JP2021157039A - Exposure device and exposure method - Google Patents

Abstract

To provide new multiplex exposure capable of uniformly dispersing exposure points.SOLUTION: An exposure device is configured to perform multiplex exposure operation at a pitch interval P based on a following formula (1), and by setting a position of a reference exposure point in a unit exposure region, an exposure point is sequentially moved among a plurality of exposure point lines, and the exposure points are caused to be scattered in a main scanning direction X as well as in a sub scanning direction Y. In the formula (1): P=(n+u/m)C+a, the pitch interval is set to P, the unit exposure region of a light modulator is set to C, m is an integer of 2 or greater, n is any integer, u is an integer smaller than m, and a is a value smaller than C.SELECTED DRAWING: Figure 4

Description

The present invention relates to an exposure apparatus that forms a pattern using a light modulation element array, and more particularly to multiple exposure.

In a maskless exposure apparatus, pattern light is projected onto a substrate by an optical modulation element array such as a DMD (Digital Micro-mirror Device) while moving a stage on which the substrate is mounted along a scanning direction. There, light modulation elements (micromirrors) mounted in a two-dimensional manner so as to project pattern light according to the position of the projection area (exposure area) on the substrate on which the photoresist layer is formed. Etc.) to control.

With a micro-order pattern resolution, it is necessary to form a pattern with a projection size (cell size) or less of a micromirror or the like, so multiple exposure is performed in which repeated exposures are performed while overlapping the exposure areas (for example, Patent Document 1, Patent Document 1, 2). There, the light modulation element array or the substrate mounting stage is arranged so that the pitch interval of the exposure operation is not an integral multiple of the cell size and the exposure area is slightly inclined with respect to the main scanning direction.

Assuming that the pitch interval in multiple exposure is P and the size of the unit exposure area (one mirror image area) of the micromirror is C, multiple exposure is performed according to the pitch interval P = A + a (A is an arbitrary integer, C> a). Be struck. As a result, a large number of exposure points (shot center positions) are two-dimensionally dispersed in a unit exposure area (one mirror image area) (see Patent Document 3).

Japanese Patent No. 4203649 Japanese Patent Publication No. 2004-514280 Japanese Patent No. 4728536

In recent years, the sensitivity of photoresists has been increased, and the number of shots to be performed in a unit exposure region has been decreasing due to an increase in light source output, an improvement in optical system performance, an improvement in throughput, and the like. Therefore, the exposure points in the unit exposure region are not dispersed and become non-uniform, and the pattern line width and contour may not have the desired accuracy.

Therefore, a new multiple exposure that can uniformly disperse the exposure points is required.

The exposure apparatus of the present invention draws an exposure area of a light modulation element array in which a plurality of light modulation elements are arranged in two dimensions and an exposure area of the light modulation element array that is inclined at a predetermined inclination angle with respect to the main scanning direction. It includes a scanning unit that moves relative to the main scanning direction with respect to the body, and an exposure control unit that modulates the plurality of light modulation elements at predetermined pitch intervals and performs a multiple exposure operation.

In the present invention, the exposure control unit switches an exposure point line that determines an exposure point for each exposure operation between a plurality of exposure point lines along the inclination angle in a predetermined unit exposure region. The “predetermined unit exposure region” indicates a region having a size corresponding to a projection region of one light modulation element when viewed from the substrate. Further, the "exposure point line" represents a line connecting the exposure points along the inclination angle direction when the multiple exposure operation is performed at predetermined pitch intervals, and is a plurality of exposure point lines parallel to each other. Is specified on the substrate. When the exposure control unit switches the exposure point line for each exposure operation, the exposure point is sequentially switched to the exposure points on different exposure point lines.

The exposure control unit can switch the exposure point lines in order among the plurality of exposure point lines arranged adjacent to each other. Further, the exposure control unit sets an exposure point line in which the exposure point moves within the predetermined unit exposure region in the next exposure operation, and an exposure point line in which the exposure point deviates from the predetermined unit exposure region in the next exposure operation. You can switch.

The exposure control unit can perform the multiple exposure operation at pitch intervals at which the exposure point intervals of the exposure point lines are equal. Alternatively, the exposure control unit can perform the multiple exposure operation at pitch intervals in which the exposure point positions along the main scanning direction of the adjacent exposure point lines are deviated. For example, the exposure control unit alternately alternates exposure point lines between the 2k-1 (k = 1, 2, ...) Th exposure point line and the 2kth exposure point line within the predetermined unit exposure region. Switch to.

