KR102415432B1 - Exposure device and exposure method - Google Patents

Abstract

An exposure apparatus WHEREIN: A pattern is formed so that there may be no exposure irregularity.
In an exposure apparatus equipped with a DMD, a plurality of divided exposure areas are defined for an exposure area, the exposure data of the first divided exposure area is stored in the buffer memory 38A, and then sequentially shifted to the buffer memory according to the exposure operation while shifting Perform multiple exposure operations. In addition, when mask data is generated and stored in the mask memory, the read address to the mask memory is changed so that the mask data is cyclically shifted for each column data for each exposure operation.

Description

Exposure apparatus and exposure method

The present invention relates to a maskless exposure apparatus for forming a pattern on a substrate or the like by means of a light modulation element array, and more particularly, to a multiple exposure operation using a mask pattern.

In the maskless exposure apparatus, a pattern is directly formed using an optical modulation element array such as a DMD in which a plurality of micromirrors are arranged in a matrix. In there, each micromirror is controlled by generating raster data based on the pattern data and inputting the raster data (exposure data) to the optical modulation element array.

In order to raise the pattern resolution, the DMD is set so that its projection area (exposure area) is inclined with respect to the scanning direction. While the drawing table on which the substrate is mounted is moved, multiple exposure operations are performed according to the pitch interval at which the projection areas between adjacent micromirrors overlap in the scanning direction and the sub-scanning direction, respectively.

In multiple exposure, the exposure pitch is adjusted so that the projection area center point (hereinafter referred to as the exposure point) at the time of the exposure shot can be scattered as much as possible within the size (cell size) of the projection area by one micromirror, have. Thereby, the resolution of the cell size or less can be acquired at the time of pattern formation (refer patent document 1, for example).

When the exposure area is slightly inclined with respect to the scanning direction, certain specific drawing is performed due to overlap of exposure areas generated between adjacent exposure heads, meandering of the mirror projection area due to the scanning mechanism, etc. The total exposure amount when the exposure area passes through the area does not become constant in each scan line due to a difference in the number of shots or the like. As a result, exposure irregularity arises.

In order to solve this problem, some micromirrors are permanently disabled, and a mask pattern that determines an unused mirror is superimposed with respect to a drawing pattern, and a drawing process is performed (for example, , see Patent Document 2). There, the number of drawing points (number of shots) in each mirror projection area is measured in advance along a scanning line, and mask data is generated so that the difference in the number of drawing points is reduced.

[Patent Document 1] Japanese Patent Laid-Open No. 2009-44060 [Patent Document 2] Japanese Patent Laid-Open No. 2007-253380

When a light modulation element such as a mirror, which is disabled by a mask pattern, is fixed, if there is a deviation in the arrangement position of the set light modulation element, the shot position (exposure point) within the cell size There is also a bias in When the distribution of exposure points becomes non-uniform and a dense area is generated, a phenomenon in which irregularities are conspicuous at the edge of the pattern occurs, resulting in a decrease in pattern resolution.

Therefore, when performing exposure using a mask pattern, it is necessary to perform a multiple exposure operation so that the distribution of exposure points may not be deflected.

The exposure apparatus of the present invention includes a light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged, and an object to be written in a state in which an exposure area by the light modulation element array is inclined with respect to a main scanning direction. A scanning unit that is moved relative to the surface of the body along the main scanning direction, an exposure data generation unit that generates exposure data according to raster data based on pattern data, and is not used during exposure operation ), a mask data generating unit that generates mask data defining the light modulating elements, and exposure for performing multiple exposure operations by controlling the plurality of light modulating elements based on the exposure data and mask data corresponding to the position of the exposure area have a control unit.

In the present invention, during the exposure operation, the mask data generating unit replaces at least a part of the mask data based on the column data along the sub-scan direction. However, "column data" indicates data corresponding to the direction in which the light modulation elements projecting a pattern along the sub-scan direction perpendicular to the main scanning direction are arranged in the light modulation element array. By replacing the column data, when the exposure area passes through the drawing target area, the exposure points are scattered even at the cell size level, and the light quantity distribution becomes uniform.

