optical system 413 guides the light modulated by the spatial light modulation unit 412 (i.e., the pattern light) to the upper surface 90 of the substrate 9. The projection optical system 413 includes an imaging optical system 42, a microlens array 43, and another imaging optical system 44. In the following description, the imaging optical systems 42 and 44 are referred to as the "first imaging optical system 42" and the "second imaging optical system 44," respectively.

The first imaging optical system 42 includes a first lens barrel 421 and a second lens barrel 422. The first lens barrel 421 and the second lens barrel 422 each hold an optical element group that is one or more optical elements (e.g., lenses). The first lens barrel 421 and the second lens barrel 422 are arranged on the optical path of the pattern light formed by the spatial light modulation unit 412. The optical element group held by the first lens barrel 421 shapes the pattern light output from the spatial light modulation unit 412 into parallel light and guides it to the second lens barrel 422. The optical element group held by the second lens barrel 422 is image-side telecentric, and guides the pattern light that has passed through the first lens barrel 421 to the microlens array 43 parallel to the optical axis J1 of the first imaging optical system 42. The first imaging optical system 42 is, for example, a magnifying optical system that images the pattern light with a lateral magnification of more than 1x (about 2x in this embodiment).

The microlens array 43 includes a number of microlenses equal to the number of micromirrors of the DMD of the spatial light modulation unit 412. The microlenses correspond to the micromirrors, respectively, and are arranged in a matrix. The optical axis of each microlens of the microlens array 43 is approximately parallel to the optical axis J1 of the first imaging optical system 42 (i.e., approximately parallel to the Y direction in FIG. 4). The light beam reflected by each micromirror of the spatial light modulation unit 412 passes through the first imaging optical system 42, and then enters the microlens corresponding to the micromirror and is focused. In other words, the microlens array 43 focuses the light from the first imaging optical system 42. The first imaging optical system 42 is designed so that the light incident on the microlenses of the microlens array 43 becomes a spot array arranged at the pitch of the microlenses of the microlens array 43. The image size of the spot array is enlarged by approximately two times by the first imaging optical system 42, and is approximately 40 mm x 20 mm.

The pattern light that passes through the microlens array 43 is reflected in the (-Z) direction by the mirror 47 located on the (-Y) side of the microlens array 43, and enters the second imaging optical system 44 located on the (-Z) side of the mirror 47. Note that the mirror 47 is not shown in FIG. 5.

The second imaging optical system 44 includes a first lens barrel 441 and a second lens barrel 442. The first lens barrel 441 and the second lens barrel 442 each hold an optical element group that is one or more optical elements (e.g., lenses). The first lens barrel 441 and the second lens barrel 442 are arranged on the optical path of the pattern light that has passed through the microlens array 43. The second imaging optical system 44 is, for example, bilaterally telecentric. By making the image side of the second imaging optical system 44 telecentric, even if the position of the upper surface 90 on the substrate 9 is shifted in a direction parallel to the optical axis J2 of the second imaging optical system 44 (i.e., the Z direction), the size of the image of the pattern light on the upper surface 90 of the substrate 9 is constant, so that the pattern can be drawn on the substrate 9 with high accuracy. Furthermore, by making the object side of the second imaging optical system 44 also telecentric, as described below, even when the microlens array 43 is moved in a direction parallel to the above-mentioned optical axis J1, it is possible to draw a pattern on the substrate 9 while maintaining the size of the image of the pattern light on the image side of the second imaging optical system 44.

The second imaging optical system 44 is, for example, a magnifying optical system that forms an image by magnifying it at a lateral magnification of more than 1 (about 3 times in this embodiment). The above-mentioned spot array is magnified about 3 times by the second imaging optical system 44, and projected onto the upper surface 90 of the substrate 9 with a size of about 120 mm x 60 mm.

