TWI688830B - Exposure device and exposure method - Google Patents

Abstract

A pattern with no uneven exposure is formed in the exposure device.

In an exposure device including a DMD, a plurality of divided exposure areas are defined for the exposure area, and the exposure data of the divided exposure area at the front end is stored in the buffer memory 38A, and sequentially shifted to the buffer memory corresponding to the exposure action and performed Multiple exposure action. In addition, if the mask data is generated and stored in the mask memory, each time the exposure operation is performed, the read address for the mask memory is changed to cyclically shift the mask data for each row of data.

Description

Exposure device and exposure method

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

The maskless exposure device uses a light modulation element array such as DMD formed by arranging a plurality of micromirrors in a matrix to form a direct pattern. Here, a raster pattern is generated based on the pattern data, and each micromirror is controlled by inputting the raster data (exposure data) to the light modulation element array.

To improve the pattern resolution, the DMD is set so that its projection area (exposure area) is inclined to the scanning direction. While moving the drawing stage on which the substrate is mounted, multiple exposure operations are performed according to the pitch intervals at which the projection areas between adjacent micromirrors overlap in the scanning direction and the sub-scanning direction, respectively.

In multiple exposures, the exposure pitch is adjusted so that the center point of the projection area (hereinafter referred to as the exposure point) during exposure shot within the projection area size (unit size) of one micromirror is dispersed as much as possible. With this, it is possible to obtain a resolution capability of less than the unit size when the pattern is formed (for example, refer to Patent Document 1).

When the exposure area is slightly inclined with respect to the scanning direction, the total number of times the exposure area passes through a specific drawing area is due to the overlapping of the exposure areas generated between adjacent exposure heads and the meandering caused by the mirror projection area of the scanning mechanism. The amount of exposure is not constant for each scan line due to differences in the number of shots. Therefore, uneven exposure occurs.

To solve this problem, a part of micromirrors is not used regularly, and a mask pattern in which a mirror is not used is superimposed on a drawing pattern, and drawing processing is performed (for example, refer to Patent Document 2). Here, the number of drawing points (number of shots) of each mirror projection area is measured in advance along the scan line, and mask data is generated to reduce the difference in the number of drawing points.

【Prior Technical Literature】

【Patent Literature】

Patent Literature 1 JP 2009-44060

Patent Document 2 JP 2007-253380

When fixing a light modulating element such as a mirror that is not used through a reticle pattern, if the arrangement position of the light modulating element set there is shifted, the irradiation position (exposure point) within the unit size will also shift. If the exposure points are unevenly distributed to produce dense areas, irregular protrusions will occur at the edges of the pattern, resulting in a decrease in the resolution of the pattern.

Therefore, when performing exposure using a reticle pattern, it is necessary to perform multiple exposure operations so that the exposure point distribution does not shift.

The exposure device of the present invention includes: a two-dimensional light modulation element array in which a plurality of light modulation elements are arranged; and in a state inclined to the main scanning direction, the light modulation element array is relatively moved to the object to be drawn along the main scanning direction The scanning part of the exposure area; the exposure data generation part that generates exposure data corresponding to the raster data based on the pattern data; the mask data generation part that generates the mask data of the light modulating element that is not used during the exposure operation; and the corresponding The exposure data and the reticle data to the position of the exposure area control the above-mentioned plural light modulating elements to perform an exposure control part of a multiple exposure operation.

In the present invention, during the exposure operation, the mask data generating unit replaces at least a part of the mask data for each row of data corresponding to the sub-scanning direction. However, in the optical modulation element array, "row data" represents data corresponding to the arrangement direction of the optical modulation elements projecting a pattern perpendicular to the sub-scanning direction of the main scanning direction. By replacing the column data, when the exposure area passes through the drawing target area, the exposure points are still dispersed in the unit size level, and the light amount distribution becomes uniform.

There are many types of replacement row data, which can be the replacement of random row data and shift to the position of the next row of data. When the number of unused mirrors along the main scanning direction is fixed for the exposure operation, and if simple replacement processing of the data is considered, the mask data generating section may cyclically shift at least a part of the row data of the mask data. Here, "cyclic shift" means to sequentially shift the row data to the next one while shifting the row data of one data end of the mask data to the data movement of the other data end.

