JP2007078764A - Exposure device and exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate a highly precise focus control without using a complicated configuration in an exposure device and an exposure method. <P>SOLUTION: A photosensitive material 150 is relatively moved with respect to a spatial optical modulation element such as a DMD 50 in which a large number of pixels each modulating irradiating light according to control signals are arrayed and divided into a plurality of block regions A to D. A microlens array 55 is disposed between the DMD 50 and the photosensitive material 150, the microlens array having microlenses converging light from the respective pixels of the DMD 50 arranged into an array and divided into block regions A to D corresponding to the block regions A to D of the DMD 50 and having microlenses 56A to 56D, respectively, having different focal lengths by the block regions A to D. At least a part of the block region capable of focusing the light onto an object exposure surface is selected and driven according to the height data on the object exposure surface at the respective positions of the photosensitive material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and an exposure method, and more particularly, to an exposure apparatus and an exposure apparatus that have a spatial light modulation element that modulates light according to a control signal and that moves relative to the photosensitive material to expose the photosensitive material. It is about the method.

  Conventionally, various exposure heads for exposing a photosensitive material using light modulated by a spatial light modulator based on image data, and exposure apparatuses for forming an image pattern on the photosensitive material by scanning the exposure head are known. It has been. The spatial light modulation element is formed by arranging a large number of pixel units for modulating irradiated light according to control signals, and one example thereof is a DMD (digital micromirror device). The DMD is a mirror device in which a large number of micromirrors that change the angle of a reflecting surface according to a control signal are two-dimensionally arranged on a semiconductor substrate such as silicon.

In Patent Document 1 and Patent Document 2, DMD is used as a spatial light modulation element, and the light path modulated by the spatial light modulation element corresponds to each pixel part of the spatial light modulation element. An exposure apparatus having a configuration in which a microlens array in which microlenses that collect light are arranged in an array is arranged is described. Furthermore, in Patent Document 2, the DMD is arranged to be inclined with respect to the scanning direction, and exposure (multiple exposure) is performed on one scanning line so as to reduce image unevenness and the scanning line at the time of scanning. A technique for improving the resolution by narrowing the interval is described.
JP 2003-337425 A Japanese Patent Laid-Open No. 2004-9595

By the way, in an exposure apparatus using a microlens array as described above, light modulated by DMD is formed into dots by a microlens of the microlens array, and the light is projected onto a photosensitive material for exposure. The resolution R at this time depends on the NA (numerical aperture) of the microlens and is expressed by the following equation (1).
R = k1 × λ / NA (1)
Here, k1: constant, λ: wavelength, NA = n × sin θ, n: refractive index θ: an angle formula extending from the image point to the radius of the exit pupil (1), the lens shape is controlled. In order to improve the resolution, it is necessary to increase the NA. On the other hand, the focal depth Z is expressed by the following equation (2).
Z = k2 × λ / NA ² (2)
As can be seen from equation (2), the greater the NA, the shallower the focal depth.

  From the above, when the exposure wavelength is constant, increasing the NA to improve the resolution decreases the depth of focus. When the depth of focus is shallow, there is a problem that the amount of blur on the exposed surface caused by a slight positional shift in the optical axis direction of light incident on the photosensitive material increases, and the sharpness of the pattern formed on the photosensitive material deteriorates. Occur. In particular, in the case of a large substrate, since the flatness of the substrate itself is not high, the influence of the positional deviation is large, and the sharpness is greatly deteriorated.

  In order to solve the above problem, it is necessary to perform focus control correctly. For this purpose, for example, it may be possible to add a mechanical autofocus mechanism. In this case, however, the structure becomes complicated. New problems such as an increase in the size and cost of the entire apparatus occur.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an exposure apparatus and an exposure method capable of easily performing high-precision focus control without using a complicated configuration.

  An exposure apparatus according to the present invention includes a plurality of pixel units that respectively modulate irradiated light according to a control signal, and a spatial light modulation element that is divided into a plurality of block regions, and the spatial light modulation element. A moving means for relatively moving the photosensitive material, and a microlens arranged in an optical path between the spatial light modulation element and the photosensitive material, and condensing light from each pixel portion of the spatial light modulation element, in an array form A microlens array that is divided into a plurality of block regions corresponding to the block region of the spatial light modulation element, the focal length of the microlens being different for each block region, and the exposure of each position of the photosensitive material Measuring means for measuring the height of the surface; and the microphone capable of focusing on each position of the exposed surface based on the height of the exposed surface at each position of the photosensitive material measured by the measuring means Control means for selecting at least a part of a block area of the lens array and driving the spatial light modulation element corresponding to at least a part of the selected block area in the relative movement. To do.

  The control means creates mapping data based on the height of the exposed surface at each position of the photosensitive material measured by the measuring means, and an approximate curve corresponding to the exposed surface based on the mapping data. You may comprise so that it may obtain | require.

  The control means may be configured to select all of the block area along the relative movement direction.

  Alternatively, the control unit may be configured to select only a part of the block area along a direction intersecting with the relative movement direction.

  In the exposure method of the present invention, a plurality of pixel units that modulate irradiated light according to control signals are arranged in parallel and divided into a plurality of block regions, and the spatial light modulator A moving means for relatively moving the photosensitive material, and a microlens arranged in an optical path between the spatial light modulation element and the photosensitive material, and condensing light from each pixel portion of the spatial light modulation element, in an array form And is exposed to light using an exposure apparatus that includes a microlens array that is divided into a plurality of block regions corresponding to the block region of the spatial light modulator and that has a different focal length of the microlens for each block region. In the exposure method, based on the height of the exposed surface at each position of the photosensitive material, and the height of the exposed surface at each position of the photosensitive material measured in the measuring step Selecting at least a part of a block region of the microlens array that can be focused on each position of the exposed surface; and moving the spatial light modulator relative to the photosensitive material while selecting the selected region. And driving the spatial light modulation element corresponding to at least a part of the block region to perform exposure.