In the drawing device 1, as the irradiation of the pattern light onto the substrate 9 continues, the temperature of the first imaging optical system 42 increases, and the focal length of the first imaging optical system 42 may vary due to the thermal lens effect. The thermal lens effect is a phenomenon in which a part of the light incident on the first imaging optical system 42 is absorbed by an optical element included in the first imaging optical system 42, causing the optical element to heat up, and the focal length varies due to shape errors and refractive index changes caused by thermal expansion of the optical element. The amount of variation in the focal length differs between the vicinity of the optical axis J1 of the first imaging optical system 42 and a position away from the optical axis J1. In addition, depending on the shape of the pattern to be drawn on the substrate 9, the light amount distribution of the pattern light incident on the first imaging optical system 42 from the spatial light modulation unit 412 may be biased, and the temperature rise near the optical axis J1 of the first imaging optical system 42 may differ from the temperature rise at a position away from the optical axis J1. In this case, there is a possibility that the difference in the change in focal length due to the thermal lens effect described above will become large between near the optical axis J1 of the first imaging optical system 42 and at a position away from the optical axis J1.

As shown in FIG. 4, in the drawing device 1, the drawing head 41 further includes a temperature sensor 45 and an array deformation mechanism 46. The temperature sensor 45 is disposed near the first imaging optical system 42 and measures the temperature of the first imaging optical system 42. Specifically, the temperature sensor 45 measures the temperature of one optical element included in the first imaging optical system 42. The array deformation mechanism 46 is a mechanism that bends the microlens array 43. Note that the temperature sensor 45 and the array deformation mechanism 46 are omitted from FIG. 5.

6 is a diagram showing one optical element 423 (a lens in this embodiment) whose temperature is measured by the temperature sensor 45. In the example shown in FIG. 4 and FIG. 5, the optical element 423 is held by the second lens barrel 422 of the first imaging optical system 42. The optical element 423 is preferably an optical element having a large thermal lens effect among the multiple optical elements included in the first imaging optical system 42. The optical element 423 is, for example, an optical element having the largest refractive index temperature coefficient (dn/dT) among the multiple optical elements included in the first imaging optical system 42. The optical element 423 may also be, for example, an optical element having the largest linear expansion coefficient among the multiple optical elements included in the first imaging optical system 42. The optical element 423 may be, for example, an optical element having a large distance in the optical axis J1 direction (i.e., a direction parallel to the optical axis J1) from the focusing position in the first imaging optical system 42.

In the example shown in FIG. 6, the temperature sensor 45 has three sensor elements 451. For example, a non-contact infrared temperature sensor can be used as each sensor element 451. Of the three sensor elements 451, the central sensor element 451 acquires the temperature at the center of the optical element 423 (hereinafter also referred to as the "first measured temperature"). The central part of the optical element 423 is a part of the optical element 423 that corresponds to the center of the microlens array 43 (i.e., the center in the X direction and the Z direction). In the example shown in FIG. 6, the central part of the optical element 423 is a part near the optical axis of the optical element 423, and is the center in the radial direction when the optical element 423 is a lens. Of the three sensor elements 451, the sensor element 451 on the (+X) side acquires the temperature of the end part on the (+X) side at the center of the optical element 423 in the Z direction (hereinafter also referred to as the "second measured temperature"). Of the three sensor elements 451, the sensor element 451 closest to the (-X) side acquires the temperature of the end portion on the (-X) side at the center of the optical element 423 in the Z direction (hereinafter also referred to as the "third measured temperature").

In FIG. 6, the measurement points 452 of each sensor element 451 on the optical element 423 are indicated by circles. The measurement point 452 of the sensor element 451 on the (+X) side and the measurement point 452 of the sensor element 451 on the (-X) side are each at a location away from the measurement point 452 of the central sensor element 451 (i.e., the center of the optical element 423). The distance in the X direction between the measurement point 452 on the (+X) side and the central measurement point 452 is approximately the same as the distance in the X direction between the measurement point 452 on the (-X) side and the central measurement point 452.