There are various configurations for replacing column data, and it is also possible to replace random column data and shift the column data to the position of the next column data. Considering that the exposure operation is performed by fixing the number of unused mirrors along the main scanning direction, and data exchange is easy, the mask data generating unit can cyclically shift at least a part of the column data of the mask data. . Here, "cyclic shift" refers to a data shift in which column data is sequentially shifted one by one laterally and column data in one data end of the mask data is shifted to the other data end.

The mask data generating unit is capable of cyclically shifting at least a portion of the column data of the mask data, and when there is a bias in the distribution of the optical modulation elements that are not used by the mask data, it is sufficient to cyclically shift some of the column data. The mask data generating unit may cyclically shift the entire column data of the mask data, and may make the distribution of exposure points more uniform. In addition, the mask data generating unit can also perform a cyclic shift for every exposure operation, and even when the exposure pitch is very short, the exposure points are scattered.

The mask data generating unit may store the generated mask data in a memory, and may replace the read address when reading the mask data from the memory. When the mask data is first determined, the mask data can be replaced only by changing the address number to be read.

The exposure data generation unit can generate a plurality of divided exposure data corresponding to each of a plurality of divided exposure areas defined by dividing the exposure area with respect to the main scanning direction. If a memory for storing raster data is prepared for each divided exposure area, it is possible to generate only the exposure data corresponding to the first divided exposure area, and to shift the exposure data sequentially to the memory of the other divided exposure area. In this case, the mask data generator may generate division mask data of the same pattern arrangement for each of the plurality of division exposure data and replace at least a portion of the division mask data. If the mask data of the first divided exposure area is used as it is, the exposure point distribution tends to be deflected, but by replacing the thermal data, the exposure point distribution can be uniformly scattered.

In the exposure method of the present invention, an exposure area by a light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged is moved relative to a drawing object along the main scanning direction in a state that is inclined with respect to the main scanning direction. , based on the pattern data, generating exposure data according to raster data, generating mask data defining light modulation elements that are not used during the exposure operation, and generating exposure data and mask data according to the position of the exposure area , in the exposure method for performing a multiple exposure operation by controlling the plurality of light modulation elements, in the exposure operation, at least a part of mask data is replaced based on column data along a sub-scan direction.

ADVANTAGE OF THE INVENTION According to this invention, in an exposure apparatus, a pattern can be formed without exposure irregularity.

1 is a block diagram of an exposure apparatus according to the present embodiment.
Fig. 2 is a diagram showing the movement direction of the exposure area with respect to the main scanning direction.
3 is a diagram illustrating a divided exposure area and a divided exposure area.
4 is a diagram showing a multiple exposure process based on exposure area division.
5 is a view showing an arrangement of micromirrors that are not used by mask data.
Fig. 6 is a diagram showing data shift during exposure operation maintenance of mask data.
7A is a diagram showing the distribution of exposure points in one cell in the case where the cyclic shift of mask data is not performed.
7B is a diagram illustrating an exposure point distribution when mask data is cyclically shifted.
Fig. 8 is a diagram showing a flow chart of multiple exposure processing.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

1 is a block diagram of an exposure apparatus according to the present embodiment. Fig. 2 is a diagram showing the movement direction of the exposure area with respect to the main scanning direction. 3 is a diagram illustrating a divided exposure area and a divided exposure area.

The exposure apparatus 10 is a maskless exposure apparatus that forms a circuit pattern by irradiating light to a substrate W having a photosensitive material such as photoresist formed on its surface, and a DMD (Digital Micro-mirror Device) 20 . The provided exposure head 30 is provided. The board|substrate W is mounted on the drawing table 18, and on the drawing table 18, the X-Y coordinate system is prescribed|regulated according to the main scanning direction (X direction) and the sub-scanning direction (Y direction).

The exposure head 30 includes an illumination optical system 24 and an imaging optical system 26 together with the DMD 20 . The light radiated from the light source 21 (laser or discharge lamp, etc.) provided in the exposure apparatus 10 is guided to the DMD 20 by the illumination optical system 24 .

