JP4114184B2 - Multiple exposure drawing apparatus and multiple exposure drawing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drawing apparatus that draws a predetermined pattern on a drawing surface using an exposure unit having a large number of modulation elements, and more particularly to a drawing apparatus that joins a plurality of partial patterns to obtain the entire pattern.
[0002]
[Prior art]
The drawing apparatus is generally used for optically drawing a fine pattern or a symbol such as a character on the surface of an appropriate drawing object. A typical example of use is drawing a circuit pattern when a printed circuit board is manufactured by a photolithography technique. In this case, the object to be drawn is on a photosensitive film for a photomask or a substrate. It is a photoresist layer.
[0003]
In recent years, a series of processes from a circuit pattern design process to a drawing process are integrated into a system, and this integrated system includes a CAD (Computer Aided Design) for designing a circuit pattern in addition to a drawing apparatus. A station, a CAM (Computer Aided Manufacturing) station for editing vector data of a circuit pattern obtained by the CAD station, and the like are provided. Vector data created by the CAD station or vector data edited by the CAM station is transferred to the drawing apparatus, where it is converted into raster data and then stored in the bitmap memory.
[0004]
As an exposure unit of a drawing apparatus, an exposure unit including, for example, a DMD (Digital Micromirror Device) or an LCD (Liquid Crystal Display) array is known. As is well known, micromirrors are arranged in a matrix on the reflective surface of the DMD, and the reflection direction of each micromirror is controlled independently, so that the entire reflective surface of the DMD can be controlled. The introduced light beam is split as a reflected light beam by the individual micromirrors. For this reason, each micromirror functions as a modulation element. In an LCD array, liquid crystal is sealed between a pair of transparent substrates, and a plurality of fine transparent electrodes aligned with each other are arranged in a matrix on both transparent substrates. The transmission and non-transmission of the light flux are controlled depending on whether or not a voltage is applied to the first and second electrodes, and thus each pair of transparent electrodes functions as a modulation element.
[0005]
The drawing apparatus is provided with an appropriate light source device corresponding to the photosensitive characteristics of the drawing object, for example, an ultra-high pressure mercury lamp, a xenon lamp, a flash lamp, an LED (Light Emitting Diode), a laser, etc., and the exposure unit has imaging optics. The system is incorporated. The light beam emitted from the light source device is introduced into the exposure unit through the illumination optical system, and each modulation element of the exposure unit modulates the light beam incident thereon according to the raster data of the circuit pattern. And is optically drawn.
[0006]
An exposure unit including a DMD or LCD array generally has an area that can be exposed to a few cm square, but the drawing area of a circuit pattern to be drawn on the drawing object is much larger than the exposure area of the exposure unit. large. Therefore, in a conventional drawing apparatus, a plurality of exposure units are arranged in a predetermined direction, and the drawing object or the exposure unit is relatively moved along a direction substantially perpendicular to the arrangement direction of the exposure units. By connecting partial circuit patterns to be drawn, the entire circuit pattern is drawn on the drawing object. In particular, a step-and-repeat method that performs drawing while alternately repeating exposure and intermittent movement is well known.
[0007]
[Problems to be solved by the invention]
In the conventional drawing apparatus as described above, there is a problem that the continuity or unity of the circuit pattern drawn on the drawing object is impaired at the boundary portion between the adjacent partial patterns. This is due to individual differences among exposure units, specifically, slight differences in the optical characteristics of the imaging optical system, and slight deviations in the mounting position of the exposure unit. In order to eliminate the difference in the optical characteristics of the imaging optical system, it is necessary to use a lens without distortion. Such a lens is not only expensive, but also requires time and labor to install it. The Further, in order to eliminate the displacement of the mounting position, it is necessary to finely adjust the position of each exposure unit with high accuracy using a dedicated instrument, and an extremely complicated and time-consuming work is required.
[0008]
Accordingly, an object of the present invention is to provide a multiple exposure drawing apparatus and a multiple exposure drawing method capable of obtaining an entire pattern having good continuity and unity in a drawing apparatus for joining partial patterns drawn by individual exposure units. Is to provide.
[0009]
[Means for Solving the Problems]
A multiple-exposure drawing apparatus according to the present invention is a multiple-exposure drawing apparatus that draws a plurality of partial patterns arranged along a first direction on a drawing surface by multiple exposure, thereby obtaining an entire pattern obtained by joining the partial patterns. An exposure unit having a large number of modulation elements arranged in a matrix and driving the modulation elements based on the raster data of the partial patterns, and the number of exposure units equal to the number of partial patterns along the first direction. Partial patterns overlap each other with respect to the arrangement means for arranging only the image forming apparatus, the moving means for moving the drawing surface relative to the exposure unit along a second direction different from the first direction, and the exposure unit for drawing two adjacent partial patterns. Modulation element selection means for gradually decreasing or gradually increasing the number of modulation elements to be driven corresponding to the boundary region at a constant rate along the second direction; And wherein the Rukoto. By gradually changing the number of modulation elements corresponding to the boundary region, it is possible to draw an entire pattern with good integration and continuity.
[0010]
In the multiple exposure drawing apparatus, the area of the boundary region preferably occupies 5 to 10% of the area of the exposure region exposed by one exposure unit.
[0011]
The multiple-exposure drawing apparatus further includes memory means for holding raster data of the entire pattern, first coordinate data indicating the relative position of the exposure unit with respect to the drawing surface, and second indicating the relative position of each modulation element in the exposure unit. Adds coordinate data to calculate relative position coordinate data of each modulation element with respect to the drawing surface, and generates address data corresponding to the pixel size of the raster data based on the relative position coordinate data for each modulation element And exposure data generating means for reading out raster data corresponding to the address data from the memory means and generating exposure data for instructing the individual modulation elements to perform exposure operation or exposure operation stop. When the modulation element selection means, specifically, from the address calculation means for the modulation element to be exposed. With providing address data to exposure data generating means to be, it is preferable to provide a dummy data to the exposure data generating means for modulating element to stop the exposure operation.
[0012]
Specifically, in the multiple exposure drawing apparatus, the entire exposure area exposed by one exposure of each exposure unit presents a rectangle having a length D1 in the first direction, and two adjacent exposure areas adjacent to each other in the first direction. Overlap by length D2 (D2 <D1). Further, it is preferable that the first direction length D2 in which two adjacent whole surface exposure regions overlap is 5 to 10% of the first direction length D1 of the whole surface exposure region. More preferably, one of two adjacent whole surface exposure regions is located on the other whole surface exposure region side, the first direction length is D2, and the second direction length is the second direction length of the whole surface exposure region. An equal triangular area is defined as the first exposure stop area, and the other one of the two adjacent whole area exposure areas is located on the one whole area exposure area side, the first direction length is D2, and the second direction length is A triangular area equal to the length in the second direction of the entire exposure area is defined as the second exposure stop area, and the exposure operation of the modulation elements corresponding to the first and second exposure stop areas is stopped.
[0013]
Also, the multiple exposure drawing method according to the present invention draws a plurality of partial patterns arranged along the first direction on the drawing surface by multiple exposure, thereby obtaining the entire pattern obtained by joining the partial patterns. A method having an exposure unit having a large number of modulation elements arranged in a matrix and driving the modulation elements based on the raster data of the partial patterns by the same number as the number of the partial patterns along the first direction. For the exposure unit that draws two adjacent partial patterns by moving the drawing surface relative to the exposure unit along a second direction different from the first direction, the modulation corresponding to the boundary region where the partial patterns overlap The number of elements to be driven is gradually decreased or increased at a constant rate along the second direction.
It is characterized by that.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a multiple exposure drawing apparatus according to the present invention will be described with reference to the accompanying drawings.
[0015]
FIG. 1 schematically shows an embodiment of a multiple exposure drawing apparatus according to the present invention as a perspective view. The multiple exposure drawing apparatus is configured to directly draw a circuit pattern on a photoresist layer formed on a substrate for manufacturing a printed circuit board.
[0016]
The multiple exposure drawing apparatus 10 includes a base 12 installed on a floor surface, and a pair of guide rails 14 are laid in parallel on the base 12, and a drawing table 16 is placed on the guide rails 14. Installed. The multiple exposure drawing apparatus 10 includes an appropriate driving mechanism (not shown) such as a ball screw driven by a stepping motor, and the drawing table 16 is relatively moved along the pair of guide rails 14 in the longitudinal direction by the driving mechanism. Be made.
[0017]
On the drawing table 16, a substrate having a photoresist layer is installed as the drawing target 30. At this time, the drawing target 30 is appropriately fixed on the drawing table 16 by appropriate clamping means (not shown).
[0018]
A gate-like structure 18 is fixed on the base 12 so as to straddle the pair of guide rails 14, and a plurality of exposure units move on the upper surface of the gate-like structure 18 in the second direction in which the drawing table 16 moves ( Hereinafter, they are arranged in two rows in a first direction (hereinafter referred to as the Y direction) perpendicular to the X direction. The eight exposure units arranged in the first row are denoted by reference numeral 20 in order from the left side of the figure. ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ The seven exposure units in the second row arranged behind are shown by reference numeral 20 from the left side of the figure. ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ Is shown.