On the other hand, the exposure control unit can perform the multiple exposure operation with the exposure point positions along the main scanning direction of the adjacent exposure point lines at the same pitch interval. For example, the exposure control unit may use the 3k-2 (k = 1, 2, ...) Th-th exposure point line, the 3k-1st exposure point line, and the 3kth exposure point line in the predetermined unit exposure region. The exposure point line is switched in order between the line and the line.

As the pitch interval of the multiple exposure operation described above, for example, the pitch interval is P, the unit exposure area of the light modulation element is C, m is an integer of 2 or more, n is an arbitrary integer, u is an integer smaller than m, and a. If the value is smaller than C, the following formula

P = (n + u / m) C + a

Can be represented by.

In the exposure method according to one aspect of the present invention, an optical modulation element array in which a plurality of optical modulation elements are arranged in two dimensions is arranged, and the exposure area of the optical modulation element array is set at a predetermined inclination angle with respect to the main scanning direction. An exposure method in which a scanning unit that is tilted to move the exposed area relative to the object to be drawn in the main scanning direction, and the plurality of optical modulation elements are modulated at predetermined pitch intervals to perform a multiple exposure operation. In a predetermined unit exposure region, the exposure point line that determines the exposure point is switched between the plurality of exposure point lines along the inclination angle for each exposure operation.

According to the present invention, a high-resolution pattern can be formed in an exposure apparatus.

It is a block diagram of the exposure apparatus which is this embodiment. It is a figure which showed the arrangement of the exposure head with respect to a stage. It is a figure which partially showed the pattern drawn on the substrate W. It is a figure which showed an example of the multiple-exposure operation using a plurality of exposure point lines. It is a figure which showed other example of the multiple-exposure operation using a plurality of exposure point lines. It is a figure which showed the modification of the multiple-exposure operation shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of the exposure apparatus according to the first embodiment. FIG. 2 is a diagram showing the arrangement of the exposure head with respect to the stage.

The exposure apparatus 10 is a maskless exposure apparatus that forms a pattern by irradiating a substrate (exposure target) W to which a photosensitive material such as a photoresist is applied or attached with light, and a stage 12 on which the substrate W is mounted is provided. It is installed so that it can be moved along the main scanning direction. The stage drive mechanism 15 moves the stage 12 along the main scanning direction X and the sub-scanning direction Y.

The exposure apparatus 10 includes a DMD 22, an illumination optical system 23, and a projection optical system 25, and is provided with a plurality of exposure heads 18 for projecting pattern light (only one exposure head is shown in FIG. 1). As shown in FIG. 2, the plurality of exposure heads 18 are staggered along the sub-scanning direction Y. The light source 20 is composed of, for example, a discharge lamp (not shown) and is driven by the light source driving unit 21.

When CAD / CAM data composed of vector data or the like is input to the exposure apparatus 10, the vector data is sent to the raster conversion circuit 26, and the vector data is converted into raster data. The generated raster data is temporarily stored in a buffer memory (not shown) and then sent to the DMD drive circuit 24.

The DMD 22 is a light modulation element array in which micromicromirrors are arranged two-dimensionally, and each micromirror selectively switches the light reflection direction by changing its posture. By controlling the attitude of each mirror by the DMD drive circuit 24, light corresponding to the pattern is projected (imaged) on the surface of the substrate W via the projection optical system 25. As a result, a pattern image is formed on the substrate W.

The stage drive mechanism 15 moves the stage 12 according to a control signal from the controller 30. The controller (exposure control unit) 30 controls the operation of the exposure device 10 and outputs a control signal to the stage drive mechanism 15 and the DMD drive circuit 24 based on the stage position information sent from the position detection unit 27.

During the exposure operation, the stage 12 moves at a constant speed, and the projection area (hereinafter referred to as the exposure area) EA of the entire DMD 22 moves relative to the substrate W along the main scanning direction X as the substrate W moves. .. As shown in FIG. 2, the plurality of exposure heads 18 are tilted by a predetermined angle α because the arrangement direction along the sub-scanning direction Y does not coincide with the sub-scanning direction Y. Therefore, when the stage 12 moves in the direction indicated by the arrow A, the exposure area EA becomes a region inclined by a predetermined angle α with respect to the main scanning direction X, and moves relative to the main scanning direction X in the inclined state. In FIG. 2, the inclination angle α is exaggerated.

The controller 30 executes multiple exposure, that is, overlap exposure in which the next exposure is performed at a position overlapping a part of the previous exposure area. The exposure operation is performed according to a predetermined pitch interval, and by modulating each micromirror of the DMD 22 according to the relative position (stage position) of the exposure area, the light of the pattern to be drawn at the position of the exposure area is sequentially projected. By drawing the entire substrate W with the plurality of exposure heads 18, a pattern is formed on the entire substrate W. The stage 12 may move intermittently instead of continuously moving.