Depending on the shape of the pattern drawn on the substrate 9, the light amount distribution of the pattern light incident on the optical element 423 may be biased, and the first measured temperature may differ from the second measured temperature and the third measured temperature. Also, the second measured temperature may differ from the third measured temperature.

Figure 7 is a view of the microlens array 43 viewed from the (-Y) side along the Y direction (i.e., along a direction parallel to the optical axis J1 of the first imaging optical system 42). Figure 8 is a view of the microlens array 43 viewed from the (+Z) side along the Z direction. The shape of the microlens array 43 perpendicular to the Y direction is a substantially rectangular shape having a pair of long sides substantially parallel to the X direction and a pair of short sides substantially parallel to the Z direction. In the following description, the X direction parallel to the pair of long sides is also referred to as the longitudinal direction of the microlens array 43.

The microlens array 43 is held by a lens frame 432 having a substantially rectangular frame shape. In FIG. 8, the lens frame 432 is indicated by a two-dot chain line. The lens frame 432 is fixed to both side edges of the microlens array 43 in the X direction and both side edges of the microlens array 43 in the Z direction over substantially the entire length. In other words, the lens frame 432 holds the microlens array 43 by contacting the side edges of the microlens array 43 over substantially the entire circumference.

The array deformation mechanism 46 has a plurality of displacement units 461 arranged near the lens frame 432. The displacement units 461 come into contact with a specific portion of the lens frame 432 and press the portion in the Y direction to cause a minute displacement. For example, a piezoelectric actuator can be used as the displacement unit 461. The array deformation mechanism 46 may also have a displacement unit 461 other than a piezoelectric actuator.

7 and 8, six displacement sections 461 are arranged on the (-Y) side of the lens frame 432. Three of the six displacement sections 461 are arranged at the (-X) side end, the center in the X direction, and the (+X) side end at the (-Z) side end of the lens frame 432 (i.e., near one long side of the lens frame 432). The other three of the six displacement sections 461 are arranged at the (-X) side end, the center in the X direction, and the (+X) side end at the (+Z) side end of the lens frame 432 (i.e., near the other long side of the lens frame 432). The three displacement sections 461 on the (+Z) side and the three displacement sections 461 on the (-Z) side are located at approximately the same position in the X direction, for example.

On the (+Y) side of the lens frame 432, six displacement parts 461 are arranged opposite the six displacement parts 461 in the Y direction with the lens frame 432 in between. Each pair of displacement parts 461 facing each other in the Y direction with the lens frame 432 in between advances and retreats in sync. For example, when the displacement part 461 on the (+Y) side of the two displacement parts 461 facing each other in the Y direction with the lens frame 432 in between pushes the lens frame 432 in the (-Y) direction and the displacement part 461 on the (-Y) side synchronously displaces in the (-Y) direction, the part of the lens frame 432 sandwiched between the two displacement parts 461 displaces in the (-Y) direction, and the part of the microlens array 43 near the two displacement parts 461 also displaces in the (-Y) direction.

9, in the drawing head 41, the central portion of the lens frame 432 in the X direction is displaced toward the (-Y) side by a plurality of displacement units 461 arranged in the central portion in the X direction, and both ends of the lens frame 432 in the X direction are displaced toward the (+Y) side by a plurality of displacement units 461 arranged at both ends in the X direction, so that the central portion of the microlens array 43 in the X direction (i.e., the central portion in the longitudinal direction) is curved so as to be convex toward the (-Y) side. At this time, by making the displacement amount of the displacement unit 461 on the (+X) side different from the displacement amount of the displacement unit 461 on the (-X) side, it is also possible to make the curved state of the microlens array 43 on the (+X) side different from the curved state on the (-X) side. Note that in FIG. 9, the degree of curvature of the microlens array 43 is drawn larger than it actually is.