The DMD 20 here is an optical modulation device in which microscopic spherical micromirrors of several micrometers to several tens of micrometers are two-dimensionally arrayed in a matrix form, for example, 1024 x 768 micromirrors. is composed of Each micromirror has either a first posture (ON state) in which the beam from the light source 21 is reflected in the direction of the exposure surface of the substrate W, and a second posture (OFF state) in which the beam is reflected in a direction outside the exposure surface (OFF state). position, and the posture is switched according to the control signal (exposure data).

In the DMD 20, each micromirror is selectively turned ON/OFF controlled, and the light reflected on the micromirror in the ON state passes through the imaging optical system 26 and is irradiated to the substrate W. Accordingly, the light irradiated to the substrate W is composed of a beam of light selectively reflected by each micromirror, and becomes patterned light according to the circuit pattern to be formed on the exposure surface.

When all the micromirrors are in the ON state, the exposure area EA serving as a spherical projection area having a predetermined size is defined on the substrate W (refer to Fig. 2). For example, when the magnification of the imaging optical system 26 is 1x, the size of the exposure area coincides with the size of the DMD 20 .

The exposure head 30 is arranged so that the exposure area EA by the DMD 20 is inclined by a predetermined minute angle α with respect to the scanning direction. As a result, the trajectory of the micro-projection area of the micromirrors arranged along the main scanning direction is shifted by a minute distance along the sub-scanning direction.

As for the exposure operation, in order to perform multiple exposure, the exposure pitch (exposure operation time interval) is determined so that the minute projection areas of each micromirror overlap each other. As a result, by shifting the exposure area EA away from the main scanning direction by the minute angle α, within one minute projection area (cell), the micro projection area center point at the time of the exposure shot (hereinafter referred to as the exposure point) ) are scattered. As a result, a pattern is formed with a resolution equal to or smaller than the cell size.

As the exposure area EA moves relative to the substrate W continuously or intermittently along the scanning direction, a circuit pattern is formed on the substrate W along the main scanning direction. When the multiple exposure operation according to one scan band is finished from end to end of the substrate W, the multiple exposure operation according to the next scan band is performed. By exposing the board|substrate W as a whole, a writing process is complete|finished. After the drawing process, developing process, etching or plating, resist peeling process, etc. are performed, and the board|substrate on which the circuit pattern was formed is manufactured.

A system control circuit 32 connected to an external workstation (not shown) controls the writing process, and the DMD driving circuit 34, the read address control circuit 37, and the writing table control circuit ( 42), etc., output a control signal to each circuit. A program for controlling the exposure operation is stored in advance in a ROM (not shown) in the system control circuit 32 .

The pattern data sent as CAD/CAM data from the workstation is vector data that is coordinate data, and the raster conversion circuit 36 converts the vector data into raster data. Raster data represented by binary data of 1 or 0 determines the position of each micromirror in the ON state or OFF state. The generated raster data is stored in serially connected buffer memories 38A to 38C.

As shown in FIG. 3, in this embodiment, by dividing the exposure area EA equally, three divided exposure areas (division exposure area|region) EA1, EA2, EA3 are prescribed|regulated. The divided exposure areas are arranged one after another with the exposure area EA1 as the head toward the main scanning direction. In the DMD 20, three division modulation areas D1, D2, and D3 are determined corresponding to the division exposure areas EA1, EA2, and EA3. Each divided exposure area is inclined by one pixel in the sub-scan direction here, and is shifted by three pixels in the entire exposure area EA. However, one pixel is set as a small projection area of one micromirror DM.

In the buffer memories 38A, 38B, and 38C, raster data for controlling the micromirrors of the division modulation areas D1, D2, and D3, respectively, are stored as exposure data. The vector data sent from the workstation is data corresponding only to the exposure area EA1, that is, the division modulation area D1 of the DMD 20, and is stored in the buffer memory 38A. Then, when the exposure operation is executed, the raster data corresponding to the new divisional modulation area D1 is stored in the buffer memory 38A, and the raster data is updated.

On the other hand, the raster data stored in the buffer memories 38A and 38B is shifted to the buffer memories 38B and 38C in accordance with the exposure operation, respectively. The raster data stored in the buffer memories 38A, 38B, and 38C is sent to the DMD driving circuit 34 in accordance with the exposure operation. Timings of reading out and writing raster data into the buffer memories 38A, 38B, and 38C are controlled by the read address control circuit 37 .