  The selecting step corresponds to the step of creating mapping data based on the height of the exposed surface at each position of the photosensitive material measured in the measuring step and the surface to be exposed based on the mapping data. And a step of obtaining an approximated curve.

  In the selecting step, the entire block area may be selected along the relative movement direction.

  In the selecting step, only a part of the block region may be selected along a direction intersecting with the relative movement direction.

  Here, the different focal lengths mean that the other is not in focus when one is in focus, and is close to the optical axis direction so that the other is in focus when one is out of focus. To do.

  According to the exposure apparatus and the exposure method of the present invention, the microlens includes a spatial light modulation element divided into block areas and a microlens array divided into block areas corresponding to the block areas of the spatial light modulation element. The array is configured so that the focal length of the microlens differs for each block region. Then, based on the measurement information of the height of the exposed surface at each position of the photosensitive material, at least a part of the block area of the microlens array that can be focused on each position on the exposed surface is selected, and the selected block area The spatial light modulator corresponding to at least a part of the light is driven. As a result, even if the NA of the microlens is increased to improve the resolution and the depth of focus of each microlens becomes shallower, the photosensitive material is wavy or warped, or a step structure or the like is formed on the exposed surface. Even if there is an uneven shape, high-precision focus control can be easily performed without using a complicated mechanism such as mechanical autofocus, and a sharp image can be formed.

  In particular, for a substrate in which the height distribution of the surface to be exposed exists within the exposure area of the exposure head, the conventional method of moving the entire exposure head has not been able to cope with it properly. Since focus control can be performed in units of block areas in the area or in smaller units that are part of the block areas, more accurate focus control can be performed, and sharper images can be formed.

  In the selection of the block area, mapping data is created based on the measurement information of the height of the exposed surface, an approximate curve corresponding to the exposed surface is obtained based on the mapping data, and the microscopic data is calculated based on the approximate curve. If at least a part of the block region of the lens array is selected, the number of measuring means to be arranged can be reduced, and highly accurate focus control can be performed efficiently.

  Here, when all of the block areas are selected along the relative movement direction, control is possible in units of block areas.

  Alternatively, if only a part of the block area is selected along the direction intersecting the relative movement direction, the focus can be controlled in a smaller unit that is a part of the block area, so that more accurate exposure is possible. become. In particular, in a conventional line head that simultaneously exposes an image for one line, focus control can be performed within one head only in the relative movement direction, whereas in this case of the present invention, only the relative movement direction can be controlled. In addition, the focus control can be performed in the direction intersecting the relative movement direction, which is very effective.

  Hereinafter, an exposure apparatus and an exposure method according to a first embodiment of the present invention will be described with reference to the drawings. The exposure apparatus and the exposure method of the present embodiment include a microlens array in which spatial light modulation elements divided into a plurality of block areas and microlenses having different focal lengths corresponding to the block areas are arranged in an array. First, the entire configuration of the exposure apparatus according to the present embodiment will be described. FIG. 1 is a perspective view showing a schematic configuration of the exposure apparatus of the present embodiment.

  As shown in FIG. 1, the exposure apparatus 100 of the present embodiment includes a rectangular thick plate-shaped installation base 156 supported by four legs 154. Two guides 158 extend along the longitudinal direction on the upper surface of the installation table 156, and a stage 152 as a moving means having a rectangular flat plate shape is provided on the two guides 158. Yes. The stage 152 is arranged so that the longitudinal direction thereof faces the extending direction of the guide 158, is supported by the guide 158 so as to be reciprocally movable on the installation table 156, and is reciprocated along the guide 158 by being driven by a driving device (not shown). Moving. The photosensitive material 150 is sucked and held on the upper surface of the stage 152 in a state where the mounting position is determined by a positioning unit (not shown).

  Gates 160 and 161 are arranged at predetermined intervals on the upstream side and the downstream side in the moving direction of the stage 152 with respect to the center of the installation table 156. The gates 160 and 161 are formed in a U shape so as to straddle the moving path of the stage 152, and both end portions are fixed to both side surfaces of the installation table 156.

  In the gate 160 arranged on the upstream side in the moving direction of the stage 152, three detection units 180 are moved in the moving direction of the stage 152 on the upper part of the front surface (above the moving path of the stage 152) facing the upstream side. Are fixedly arranged at predetermined intervals along a direction orthogonal to the direction. The detection unit 180 includes a CCD camera 182 arranged on the upstream side and a displacement sensor 184 as a measuring means arranged on the downstream side, which are integrated into a substantially box shape. The detection unit 180 includes a lens unit 186 of the CCD camera 182, Both of the sensor portions 188 of the displacement sensor 184 are directed downward.

  In the gate 161 arranged on the downstream side in the moving direction of the stage 152, the scanner 162 is fixedly arranged on the upper part of the rear surface facing the downstream side (above the moving path of the stage 152). Therefore, the photosensitive material 150 moves relative to the scanner 162 as the stage 152 moves. The distance between the scanner 162 and the detection unit 180 is an exposure start position by an exposure head 166 described later provided in the scanner 162 and a photographing position by the CCD camera 182 of the detection unit 180 (the optical axis center of the lens unit 186). The distance is set to be slightly longer than the longitudinal dimension of the photosensitive material 150.