[0019]
Exposure unit 20 in the first row ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ And the exposure unit 20 in the second row ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ Are arranged in a so-called staggered pattern. That is, the distance between two adjacent exposure units is set to be approximately equal to the width of one exposure unit, and the exposure unit 20 in the second row. ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ The arrangement pitch of the exposure units 20 in the first row is ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ Is shifted by a half pitch with respect to the array pitch.
[0020]
In the present embodiment, 15 exposure units 20 ₀₁ ~ 20 ₁₅ Are configured as DMD units, and the reflection surface of each exposure unit is formed of 1310720 micromirrors arranged in a 1024 × 1280 matrix, for example. Each exposure unit 20 ₀₁ ~ 20 ₁₅ Are arranged such that 1024 micromirrors are arranged along the X direction and 1280 micromirrors along the Y direction.
[0021]
An appropriate location on the upper surface of the gate-shaped structure 18, for example, the first exposure unit 20 ₀₁ A light source device 22 is provided on the left side of FIG. The light source device 22 includes a plurality of LEDs (Light Emitting Diodes) (not shown), and the light emitted from these LEDs is collected and emitted from the exit of the light source device 22 as a parallel light flux. As the light source device 22, a laser, an ultra-high pressure mercury lamp, a xenon lamp, a flash lamp, or the like may be used in addition to the LED.
[0022]
A bundle of 15 optical fiber cables is connected to the exit of the light source device 22, and each optical fiber cable 24 includes 15 exposure units 20. ₀₁ ~ 20 ₁₅ Thus, the light source device 22 extends to each exposure unit 20. ₀₁ ~ 20 ₁₅ Illumination light is introduced.
[0023]
Exposure unit 20 ₀₁ ~ 20 ₁₅ Modulates the illumination light from the light source device 22 in accordance with the circuit pattern to be drawn, and emits the light toward the drawing target 30 on the drawing table 16 moving downward in the drawing, that is, inside the gate-like structure 18. To do. Thereby, only the part irradiated with illumination light in the photoresist layer formed on the upper surface of the drawing object 30 is exposed.
[0024]
FIG. 2 shows the first exposure unit 20. ₀₁ The main components are conceptually illustrated. The other 14 exposure units 20 ₀₂ ~ 20 ₁₅ Is the first exposure unit 20 ₀₁ The configuration and function are the same as those in FIG.
[0025]
First exposure unit 20 ₀₁ Includes an illumination optical system 26 and an imaging optical system 28, and a DMD element 27 is provided on the optical path between them. The DMD element 27 is a device that operates, for example, an electrostatic field effect on a highly reflective square micromirror made of aluminum sputtering on a wafer.
[0026]
On the silicon memory chip of the DMD element 27, micromirrors having a size of C × C are spread in a matrix of 1024 × 1280, and these micromirrors operate independently. C is, for example, 20 μm. Here, the micromirror is indicated by a symbol M (m, n) (1 ≦ m ≦ 1024; 1 ≦ n ≦ 1280). The parameter m is the first exposure unit 20 ₀₁ The line number along the X-axis direction of the first exposure unit 20 ₀₁ The row numbers along the Y-axis direction are respectively shown.
[0027]
The illumination optical system 26 includes a convex lens 26A and a collimator lens 26B, and the convex lens 26A is optically coupled to an optical fiber cable 24 extended from the light source device 22. By such an illumination optical system 26, the light beam emitted from the optical fiber cable 24 is shaped into a parallel light beam LB that illuminates the entire reflecting surface of the DMD element 27. The imaging optical system 28 includes two convex lenses 28A and 28C and a reflector 28B disposed between the two convex lenses 28A and 28C. The magnification of the imaging optical system 28 is, for example, equal magnification (magnification 1). Is set.
[0028]
First exposure unit 20 ₀₁ The 1310720 micromirrors M (m, n) (1 ≦ m ≦ 1024; 1 ≦ n ≦ 1280) included in each can independently rotate and tilt about a diagonal line, and have two stable postures, Specifically, a first reflection position (hereinafter referred to as an exposure position) for reflecting the incident light beam toward the imaging optical system 28 and the light beam are reflected so as to be deflected from the imaging optical system 28. It is positioned at a second reflection position (hereinafter referred to as a non-exposure position). Normally, all the micromirrors M (m, n) are positioned at the non-exposure position, but each individual unit exposure area is rotated and displaced from the non-exposure position to the exposure position. . The rotational displacement between the non-exposure position and the exposure position of each micromirror M (m, n) is controlled by exposure data generated based on the raster data of the circuit pattern.
[0029]
When an arbitrary micromirror M (m, n) is positioned at the exposure position, the spot light incident thereon is indicated by a one-dot chain line LB. ₁ As shown in the figure, the light is reflected toward the imaging optical system 28 and guided by the imaging optical system 28 onto the drawing surface 32 of the drawing object 30 placed on the drawing table 16. If the size of the micromirror M (m, n) is C × C, the magnification of the imaging optical system 28 is equal, so that the reflection surface of the micromirror M (m, n) is on the drawing surface 32. An image is formed as an exposure area having an area of C × C. An exposure area having an area C × C obtained by one micromirror M (m, n) is referred to as a unit exposure area U (m, n) in the following description.
[0030]
On the other hand, when the micromirror M (m, n) is positioned at the non-exposure position, the spot light is a one-dot chain line LB. ₂ As shown in FIG. 5, the light is reflected toward the light absorbing plate 29 and absorbed by the light absorbing plate 29, that is, the spot light LB. ₂ Does not reach the drawing surface 32 and the corresponding region (area C × C) on the drawing surface 32 is not exposed.
[0031]
First exposure unit 20 ₀₁ When all the 1310720 micromirrors M (1,1) to M (1024,1280) included in are placed at the exposure position, all the micromirrors M (1,1) to M (1024,1280) All the reflected spot lights are made incident on the imaging optical system 28, and an area (C × 1024) × (C × 1280) on the drawing surface 32 is exposed. First exposure unit 20 ₀₁ The area that can be exposed by all the micromirrors is hereinafter referred to as the entire surface exposure area Ua. ₀₁ As mentioned. If one side length C of the unit exposure region U (m, n) is 20 μm, the entire exposure region Ua ₀₁ The area is 25.6 mm (= 1024 × 20 μm) × 20.48 mm (= 1280 × 20 μm), and the total number of pixels included therein is 1024 × 1280.
[0032]
As is apparent from FIG. 2, the unit exposure areas U (1,1), U (1,2), U (1,3), U (1,4), U (1,5),. 1,1280) is the first exposure unit 20 ₀₁ Obtained from 1280 micromirrors M (1,1) to M (1,1280) in the first line along the Y axis of the unit exposure areas U (2,1) and U (2,2). , U (2,3), U (2,4), U (2,5),..., U (2,1280) are the first exposure unit 20. ₀₁ Obtained from 1280 micromirrors M (2,1) to M (2,1280) in the second line along the Y-axis, and unit exposure areas U (3,1) and U (3,2) , U (3,3), U (3,4), U (3,5),..., U (3,1280) are the first exposure unit 20. ₀₁ Obtained from the third-line micromirrors M (3,1) to M (3,1280) along the Y-axis.
[0033]
The unit exposure area U (1,1) corresponding to the micromirror M (1,1) is the entire surface exposure area Ua. ₀₁ The unit exposure area U (1024, 1) corresponding to the micromirror M (1024, 1) is located in the lower left corner of FIG. ₀₁ It is located in the upper left corner of the figure. The unit exposure area U (1,1280) corresponding to the micromirror M (1,1280) is the entire surface exposure area Ua. ₀₁ The unit exposure area U (1024, 1280) corresponding to the micromirror M (1024, 1280) is located in the lower right corner in FIG. ₀₁ It is located in the upper right corner of the figure.
[0034]
With reference to FIGS. 3A to 3C, the drawing of the drawing surface 32 in the multiple exposure drawing apparatus 10 will be described. FIGS. 3A to 3C are plan views showing the relative positional relationship between the drawing surface 32 and the entire exposure area, and are diagrams showing stepwise changes in the drawing operation.
[0035]
As a drawing method, an operation of intermittently moving the drawing table 16 along the main scanning direction (X direction) and an operation of drawing a circuit pattern partially by exposure when the drawing table 16 is stopped are alternately repeated. Thus, a step and repeat method in which each drawing area is added to obtain an entire circuit pattern may be adopted, or a drawing operation may be performed simultaneously while moving the drawing table 16 at a constant speed. There may be. In this embodiment, a step-and-repeat method is adopted for easy explanation. That is, the multiple exposure drawing apparatus 10 employs a drawing method in which a circuit pattern is drawn by multiple exposure while the drawing table 16 is moved intermittently at a predetermined movement interval.
[0036]
An XY orthogonal coordinate system is defined on the plane including the drawing surface 32, and the X axis is the exposure unit 20. ₀₁ ~ 20 ₁₅ Is perpendicular to the direction of arrangement. In addition, the drawing surface 32 moves relatively along the negative direction of the X axis.