When the microlens array 43 is curved so as to be convex toward the (-Y) side, the center of the lens frame 432 in the X direction is displaced toward the (-Y) side, and both ends in the X direction do not have to be displaced in the Y direction. Alternatively, both ends in the X direction of the lens frame 432 are displaced toward the (+Y) side, and the center in the X direction does not have to be displaced in the Y direction. That is, in the drawing head 41, the center in the longitudinal direction of the microlens array 43 is displaced in the Y direction relative to both ends in the longitudinal direction, thereby curving the microlens array 43 in the Y direction.

In the case of the drawing head 41, when the microlens array 43 is curved so that the center of the microlens array 43 in the X direction is convex toward the (+Y) side, the procedure is the same as above, except that the displacement of each displacement section 461 in the Y direction is in the opposite direction.

In the drawing device 1, as described above, due to the thermal lens effect during drawing on the substrate 9, the focal length of the first imaging optical system 42 (i.e., the distance to the focal point in the Y direction) fluctuates, and the imaging surface of the pattern light to be positioned on the microlens array 43 (i.e., the virtual surface on which the images of the multiple micromirrors of the DMD of the spatial light modulation unit 412 are imaged) may be curved and shifted in the Y direction from the microlens array 43. In addition, the amount of variation in the focal length may differ between the center of the microlens array 43 corresponding to the vicinity of the optical axis J1 of the first imaging optical system 42 and the end of the microlens array 43. The microlens array 43 illustrated in FIG. 7 has a substantially rectangular shape that is long in the X direction, so the difference in the amount of variation in the focal length in the X direction becomes large. In other words, the degree of curvature of the imaging surface increases in the X direction.

In the drawing device 1, the temperature of the optical element 423 is measured by the temperature sensor 45 shown in FIG. 6, and the focus control unit 115 (see FIG. 3) controls the array deformation mechanism 46 based on the measured temperature, thereby curving the microlens array 43 in accordance with the curvature of the imaging surface of the pattern light.

Specifically, as shown in FIG. 10, the first measured temperature, the second measured temperature, and the third measured temperature of the optical element 423 are acquired by the three sensor elements 451 (see FIG. 6) of the temperature sensor 45 (step S11). The acquired first measured temperature, second measured temperature, and third measured temperature are sent from the temperature sensor 45 to the memory unit 111 (see FIG. 3).

The storage unit 111 stores temperature-displacement information in advance. The temperature-displacement information is information indicating the relationship between the first measured temperature, the second measured temperature, and the third measured temperature and the displacement amount of the multiple displacement units 461 of the array deformation mechanism 46. The temperature-displacement information includes multiple combinations of the first measured temperature, the second measured temperature, and the third measured temperature, and each combination is associated with an optimal displacement amount of the lens frame 432 by the multiple displacement units 461. The optimal displacement amount is determined in advance so that the shape of the microlens array 43 curved by the array deformation mechanism 46 in a planar view (i.e., the shape when viewed along the Z direction) and the shape of the curved image plane of the pattern light when the temperature of the optical element 423 is the first measured temperature, the second measured temperature, and the third measured temperature are suitably close to each other in a planar view. The temperature-displacement information may be obtained by simulation, or may be obtained by changing the temperature of the optical element 423 in various ways in the drawing device 1.

The focus control unit 115 determines the amount of displacement of the multiple displacement units 461 based on the first measured temperature, the second measured temperature, and the third measured temperature acquired in step S11 and the above-mentioned temperature-displacement information, and controls the array deformation mechanism 46 based on the amount of displacement to deform the microlens array 43 (step S12). This allows each microlens of the microlens array 43 to suitably approach the imaging position of the light from the corresponding micromirror of the spatial light modulation unit 412 in the optical axis J1 direction. Preferably, the position of each microlens of the microlens array 43 in the optical axis J1 direction coincides with the imaging position of the light from the corresponding micromirror.