  Further, the driving device of the stage 152, the scanner 162, and the detection unit 180 are connected to a controller 190 as control means for controlling them. By this controller 190, during the exposure operation of the exposure apparatus 100 described later, the stage 152 is controlled to move at a predetermined speed, the detection unit 180 is controlled to detect the photosensitive material 150 at a predetermined timing, and the exposure head 166 is controlled. The photosensitive material 150 is controlled to be exposed at a predetermined timing.

  As shown in FIGS. 2 and 3B, the scanner 162 includes a plurality of (e.g., 8) exposure heads 166 arranged in a substantially matrix of m rows and n columns (e.g., 2 rows and 5 columns). Yes. In the following description, when individual exposure heads arranged in the m-th row and the n-th column are shown, they are expressed as an exposure head 166 mn.

  As shown in FIG. 2, the exposure area 168 that is an area exposed by the exposure head 166 has a rectangular shape with a short side along the sub-scanning direction, and is inclined at a predetermined inclination angle θ with respect to the sub-scanning direction. ing. As the stage 152 moves, a strip-shaped exposed area 170 is formed for each exposure head 166 in the photosensitive material 150. As shown in FIGS. 1 and 2, the sub-scanning direction is opposite to the stage moving direction. In the following, when an exposure area by individual exposure heads arranged in the m-th row and the n-th column is shown, it is expressed as an exposure area 168 mn.

Further, as shown in FIGS. 3A and 3B, the exposure heads in the respective rows arranged in a line so that each of the strip-shaped exposed areas 170 partially overlaps the adjacent exposed areas 170. Each of 166 is arranged at a predetermined interval in the arrangement direction. Therefore, can not be exposed portion between the exposure area _{168 11} in the first row and the exposure area _{168 12,} it can be exposed by the second row of the exposure area _{168 21.}

  As shown in FIGS. 4 and 5, each exposure head 166 is a digital micromirror device (hereinafter, DMD) as a spatial light modulation element that modulates an incident light beam for each pixel unit according to image data. 50). The DMD 50 is connected to the controller 190 having a scanner control unit including a data processing unit and a mirror drive control unit. The DMD 50 is divided into a plurality of block areas, and the data processing unit of the controller 190 drives and controls each micromirror in the block area to be controlled by the DMD 50 for each exposure head 166 based on the input image data. A control signal is generated. The mirror drive control unit controls the angle of the reflection surface of each micromirror of the DMD 50 for each exposure head 166 based on the control signal generated by the image data processing unit. The control of the angle of the reflecting surface will be described later.

  On the light incident side of the DMD 50, a fiber array light source 66 including a laser emitting portion 68 in which the emitting end portion (light emitting point) of the optical fiber is arranged in a line along a direction corresponding to the long side direction of the exposure area 168, A lens system 67 for correcting the laser light emitted from the fiber array light source 66 and condensing it on the DMD, and a mirror 69 for reflecting the laser light transmitted through the lens system 67 toward the DMD 50 are arranged in this order. In FIG. 4, the lens system 67 is schematically shown.

  As shown in detail in FIG. 5, the lens system 67 condenses the condensing lens 71 that condenses the laser light B as illumination light emitted from the fiber array light source 66, and is inserted into the optical path of the light that has passed through the condensing lens 71. The rod-shaped optical integrator 72 (hereinafter referred to as a rod integrator) 72 and a collimator lens 74 disposed on the light exit side of the rod integrator 72. The condensing lens 71, the rod integrator 72, and the collimator lens 74 cause the laser light emitted from the fiber array light source 66 to enter the DMD 50 as a light beam that is close to parallel light and has a uniform beam cross-sectional intensity.

  The laser beam B emitted from the lens system 67 is reflected by the mirror 69 and irradiated to the DMD 50 via a TIR (total reflection) prism 70. In FIG. 4, the TIR prism 70 is omitted.

  As shown in FIG. 6, in the DMD 50, a large number (for example, 1024 × 768) of micromirrors (micromirrors) 62, each constituting a pixel portion (pixel), are arranged in a lattice pattern on an SRAM cell (memory cell) 60. This is a mirror device. In each pixel, a micromirror 62 supported by a support column is provided at the top, and a material having high reflectance such as aluminum is deposited on the surface of the micromirror 62. The reflectance of the micromirror 62 is 90% or more, and the arrangement pitch is 13.7 μm as an example in both the vertical and horizontal directions. A silicon gate CMOS SRAM cell 60 manufactured in a normal semiconductor memory manufacturing line is disposed directly below the micromirror 62 via a support including a hinge and a yoke, and the entire structure is monolithic. ing.

  When a digital signal is written in the SRAM cell 60 of the DMD 50, the micromirror 62 supported by the support is tilted in a range of ± α degrees (for example, ± 12 degrees) with respect to the substrate side on which the DMD 50 is disposed with the diagonal line as the center. It is done. FIG. 7A shows a state in which the micromirror 62 is tilted to + α degrees in the on state, and FIG. 7B shows a state in which the micromirror 62 is tilted to −α degrees in the off state. Therefore, by controlling the tilt of the micromirror 62 in each pixel of the DMD 50 according to the image signal as shown in FIG. 6, the laser light B incident on the DMD 50 is reflected in the tilt direction of each micromirror 62. The

  FIG. 7 shows an example of a state in which a part of the DMD 50 is enlarged and the micromirror 62 is controlled to + α degrees or −α degrees. On / off control of each micromirror 62 is performed by a controller (not shown) connected to the DMD 50. Further, a light absorber (not shown) is arranged in the direction in which the laser beam B reflected by the off-state micromirror 62 travels. The on / off control of each micromirror 62 is performed by a scanner control unit including the above-described data processing unit and mirror drive control unit in response to a command from the controller 190.