[0037]
A rectangular area surrounded by a broken line indicates 15 exposure units 20. ₀₁ ~ 20 ₁₅ The entire exposure area Ua obtained on the XY plane by ₀₁ ~ Ua ₁₅ It is. First row whole exposure area Ua ₀₁ , Ua ₀₃ , Ua ₀₅ , Ua ₀₇ , Ua ₀₉ , Ua ₁₁ , Ua ₁₃ And Ua ₁₅ Are arranged so that the lower side in the figure coincides with the Y-axis, and the entire exposure area Ua in the second row ₀₂ , Ua ₀₄ , Ua ₀₆ , Ua ₀₈ , Ua _Ten , Ua ₁₂ And Ua ₁₄ Are arranged so that the lower side in the figure coincides with a straight line separated by a distance S from the Y axis to the negative side.
[0038]
X-axis is exposure unit 20 ₀₁ ~ 20 ₁₅ In order to form a right angle to the arrangement direction of each exposure unit 20 ₀₁ ~ 20 ₁₅ Of these, 1310720 (1024 × 1280) micromirrors are also arranged in a matrix along the X and Y axes.
[0039]
In FIG. 3, the coordinate origin of the XY orthogonal coordinate system is the first exposure unit 20 in the first row. ₀₁ The overall exposure area Ua obtained by ₀₁ Although it is illustrated so as to coincide with the lower left corner of the drawing, the coordinate origin is precisely the first exposure unit 20. ₀₁ Is located at the center of the unit exposure region U (1, 1) obtained by the first micromirror M (1, 1) of the first line along the Y axis. As described above, in the present embodiment, the size of the unit exposure region U (1,1) is 20 μm × 20 μm, so the Y axis is the entire exposure region Ua by the first exposure unit 20. ₀₁ It has entered the inner side by 10 μm from the boundary. In other words, the eight exposure units 20 in the first row. ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ The centers of all 1280 micromirrors M (1, n) (1 ≦ n ≦ 1280) included in the first lines are positioned on the Y axis.
[0040]
Since the drawing surface 32 is moved by the drawing table 16 in the negative direction along the X axis as shown by the white arrow, the entire exposure area Ua ₀₁ ~ Ua ₁₅ Moves relative to the drawing surface 32 in the positive direction of the X axis.
[0041]
The drawing start position SL set on the drawing surface 32 is the Y axis, that is, the eight exposure units 20 in the first row. ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ The first row entire exposure area Ua corresponding to ₀₁ , Ua ₀₃ , Ua ₀₅ , Ua ₀₇ , Ua ₀₉ , Ua ₁₁ , Ua ₁₃ And Ua ₁₅ First, the exposure unit 20 in the first row is matched. ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ Thus, the exposure of the drawing surface 32 is started.
[0042]
As shown in FIG. 3A, the entire surface exposure area Ua in the first row. ₀₁ , Ua ₀₃ , Ua ₀₅ , Ua ₀₇ , Ua ₀₉ , Ua ₁₁ , Ua ₁₃ And Ua ₁₅ The micromirror corresponding to the portion that does not reach the Y-axis does not operate while being positioned at the non-exposure position, and the entire exposure area Ua in the second row ₀₂ , Ua ₀₄ , Ua ₀₆ , Ua ₀₈ , Ua _Ten , Ua ₁₂ And Ua ₁₄ Has not reached the Y axis, the exposure unit 20 ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ The exposure due to is also stopped. In FIG. 3, eight exposure units 20 in the first row. ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ The area (partial pattern) exposed by the above is shown by hatching rising to the right.
[0043]
Further, the drawing surface 32 moves and the entire exposure area Ua. ₀₂ , Ua ₀₄ , Ua ₀₆ , Ua ₀₈ , Ua _Ten , Ua ₁₂ And Ua ₁₄ When the boundary of the two coincides with the Y axis, the seven exposure units 20 in the second row ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ The exposure by is started. As shown in FIG. 3B, the exposure unit 20 in the second row. ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ The exposure by means of the exposure unit 20 in the first row ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ It always proceeds with a delay of S from the exposure by. In FIG. 3, the exposure unit 20 in the second row. ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ The area exposed by is shown with a right-down hatching.
[0044]
Further, the drawing surface 32 is relatively moved, and as shown in FIG. 3C, the entire exposure area Ua in the first row. ₀₁ , Ua ₀₃ , Ua ₀₅ , Ua ₀₇ , Ua ₀₉ , Ua ₁₁ , Ua ₁₃ And Ua ₁₅ When the boundary of the image reaches the drawing end position EL, the exposure unit 20 in the first row ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ The exposure by is stopped. Strictly speaking, the micromirror M (m, n) corresponding to the unit exposure region U (m, n) that has reached the drawing end position EL is sequentially stopped at the non-exposure position. When the drawing surface 32 further advances from the state of FIG. 3C by the distance S, the entire exposure area Ua in the second row. ₀₂ , Ua ₀₄ , Ua ₀₆ , Ua ₀₈ , Ua _Ten , Ua ₁₂ And Ua ₁₄ Reaches the drawing end position EL, and the exposure unit 20 in the second row ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ The exposure by is stopped.
[0045]
As described above, the drawing surface 32 relatively moves in parallel with the X axis, so that the 15 exposure units 20 are exposed. ₀₁ ~ 20 ₁₅ In this case, a circuit pattern is partially drawn by exposing each band-like area parallel to the X axis, and the width of each band-like area is set to the entire surface exposure area Ua. ₀₁ ~ Ua ₁₅ Substantially matches the width of. A border portion between two adjacent belt-like regions is overlapped by a minute amount. In order to match circuit patterns to be drawn on the same line, the exposure unit 20 in the first row is used. ₀₁ , 20 ₀₃ , 20 ₀₅ , 20 ₀₇ , 20 ₀₉ , 20 ₁₁ , 20 ₁₃ And 20 ₁₅ When exposure data corresponding to a circuit pattern of a predetermined line is given to the exposure unit 20 in the second row. ₀₂ , 20 ₀₄ , 20 ₀₆ , 20 ₀₈ , 20 _Ten , 20 ₁₂ And 20 ₁₄ Is provided with exposure data of the same line at a timing delayed by the time the drawing surface 32 moves the distance S.
[0046]
Details of the drawing of FIG. 3 will be described with reference to FIG. FIG. 4 shows the first exposure unit 20. ₀₁ The entire exposure area Ua on the drawing surface 32 exposed by ₀₁ A part of is shown.
[0047]
Basically, the relative movement distance of the drawing surface 32 is the first exposure unit 20. ₀₁ Full exposure area Ua ₀₁ Is set to be smaller than the length in the X direction (C × 1024). ₀₁ Is exposed multiple times, that is, multiple exposure is performed. For example, when the relative movement distance of the drawing surface 32 per exposure is set to a distance A (for example, A = 4C) that is an integral multiple of one side length C of the unit exposure region U (m, n), the first Exposure unit 20 ₀₁ Moves along the X axis to the positive side by A (= 4C), and the center of the unit exposure area U (m, n) always coincides with the same point. For this reason, the area C × C area of the drawing surface 32 exposed by the first micromirror M (1,1) in the first row is further the (4k + 1) th first micromirror M (4k + 1,1). ) (Where 1 ≦ k ≦ 255), and a total of 256 times (= 1024 C / A) is subjected to multiple exposure.
[0048]
In FIG. 4, the moving distance of the drawing surface 32 is not an integral multiple of the side length C of the unit exposure region U (m, n). For example, the distance A (A = 4C) and the distance a (0 <a <C). The example set to the sum of and is shown.
[0049]
The drawing surface 32 is moved to the negative side along the X axis by the drawing table 16, that is, the first exposure unit 20. ₀₁ Moves relative to the drawing surface 32 toward the positive side of the X axis, and the unit exposure area Ua ₀₁ When reaching the drawing start position SL on the drawing surface 32, the first exposure unit 20 is temporarily stopped there. ₀₁ The first exposure is performed by operating 1280 micromirrors M (1,1) to M (1,1280) included in the first line in accordance with the exposure data of the circuit pattern to be drawn. The relative position of the drawing surface 32 at this time is defined as the first exposure position.
[0050]
When the first exposure is completed, the first exposure unit 20 ₀₁ Again moves relative to the positive side along the X axis, and its unit exposure area Ua. ₀₁ When the amount of movement of (A + a) becomes 1, the first exposure unit 20 ₀₁ Is determined to have reached the second exposure position and stopped, and the first exposure unit 20 is stopped. ₀₁ The first to fifth line micromirrors M (1,1) to M (5,1280) are operated in accordance with the exposure data of the circuit pattern, and the second exposure is performed.
[0051]
When the second exposure is completed, the first exposure unit 20 ₀₁ Is further moved along the X axis to the positive side by the movement amount (A + a) and stopped at the third exposure position. ₀₁ The first to ninth lines of micromirrors M (1,1) to M (9,1280) are operated according to the exposure data of the circuit pattern to perform the third exposure.
[0052]
Thus, the first exposure unit 20 ₀₁ Is stopped every time it is moved to the positive side along the X axis by the movement amount (A + a), and the exposure operation is repeated, so that the same area of the drawing surface 32 is moved to the first exposure unit 20. ₀₁ As a result, multiple exposure is performed multiple times.