In the drawing device 1, the above-mentioned steps S11 to S12 are continuously performed while a pattern is being drawn on the substrate 9. This makes it possible to maintain the position of each microlens of the microlens array 43 in the optical axis J1 direction close to the imaging position of the light from the corresponding micromirror, even if the temperature of the optical element 423 changes during drawing. As a result, it is possible to suppress the occurrence of the phenomenon in which the image of the micromirror formed on one microlens spreads to adjacent microlenses (so-called light leakage), and suppress deterioration of drawing accuracy.

In addition, in the drawing device 1, it is not necessary to acquire the first measured temperature, the second measured temperature, and the third measured temperature of the optical element 423. For example, when the imaging surface of the pattern light from the first imaging optical system 42 is curved in substantially the same manner on the (+X) side and the (-X) side of the optical axis J1, only the first measured temperature and the second measured temperature of the optical element 423 may be acquired by the temperature sensor 45. In this case, the temperature-displacement information includes a plurality of combinations of the first measured temperature and the second measured temperature, and each combination is associated with an optimal displacement amount of the lens frame 432 by the plurality of displacement units 461. Also, for example, when the curvature state of the imaging surface of the pattern light from the first imaging optical system 42 can be obtained with a certain degree of accuracy only from the first measured temperature of the optical element 423, only the first measured temperature of the optical element 423 may be acquired by the temperature sensor 45. In this case, the temperature-displacement information includes a plurality of first measured temperatures, and each first measured temperature is associated with an optimal displacement amount of the lens frame 432 by the plurality of displacement units 461.

As described above, the drawing device 1 that draws on the substrate 9 includes a substrate holding unit (stage 21 in the above example), a drawing head 41, a substrate moving mechanism (stage moving mechanism 22 in the above example), and a focus control unit 115. The substrate holding unit holds the substrate 9. The drawing head 41 draws a pattern by irradiating light onto the substrate 9. The substrate moving mechanism moves the substrate holding unit relative to the drawing head 41. The focus control unit 115 adjusts the imaging position of the light irradiated from the drawing head 41 onto the substrate 9.

The drawing head 41 includes a spatial light modulation unit 412, an imaging optical system (in the above example, the first imaging optical system 42), a microlens array 43, a temperature sensor 45, and an array deformation mechanism 46. The spatial light modulation unit 412 spatially modulates light from a light source. The imaging optical system is arranged on the optical path of light from the spatial light modulation unit 412. The microlens array 43 has a plurality of microlenses and focuses light from the imaging optical system. The temperature sensor 45 measures the temperature of the imaging optical system. The array deformation mechanism 46 bends the microlens array 43. The focus control unit 115 controls the array deformation mechanism 46 based on the temperature of the imaging optical system measured by the temperature sensor 45, thereby moving each position of the plurality of microlenses in the optical axis J1 direction closer to the imaging position of the light from the imaging optical system.

As a result, even if the focal length of the imaging optical system fluctuates due to the thermal lens effect and the amount of fluctuation in the focal length differs between the vicinity of the optical axis J1 and a portion away from the optical axis J1, it is possible to suppress the occurrence of a phenomenon in which the image of the micromirror formed on one microlens in the microlens array 43 spreads to an adjacent microlens (so-called light leakage). As a result, it is possible to suppress a decrease in drawing accuracy due to the thermal lens effect.

As described above, it is preferable that the temperature sensor 45 obtains a first measured temperature, which is the temperature at the center of one of the optical elements 423 included in the projection optical system, and the focus control unit 115 controls the array deformation mechanism 46 based on the first measured temperature. This allows the thermal lens effect in the projection optical system to be accurately estimated. As a result, the influence of the thermal lens effect in the projection optical system can be suitably suppressed, and the deterioration of drawing accuracy can be suitably suppressed.

As described above, it is preferable that the temperature sensor 45 also acquires a second measured temperature, which is the temperature at another location spaced from the center of the one optical element 423, and the focus control unit 115 controls the array deformation mechanism 46 based on the first measured temperature and the second measured temperature. This allows the thermal lens effect in the projection optical system to be estimated with even greater accuracy. As a result, the influence of the thermal lens effect in the projection optical system can be more effectively suppressed, and the deterioration of drawing accuracy can be even more effectively suppressed.