  Here, the DMD 50 of the present embodiment is divided into four block areas A, B, C, and D, and each block area is configured by L rows × M columns of micromirrors 62. This block area is treated as a unit of control, and the controller 190 generates and transmits a control signal for driving the micromirror 62 for each of the block areas A, B, C, and D.

  FIG. 8 shows an exposure area 168 that is a two-dimensional image obtained by one DMD 50 and block areas A, B, C, and D in the exposure area 168 corresponding to the block areas A, B, C, and D. In FIG. 8, for the sake of simplicity, the number of matrices is reduced, and L = 4, M = 16, and K = 4.

As shown in FIG. 8, the DMD 50 is disposed so that the exposure area 168 is inclined at an inclination angle θ of θ = ± tan ⁻¹ (k / L) with respect to the sub-scanning direction. Here, k is a natural number relatively prime to L, or a number equal to L. By tilting the exposure area 168 in this manner, the pitch of the scanning trajectory (scanning line) of the exposure beam by each micromirror 62 becomes narrower than the pitch of the scanning line when the exposure area 168 is not tilted, thereby improving the resolution. be able to.

Further, by setting the inclination angle θ of the exposure area 168 to ± tan ⁻¹ (k / L) with respect to the sub-scanning direction, the reflected light image (exposure beam) of each block region can be scanned on one scanning line. . For example, focusing on the scanning line L1 in FIG. 8, the reflected light images (exposure beams) of the block areas A, B, C, and D indicated by black circles in FIG. 8 can be scanned on the scanning line L1. The sub-scanning direction is a direction opposite to the stage moving direction, and the main scanning direction is a direction perpendicular to the sub-scanning direction.

  As shown in FIGS. 4 and 5, an imaging optical system 51 that images the laser beam B reflected by the DMD 50 onto the photosensitive material 150 is disposed on the light reflecting side of the DMD 50. Although this imaging optical system 51 is schematically shown in FIG. 4, as shown in detail in FIG. 5, an optical system comprising lens systems 52 and 54 and a microlens through which light transmitted through this optical system is incident An array 55 and an aperture array 59 are included.

  The optical system including the lens systems 52 and 54 enlarges an image formed by the DMD 50 and forms an image on the microlens array 55. The microlens array 55 corresponds to each pixel portion of the DMD 50, and is formed by two-dimensionally arranging a large number of microlenses 56 that collect the light from each pixel portion. Each microlens 56 is arranged in the vicinity of the imaging position of the micromirror 62 by the lens systems 52 and 54 at a position where the laser beam B from the corresponding micromirror 62 is incident. The aperture array 59 is formed by forming a large number of apertures (openings) corresponding to the microlenses 56 of the microlens array 55. In the figure, the photosensitive material 150 is sub-scanned in the direction of arrow F.

  As shown in FIG. 9, the microlens array 55 is divided into four block areas A, B, C, and D corresponding to the block areas A, B, C, and D of the DMD. The focal length is different. Hereinafter, the microlenses arranged in the block areas A, B, C, and D are referred to as microlenses 56A, 56B, 56C, and 56D, respectively. In FIG. 9, the number of matrices is shown smaller than the actual number for simplification. As schematically shown in FIG. 10, the focal lengths of the micro lenses 56A, 56B, 56C, and 56D are set to increase in this order, and the difference is, for example, several tens of μm. Note that the microlens arranged in the microlens array 55 is preferably set in consideration of not only the focal length but also the focal depth.

  Similar to the tilt of the DMD 50 described above, the lens arrangement direction of the microlens array 55 also has a tilt angle θ with respect to the sub-scanning direction. Similarly to the scanning of the micro mirror 62 of the DMD 50 described above, the micro lens array 55 also has a micro lens in each block area A, B, C, D on the scanning line L1, as indicated by a black circle in FIG. The lenses 56A, 56B, 56C, and 56D can be scanned. That is, the same position on the photosensitive material 150 can be exposed with light from microlenses 56A, 56B, 56C, and 56D having different focal lengths.

  The outline of the operation of the exposure apparatus 100 according to the present embodiment described above is as follows. First, in the exposure apparatus 100, the scanner 162 (each exposure head 166) that scans and exposes the photosensitive material 150 with a laser beam modulated according to image data, and the photosensitive material 150 are moved along the sub-scanning direction by the stage 152. Move relative to the direction. For this photosensitive material 150, the CCD camera 182 of the detection unit 180 detects the reference portion of the exposure position provided on the photosensitive material 150 (alignment measurement), and the displacement sensor 184 provided in the vicinity of the CCD camera 182 Simultaneously with the detection of the reference portion by the camera 182, the height of the exposed surface 151 at each position of the photosensitive material 150 is measured (focus measurement). The controller 190 performs correction control of the exposure position deviation by the laser light based on the detection information from the CCD camera 182, and the focal position of the laser light is exposed to the photosensitive material 150 based on the measurement information by the displacement sensor 184. In order to coincide with the surface 151, a block region of the microlens array that can be focused is selected. Next, while moving the scanner 162 with respect to the photosensitive material 150, the block area of the DMD 50 corresponding to the selected block area is driven to perform exposure while performing focus control with high accuracy.

  The details of the above operation and the contents of data processing in the above operation will be described below with reference to FIGS. Image data corresponding to the exposure pattern is input to the controller 190 and temporarily stored in a frame memory in the controller. This image data is data representing the density of each pixel constituting the image by binary values (whether or not dots are recorded).

  Next, the photosensitive material 150 is set on the stage 152, and the operator performs an exposure start input operation from the operation unit of the controller 190. The photosensitive material 150 for performing image exposure with the exposure apparatus 100 is a photosensitive epoxy resin or the like on the surface of a substrate or glass plate as a material for forming a pattern (image exposure) such as a printed wiring board or a liquid crystal display device In the case of a dry film, a laminate or the like is applied.