The drawing table control circuit 42 outputs a control signal to the drive circuit 44 to control the movement of the X-Y stage mechanism 46 . The position detection sensor 48 detects the relative position of the exposure area EA by detecting the position of the drawing table 18 . The system control circuit 32 controls the DMD drive circuit 34 , the read address control circuit 37 , etc. based on the relative position of the exposure area EA detected through the drawing table control circuit 42 . A light detection unit (not shown) provided at the end of the drawing table receives the illumination light from the exposure head 30 and detects the exposure amount of each scanning line along the main scanning direction.

The DMD drive circuit 34 has a bitmap memory that stores raster data (exposure data) of the entire micromirror of the DMD 20, and selectively controls the DMD 20 based on the raster data as binary data. output a signal. When raster data according to the relative position of the exposure area EA is input from the buffer memories 38A, 38B, 38C, the control signal of the micromirror is output to the DMD 20 as a drawing signal while synchronizing with the clock pulse signal matching the exposure timing. do. Accordingly, the micromirror of the DMD is controlled ON/OFF based on the corresponding raster data.

On the other hand, the system control circuit 32 generates raster data (hereinafter, referred to as mask data) for determining the micromirror that becomes unused (OFF state) regardless of the pattern. The generated mask data is stored in a mask memory 50 constituted by a buffer memory or the like. During the exposure operation, it is read by the read address control circuit 37 and superimposed with the raster data output from the buffer memories 38A to 38C.

4 is a diagram showing a multiple exposure process based on exposure area division. Here, the character patterns of A, B, and C are shown as drawing patterns instead of the circuit patterns.

In FIG. 4, the drawing characters A, B, and C indicated by the border line are shown in the position where a pattern is formed, respectively. As for the multiple exposure operation here, in order to simplify the explanation, the exposure operation is performed according to the exposure positions P2, P3, and P4. That is, the distance RT (exposure pitch) at which the exposure area EA moves in one exposure operation is determined by the width RS along the scanning direction of each of the divided exposure areas EA1, EA2, and EA3 divided into thirds.

When the divided exposure area EA1 reaches the exposure position P2, raster data for drawing the character "A" is stored in the buffer memory 38A. The buffer memories 38B and 38C store raster data for positioning the micromirrors in the division modulation areas D2 and D3 of the DMD 20 in the OFF state. In addition, since the exposure area EA is inclined with respect to the scanning direction, here, let the vertex of the exposure area EA which moves the board|substrate W first be an exposure position.

When the divided exposure area EA1 moves further by the distance RT and reaches the exposure position P3 where the letter "B" should be patterned, the divided exposure area EA2 reaches the exposure position P2, and the position where the letter "A" should be patterned is reaching Therefore, the raster data newly generated by the raster conversion circuit 36, that is, the raster data corresponding to the character "B" is stored in the buffer memory 38A. At the same time, raster data corresponding to the character "A" stored in the buffer memory 38A is stored in the buffer memory 38B, and the raster data stored in the buffer memory 38B is stored in the buffer memory 38C. is stored

When the divided exposure area EA1 moves further by the distance RT to reach the exposure position P4 where the letter "C" should be patterned (refer to Fig. 7), the divided modulation area D2 of the DMD 20 must pattern the letter "B" The exposure position P3 to be performed is reached, and the divisional modulation area D3 reaches the exposure position P2 where the character "A" is to be patterned. In this case, the newly generated raster data of the character “C” is stored in the buffer memory 38A, and the raster data corresponding to the characters “B” and “C” stored in the buffer memories 38A and 38B are respectively It is stored in the buffer memories 38B and 38C.

In this way, when the exposure areas EA1 to EA3 each reach the exposure position, raster data corresponding to the pattern to be formed at the exposure position of the first divided exposure area EA1 is generated based on the vector data and stored in the buffer memory 38A. do. Then, the raster data stored in the buffer memories 38A and 38B until then is read and sent to the buffer memories 38B and 38C, respectively. In addition, the exposure pitch is not limited to this, You may implement multiple exposure with a shorter exposure pitch.