[0053]
Since the movement distance of the drawing surface 32 is (A + a = 4C + a), the centers of the overlapping unit exposure regions U (m, n) are gradually shifted by the distance a, and the same region is not always subjected to multiple exposures 256 times. Therefore, in order to expose the predetermined area 256 times, only 256 centers of the unit exposure areas U (m, n) are evenly arranged in the predetermined area, and the multiple exposure is substantially performed 256 times.
[0054]
3 and 4, the moving direction of the drawing surface 32 is parallel to the X axis. However, as shown in FIG. 5, the drawing surface 32 may be moved with a slight angle with respect to the X axis. For example, when the drawing object 30, that is, the drawing surface 32 is fixed on the drawing table 16 while being inclined with respect to the X axis, and the drawing table 16 is moved to the negative side along the X axis by a predetermined distance, The unit exposure area U (m, n) is not only shifted to the positive side along the X axis with respect to the drawing surface 32 but also shifted relative to the negative side along the Y axis by a predetermined distance. Become.
[0055]
FIG. 5 is a diagram showing the displacement of the unit exposure region U (m, n) over time when the drawing object 30 is sequentially moved while being inclined by the angle α with respect to the X axis. Referring to FIG. 5, the entire exposure area Ua at the first exposure position. ₀₁ Is indicated by a broken line, and the entire exposure area Ua at the second exposure position ₀₁ Is indicated by a one-dot chain line, and the entire exposure area Ua at the third exposure position ₀₁ A part of is indicated by a solid line. The shift amount along the negative side of the Y axis of each unit exposure region U (m, n) is indicated by b.
[0056]
The first exposure unit 20 at the first exposure position ₀₁ Focusing on the unit exposure areas U (1,1), U (1,2),... U (1,1280) obtained by the micromirrors M (1,1) to M (1,1280) of the first line of The first exposure unit 20 at the second exposure position for these unit exposure regions U (1,1), U (1,2),... U (1,1280). ₀₁ Unit exposure areas U (5,1), U (5,2),... U (5,1280) obtained by the fifth-line micromirrors M (5,1) to M (5,1280) And overlap each other by being shifted by (+ a) and (−b) along the Y axis, respectively, and at the third exposure position, the first exposure unit 20 ₀₁ Unit exposure areas U (9,1), U (9,2),... U (9,1280) obtained by the ninth-line micromirrors M (9,1) to M (9,1280) They are shifted from each other in the axial direction and the Y-axis direction by (+ 2a) and (−2b), and overlap each other. In FIG. 5, three unit exposure regions U (1,1), U (5,1) and U (9,1) that overlap each other are exemplarily shown by a dashed line, an alternate long and short dash line, and a solid leader line. ing.
[0057]
Here, when the relative position of each unit exposure region U (m, n) is represented by the exposure point CN (m, n) as the center, the exposure point CN (5, 1) at the second exposure position is The exposure point CN (1, 1) at the first exposure position is separated from the exposure point CN (1, 1) by (+ a, -b), and the exposure point CN (9, 1) at the third exposure position is exposed at the first exposure position. The point CN (1, 1) exists at a distance of (+ 2a, -2b). The distance between adjacent exposure points in each line matches the size C (= 20 μm) of the unit exposure region U (m, n).
[0058]
As described above, when the movement distance is the sum of the integral multiple of one side length C of the unit exposure region U (m, n) and the distance a (0 <a <C), the distances a and b are appropriately set. The exposure points CN can be uniformly distributed in a region (area C × C) having the same size as each unit exposure region U (m, n).
[0059]
For example, as shown in FIG. 6, in order to distribute 240 exposure points in a region (area C × C = 20 μm × 20 μm) having the same size as the unit exposure region U (m, n), the X axis It is sufficient to arrange 16 exposure points along 15 and 15 along the Y axis, and the distances a and b are determined by the following calculation formulas.
a = C / 16 = 20 μm / 16 = 1.25 μm
b = C / 256 = 20 μm / 240 = 0.0833 μm
[0060]
Needless to say, setting the distance b to 0.0833 μm means that when the drawing table 16 is moved to the negative side of the X axis by a distance (A + a = 81.25 μm), each unit exposure area U (m , N) set the inclination angle α (about 0.0588 degrees) of the drawing table 16 so that the negative side of the Y-axis is shifted by 0.0833 μm.
[0061]
In FIG. 6, the exposure point indicated by the reference symbol CN (1, 1) is, for example, the first exposure unit 20 at the first exposure position. ₀₁ Assuming that the unit exposure area U (1,1) is obtained by the first micromirror M (1,1) included in the first line, the exposure point CN (5 , 1) is the first exposure unit 20 at the second exposure position. ₀₁ Is the center of the unit exposure region U (5, 1) obtained by the first micromirror M (5, 1) of the fifth line, and the exposure point CN (9, 1) is the first exposure at the third exposure position. Unit 20 ₀₁ Becomes the center of the unit exposure region U (9, 1) obtained by the micromirror M (9, 1) at the head of the ninth line.
[0062]
Further, an exposure point CN (61, 1) that is separated from the exposure point CN (1, 1) by a distance (+ 16a, −16b) is a micromirror M (61, 1) at the head of the 61st line at the 16th exposure position. The exposure point CN (65,1) that is the center of the unit exposure region U (61,1) obtained by () and is separated from the exposure point CN (1,1) by the distance (0, -a) is the 17th exposure. This is the center of the unit exposure area U (65, 1) obtained by the micromirror M (65, 1) at the head of the 65th line at the position. Similarly, an exposure point CN (897,1) that is separated from the exposure point CN (1,1) by a distance (0, -14a) is a micromirror M (897,1) at the head of the 897th line at the 225th exposure position. The exposure point CN (957,1), which is the center of the unit exposure area U (897,1) obtained by (1) and is separated from the exposure point CN (1,1) by the distance (15a, -15a), is the 240th exposure. This is the center of the unit exposure region U (957, 1) obtained by the first micromirror M (957, 1) of the 957th line at the position.
[0063]
Thus, 15 exposure units 20 ₀₁ ~ 20 ₁₅ If the drawing table 16 is intermittently moved to the negative side of the X axis under the above-described conditions, the exposure units 20 ₀₁ ~ 20 ₁₅ The center of the unit exposure region U (m, n) obtained by the individual micromirrors M (m, n), that is, the exposure point CN (m, n) has pitches a and b along the X axis and Y axis, respectively. Thus, 240 exposure points are uniformly distributed in a region C × C (20 μm × 20 μm) having the same size as the unit exposure region U (m, n).
[0064]
The exposure unit 20 ₀₁ ~ 20 ₁₅ It is of course possible to distribute the individual exposure points at a higher density over the entire drawing surface 32. For example, within an area of 20 μm × 20 μm, 480 exposure points, which are twice the above example, are uniformly distributed. In the case of arrangement, the distance A is set to twice the size C of the unit exposure area (40 μm), and the distances a and b are set to 1.25 / 2 μm and 0.0833 / 2 μm, respectively.
[0065]
In the example shown in FIG. 6, the 16 exposure points are arranged in parallel along the Y axis, but the exposure points are inclined along the Y axis by slightly changing the values of the distances a and b. It is also possible to arrange them.
[0066]
As described above, in the multiple exposure drawing apparatus 10 of the present embodiment, when drawing is performed based on the raster data of the circuit pattern, the circuit pattern is stored in whatever size the pixel size of the circuit pattern data is. It is possible to draw. In other words, it can be said that the pixel concept for the circuit pattern to be drawn does not exist on the multiple exposure drawing apparatus 10 side.
[0067]
For example, when the pixel size of the raster data is set to 20 μm × 20 μm, if “1” is given to any 1-bit data, one pixel area (20 μm × 20) corresponding to the 1-bit data at the time of exposure operation. The micromirror M (m, n) corresponding to each exposure point CN (m, n) included in 20 μm) is operated by the 1-bit data and rotated from the non-exposure position to the exposure position. One pixel area (20 μm × 20 μm) is subjected to multiple exposure for a total of 240 times.
[0068]
As another example, when the pixel size of raster data is set to 10 μm × 10 μm, if “1” is given to arbitrary 1-bit data, one corresponding to the 1-bit data at the time of exposure operation. The micromirror M (m, n) corresponding to each exposure point CN (m, n) included in the pixel area (10 μm × 10 μm) is operated by the 1-bit data and rotated from the non-exposure position to the exposure position. As a result, one pixel region (10 μm × 10 μm) is subjected to multiple exposure for a total of 60 times.
[0069]
Note that the exposure time, that is, the time during which each micromirror M (m, n) is held at the exposure position, the number of exposures in one pixel region on the drawing surface 32, the object to be drawn 30 (in this embodiment, photo It is determined based on the sensitivity of the resist layer), the light intensity of the light source device 22, and the like, and is set so as to obtain a desired exposure amount for each one-pixel exposure region.
[0070]
FIG. 7 is a block diagram of the multiple exposure drawing apparatus 10. As shown in the figure, the multiple exposure drawing apparatus 10 is provided with a system control circuit 34 composed of a microcomputer. That is, the system control circuit 34 is a central processing unit (CPU), a read-only memory (ROM) that stores programs and constants for executing various routines, and a write / read function that temporarily stores operation data and the like. And a general memory (RAM) and an input / output interface (I / O), and controls the overall operation of the multiple exposure drawing apparatus 10.