  When the exposure operation of the exposure apparatus 100 is started by the above input operation, the controller 190 controls the driving device, and the stage 152 starts moving at a constant speed from the origin position along the guide 158 to the downstream side. Each detection unit 180 is controlled and operated by the controller 190 in synchronization with the start of the movement of the stage or at a timing just before the leading edge of the photosensitive material 150 reaches just below the CCD camera 182 of the detection unit 180.

  As the stage 152 moves, when the photosensitive material 150 passes below the detection unit 180, alignment measurement by the CCD camera 182 and focus measurement by the displacement sensor 184 are performed simultaneously.

  First, when the photosensitive material 150 passes under the three CCD cameras 182, as shown in FIG. 11A, each CCD camera 182 images the photosensitive material 150, and the captured image data (photographing). Data) is output to the data processing unit of the controller 190.

  The data processing unit detects an alignment mark or a reference hole provided in the photosensitive material 150 as an alignment reference portion or an edge portion or a corner portion of the photosensitive material 150 as an alignment reference portion from the input photographing data. The proper exposure position with respect to the position and the exposed surface 151 is grasped. Then, at the time of image exposure by the scanner 162, which will be described later, correction control (alignment) is performed in which a control signal generated based on the image data of the exposure pattern stored in the frame memory is adjusted to the appropriate exposure position to perform image exposure. .

  Further, when the photosensitive material 150 passes below the three displacement sensors 184, each displacement sensor 184 detects the leading edge and the trailing edge of the photosensitive material 150 (edge detection processing) as shown in FIG. Then, the height of the exposed surface 151 at each position is measured, and height data (focus measurement data) as measurement information is output to the scanner control unit of the controller 190. Here, the height is a distance in the optical axis direction from a certain reference point to the exposed surface.

  The scanner control unit recognizes the leading end and the trailing end of the photosensitive material 150 based on the input focus measurement data, and executes arithmetic processing for grasping the waviness and thickness dimension error of the photosensitive material 150.

  Assuming that the moving direction (sub-scanning direction) of the photosensitive material 150 is the Y direction and the direction orthogonal to the moving direction (main scanning direction) is the X direction, the arithmetic processing in the Y direction is first performed by the displacement sensor 184 with the photosensitive material 150. A plurality of average values of data acquired at a predetermined movement interval are obtained along with the movement. In this embodiment, as shown in FIG. 12A, the average calculation interval for calculating the average value of the data with the movement of the photosensitive material 150 is set to 1 mm, and the measurement interval is 200 μm. And perform averaging.

  As shown in FIG. 12B, the scanner control unit of the controller 190 calculates a moving average value every time the photosensitive material 150 moves 1 mm in the Y direction (stage movement direction) from the measurement start position after the start of the measurement operation. Data (average value data of five measurements) is sequentially stored in the frame memory. As this moving average value data, data from the measurement start position to the measurement end position is stored.

  In addition, in order to remove noise data, data exceeding a preset measurement range is treated as not subject to averaging calculation processing, and clear data (invalid data) when this data continues for a predetermined number of times (for example, 15 times). ). For example, when a through hole is formed in the substrate of a printed wiring board serving as a photosensitive material and the through hole is detected, clear data is obtained. The clear data is also stored before the photosensitive material 150 reaches the measurement start position (before detection of the leading edge of the photosensitive material 150) and after passing through the measurement end position (after detection of the trailing edge of the photosensitive material 150). However, it is possible to specify in advance that the height of the corresponding area is not measured or to cancel the data in the corresponding area for a through hole such that the formation position can be grasped in advance.

  Subsequently, the scanner control unit shifts each stored moving average value data by 1/2 of the average calculation interval (1 mm × 1/2 = 0.5 mm) in the measurement start direction, and each averaging calculation measurement section. Is set as the Z coordinate value corresponding to the XY coordinate value of the intermediate point. Further, this Z coordinate value is mapped to each Y coordinate value and each X coordinate value that is the installation position of the three displacement sensors 184 to create mapping data as shown in FIG. 13, and based on this mapping data Thus, an approximate curve corresponding to the exposed surface 151 is obtained.

  First, an approximate curve in the X direction is obtained by the following calculation process. As shown in FIG. 14, in the X direction cross section at a specific Y direction position (Y coordinate value obtained by shifting the moving average value data), the central portion of the photosensitive material 150 is warped so as to rise from both side ends. Three (X, Y, Z) coordinate values of the exposed surface 151 are acquired from the distance between the exposed surface and the displacement sensor measured by the three displacement sensors 184, and the following (3) The radius of curvature: R that applies to the equation is derived.

(X−X ₀ ) ² + (Z−Z ₀ ) ² = R ² (3)
A curve (curvature circle) drawn by R calculated from the equation (3) becomes an approximate curve in the X-direction cross section of the exposed surface 151.

Further, the distance in the X direction from the center of curvature (X ₀ , Y ₀ , Z ₀ ) of the approximate curve drawn by R to the optical axis L of the exposure head 166: HX, the optical axis of the exposure head 166 from the center of curvature to the approximate curve If the Z-direction distance at the position is Z, then R, HX, and Z have the following relationship (4).

R ² = HX ² + Z ² (4)
A Z coordinate value (Zn) at the optical axis position (Xn, Yn) of the exposure head 166 is obtained from Z calculated by the equation (4). Further, a curve obtained by connecting the Z coordinate value (Zn) at the optical axis position (Xn, Yn) of the exposure head 166 with each Y coordinate value obtained by shifting each moving average value data becomes an approximate curve in the Y direction.