As described above, it is preferable that the optical element 423 is an optical element having the largest refractive index temperature coefficient among the multiple optical elements included in the imaging optical system. In this way, by selecting the optical element 423 having the largest thermal lens effect among the multiple optical elements and controlling the array deformation mechanism 46 based on the temperature of the optical element 423, it is possible to effectively suppress the influence of the thermal lens effect in the projection optical system and effectively suppress the deterioration of the drawing accuracy.

As described above, it is also preferable that the optical element 423 is the optical element with the largest linear expansion coefficient among the multiple optical elements included in the imaging optical system. In this way, by selecting the optical element 423 with the largest thermal lens effect among the multiple optical elements and controlling the array deformation mechanism 46 based on the temperature of the optical element 423, it is possible to suitably suppress the influence of the thermal lens effect in the projection optical system and suitably suppress the deterioration of drawing accuracy.

In the above example, the shape of the microlens array 43 perpendicular to the optical axis J1 is a rectangle having one set of long sides and one set of short sides. In this case, it is preferable that the array deformation mechanism 46 includes a displacement unit 461 that displaces the center portion of the microlens array 43 in the longitudinal direction parallel to the set of long sides in the optical axis J1 direction relative to both ends of the microlens array 43 in the longitudinal direction. In this way, by adjusting the positions of the multiple microlenses of the microlens array 43 in the longitudinal direction where the difference in the amount of focal length variation due to the thermal lens effect is large, the influence of the thermal lens effect can be suitably suppressed, and the deterioration of drawing accuracy can be suitably suppressed.

The above-mentioned drawing device 1 can be modified in various ways.

For example, the optical element 423 described above is not necessarily limited to a lens, but may be another optical element such as a prism.

In the projection optical system 413, in addition to the array deformation mechanism 46, an array movement mechanism that moves the microlens array 43 in the direction of the optical axis J1 may be provided. Then, in cases such as when the amount of variation in focal length due to the thermal lens effect is large, the position of each of the multiple microlenses in the direction of the optical axis J1 may be brought closer to the imaging position of the light from the first imaging optical system 42 by combining the curvature of the microlens array 43 by the array deformation mechanism 46 and the movement of the microlens array 43 by the array movement mechanism. This makes it possible to more effectively suppress the influence of the thermal lens effect in the first imaging optical system 42, and more effectively suppress the deterioration of the drawing accuracy.

In the imaging device 1, the control of the array deformation mechanism 46 by the focus control unit 115 does not necessarily have to be based on the temperature of the optical element 423 of the first imaging optical system 42, so long as it is based on the temperature of the first imaging optical system 42. For example, the temperature of the first lens barrel 421 or the second lens barrel 422 may be measured by the temperature sensor 45, and the array deformation mechanism 46 may be controlled based on that temperature.

In addition, in the drawing device 1, the temperature of the second imaging optical system 44 may also be measured, and the focus control unit 115 may control the array deformation mechanism 46 based on the temperature of the first imaging optical system 42 and the temperature of the second imaging optical system 44. This can also suppress the influence of fluctuations in focal length due to the thermal lens effect of the optical elements included in the second imaging optical system 44. As a result, the deterioration of drawing accuracy due to the thermal lens effect can be further suppressed.

In the spatial light modulation unit 412, the DMD does not necessarily have to have multiple micromirrors arranged in a matrix, but may have multiple micromirrors arranged in a line. Also, instead of a DMD, the spatial light modulation unit 412 may have other spatial light modulation elements such as a GLV (Grating Light Valve) (registered trademark of Silicon Light Machines, Sunnyvale, California).