[0071]
The drawing table 16 is driven along the X-axis direction by the drive motor 36. The drive motor 36 is configured as a stepping motor, for example, and the drive control is performed according to the drive pulse output from the drive circuit 38. As described above, a drive mechanism including a ball screw or the like is interposed between the drawing table 16 and the drive motor 36. Such a drive mechanism is symbolically indicated by a broken-line arrow in FIG. Yes.
[0072]
The drive circuit 38 is operated under the control of the drawing table control circuit 40, and the drawing table control circuit 40 is connected to a drawing table position detection sensor 42 provided in the drawing table 16. The drawing table position detection sensor 42 detects an optical signal from a linear scale 44 installed along the movement path of the drawing table 16 and detects its position along the X-axis direction of the drawing table 16. In FIG. 7, the detection of the optical signal from the linear scale 44 is symbolically shown by a broken line arrow.
[0073]
During movement of the drawing table 16, the drawing table position detection sensor 42 sequentially detects a series of optical signals from the linear scale 44 and outputs them to the drawing table control circuit 40 as a series of detection signals (pulses). In the drawing table control circuit 40, a series of detection signals input thereto are appropriately processed, and a series of control clock pulses are generated based on the detection signals. A series of control clock pulses are output from the drawing table control circuit 40 to the drive circuit 38, and the drive circuit 38 generates drive pulses for the drive motor 36 according to the series of control clock pulses. In short, the drawing table 16 can be moved along the X-axis direction with an accuracy corresponding to the accuracy of the linear scale 44. Such movement control of the drawing table 16 is well known.
[0074]
As shown in FIG. 7, the drawing table control circuit 40 is connected to the system control circuit 34, whereby the drawing table control circuit 40 is performed under the control of the system control circuit 34. On the other hand, a series of detection signals output from the drawing table position detection sensor 42 are also input to the system control circuit 34 via the drawing table control circuit 40, whereby the system control circuit 34 moves the drawing table 16 along the X axis. The position can always be monitored.
[0075]
The system control circuit 34 is connected to a CAD station or CAM station via a LAN (Local Area Network), and the vector data of the circuit pattern created and processed there is transferred to the system control circuit 34 from the CAD station or CAM station. A hard disk device 46 is connected to the system control circuit 34 as data storage means. When the circuit pattern vector data is transferred from the CAD station or CAM station to the system control circuit 34, the system control circuit 34 stores the circuit pattern vector data. Once written to the hard disk device 46, it is stored. A keyboard 48 is connected to the system control circuit 34 as an external input device, and various command signals and various data are input to the system control circuit 34 via the keyboard 48.
[0076]
The raster conversion circuit 50 is operated under the control of the system control circuit 34. Prior to the drawing process, vector data of a circuit pattern to be drawn is read from the hard disk device 46 and output to the raster conversion circuit 50 where it is converted into raster data. This raster data is written into the bitmap memory 52. In short, the bit map memory 52 stores bit data representing circuit patterns of “0” and “1”. Data conversion processing by the raster conversion circuit 50 and data writing processing to the bitmap memory 52 are started by a command signal input via the keyboard 48.
[0077]
The bitmap memory 52 includes 15 exposure data generation circuits 54. ₀₁ ~ 54 ₁₅ (In FIG. 7, four exposure data generation circuits 54 are provided. ₀₁ , 54 ₀₂ , 54 ₀₃ And 54 ₁₅ Connected only). 15 exposure data circuits 54 ₀₁ ~ 54 ₁₅ Each has 15 exposure units 20 ₀₁ ~ 20 ₁₅ The necessary raster data is read from the bitmap memory 52, exposure data to be given to each exposure unit is generated and output to the DMD drive circuit 56.
[0078]
Exposure data is exposure unit 20 ₀₁ ~ 20 ₁₅ Bit data for positioning each micromirror included in the exposure position or non-exposure position. When the exposure data is '1', the micromirror is determined as the exposure position, and when the exposure data is '0' The mirror is set at the non-exposure position. Exposure data is exposure unit 20 ₀₁ ~ 20 ₁₅ It is rewritten every time the exposure operation is repeated.
[0079]
The DMD driving circuit 56 uses the exposure unit 20 based on the given exposure data. ₀₁ ~ 20 ₁₅ Are operated independently, whereby each exposure unit 20 is operated. ₀₁ ~ 20 ₁₅ The individual micromirrors selectively perform the exposure operation.
[0080]
In FIG. 7, the exposure operation of each micromirror is symbolically illustrated by a dashed arrow. In FIG. 7, only one exposure unit is shown in order to avoid complication of the drawing, but in reality, 15 exposure units (20 ₀₁ ~ 20 ₁₅ Needless to say, they exist and are each driven by the DMD drive circuit 56.
[0081]
FIG. 8 schematically shows part of raster data of a circuit pattern developed on the bitmap memory 52. The line number L shown in the figure corresponds to the drawing line number along the Y axis of the circuit pattern to be drawn on the drawing surface 32, and each line includes 1280 × 15 bit data. As shown in the figure, each bit data is indicated by “B”, and “B” is given either “1” or “0” according to the circuit pattern to be drawn.
[0082]
According to the present invention, the pixel size of circuit pattern data (raster data), that is, the size of each bit data “B” can be given various sizes at the design stage of the circuit pattern. For example, if the size of the bit data “B” is 10 μm × 10 μm, the width of the drawing line to be drawn on the drawing surface 32 is also 10 μm, and if the size of the bit data “B” is 20 μm × 20 μm, the drawing line When the size of the bit data “B” is 30 μm × 30 μm, the width of the drawing line is also 30 μm.
[0083]
As shown in FIG. 8, 1280 × 15 bit data included in each line is divided into first to fifteenth groups. When the drawing surface 32 moves in a direction parallel to the X axis as shown in FIGS. 3 and 4, the first exposure unit 20 ₀₁ The data necessary for the circuit pattern to be drawn is raster data for 1280 bits from the left end. On the other hand, when the drawing surface 32 moves relative to the X axis as shown in FIG. ₀₁ Shifts along the Y-axis, the generation of exposure data requires raster data of 1280 bits or more.
[0084]
Therefore, in the present embodiment, the first exposure data generation circuit 54 is used. ₀₁ Read out the raster data for (1280 + β) bits from the top (left end in the figure) from the bitmap memory 52, and 1280 microarrays arranged in the Y-axis direction from the read raster data of the first group. Select 1280-bit raster data to be given to the mirror and output it as exposure data.
[0085]
Second exposure data generation circuit 54 ₀₂ Read out from the bitmap memory 52, the raster data for 1280 bits from the 1281st to 2560th from the left end, and the raster data for (1280 + 2β) bits larger by the preceding and subsequent β bits as a second group, Second exposure unit 20 ₀₂ The exposure data to be given to is generated. Third to fourteenth exposure data generation circuit 54 ₀₃ ~ 54 ₁₄ Also for the second exposure data generation circuit 54 ₀₂ Similarly, (1280 + 2β) bits of raster data are read to generate exposure data. 15th exposure data generation circuit 54 ₁₅ Reads the last (1280 + β) bits of raster data (the right end in the figure) to generate exposure data.
[0086]
The number of bits β is a constant set in advance in the system control circuit 34, and is preferably a positive number larger than the number of bits corresponding to the relative movement amount of the first exposure unit along the Y axis, for example, about several tens. Moreover, it is not necessary to make all the numbers of raster data in each group equal, and each group may be arbitrarily changed.
[0087]
For each bit data “B” of each group, address data [L _x , R _y ] Is given. Address data component L _x Indicates the line number L (FIG. 8), and the address data component R _y Indicates how many bits are counted from the most significant bit of each group. For example, address data [000001,0001] represents the most significant bit bit data “B” of line number 1 of each group, and address data [000003,0001] represents the most significant bit bit data of line number 3 of each group. The address data [000001, 1278] represents the 1278th bit data “B” counted from the most significant bit of the line number 1 of each group, and the address data [000003, 1278] represents each group. The 1278th bit data “B” counted from the most significant bit of the line number 3 represents the bit data “B” of the least significant bit of the line number 1 of each group, and the address data [000001,1280] represents the address. Data [000003, 1280] is line number 3 of each group. It represents the bit data "B" of the least significant bit.
[0088]
Here, the first exposure unit 20 ₀₁ The relationship between the individual micromirrors M (m, n) and the bit data “B” at each exposure position will be described. Other exposure unit 20 ₀₂ ~ 20 ₁₅ For the first exposure unit 20 ₀₁ Therefore, the description is omitted here.
[0089]
Exposure unit 20 ₀₁ Are sequentially moved by a distance (A + a) in the X-axis direction from the exposure start position, that is, the first exposure position, and reach the i-th exposure position, the exposure unit 20 at that time ₀₁ , Specifically, the XY coordinates Xs (i) and Ys (i) of the exposure point CN (1,1) corresponding to the first micromirror M (1,1) of the first line are exposure position data. It is defined as (first coordinate data) and is expressed by the following equations (1) and (2).