  Based on the approximate curve obtained as described above, a block region of the microlens array 55 that can be focused on the exposed surface 151 is selected along the Y direction. In this selection, the entire block area is selected instead of partially selecting the block area. As an example, FIG. 15 shows an approximate curve in the Y direction and a block area name selected based on the approximate curve. The horizontal axis in FIG. 15 is the position in the Y direction (sub-scanning direction), and the vertical axis is the position in the Z direction (height of the exposed surface). In the example shown in FIG. 15, considering the focal lengths of the micro lenses 56A, 56B, 56C, and 56D, the Z direction (height direction) is divided into four sections, and a block area that can be focused is selected for each section. ing. For example, for the section with the highest height, the block area A in which the microlens 56A having the shortest focal length among the above four is selected as the block area that can be focused.

  When the scanner control unit determines whether the difference between the maximum value and the minimum value of the Z coordinate value exceeds a preset threshold value in the mapping data shown in FIG. 13, and determines that the threshold value is exceeded. In this case, it is determined that the waviness or thickness dimension error of the photosensitive material 150 is large and the accuracy is poor, and the controller 190 performs error control. In the error control, when it is determined that the photosensitive material 150 is inaccurate, the exposure is not immediately performed and the exposure operation is immediately stopped and the stage 152 is returned to the most upstream position. Then, information (error information) for notifying that the exposure operation is stopped is displayed on the monitor of the controller 190.

  When the photosensitive material 150 passes through the detection unit 180, alignment measurement and focus measurement (simultaneous measurement) by the detection unit 180 are completed. Further, the photosensitive material 150 that has passed through the detection unit 180 moves toward the scanner 162 as the stage 152 moves. When the exposure material reaches the exposure start position, each exposure head 166 of the scanner 162 irradiates a light beam to irradiate the photosensitive material 150. Image exposure on the surface 151 to be exposed is started (see FIG. 11B).

  Here, the image data stored in the frame memory in the controller is sequentially read for each of a plurality of lines, and the data processing unit generates a control signal for each exposure head 166 based on the read image data. With this control signal, exposure is performed by driving the block area of the DMD 50 corresponding to the selected block area. The control signal is subjected to the correction of the exposure position deviation with respect to the photosensitive material 150 subjected to the alignment measurement by the above-described correction control (alignment).

  By using the above-described configuration and method, high-precision focus control is possible, and the configuration is simplified compared to the case of using mechanical means for moving the photosensitive material in the focus depth direction as in the past. While being able to suppress the enlargement of the whole apparatus. In particular, in the relative movement between the scanner 162 and the photosensitive material 150 at the time of exposure, only the on / off control of the micromirrors in the selected block area is performed, and therefore an autofocus mechanism that mechanically moves the exposure head 166 up and down. In this case, there is no vibration generated, and an image with high sharpness can be formed in a more stable state.

  Further, for a substrate having a height distribution of the exposed surface within the exposure area of the exposure head, the conventional method of moving the entire exposure head has not been able to respond appropriately, but according to the present embodiment, Since focus control can be performed in units of block areas in the exposure area, more accurate focus control is possible.

  Furthermore, in this embodiment, the three displacement sensors 184 are arranged along the main scanning direction, and the height measurement points with the exposed surface 151 of the photosensitive material 150 are three in the main scanning direction. It is possible to measure the unevenness or undulation shape of the exposed surface 151 due to the waviness or warpage of the photosensitive material 150 in the main scanning direction.

  Furthermore, in this embodiment, since an approximate curve is created and focus control is performed using this, when arranging a plurality of displacement sensors 184 along the direction intersecting the scanning direction, the number of arrangements is set. The focal point position of the laser beam can be adjusted to the surface 151 to be exposed with high accuracy by a simplified configuration with as little as possible. Specifically, in the present embodiment, the number of exposure heads 166 is ten, whereas the number of displacement sensors 184 is three, and a configuration in which the number of displacement sensors is reduced is possible. The number of displacement sensors 184 as position information acquisition means is not limited to three, and may be provided for each exposure head. In such a case, position information can be acquired with higher accuracy, Can be exposed with high accuracy.

  In the present embodiment, the measurement data of the height of the photosensitive material 150 with respect to the exposed surface 151 measured by the displacement sensor 184 includes the unevenness and the undulating shape of the exposed surface 151 due to the waviness and warpage of the photosensitive material 150. If the preset threshold value is exceeded due to the large or large thickness error of the photosensitive material 150, the scanner control unit of the controller 190 controls the scanner 162 so that the photosensitive material 150 is not exposed. . Thereby, the useless exposure time with respect to the photosensitive material 150 with poor accuracy is reduced, and the productivity can be improved. Further, as in this embodiment, an exposure apparatus whose configuration and exposure operation are controlled so that the height measurement of the entire exposure range on the exposed surface 151 is completed before the exposure to the photosensitive material 150 by the scanner 162 is started. If it is 100, the exposure operation for the photosensitive material 150 with poor accuracy is stopped before exposure, and the waste of the photosensitive material 150 can be reduced.

  The exposure apparatus according to the second embodiment of the present invention will be described below. In the first embodiment, the block area is generally selected along the Y direction, and the DMD 50 is controlled in units of the block area. However, in this embodiment, the block area is partially divided along the X direction. This is basically different from the first embodiment in that the DMD 50 corresponding to this portion is controlled. Hereinafter, description will be made by paying attention to this point, and redundant description of the same configuration as that of the first embodiment will be omitted.

  The DMD 50 of this embodiment has the same configuration as that of the first embodiment and is divided into four block areas A, B, C, and D as shown in FIG. This is possible not for each region but for each micromirror 62. The microlens array 55 of the present embodiment has the same configuration as that of the first embodiment, and is divided into four block areas A, B, C, and D as shown in FIG. The focal length is different.