The reticle data generating unit can cyclically shift at least a part of the row data of the reticle data, and can cyclically shift a part of the row data when the distribution of the light modulation elements that are not used through the reticle data is shifted. The mask data generating unit may also cyclically shift the entire row data of the mask data, so that the exposure point distribution can be more uniform. In addition, the mask data generating unit may perform cyclic shift every time the exposure operation is performed, and even when the exposure pitch is very short, the exposure points are still scattered.

The mask data generating part stores the generated mask data in the memory, and can replace the read address when reading the mask data from the memory. If the initial mask data is determined, replacement of the mask data by only changing the readout address number is possible.

The exposure data generating section may generate a plurality of divided exposure data corresponding to the plurality of divided exposure areas defined by dividing the above-mentioned exposure areas in the main scanning direction, respectively. If the memory stores raster data for each divided exposure area, only the exposure data corresponding to the divided exposure area at the front end can be generated, and the exposure data can be sequentially shifted to the memory of other divided exposure areas. In this case, the mask data generating unit may generate a divided mask pattern that has the same pattern for each of the plurality of divided exposure data, and replaces at least a part of the divided mask pattern. When the mask data of the divided exposure area at the front end is used in this way, although the deviation of the exposure point distribution is easily generated, the distribution of the exposure point can be uniformly dispersed by replacing the row data.

The exposure method of the present invention includes: in a state inclined to the main scanning direction, relatively moving the object to be drawn along the main scanning direction 2-dimensionally disposing an exposure area of a light modulation element array of a plurality of light modulation elements; based on pattern data Generate the exposure data corresponding to the raster data; generate the mask data of the light modulating element that is not used in the exposure action; and control the plurality of light modulating elements based on the exposure data and the mask data corresponding to the position of the exposure area to Perform multiple exposure operations; wherein, during the exposure operation, for each row of data corresponding to the sub-scanning direction, at least a part of the mask data is replaced.

According to the present invention, in the exposure device, a pattern without uneven exposure can be formed.

10: Exposure device

18: portray the platform

20: DMD (optical modulation element array)

21: Light source

24: Illumination optical system

26: Imaging optical system

30: Exposure head

32: System controller circuit (mask data generation section)

34: DMD drive circuit

36: Raster conversion circuit

37: readout address control circuit (mask data generation section)

38A, 38B, 38C: buffer memory

42: Describe the platform control circuit

44: Drive circuit

46: X-Y platform mechanism

48: Position detection sensor

50: Mask memory

D1, D2, D3: Split modulation area

DM: Micromirror

EA: exposure area

EA1~EA3‧‧‧Split exposure area

ME‧‧‧mask information

MET‧‧‧The most advanced data

P0~P4‧‧‧Exposure position

RS‧‧‧ amplitude

RT‧‧‧Distance

S101~S105‧‧‧Step

W‧‧‧Substrate

Figure 1 is a block diagram of an exposure apparatus of this embodiment type.

FIG. 2 is a diagram showing the movement direction of the exposure area in the main scanning direction.

FIG. 3 is a diagram showing divided exposure areas and divided exposure areas.

FIG. 4 is a diagram showing a multiple exposure process based on the exposure area division.

Fig. 5 is a diagram showing the arrangement of micromirrors that are not used through the mask data.

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

FIG. 7A is a diagram showing the distribution of exposure points in one unit when the reticle data is not cyclically shifted.

FIG. 7B is a diagram showing the distribution of exposure points in the case where the mask data is cyclically shifted.

FIG. 8 is a diagram showing the flow of multiple exposure processing.

The following describes embodiments of the present invention with reference to the drawings.

Figure 1 is a block diagram of an exposure apparatus of this embodiment type. FIG. 2 is a diagram showing the movement direction of the exposure area in the main scanning direction. FIG. 3 is a diagram showing divided exposure areas and divided exposure areas.