Also for the mask data, like the exposure data according to the pattern, only the mask data for the division exposure area EA1 at the head is generated. When the generated mask data is stored in the mask memory 50, the same mask data is read from the mask memory 50 as the exposure areas EA2 and EA3 reach the same position as the exposure area EA1, respectively.

Fig. 5 is a diagram showing the arrangement of micromirrors that are not used by mask data. However, the micromirror arrangement of the DMD 20 is different from FIG. 2 .

In Fig. 5, micromirrors that are not used (that is, in an OFF state) are displayed in white, and the black micromirrors are set to an ON state or an OFF state based on the pattern data. When mask data is set for one divided exposure area EA1, the same mask data is used for the other divided exposure areas EA2 and EA3.

The setting of the number of unused micromirrors of white color in each scanning line is possible by detecting the deflection of the exposure amount distribution before the actual exposure operation. Here, all the micromirrors are turned on in advance to project patterned light, the light detection unit receives the patterned light as the drawing table 18 moves, and the total exposure amount of each scanning line is calculated when scanning once. do. Then, an unused micromirror is determined based on the deviation of the exposure amount distribution at that time. In addition, although the position of the unused micromirror is biased toward the periphery in FIG. 5 , it is often set to the central part depending on the exposure operation environment.

When multiple exposure operation is performed using mask data, the total exposure amount with respect to a specific drawing area|region when exposure area EA of DMD 20 passes does not differ depending on the scan line. That is, the exposure amount distribution along the sub-scan direction becomes uniform. However, if the micromirror that is not used is fixed, in a certain pattern light projection target area, the number of exposures will be dense.

In Fig. 5, there are many micromirrors that are not used by the mask data in the vicinity of both ends along the sub-scan direction. Therefore, in the drawing area where the number of unused micromirrors is large, the center of the microprojection area during the exposure operation, that is, the portion where the exposure points overlap, and the portion where the exposure points do not exist are mixed.

When the distribution of the exposure points in the cell after the exposure area EA has passed is deflected and becomes non-uniform, a phenomenon in which the pattern edge formed in the area part with insufficient exposure amount will wave will occur. Then, in this embodiment, the mask data is shifted for each column data for each exposure operation, and the position of the micromirror that is not used is replaced.

Fig. 6 is a diagram showing data shift during exposure operation maintenance of mask data.

When performing the 1st - 3rd exposure operation|movement, the 1st unused mirror is determined by the mask data ME with respect to division|segmentation projection area EA1 shown in FIG. In the second exposure operation, in the first exposure operation, the column data MET at the frontmost end is shifted to the last, and the other column data is in the leading direction (main scanning direction). Shift sideways. Also at the time of the exposure operation of the 3rd time, similarly, it is made to shift in order to the front side. By repeating this, the column data of the mask data ME is shifted to circulate (hereinafter referred to as cyclic shift).

Fig. 7A is a diagram showing the distribution of exposure points within one cell when the mask data is not subjected to cyclic shift. Fig. 7B is a diagram showing the distribution of exposure points when mask data is cyclically shifted. In addition, the exposure point size is drawn large about the spot (spot) where the exposure point overlaps in the same place.

As can be seen by comparing Figs. 7A and 7B, when the mask data is cyclically shifted, exposure points are scattered within the cell region, and there is no bias compared to the distribution of exposure points without shift in which the denseness becomes remarkable. As a result, non-uniformity in the exposure amount within the cell is eliminated, and a stable line can be formed even in the pattern edge portion.

On the other hand, in this cyclic shift of the mask data, since the total number of unused mirrors along the main scanning direction does not change constantly, there is no substantial change in the total exposure amount of each scanning line, and the exposure amount distribution along the sub-scan direction does not undergo a cyclic shift. As in the case of not, it becomes a uniform distribution.

Fig. 8 is a diagram showing a flow chart of multiple exposure processing.

When the position of the exposure area is detected and it is determined that the exposure position has been reached (S101, S102), raster data is read from the buffer memory 38A corresponding to the divided exposure area on the front side, and the buffer memory 38A and the buffer memory The raster data stored in (38B) is transmitted to the buffer memory 38B and the buffer memory 38C, respectively (S103). At this time, the raster data is corrected along the sub-scanning direction in accordance with the minute angle α.