[0090]
Xs (i) = (A + a) (i-1) (1)
Ys (i) = − b (i−1) (2)
Here, “i” is the number of exposures.
[0091]
The exposure position data Xs (i) and Ys (i) are obtained for each exposure operation, that is, the exposure unit 20. ₀₁ Each time the relative movement is performed, the system control circuit 34 sequentially calculates. The exposure position data Xs (0) and Ys (0) at the exposure start position are both 0.
[0092]
Subsequently, the first exposure unit 20 ₀₁ In order to specify the relative position of an arbitrary micromirror M (m, n) (1 ≦ m ≦ 1024, 1 ≦ n ≦ 1280) in FIG. A two-dimensional coordinate system having two axes parallel to the X-axis and the Y-axis with the exposure point CN (1,1) as the origin is set, and the relative coordinates Xp () of the exposure point CN (m, n) in this two-dimensional coordinate system. m, n) and Yp (m, n) are defined as exposure point coordinate data (second coordinate data). That is, the nth micromirror M (m, n) in the mth line is separated from the first micromirror M (1,1) in the first line by a distance Xp (m, n) in the X direction. The exposure operation is always performed at a position separated by a distance Yp (m, n) in the Y direction. The exposure point coordinate data Xp (m, n) and Yp (m, n) are expressed as the following equations (3) and (4).
[0093]
Xp (m, n) = (m−1) C (3)
Yp (m, n) = (n−1) Cb (m−1) (4)
Here, C is the size of the unit exposure region U (m, n), and b is the amount of movement in the Y direction when the exposure point CN (m, n) is relatively moved by (A + a) in the X-axis direction. .
[0094]
The exposure point coordinate data Xp (m, n) and Yp (m, n) are eigenvalues corresponding to 1280 micromirrors, calculated by the system control circuit 34 when the distance b is determined, and stored in the RAM. It is stored and reviewed every time drawing of the entire drawing surface 32 is performed, and updated as necessary.
[0095]
First exposure unit 20 ₀₁ Reaches the i-th exposure position from the exposure start position, that is, the relative position coordinate data of the micromirror M (m, n), that is, the XY coordinates P [x (m, n), y of the exposure point CN (m, n). (M, n)] can be represented by the sum of exposure position data and exposure point coordinate data, as shown in the following equations (5) and (6).
[0096]
x (m, n) = Xs (i) + Xp (m, n) (5)
y (m, n) = Ys (i) + Yp (m, n) (6)
[0097]
When an exposure point CN (m, n) corresponding to an arbitrary micromirror M (m, n) is included in a certain pixel area at the i-th exposure position, bit data “ B ”address [L _x , R _y ] Can be expressed by the following equation using the calculation results of the two equations (5) and (6).
[0098]
L _x = INT [x (m, n) / PS] +1 (7)
R _y = INT [y (m, n) / PS] +1 (8)
Here, generally, when division e / f is performed, the operator INT [e / f] represents the quotient of division e / f, and when 0 ≦ e <f, INT [e / f] = 0. Is defined as “PS” represents the size of the bit data “B”.
[0099]
Thus, at the i-th exposure position, the exposure data for operating the micromirror M (m, n) corresponding to the XY coordinates P [x (m, n), y (m, n)] is ( 7) and the address [L determined by the calculation result of the expression (8) _x , R _y ] Bit data “B” is read from the bitmap memory 52.
[0100]
When the X component of the XY coordinates P [x (m, n), y (m, n)] is a negative value, that is, x (m, n) <0, the exposure point CN (m, n) has not yet entered the drawing area on the drawing surface 32, and the micromirror M (m, n) is operated according to the dummy data "0". When the Y component of the XY coordinates P [x (m, n), y (m, n)] is a negative value, that is, y (m, n) <0, the exposure point CN (m, n n) is considered to exceed the negative boundary line along the Y axis of the drawing region, and in this case, the micromirror M (m, n) is operated according to the dummy data “0”.
[0101]
As described above, in the multiple exposure drawing apparatus 10 of the present embodiment, the exposure unit 20 ₀₁ ~ 20 ₁₅ Are arranged in the Y direction which is the first direction, and the individual exposure units 20 are arranged. ₀₁ ~ 20 ₁₅ Thus, a partial circuit pattern is drawn by multiple exposure on the drawing area divided in the Y direction, and one exposure area (entire exposure area U in the X direction which is the second direction) is drawn. ₀₁ , ..., U ₁₅ The exposure operation is performed while moving a distance relatively shorter than the size of (). Specifically, every time a predetermined distance of movement, 15 exposure units 20 ₀₁ ~ 20 ₁₅ Relative position coordinates of 1280 × 1024 micromirrors M (m, n) included in the image, that is, XY coordinates P [x (m, n), y (m, n)] of the exposure point CN (m, n). By calculating and positioning the micromirror M (m, n) at the exposure position or the non-exposure position based on the bit data corresponding to the XY coordinates P, the entire circuit pattern is placed on the drawing object that is being exposed. I'm drawing.
[0102]
Here, as a feature of this embodiment to be noted, the individual exposure units 20 are provided. ₀₁ ~ 20 ₁₅ In other words, the entire circuit pattern can be obtained by partially overlapping the band-shaped regions exposed by the above, that is, partial patterns (see FIG. 3) and joining them in the Y direction. At the boundary between two adjacent band-like regions, due to individual differences of exposure units, specifically, the optical characteristics of the imaging optical system are slightly different, or due to a slight shift in the mounting position of the exposure unit, The continuity or unity of the circuit pattern is impaired in the Y direction. Therefore, in this embodiment, two adjacent belt-like regions are partially overlapped, and the number of micromirrors to be operated by both exposure units is changed in both the X direction and the Y direction, thereby providing continuity and integrity. An unbroken drawing circuit pattern is obtained.
[0103]
With reference to FIG. 10, the overlapping of the band-like regions (partial patterns) will be described in detail. FIG. 10 shows the first, second and third exposure units 20. ₀₁ , 20 ₀₂ And 20 ₀₃ Full exposure area Ua corresponding to ₀₁ , Ua ₀₂ And Ua ₀₃ And each exposure unit 20 ₀₁ , 20 ₀₂ And 20 ₀₃ A strip-shaped area Ra which is multiple-exposed by ₀₁ , Ra ₀₂ And Ra ₀₃ It is a schematic diagram which shows the relationship. In order to simplify the description, a case where the drawing surface 32 is moved parallel to the X axis (FIG. 3) will be described here.
[0104]
First exposure unit 20 ₀₁ Is the entire exposure area Ua on the drawing surface 32. ₀₁ Is drawn by multiple exposure. This belt-like region is designated as the first belt-like region Ra. ₀₁ (Indicated by the upward hatching) and the length in the Y direction is defined as the exposure width D1. This first strip region Ra ₀₁ The Y-direction length of the circuit pattern drawn is equivalent to about 1/15 of the Y-direction length of the entire circuit pattern. Similarly, the second exposure unit 20 ₀₂ The region of the exposure width D1 that is subjected to multiple exposure by the second strip region Ra ₀₂ The third exposure unit 20 (indicated by the right-down hatching) ₀₃ The region of the exposure width D1 that is subjected to multiple exposure by the third strip region Ra ₀₃ It is defined as
[0105]
Two adjacent belt-like regions, for example, the first belt-like region Ra ₀₁ And the second strip region Ra ₀₂ Are partially overlapping each other, and the overlapping region is defined as the first boundary region Rb. ₀₁ And the length in the Y direction is defined as the boundary width D2. This boundary width D2 is 5 to 10% of the exposure width D1. First boundary region Rb ₀₁ Is the first exposure unit 20 ₀₁ And the second exposure unit 20 ₀₂ Both are subjected to multiple exposure.
[0106]
First exposure unit 20 ₀₁ The area that can be exposed by one exposure operation is a rectangular overall exposure area Ua surrounded by a thick solid line. ₀₁ However, the second exposure unit 20 indicated by the hatching of the broken line ₀₂ Side (upper side in the figure) edge triangle area Ud ₀₁ Is not exposed. That is, the first exposure unit 20 ₀₁ The triangular region Ud ₀₁ The micromirrors corresponding to are kept in the non-exposure position and do not operate according to the raster data. On the other hand, the second exposure unit 20 ₀₁ In FIG. 5, the entire exposure area Ua ₀₂ First exposure unit 20 of ₀₁ Triangular region Uc on the side (lower side in the figure) edge ₀₂ The micro-mirror corresponding to is also stopped at the non-exposure position and does not substantially operate.
[0107]
Therefore, the first boundary region Rb ₀₁ First exposure unit 20 used for exposure ₀₁ The number of micromirrors gradually decreases at a constant rate along the X axis in the negative direction (left side of the figure), while the first boundary region Rb ₀₁ Second exposure unit 20 used for exposure of ₀₂ The number of micromirrors gradually increases at a constant rate in the negative direction along the X axis. Similarly in the Y direction, the first boundary region Rb ₀₁ First exposure unit 20 used for exposure ₀₁ The number of micromirrors gradually decreases from a total of 1024 at a constant rate toward the positive direction (upward in the figure) along the Y axis and finally reaches zero, while the first boundary region Rb ₀₁ Second exposure unit 20 used for exposure of ₀₂ The number of micromirrors gradually increases from 0 to a constant rate in the positive direction along the Y axis, and finally reaches 1024.