The exposure device 10 is a maskless exposure device that forms a circuit pattern by irradiating light to a substrate W formed of a photosensitive material such as a photoresist on the surface, and includes an exposure head 30 provided with a DMD (Digital Micro-mirror Device) 20. The substrate W is mounted on the drawing stage 18, and the drawing stage 18 defines an X-Y coordinate system along the main scanning direction (X direction) and the sub scanning direction (Y direction).

The exposure head 30 includes an illumination optical system 24 in addition to the DMD 20 to And imaging optical system 26. The light emitted from the light source 21 (laser or discharge bulb, etc.) included in the exposure device 10 is guided to the DMD 20 by the illumination optical system 24.

The DMD20 here is a light modulation device in which two micro-mirrors of several micrometers to several tens of micrometers are arranged in a matrix in a two-dimensional manner. For example, it is composed of 1024×768 micromirrors. Each micromirror is placed in any one of the first posture (ON state) that reflects the light beam from the light source 21 to the direction of the exposure surface of the substrate W and the second posture (OFF state) that reflects to the direction outside the exposure surface, the posture is Switch according to control signal (exposure data).

The DMD 20 selectively ON/OFF controls each micromirror, and the light reflected on the micromirror in the ON state is irradiated to the substrate W through the imaging optical system 26. Therefore, the light irradiated to the substrate W is composed of light beams of light selectively reflected by each micromirror, and becomes pattern light corresponding to the circuit pattern to be formed on the exposure surface.

When all micromirrors are in an ON state, an exposure area EA (refer to FIG. 2) that is a rectangular projection area having a predetermined size is defined on the substrate W. For example, in the case where the magnification of the imaging optical system 26 is doubled, the size of the exposure area coincides with the size of the DMD 20.

The exposure head 30 is configured such that the exposure area EA of the DMD 20 is inclined by a predetermined minute angle α with respect to the scanning direction. Therefore, the trajectory of the micro projection area of the micromirror arranged along the main scanning direction is displaced by only a small distance along the sub scanning direction.

Regarding the exposure operation, in order to perform multiple exposures, the exposure interval (exposure operation time interval) is determined such that the minute projection areas of the micromirrors overlap each other. Therefore, since the exposure area EA is moved by a slight angle α from the main scanning direction, the center point of the micro projection area (hereinafter referred to as the exposure point) at the time of exposure irradiation becomes dispersed within one micro projection area (unit) . Therefore, the unit ruler The resolution below the inch size forms the pattern.

As the exposure area EA moves continuously or intermittently relative to the substrate W along the scanning direction, a circuit pattern will be formed on the substrate W along the main scanning direction. When the multiple exposure operation along one scanning band is completed from one end to one end of the substrate W, the multiple exposure operation along the next scanning band is performed. By exposing the substrate W as a whole, the drawing process is ended. After the drawing process, development processing, etching or electroplating, photoresist stripping processing, etc. are performed to manufacture a circuit pattern-formed substrate.

A system controller circuit 32 connected to an external workstation (not shown) controls the drawing process, and outputs control signals to the DMD drive circuit 34, read address control circuit 37, drawing platform control circuit 42, and other circuits. The program for controlling the exposure operation is pre-stored in a ROM (not shown) in the system controller circuit 32.

The pattern data transmitted from the workstation as CAD/CAM data is vector data with coordinate data, and the raster conversion circuit 36 converts the vector data into raster data. The raster data represented by the binary data of 1 or 0 determines whether the position of each micromirror is ON or OFF. The generated raster data is stored in the buffer memory 38A~38C connected in series.

As shown in FIG. 3, in the present embodiment, by dividing the exposure area EA equally, three divided exposure areas (divided exposure areas) EA1, EA2, and EA3 are defined. The divided exposure areas are arranged side by side in the main scanning direction, starting with the exposure area EA1. The DMD 20 determines three divided modulation areas D1, D2, and D3 corresponding to the divided exposure areas EA1, EA2, and EA3. Each divided exposure area is inclined by 1 pixel in the sub-scanning direction and the entire exposure area EA is displaced by 3 pixels. However, one pixel is a tiny projection area of one micromirror DM.