On the other hand, in accordance with the read out of the raster data from the buffer memory 38B, the mask data obtained by cyclically shifting the column data by one column is read from the mask memory 50 (S104, S105). Specifically, the read address control circuit 37 shifts the address order when data is read. The raster data output from the buffer memories 38A, 38B, 38C is logically corrected with the read mask data, and a micromirror (unused mirror) corresponding to the address position of the mask data is applied to the pattern. Regardless, it is set to OFF state.

As described above, according to the present embodiment, in the exposure apparatus provided with the DMD 20, a plurality of divided exposure areas EA1 to EA3 are defined for the exposure area EA, and the exposure data of the first divided exposure area EA1 is stored in the buffer memory 38A. ), the multiple exposure operation is performed while sequentially shifting to the buffer memories 38B and 38C according to the exposure operation. In addition, when mask data is generated and stored in the mask memory 50, the read address to the mask memory 50 is changed so that the mask data is cyclically shifted for each exposure operation and each column data. In the case of a multiple exposure operation based on a divided exposure area, the mask data of one divided exposure area is useful for another divided exposure area, but the distribution of exposure points is not biased by cyclic shifting.

Note that the data shift is not limited to shifting to the next column data, and only a predetermined number of columns may be shifted. In addition, it may be made to cyclically shift only a part of the mask data under the condition that the distribution of the exposure points is not biased. On the other hand, it is also possible to shift randomly without cyclic shifting.

The above-mentioned replacement of the mask data for each column data is not limited to the multiple exposure operation based on the divided exposure area, and it is possible to replace the data for each column according to the exposure operation even for the mask data determined for the entire DMD. do. Also in this case, the distribution of exposure points in the vicinity of adjacent scan bands is improved.

10: exposure apparatus
20: DMD (Light Modulation Element Array)
32: system control circuit (mask data generator)
37: read address control circuit (mask data generation unit)
50: mask memory

Claims (7)

a light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged;
a scanning unit for relatively moving an object to be drawn along the main scanning direction in a state where the exposure area by the optical modulation element array is inclined with respect to the main scanning direction;
an exposure data generation unit that generates exposure data according to the raster data based on the pattern data;
a mask data generation unit for generating mask data defining light modulation elements that are not used during an exposure operation;
an exposure control unit that controls the plurality of light modulation elements to execute multiple exposure operations based on exposure data and mask data corresponding to the position of the exposure area;
The exposure apparatus according to claim 1, wherein the mask data generating unit replaces at least a portion of the mask data for each column data in the sub-scan direction during the exposure operation. The method of claim 1,
The exposure apparatus according to claim 1, wherein the mask data generating unit cyclically shifts column data of at least a part of the mask data. 3. The method of claim 2,
The exposure apparatus according to claim 1, wherein the mask data generating unit cyclically shifts the entire column data of the mask data. 4. The method according to any one of claims 2 to 3,
The exposure apparatus according to claim 1, wherein the mask data generating unit cyclically shifts at least a part of the column data or the entire column data of the mask data for each exposure operation. 4. The method according to any one of claims 1 to 3,
The mask data generation unit stores the generated mask data in a memory;
The exposure apparatus according to claim 1, wherein the mask data generating unit replaces a read address when reading the mask data from the memory. 4. The method according to any one of claims 1 to 3,
the exposure data generation unit generates a plurality of divided exposure data corresponding to each of a plurality of divided exposure areas defined by dividing the exposure area with respect to a main scanning direction;
and the mask data generating unit generates division mask data of the same pattern arrangement for each of the plurality of division exposure data, and replaces at least a portion of the division mask data. An exposure area by a light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged is moved relative to the object to be drawn along the main scanning direction in a state that is inclined with respect to the main scanning direction;
Based on the pattern data, generating exposure data according to the raster data,
Generates mask data that determines the light modulation device that is not used during the exposure operation,
An exposure method for performing a multiple exposure operation by controlling the plurality of light modulation elements based on exposure data and mask data corresponding to a position of an exposure area, the exposure method comprising:
An exposure method in which at least a part of mask data is replaced for each column data along a sub-scan direction during an exposure operation.

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