[0108]
Thus, the two exposure units 20 ₀₁ , 20 ₀₂ The number of micromirrors operating in the first direction along the positive direction of the Y axis (first exposure unit 20 ₀₁ ) Gradually decreases and the other (second exposure unit 20) ₀₂ ) Increases, the first exposure unit 20 moves forward in the positive direction of the Y axis. ₀₁ The second exposure unit 20 is gradually reduced as the influence of the second exposure unit 20 decreases. ₀₂ The effect of gradually increases. Accordingly, the two exposure units 20 ₀₁ , 20 ₀₂ Generation of a clear streak caused by a difference in optical characteristics of each other and a slight displacement of the mounting position is prevented, and the first strip region Ra in the Y direction is prevented. ₀₁ To the second strip region Ra ₀₂ The circuit pattern that reaches is connected continuously and integrally.
[0109]
Second exposure unit 20 ₀₂ The second strip region Ra which is multiple-exposed by ₀₂ And the third exposure unit 20 ₀₃ The third strip region Ra which is multiple-exposed by ₀₃ Similarly, the second boundary region Rb where the two overlap each other ₀₂ As a result of blurring, the second and third exposure units 20 ₀₂ , 20 ₀₃ The generation of clear streaks due to the difference in the optical characteristics and the minute displacement of the mounting position is prevented, and the circuit patterns are connected continuously and integrally.
[0110]
The first exposure unit 20 located at the end most in the Y direction. ₀₁ Full exposure area U ₀₁ However, the triangular region is not provided because it is not necessary to connect the lower sides in the figure. A fifteenth exposure unit 20 provided at the opposite end. ₁₅ Full exposure area U ₁₅ Similarly, no triangular area is provided on the side to be the edge of the drawing area. Remaining exposure unit 20 ₀₄ ~ 20 ₁₄ For the second and third exposure units 20 ₀₂ , 20 ₀₃ Perform the same connection as.
[0111]
Referring to FIG. 11, second exposure unit 20 ₀₂ Parallelogram region Ub ₀₂ A procedure for operating only the micromirror corresponding to the above will be described. As shown in FIG. 11A, the second exposure unit 20 ₀₂ The exposure point corresponding to each micromirror is a rectangular overall exposure region U ₀₂ The relative position of an arbitrary exposure point CN (m, n) (1 ≦ m ≦ 1024, 1 ≦ n ≦ 1280) is a two-dimensional coordinate with the exposure point CN (1, 1) as the origin. That is, it is expressed by exposure point coordinate data [Xp (m, n), Yp (m, n)].
[0112]
Here, the predetermined value yd shown in the equation (9) is added to the Y component Yp (m, n) of the exposure point coordinate data, respectively, and the coordinate conversion of the exposure point CN (m, n) is performed. By this coordinate conversion, the distribution shape of the exposure points is transformed from a rectangle into a parallelogram as shown in FIG. D2 is the boundary width.
yd (m, n) = (m / 1024) × D2 (9)
[0113]
Then, an exposure point whose Y component value {Yp (m, n) + yd (m, n)} is equal to or larger than the boundary width D2 and equal to or smaller than the exposure width D1 is determined as an exposure execution group, and the Y component value is equal to the boundary width. By dividing exposure points smaller than D2 or larger than exposure width D1 into exposure stop groups, the exposure points are divided into two groups. In FIG. 11C, the area including the exposure point of the exposure execution group is indicated by hatching. FIG. 11C shows a case where an arbitrary exposure point CN (m, n) is included in the exposure execution group. At this time, the second exposure unit 20 ₀₂ The micromirror (M (m, n)) corresponding to the exposure point CN (m, n) is determined as the micromirror to be exposed. On the other hand, dummy data “0” is given to the micromirrors corresponding to the exposure points of the exposure stop group, so that these micromirrors do not perform the exposure operation.
[0114]
Therefore, as shown in FIG. 11D, the distribution shape of the micromirrors (indicated by hatching) corresponding to the exposure points of the exposure execution group, that is, the shape of the region actually exposed on the drawing surface 32 is the right shoulder. It becomes a parallelogram having sides inclined upward. In FIG. 11D, the hatched area is the parallelogram area Ub in FIG. ₀₂ It corresponds to. Thus, in the present embodiment, the micromirror to be operated is determined using only the exposure point coordinate data [Xp (m, n), Yp (m, n)]. The second exposure unit 20 ₀₂ In FIG. 1, the upper limit value of the Y coordinate for grouping is D1, and the lower limit value is D2. ₀₁ Thus, when exposing the most negative side in the Y direction, the upper limit value is D1 and the lower limit value is 0, and the fifteenth exposure unit 20 ₀₁ Thus, when exposing the most positive side in the Y direction, the upper limit value is (D1 + D2) and the lower limit value is D2.
[0115]
12 shows the first exposure data generation circuit 54 shown in FIG. ₀₁ It is a block diagram which shows the structure of in detail. In FIG. 12, the remaining 14 exposure data generation circuits 54 are shown. ₀₂ ~ 54 ₁₅ The first exposure data generation circuit 54 ₀₁ The description is omitted here.
[0116]
First exposure data generation circuit 54 ₀₁ Is the first exposure area Ra ₀₁ In order to draw a circuit pattern on the first exposure area Ra ₀₁ And the first exposure area Ra ₀₁ The raster data of the circuit pattern corresponding to the larger area (hereinafter referred to as the first divided area), that is, the first group of raster data shown in FIG. 20 ₀₁ The exposure data to be given to is generated.
[0117]
More specifically, the first exposure data generation circuit 54 ₀₁ Includes a divided area check circuit 72 and a divided area memory 74, and the divided area check circuit 72 has address data (hereinafter referred to as divided area data) of raster data corresponding to the first divided area by the system control circuit 34. And raster data corresponding to the first divided area is extracted from the raster data sequentially read from the bitmap memory 52 and stored in the divided area memory 74.
[0118]
First exposure data generation circuit 54 ₀₁ Is provided with an exposure point coordinate data memory 76. In this exposure point coordinate data memory 76, exposure point coordinate data [Xp (m) corresponding to the micromirrors M (m, n) arranged in a 1024 × 1280 matrix. , N), Yp (m, n)] (1 ≦ m ≦ 1024, 1 ≦ n ≦ 1280) is stored. The exposure point coordinate data [Xp (m, n), Yp (m, n)] is reviewed each time the entire drawing surface 32 is drawn, and is given from the system control circuit 34 and updated as necessary. .
[0119]
First exposure data generation circuit 54 ₀₁ The counter 82 is supplied with the basic control clock pulse CLK 1 and the exposure clock pulse E_CLK from the system control circuit 34, and the output is input to the exposure point coordinate data memory 76 and the exposure data memory 92.
[0120]
The basic control clock pulse CLK1 is a pulse for controlling the timing for sequentially operating each of the 1310720 micromirrors, and the exposure clock pulse E_CLK is a pulse for controlling the exposure start timing. The cycle of the exposure clock pulse E_CLK is set to 1310720 times or more of the cycle of the clock pulse CLK1.
[0121]
The counter 82 counts the number of pulses of the basic control clock pulse CLK1, and outputs the count value. This count value is reset to the initial value 0 every time the exposure clock pulse E_CLK is input. Accordingly, the output from the counter 82 corresponds to address data indicating the order in which the bit data to be applied to each micromirror is read from the exposure point coordinate data memory 76 or the exposure data memory 92.
[0122]
The first exposure data generation circuit 54 ₀₁ Is provided with an exposure position data memory 86. The exposure position data memory 86 changes the first exposure unit 20 that changes every exposure operation. ₀₁ Exposure position data [Xs (i), Ys (i)] (i is the number of exposures) is stored. The exposure position data [Xs (i), Ys (i)] is supplied from the system control circuit 34 and updated every drawing operation, that is, whenever the parameter i is updated.
[0123]
First exposure data generation circuit 54 ₀₁ The counter 84 receives the exposure clock pulse E_CLK from the system control circuit 34 and counts the number of pulses. The count value (i) is output to the exposure position data memory 86 as address data for reading the exposure position data [Xs (i), Ys (i)] from the exposure position data memory 86.
[0124]
The exposure point coordinate data memory 76 operates in synchronism with the basic control clock pulse CLK1, and each time the values of parameters m and n, which are address data, are updated, the exposure point coordinate data is sequentially supplied to the gradient processing circuit 78 and the adder 88. [Xp (m, n), Yp (m, n)] is output. The exposure position data memory 86 outputs exposure position data [Xs (i), Ys (i)] to the adder 88 every time the parameter i which is address data is changed in synchronization with the exposure clock pulse E_CLK.
[0125]
The tilt control circuit 78 gives tilt data, that is, yd (m, n) (see equation (9)) to be added to the Y component Yp (m, n) of the individual exposure point coordinate data. The inclination data yd (m, n) is sequentially added to the Y component Yp (m, n) of the exposure point coordinate data sequentially read from the exposure point coordinate data memory 76.