  The operation of this embodiment will be described below. Among the operations of the present embodiment, the processes up to the step of obtaining the height of each position of the photosensitive material 150 and obtaining the approximate curve are the same as in the first embodiment. When an approximate curve in the X direction at each Y-direction position is obtained, a part of the block region of the microlens array 55 that can be focused on the exposed surface 151 is selected along the X direction based on the approximate curve. In this selection, the X direction may be divided into predetermined units smaller than the block area, and may be selected for each predetermined unit, or may be selected for each microlens.

  As an example, FIG. 16 shows an approximate curve in the X direction at a certain position in the Y direction, a block area name selected based on this approximate curve, and a reflected light image of the DMD 50 corresponding to a part of the selected block area, as a black circle. The figure is shown. The horizontal axis of the approximate curve in FIG. 16 is the position in the X direction (main scanning direction), and the vertical axis is the position in the Z direction (height of the exposed surface). In the example shown in FIG. 16, considering the focal lengths of the micro lenses 56A, 56B, 56C, and 56D, the Z direction (height direction) is divided into four sections, and a block area that can be focused is selected for each section. ing. For example, for the section with the highest height, the block area A in which the microlens 56A having the shortest focal length among the above four is selected as the block area that can be focused.

  In the following operation, when the control signal is generated for each exposure head 166 based on the image data read out by the data processing unit and the DMD 50 is driven by the control signal, one of the block areas selected as described above is used. The control and driving for each micromirror 62 corresponding to each unit is different from the first embodiment, and other operations are the same as those of the first embodiment.

  As described above, according to the present embodiment, in addition to the effects of the first embodiment, not only the sub-scanning direction (Y direction) which is the relative movement direction within one head but also the main scanning direction (X direction) is focused. The effect that it can be controlled is obtained. In the case of simultaneously exposing an image for one line as in the conventional line head, the focus control can be performed in one head only in one direction. Therefore, the above effect of the present embodiment is very effective. .

  In addition to the method using the above approximate curve, the selection of the block area includes mapping data in which the surface to be exposed is mapped in a contour line corresponding to the focal length of each microlens, frame data corresponding to image information, and a block It is also possible to adopt a method using data. Hereinafter, this method will be described.

  The mapping data is obtained by selecting the microlenses 56A, 56B, 56C, and 56D that can be focused at each position based on the height data of the exposed surface 151 at each position of the photosensitive material 150, and is shown in FIG. As described above, the photosensitive material 150 is mapped in contour lines corresponding to the focal lengths of the four types of microlenses. This is disassembled into regions corresponding to the microlenses 56A, 56B, 56C, and 56D, and hatched portions are shown as FIGS. 18A, 18B, 18C, and 18D, respectively. 17 and 18 both show regions where the photosensitive material 150 has positions in the X and Y directions from (0, 0) to (Xn, Ym).

  The frame data is obtained by transforming the pixel data in the image pattern to be formed into a position taking into account the inclination of the DMD by specifying the pixel data corresponding to each micromirror 62 and rearranging the data again. It is determined according to the scanning speed and the modulation time (modulation period). The block data is data corresponding to the block areas A, B, C, and D shown in FIG. 8, and is determined by the arrangement of the block areas.

  In the scanner control unit, the mapping data, the frame data, and the block data are ANDed, and in the case of TRUE, the micromirror 62 is controlled to be turned on so that each position on the exposed surface 151 is focused. Thus, a desired image can be formed.

  In the above embodiment, the DMD is divided into four block regions along the side direction of the DMD. However, the DMD may be divided along the relative movement direction or the orthogonal direction instead of the side direction of the DMD. In many cases, the number of blocks and the configuration of the block area can be arbitrarily set. For example, as shown in FIG. 19, four types of microlenses a, b, c, and d having different focal lengths are arranged in a staggered pattern in which microlenses having the same focal length are arranged in an oblique direction. An area in which microlenses having a focal length are arranged may be a block area. When the outer diameters of the microlenses are different, a staggered lattice arrangement in which a large outer diameter lens and a small outer diameter lens are arranged adjacent to each other so as to avoid contact between adjacent lenses is advantageous in terms of space utilization. Further, a configuration in which the block regions themselves are arranged in a staggered pattern is also possible.

  In the height measurement and the creation of the approximate curve, the main scanning direction may be divided into a plurality of regions. Alternatively, when a substrate having anisotropy in flatness such as a glass substrate is used and there is no problem in the flatness in the main scanning direction, only one focus is detected in the main scanning direction, and the result is A block area that can be focused may be selected and exposed only in the sub-scanning direction by the same method as described above.

  In the above embodiment, the alignment measurement by the CCD camera 182 and the focus measurement by the displacement sensor 184 are simultaneously performed. However, it is not always necessary to perform the simultaneous measurement, and the alignment measurement and the focus measurement are performed at different timings. You may make it perform.

  Note that, instead of the imaging optical system 51 of the above-described embodiment, an imaging optical system 51 in which an optical system including lens systems 57 and 58 for the purpose of magnification conversion or the like is inserted between the microlens 55 and the photosensitive material 150. The present invention can also be applied to the exposure head shown in FIG.