Control each division modulation in buffer memory 38A, 38B, 38C The grating data of the micromirrors in the fields D1, D2, D3 are stored as exposure data. The vector data transmitted from the workstation is data corresponding only to the segmentation modulation area D1 of the exposure area EA1, that is, the DMD20, and is stored in the buffer memory 38A. Then, each time the exposure operation is performed, the raster data corresponding to the new division 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 are respectively shifted to the buffer memories 38B and 38C in accordance with the exposure operation. The raster data stored in the buffer memories 38A, 38B, and 38C are transmitted to the DMD drive circuit 34 in accordance with the exposure operation. The timing of reading and writing the raster data of the buffer memories 38A, 38B, and 38C is controlled by the read address control circuit 37.

The drawing platform control circuit 42 outputs a control signal to the driving circuit 44 to control the movement of the X-Y platform mechanism 46. The position detection sensor 48 detects the relative position of the exposure area EA by detecting the position of the drawing platform 18. The system controller circuit 32 controls the DMD drive circuit 34, the read address control circuit 37, and the like based on the relative position of the exposure area EA detected through the drawing platform control circuit 42. A light detection unit (not shown) provided at the side edge of the drawing stage 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 driving circuit 34 includes a bitmap memory that stores raster data (exposure data) of the entire micromirror of the DMD20, and selectively outputs control signals to the DMD20 based on the raster data of the binary data. When the raster data corresponding to the relative position of the exposure area EA is input from the buffer memories 38A, 38B, and 38C, it is synchronized with the clock pulse signal consistent with the exposure timing, and the control signal of the micromirror is output to the DMD 20 as a drawing signal. With this, the DMD micromirror performs ON/OFF control based on the corresponding grating data.

On the other hand, the system controller circuit 32 generates raster data (hereinafter referred to as reticle data) that determines micromirrors that are not used (OFF state) regardless of the pattern. The generated mask data is stored in the mask memory 50 composed of buffer memory and the like. During the exposure operation, it is read by the read address control circuit 37 and coincides with the raster data output from the buffer memories 38A to 38C.

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

In FIG. 4, the drawing characters A, B, and C indicated by the frames represent the positions where the patterns are formed. Here, in order to simplify the explanation, the multiple exposure operation is performed in accordance with the exposure positions P2, P3, and P4. That is, the movement distance RT (exposure pitch) of the exposure area EA in one exposure operation is determined to be the amplitude RS of the three-thirds exposure areas EA1, EA2, and EA3 in the scanning direction.

When the divided exposure area EA1 reaches the exposure position P2, the raster data depicting the text "A" is stored in the buffer memory 38A. The buffer memory 38B, 38C stores raster data that causes the micromirrors in the divided modulation areas D2, D3 of the DMD 20 to be all placed in the OFF state. In addition, since the exposure area EA is inclined to the scanning direction, here, the vertex of the exposure area EA that first enters the substrate W is the exposure position.

In the case where the divided exposure area EA1 then moves only by the distance RT and reaches the exposure position P3 where the pattern formation character "B" is formed, the divided exposure area EA2 reaches the exposure position P2 and reaches the position where the pattern formation character "A" is formed. For this reason, the raster data newly generated in the raster conversion circuit 36, that is, the raster data corresponding to the character "B", are stored in the buffer memory 38A. At the same time, the raster data originally stored in the buffer memory 38A corresponding to the text "A" is stored in the buffer memory 38B, and the raster data originally stored in the buffer memory 38B is stored in the buffer memory 38C.

In the case where the divided exposure area EA1 then moves only by the distance RT to reach the exposure position P4 where the pattern formation character "C" is formed (see FIG. 7), the divided modulation area D2 of the DMD20 reaches the exposure where the pattern formation character "B" is reached Position P3, and the divided modulation area D3 reaches the exposure position P2 where the pattern "A" should be formed. 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 "A" originally stored in the buffer memory 38A and 38B are stored in Buffer memory 38B, 38C.