As described above, since the exposure area EA is inclined with respect to the main scanning direction X, the exposure center point (shot center position, hereinafter referred to as the exposure point) when each micromirror is modulated at a predetermined pitch interval is , When viewed from the substrate, it is located on the line along the inclination angle. In the present embodiment, the multiple exposure operation is performed while selectively switching such lines (hereinafter referred to as exposure point lines). This will be described in detail below.

FIG. 3 is a diagram partially showing the pattern projected on the substrate W. The main scanning direction X and the fortune scanning direction Y define a drawing coordinate system on the substrate W.

The pattern by one micromirror of DMD22 becomes a square pattern of width C according to the square micromirror. For example, C is 10 μm or less. In the multiple exposure operation that requires overlap exposure, the exposure operation is repeated at pitch intervals that are not integral multiples of C.

Assuming that the exposure point N1 forming the pattern S1 is set as the exposure start point, the next exposure point N2 is shifted upward in the sub-scanning direction Y by the inclination angle α with respect to the main scanning direction X of the exposure area EA. FIG. 3 shows a pattern S1 and a pattern S2 that are continuously exposed. The DMD 22 has a structure in which a predetermined number of micromirrors are arranged (for example, 3840 × 2160) along the vertical direction corresponding to the sub-scanning direction Y and the horizontal direction corresponding to the main scanning direction X, and the patterns S1 and S2 are the main scanning. It is exposed by micromirrors arranged laterally along the direction X. When the exposure operation is repeated at a constant pitch interval, the subsequent exposure points are determined at positions on the exposure point line L1 extending from the exposure point N1 along the inclination angle α.

On the other hand, since a large number of micromirrors are arranged in the lateral direction of the DMD 22, the following pattern can be formed on the side opposite to the main scanning direction X (−X direction) from the exposure start point. FIG. 3 shows a pattern S3 of an exposure point N3 which is an exposure start point and a pattern S4 of the next exposure point N4. The exposure point N4 of the pattern S4 is located on the exposure point line L3 different from the exposure point line L2 extending from the exposure point N3 along the inclination angle α.

By the way, when a region on a substrate having a size corresponding to a projection region of one micromirror is set as a unit exposure region, in order to make the pattern resolution to be exposed equal to or less than the size of the unit exposure region, the pitch is equal to or less than the unit exposure region. It is necessary to perform multiple exposures with the above to disperse the exposure points, but the first exposure point (hereinafter referred to as the reference exposure point) in a certain unit exposure area is not always located at the end of the unit exposure area, and the position is not always located. Can be set arbitrarily.

For example, instead of the unit exposure region E1 in which the reference exposure point N5 is the end point of the square region as in the conventional case, the unit exposure region E2 in which the intermediate point of the square region is the reference exposure point N6 can be defined. Then, by adjusting the exposure pitch, the next exposure point after the reference exposure point N6 is not the exposure point line L4 extending from the reference exposure point N6 in the direction of the inclination angle α, but is parallel to the exposure point line L4 and is within the unit exposure area E2. It can be defined as the exposure point line L5 in which the exposure point fits in.

While the exposure area EA moves relative to each other, if an exposure point (shot center position) located in the unit exposure area is on one of the exposure point lines for each exposure timing, the exposure operation is repeated while changing the exposure point lines in order. Can be done. This makes it possible to narrow the spacing between adjacent exposure points in the sub-scanning direction Y, unlike the main scanning direction X where the pitch spacing is constant.

In the present embodiment, the pitch interval of the exposure operation is determined by the following equation. However, the pitch interval is P, the size (width) of the unit exposure area of the light modulation element is C, m is an integer of 2 or more, n is an arbitrary integer, and u is an integer smaller than m. Further, a represents a value smaller than C.

P = (n + u / m) C + a ... (1)

FIG. 4 is a diagram showing an example of a multiple exposure operation using a plurality of exposure point lines.

Here, the intermediate point obtained by dividing the end edge of the unit exposure region E into two equal parts in the main scanning direction X is set as the reference exposure point N1. Then, the exposure operation is performed at the pitch interval P so that the exposure points alternate between the two adjacent exposure point lines. Specifically, in equation (1), m = 2 and u = 1 are defined.