In the above example, the array deformation mechanism 46 bends the microlens array 43 in the X direction by displacing the center of the microlens array 43 in the longitudinal direction (i.e., the X direction) relative to both ends, but is not limited to this. For example, the array deformation mechanism 46 may bend the microlens array 43 in the Z direction by displacing the center of the microlens array 43 in a direction perpendicular to the longitudinal direction (i.e., the Z direction) relative to both ends. Alternatively, the array deformation mechanism 46 may bend the microlens array 43 in both the X direction and the Z direction.

The shape of the microlens array 43 perpendicular to the Y direction does not necessarily have to be approximately rectangular, and may be modified in various ways. For example, the shape of the microlens array 43 may be approximately square.

The projection optical system 413 does not necessarily need to include the second imaging optical system 44. In addition, the pattern light that passes through the microlens array 43 does not necessarily need to be reflected by the mirror 47. In other words, the mirror 47 may be omitted, and the spatial light modulation unit 412, the first imaging optical system 42, and the microlens array 43 may be arranged in a straight line in the Z direction.

The above-mentioned substrate 9 is not necessarily limited to a printed wiring board. The drawing device 1 may detect the position of, for example, a semiconductor substrate, a glass substrate for a flat panel display device such as a liquid crystal display device or an organic EL display device, a glass substrate for a photomask, a substrate for a solar panel, etc.

The configurations in the above embodiment and each modified example may be combined as appropriate as long as they are not mutually inconsistent.

REFERENCE SIGNS LIST 1 Drawing device 9 Substrate 21 Stage 22 Stage moving mechanism 41 Drawing head 42 First imaging optical system 43 Microlens array 45 Temperature sensor 46 Array deformation mechanism 115 Focus control section 412 Spatial light modulation section 423 Optical element 461 Displacement section

Claims (6)

A drawing apparatus for drawing on a substrate, comprising:
A substrate holder for holding a substrate;
a drawing head that draws a pattern on the substrate by irradiating the substrate with light;
a substrate moving mechanism that moves the substrate holding unit relative to the drawing head;
a focus control unit that adjusts an imaging position of light irradiated from the drawing head onto the substrate;
Equipped with
The imaging head includes:
a spatial light modulation unit that spatially modulates light from a light source;
an imaging optical system disposed on an optical path of light from the spatial light modulation unit;
a microlens array having a plurality of microlenses and configured to collect light from the imaging optical system;
a temperature sensor for measuring a temperature of the imaging optical system;
an array deformation mechanism for curving the microlens array;
Equipped with
The focus control unit controls the array deformation mechanism based on the temperature measured by the temperature sensor of the imaging optical system, thereby bringing the positions of each of the multiple microlenses in the optical axis direction closer to the imaging position of light from the imaging optical system. The drawing device according to claim 1 ,
The temperature sensor acquires a first measured temperature which is a temperature at a center portion of one optical element included in the imaging optical system;
The imaging apparatus, wherein the focus control unit controls the array deformation mechanism based on the first measured temperature. The drawing device according to claim 2,
The temperature sensor also acquires a second measured temperature, which is a temperature at another portion of the one optical element that is spaced apart from the central portion;
The drawing apparatus, wherein the focus control unit controls the array deformation mechanism based on the first measured temperature and the second measured temperature. 4. The drawing device according to claim 2,
The imaging apparatus according to claim 1, wherein the one optical element is an optical element having a maximum refractive index temperature coefficient among a plurality of optical elements included in the imaging optical system. 5. The drawing device according to claim 2,
The imaging apparatus according to claim 1, wherein the one optical element is an optical element having a maximum linear expansion coefficient among a plurality of optical elements included in the imaging optical system. 6. The drawing device according to claim 1,
The shape of the microlens array perpendicular to the optical axis direction is a rectangle having one pair of long sides and one pair of short sides,
The array deformation mechanism is characterized in that it includes a displacement unit that displaces a central portion of the microlens array in a longitudinal direction parallel to the pair of long sides in the optical axis direction relative to both ends of the microlens array in the longitudinal direction.

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