As such, when the exposure areas EA1 to EA3 reach the exposure positions, the raster data corresponding to the pattern of the exposure position of the divided exposure area EA1 should be formed based on the vector data and stored in the buffer memory 38A. Then, the raster data previously stored in the buffer memories 38A and 38B are read out and sent to the buffer memories 38B and 38C, respectively. In addition, the exposure pitch is not limited to this, and multiple exposures can be performed with a shorter exposure pitch.

For the mask data, the same as the exposure data corresponding to the pattern, only the mask data for the first divided exposure area EA1 is generated. If the generated mask data is stored in the mask memory 50, corresponding to the exposure areas EA2 and EA3 respectively reach the same position as the exposure area EA1, the same mask data is read from the mask memory 50.

Fig. 5 is a diagram showing the arrangement of micromirrors that are not used through the mask data. However, the micromirror arrangement of the DMD20 is different from the second figure.

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

By detecting the shift in the exposure amount distribution before the actual exposure action, the number of white unused micromirrors in each scan line is set to be feasible. Here, the pattern light is projected with all the micromirrors turned on in advance, and the light detection unit receives the pattern light as the drawing stage 18 moves, and calculates the total exposure amount of each scanning line in one scan. Then, based on the shift in the exposure amount distribution at this time, it is decided not to use the micromirror. In addition, in FIG. 5, although the position of the unused micromirror is shifted to the peripheral portion, it is often set at the center portion depending on the exposure operation environment.

When using the mask data to perform multiple exposures, the total exposure of a particular drawing area when the exposure area EA of the DMD20 passes through is not different due to scan lines. This means that the exposure amount distribution along the sub-scanning direction is uniform. Nonetheless, when a micromirror that is not used is fixed, in a certain projected light projection object area, the density of exposure times may occur.

In FIG. 5, there are many micromirrors that are not used through the mask data near both ends along the sub-scanning direction. For this reason, in the drawing area where the number of micromirrors is not used, the center of the micro projection area during the exposure operation, that is, the part where the exposure point overlaps and the part where the exposure point does not exist are mixed.

When the distribution of the exposure points in the cell after the exposure area EA passes is shifted and becomes non-uniform, the edge of the pattern formed in the portion of the area where the exposure amount is insufficient will produce a ripple phenomenon. Therefore, in this embodiment, each time the exposure is performed, the mask data is shifted for each row of data to replace the position of the unused micromirror.

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

In the case of performing the first to third exposure operations, the mask data ME of the divided projection area EA1 shown in FIG. 6 is used to determine whether to use the mirror for the first time. In the second exposure operation, the front row data MET in the first exposure operation is shifted to the rearmost end, and the other row data is shifted to the front end direction (main scanning direction) to the next wall. In the third exposure operation, it is also sequentially shifted toward the front end side. By repeating this, the row data of the mask data ME is shifted to be cyclic (hereinafter referred to as cyclic shift).

FIG. 7A is a diagram showing the distribution of exposure points in one unit when the reticle data is not cyclically shifted. FIG. 7B is a diagram showing the distribution of exposure points in the case where the mask data is cyclically shifted. In addition, for a spot where the exposure point is repeated at the same place, the exposure point is drawn enlarged.

Comparing Figure 7A and Figure 7B, it can be seen that when the reticle data is cyclically shifted, the exposure points in the unit area become scattered, which is not shifted compared to the dense and dense distribution of unexposed exposure points, and there is no offset . Therefore, there is no variation in the exposure amount in the cell, and a stable line can also be formed at the edge of the pattern.

On the other hand, such reticle data cyclic shift, because the total number of unused mirrors along the main scanning direction is fixed, the total exposure of each scan line does not change substantially, the exposure along the sub-scanning direction The distribution has the same uniform distribution as the case without cyclic shift.

FIG. 8 is a diagram showing the flow of multiple exposure processing.

When the position of the exposure area is detected and it is judged that the exposure position is reached (S101, S102), the raster data is read out from the buffer memory 38A corresponding to the divided exposure area on the front end side while storing the buffer memory 38A and the buffer memory 38B The raster data is sent to the buffer memory 38B and the buffer memory 38C respectively (S103). At this time, the raster data is compensated along the sub-scanning direction in accordance with the minute angle α .