  In the above description, the exposure head including the DMD as the spatial light modulation element has been described. However, in addition to such a reflective spatial light modulation element, a transmissive spatial light modulation element (LCD) can also be used. For example, a liquid crystal shutter such as a MEMS (Micro Electro Mechanical Systems) type spatial light modulator (SLM), an optical element (PLZT element) that modulates transmitted light by an electro-optic effect, or a liquid crystal light shutter (FLC). It is also possible to use a spatial light modulation element other than the MEMS type, such as an array. Note that MEMS is a general term for a micro system that integrates micro-sized sensors, actuators, and control circuits based on a micro-machining technology based on an IC manufacturing process, and a MEMS type spatial light modulator is an electrostatic force. It means a spatial light modulation element driven by an electromechanical operation using Further, a plurality of GLVs (Grating Light Valves) arranged in two dimensions can be used. In the configuration using these reflective spatial light modulator (GLV) and transmissive spatial light modulator (LCD), a lamp or the like can be used as a light source in addition to the laser described above.

1 is a perspective view showing an exposure apparatus according to a first embodiment of the present invention. 1 is a perspective view showing the configuration of a scanner of the exposure apparatus in FIG. (A) is a plan view showing an exposed area formed on a photosensitive material, and (B) is a view showing an arrangement of exposure areas by each exposure head. 1 is a perspective view showing a schematic configuration of an exposure head of the exposure apparatus of FIG. Sectional drawing which shows the structure of the exposure head of FIG. Partial enlarged view showing the configuration of a digital micromirror device (DMD) (A) And (B) is explanatory drawing for demonstrating operation | movement of DMD. Diagram showing exposure area by DMD Diagram showing the configuration of the microlens array Sectional view showing microlenses with different focal lengths (A) is a side view showing a state of focus measurement by the exposure apparatus of FIG. 1, and (B) is a side view showing a state of focus control of laser light emitted from the exposure head. (A), (B) is explanatory drawing for demonstrating the content of the arithmetic processing in focus measurement and control by the exposure apparatus of FIG. The figure which shows the mapping data produced in the arithmetic processing in the focus measurement and control by the exposure apparatus of FIG. Explanatory drawing for demonstrating the content which calculates | requires the approximate curve in the X direction cross section of the to-be-exposed surface of a photosensitive material in the focus measurement and control by the exposure apparatus of FIG. Diagram showing approximate curve and selected block area The figure which shows the reflected light image of DMD corresponding to the approximate curve and a part of selected block area | region in the 2nd Embodiment of this invention. Explanatory diagram for explaining mapping data Explanatory diagram for explaining mapping data The figure which shows the structure of the block area | region of another example of this invention Sectional drawing which shows the structure of another exposure head which can apply this invention

Explanation of symbols

50 Digital Micromirror Device (DMD)
Reference Signs List 51 Imaging optical system 52, 54 Lens system 55 Micro lens array 56, 56A, 56B, 56C, 56D Micro lens 59 Aperture array 62 Micro mirror 66 Fiber array light source 67 Lens system 68 Laser emitting unit 71 Condensing lens 72 Rod integrator 100 Exposure device 150 Photosensitive material 151 Surface to be exposed 152 Stage 162 Scanner 166 Exposure head 168 Exposure area 170 Exposed area 180 Detection unit 182 CCD camera 184 Displacement sensor 190 Controller A, B, C, D Block area

Claims (8)

Spatial light modulation elements divided into a plurality of block regions, in which a large number of pixel units that modulate the irradiated light according to control signals are arranged in parallel,
Moving means for moving the photosensitive material relative to the spatial light modulator;
Microlenses arranged in an optical path between the spatial light modulation element and the photosensitive material and condensing light from each pixel portion of the spatial light modulation element are arranged in an array, and the spatial light modulation element A microlens array that is divided into a plurality of block areas corresponding to the block area, and the focal length of the microlens is different for each block area;
Measuring means for measuring the height of the exposed surface at each position of the photosensitive material;
Based on the height of the exposed surface at each position of the photosensitive material measured by the measuring means, at least a part of the block region of the microlens array that can be focused on each position on the exposed surface is selected. An exposure apparatus comprising: a control unit that drives the spatial light modulation element corresponding to at least a part of the selected block region in the relative movement.   The control means creates mapping data based on the height of the exposed surface at each position of the photosensitive material measured by the measuring means, and an approximate curve corresponding to the exposed surface based on the mapping data. 2. The exposure apparatus according to claim 1, wherein at least a part of the block region of the microlens array is selected based on the approximate curve.   The exposure apparatus according to claim 1, wherein the control unit selects all of the block areas along the relative movement direction.   The exposure apparatus according to claim 1, wherein the control unit selects only a part of the block region along a direction intersecting with the relative movement direction. A large number of pixel units for modulating the irradiated light according to the control signal are arranged in parallel, and the spatial light modulation element divided into a plurality of block regions and the movement for moving the photosensitive material relative to the spatial light modulation element And a microlens arranged in an optical path between the spatial light modulation element and the photosensitive material and collecting light from each pixel portion of the spatial light modulation element in an array, and the spatial light In an exposure method in which exposure is performed using an exposure apparatus that is divided into a plurality of block areas corresponding to the block area of the modulation element and includes a microlens array having a different focal length of the microlens for each block area.
Measuring the height of the exposed surface at each position of the photosensitive material;
Based on the height of the exposed surface at each position of the photosensitive material measured in the measuring step, select at least a part of the block region of the microlens array that can be focused on each position on the exposed surface. And a process of
And performing exposure by driving the spatial light modulation element corresponding to at least a part of the selected block region while moving the spatial light modulation element relative to the photosensitive material. Exposure method. The step of selecting includes
Creating mapping data based on the height of the exposed surface at each position of the photosensitive material measured in the measuring step;
6. An exposure method according to claim 5, further comprising: obtaining an approximate curve corresponding to the surface to be exposed based on the mapping data.   7. The exposure method according to claim 5, wherein in the selecting step, the entire block area is selected along the relative movement direction.   7. The exposure method according to claim 5, wherein in the selecting step, only a part of the block region is selected along a direction intersecting with the relative movement direction.

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