[0126]
The exposure width check circuit 80 adds the Y component of each exposure point coordinate data [Xp (m, n), Yp (m, n)] and the inclination data {Yp (m, n) + yd (m, n). }, The exposure point CN (m, n) is divided into the exposure execution group or the exposure stop group described above, and the upper limit value (D1) and the lower limit value (0) for determining each group are exposures. It is given by the system control circuit 34 as width data. When the Y component {Yp (m, n) + yd (m, n)} is within the range between the lower limit value and the upper limit value, the data “1” is set so that the corresponding exposure point CN (m, n) is determined as the exposure execution group. "" Is output, and when the Y component is outside the range between the lower limit value and the upper limit value, data "0" is output to set the corresponding exposure point CN (m, n) as the exposure stop group.
[0127]
Individual exposure point coordinate data [Xp (m, n), Yp (m, n)] and current exposure position data [Xs (i), Ys (i)] are input to the adder 88. If the output of the exposure width check circuit 80 is “1”, the relative position coordinate data [x (m, n), y (m, n)] which is the sum of the two is output to the pixel processing circuit 90. When the output of the exposure width check circuit 80 is “0”, “0” is output. Since the exposure position data [Xp (m, n), Yp (m, n)] and the exposure point coordinate data [Xs (i), Ys (i)] are values expressed in μm units, the pixel processing circuit 90 Then, the relative position coordinate data [x (m, n), y (m, n)] expressed in units of μm is converted into data based on the pixel size PS of the raster data to be drawn. Read address data [L when this data is read out from the divided area memory 74 _x , R _y ]. When the value output from the adder 88 is “0”, there is no corresponding address, that is, the exposure point CN (m, n) is regarded as an exposure stop group, and the exposure data memory 92 stores dummy data “ 0 "is given.
[0128]
The raster data read from the divided area memory 74 is temporarily stored in the exposure data memory 92, and the exposure data is based on the output from the counter 82, that is, the address data indicating the order of reading the bit data to be applied to each micromirror. And output to the DMD driving circuit 56. When the coordinate conversion of the circuit pattern is performed, the system control circuit 34 uses the exposure point coordinate data [Xs (i), Ys (i)] or the exposure position coordinate data [Xp (m, n), Yp (m, n)] is subjected to coordinate transformation, and the position of raster data to be read out may be changed accordingly.
[0129]
Thus, the first exposure unit 20 ₀₁ In (1), raster data of (1280 + β) bits corresponding to a divided area longer than the exposure width D1 by a predetermined length is read, and a strip-shaped area Ra included in the divided area is read out. ₀₁ Exposure data for multiple exposure is generated. In the present embodiment, raster data corresponding to a divided area wider than the belt-like region is read to generate exposure data. Therefore, when the belt-like region is shifted in the Y direction as described above, or the circuit pattern is subjected to coordinate transformation (rotation, Enlargement, reduction, movement, etc.) can be adequately handled. The second to fifteenth exposure data generation circuits 54 ₀₂ ~ 54 ₁₅ It goes without saying that exposure data is also generated in the same way.
[0130]
【The invention's effect】
As described above, the multiple exposure drawing apparatus of the present invention combines the partial patterns drawn by the individual exposure units in a partially overlapping manner, and determines the number of modulation elements to be driven corresponding to the boundary region where the partial patterns overlap. Since the transition is made gradually along the relative movement direction of the drawing surface, there is an advantage that the entire pattern having good continuity and unity can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a multiple exposure drawing apparatus according to the present invention.
FIG. 2 is a schematic conceptual diagram for explaining functions of an exposure unit used in the multiple exposure drawing apparatus according to the present invention.
3 is a plan view for explaining a drawing surface of an object to be drawn on the drawing table of the multiple exposure drawing apparatus shown in FIG. 1 and an exposure area by each exposure unit; FIG.
FIG. 4 is a schematic diagram for explaining the principle of a multiple exposure drawing method executed by a multiple exposure drawing apparatus according to the present invention, in which exposure units are arranged at a plurality of exposure positions along the X axis of an XY coordinate system. It is a figure which shows the state moved sequentially.
FIG. 5 is a schematic diagram similar to FIG. 4, and when the exposure unit is sequentially moved to a plurality of exposure positions along the X axis of the XY coordinate system, the exposure unit moves a predetermined distance along the Y axis. It is a figure which shows the state displaced only by time.
FIG. 6 shows how the center of a unit exposure area obtained by a predetermined micromirror of the exposure unit is distributed within the predetermined area when the exposure unit is sequentially moved to a plurality of exposure positions according to the multiple exposure method of the present invention. It is explanatory drawing which shows whether to do.
FIG. 7 is a block diagram of a multiple exposure drawing apparatus according to the present invention.
FIG. 8 is a schematic diagram showing a part of raster data of a circuit pattern to be drawn by the multiple exposure drawing apparatus according to the present invention developed on a bitmap memory.
9 is a schematic diagram showing a relationship between a part of the bit data shown in FIG. 8 and its read address data. FIG.
FIG. 10 is a view for explaining superposition of band-like regions drawn by individual exposure units.
FIG. 11 is a schematic diagram showing a procedure for controlling the number of micromirrors that draw a boundary region where belt-like regions overlap.
12 is a block diagram showing in detail the inside of the first exposure data generation circuit shown in FIG. 7;
[Explanation of symbols]
10 Multiple exposure drawing device
20 ₀₁ ... 20 ₁₅ Exposure unit
27 DMD element
M (m, n), M (1, 1), ... M (1024, 1280) Micromirror (modulation element)
30 Drawing object
32 Drawing surface
34 System control circuit
54 ₀₁ ... 54 ₁₅ Exposure data generation circuit

Claims (7)

A multiple-exposure drawing apparatus that obtains an entire pattern obtained by connecting the partial patterns by drawing a plurality of partial patterns arranged along the first direction on a drawing surface by multiple exposure,
An exposure unit having a large number of modulation elements arranged in a matrix, and driving the modulation elements based on raster data of the partial pattern;
Arrangement means for arranging the exposure units by the same number as the number of the partial patterns along the first direction;
Moving means for moving the drawing surface relative to the exposure unit along a second direction different from the first direction;
Modulation that gradually reduces or gradually increases the number of modulation elements to be driven corresponding to the boundary region where the partial patterns overlap for each exposure unit that draws two adjacent partial patterns along the second direction. A multi-exposure drawing apparatus comprising: an element selecting unit. 2. The multiple exposure drawing apparatus according to claim 1, wherein an area of the boundary region occupies 5 to 10% of an area that can be drawn by one exposure unit. Memory means for holding raster data of the entire pattern;
The first coordinate data indicating the relative position of the exposure unit with respect to the drawing surface and the second coordinate indicating the relative position of each of the modulation elements in the exposure unit are added to make the relative of the individual modulation elements with respect to the drawing surface. Address calculation means for calculating position coordinate data and generating address data corresponding to the pixel size of the raster data based on the relative position coordinate data for each of the modulation elements;
Exposure data generating means for reading out raster data corresponding to the address data from the memory means and generating exposure data for instructing the individual modulation elements to perform exposure operation or exposure operation stop; and
The modulation element selection means supplies the exposure data generation means with the address data obtained from the address calculation means for the modulation elements to be exposed, and the exposure data generation means for dummy data for the modulation elements to be stopped for exposure. The multiple-exposure drawing apparatus according to claim 1, wherein The entire exposure area exposed by one exposure of each of the exposure units has a rectangular shape with a length D1 in the first direction, and two entire exposure areas adjacent in the first direction have a length D2 (D2 <D1). The multiple exposure drawing apparatus according to claim 1, wherein the multiple exposure drawing apparatus overlaps. 5. The multiple exposure drawing according to claim 4, wherein a first direction length D <b> 2 in which two adjacent whole surface exposure regions overlap is 5 to 10% of a first direction length D <b> 1 of the whole surface exposure region. apparatus. One of two adjacent whole surface exposure regions is located on the other whole surface exposure region side, has a first direction length D2 and a second direction length equal to the second direction length of the whole surface exposure region. The region is defined as a first exposure stop region, and the other one of the two adjacent whole surface exposure regions is located on the one whole surface exposure region side, the first direction length is D2, and the second direction length is the whole surface exposure. The triangular area equal to the length in the second direction of the area is defined as the second exposure stop area, and the exposure operation of the modulation element corresponding to the first and second exposure stop areas is stopped. 5. The multiple exposure drawing apparatus according to 4. A multiple exposure drawing method for obtaining a whole pattern obtained by joining the partial patterns by drawing a plurality of partial patterns arranged along a first direction on a drawing surface by multiple exposure,
An exposure unit having a large number of modulation elements arranged in a matrix and driving the modulation elements based on the raster data of the partial patterns is arranged in the first direction by the same number as the number of the partial patterns. The drawing surface is moved relative to the exposure unit along a second direction different from the first direction, and an exposure unit that draws two adjacent partial patterns in a boundary region where the partial patterns overlap. A multiple exposure drawing method, wherein the number of corresponding modulation elements to be driven is gradually decreased or gradually increased at a constant rate along the second direction.

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