On the other hand, in accordance with the reading of the raster data from the buffer memory 38B, the mask data of the row of data that is cyclically shifted by only one row is read from the mask memory 50 (S105). Specifically, the read address control circuit 37 shifts the address sequence at the time of data reading. The read mask data is output from the raster data of the buffer memory 38A, 38B, 38C, which is corrected by logical AND with the mask data, and corresponds to the micromirror of the address position of the mask data ( (No mirror is used) Set to the OFF state regardless of the pattern.

In this way, according to this embodiment, in the exposure apparatus including 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 front divided exposure area EA1 is stored in the buffer memory 38A, Correspondingly, the exposure operation is sequentially shifted to the buffer memories 38B, 38C and multiple exposure operations are performed. Furthermore, if the mask data is generated and stored in the mask memory 50, the read address for the mask memory 50 is changed every time the exposure operation is performed to cyclically shift the mask data for each row of data. In the case of multiple exposure operations based on divided exposure areas, although the mask data of one divided area is transferred to other divided exposure areas, there is no shift in the exposure point distribution by cyclic shift.

In addition, the data shift is not limited to the shift to the next row of data, but may be a shift of a predetermined number of rows. In addition, under the condition that the exposure point distribution is not shifted, only a part of the mask data may be cyclically shifted. On the other hand, without cyclic shift, random shift is also possible.

The replacement of each row of data of the above mask data is not limited to the multiple exposure operation based on the divided exposure area. For the mask data determined for the general DMD as a whole, the data can be replaced in each row in accordance with the exposure operation. In this case, it is also possible to improve the exposure point distribution in the vicinity of adjacent scanning bands.

ME‧‧‧mask information

MET‧‧‧The most advanced data

Claims (7)

An exposure device includes: a two-dimensional light modulation element array in which a plurality of light modulation elements are arranged; in a state inclined to the main scanning direction, relative movement of the light modulation element array to the object to be drawn along the main scanning direction The scanning part of the exposure area; the exposure data generation part that generates exposure data corresponding to the raster data based on the pattern data; the mask data generation part that generates the mask data of the light modulating element that is not used in the exposure operation; and the corresponding The exposure data and the mask data at the position of the exposure area control the plurality of light modulating elements to perform the multiple exposure operation; the exposure control unit is characterized in that: during the exposure operation, the mask data generating unit corresponds to the sub-scanning direction. Each row of information replaces at least part of the mask information. The exposure apparatus according to item 1 of the scope of the patent application, wherein the mask data generating section cyclically shifts at least a part of the row data of the mask data. An exposure apparatus as described in item 2 of the patent application range, wherein the mask data generating section cyclically shifts the entire row of the mask data. The exposure device as described in item 3 of the patent application range, wherein the mask data generating unit cyclically shifts at least a part of the row data or the entire row data of the mask data each time an exposure operation is performed. The exposure device as described in item 1 of the patent application scope, wherein: the mask data generating section stores the generated mask data in a memory; the mask data generating section replaces when reading mask data from the memory Read the address. The exposure apparatus according to any one of items 1 to 5 of the patent application range, wherein the exposure data generating section generates a plurality of plural exposure areas corresponding to a plurality of divided exposure areas defined by dividing the exposure area in the main scanning direction, respectively Divided exposure data; the reticle data generation unit generates divided reticle data respectively configured with the same pattern for the plural divided exposure data, and replaces at least a part of the divided reticle data. An exposure method, comprising: in a state inclined to the main scanning direction, relative to the main scanning direction of the object to be moved relative to the two-dimensional configuration of a plurality of light modulation elements of the light modulation element array exposure area; generated based on pattern data Exposure data corresponding to raster data; generating mask data of light modulating elements that are not used in determining the exposure action; and controlling the above plural light modulating elements to execute based on the exposure data and mask data corresponding to the position of the exposure area Multiple exposure action; wherein, during the exposure action, for each row of data corresponding to the sub-scanning direction, at least a part of the mask data is replaced.

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