When the exposure operation is performed at the reference exposure point N1 (see FIG. 4 (A)) and the pitch interval P advances, the distance a from the end edge of the unit exposure region E on the opposite side of the reference exposure point N1 to the main scanning direction X. A new exposure point N2 is set at a position only separated by. The next exposure operation is performed at the exposure point N2 which is not located on the exposure point line L1 of the exposure point N1. On the exposure point line L1, the micromirror is not exposed without being modulated (see FIG. 4B).

Further advancing by the pitch distance interval P, the exposure operation is performed at the exposure point N3 on the exposure point line Ll1 (see FIG. 4C). By repeating this every time the pitch interval P advances, the exposure points are alternately changed between the exposure point lines L1 and L2. FIG. 4D shows exposure points N1 to N9 that are sequentially determined in chronological order.

The exposure point N5 on the exposure point line L1 is located at the end of the unit exposure area E, and the next exposure point on the exposure point line L1 deviates from the unit exposure area E. At the same time, the exposure points N7 are distributed at the other end of the unit exposure region E. Then, in the subsequent exposure operation, the exposure point line L3 extending from the exposure point N7 is replaced with the exposure point line L1, and the exposure point is moved alternately between the exposure point line L2 and the exposure point line L3. .. Since the exposure points on each exposure point line are exposed at a distance interval of 2a, they are separated from each other by a distance interval of 2a in the main scanning direction X.

In this way, within the unit exposure area E, exposure is performed while alternately switching the exposure point lines between the 2k-1st exposure point line (k is an integer of 1 or more) and the 2kth exposure point line from the bottom. As a result of the operation, the exposure point positions along the main scanning direction X are shifted from each other in the adjacent exposure point lines, and the multiple exposure operation is performed in which the exposure points are distributed at more positions along the sub-scanning direction Y. be able to. Therefore, it is possible to form a pattern in which the exposure amount is uniformly dispersed while suppressing the number of exposures (the number of exposure point distributions) in the unit exposure region E.

FIG. 5 is a diagram showing another example of the multiple exposure operation using a plurality of exposure point lines.

Here, one dividing point when the end edge of the unit exposure region E is divided into three equal parts in the main scanning direction X is set as a reference exposure point N1. Then, the exposure operation is performed at a pitch interval P in which the exposure points are alternately changed between the three exposure point lines arranged adjacent to each other. Specifically, m = 3 and u = 1 are defined for Eq. (1).

When the exposure operation is performed at the reference exposure point N1 (see FIG. 5A) and the pitch interval P advances, the distance from the divided position obtained by dividing the end edge of the other unit exposure area E into three equal parts in the main scanning direction X. The exposure point N2 is set in the unit exposure region E at a position separated by a. The next exposure operation is performed at this exposure point N2 (see FIG. 5B). The exposure point N2 is not located on the exposure point line L1 of the exposure point N1, and the exposure operation is not performed on the exposure point line L1.

Further advancing by the pitch interval P, the exposure point N3 is set at a position separated by a distance a in the main scanning direction X from the end of the unit exposure region E. The exposure operation is performed at the exposure point N3 (see FIG. 5C). No exposure operation is performed on the exposure point line L1 and the exposure point line L2. Between the exposure point lines L1 to L3, such an exposure operation of sequentially shifting the exposure points to different exposure point lines is repeated. FIG. 5D shows exposure points N1 to N9 that are sequentially determined in chronological order.

The exposure point N5 on the exposure point line L1 is located at the end of the unit exposure area E, and the next exposure point on the exposure point line L1 deviates from the unit exposure area E. On the other hand, when the two pitch intervals P are advanced, the exposure points N8 are distributed at the other end of the unit exposure region E. In the subsequent exposure operation, the exposure point line L4 extending from the exposure point N8 is replaced with the exposure point line L1, and the exposure point is sequentially changed between the exposure point line L2 and the exposure point line L3. The exposure points located along each exposure point line are the same with a distance interval of 3a.

In this way, in the unit exposure area E, the exposure operation of sequentially switching the exposure point lines between the 3k-2nd exposure point line, the 3k-1st exposure point line, and the 3kth exposure point line is performed. As a result, the exposure points are distributed at more positions along the sub-scanning direction Y, and the multiple exposure operation with no bias in the exposure amount can be performed.

FIG. 6 is a diagram showing a modified example of the multiple exposure operation shown in FIG.

Here, the exposure operation is performed at the pitch interval P defined by m = 3 and u = 2 in the equation (1). As shown in FIG. 5A, the reference exposure point N1 is located on the main scanning direction X side when the end edge of the unit exposure region E is divided into three equal parts. Then, each time the pitch interval P advances, the exposure points N2 and the exposure points N3 are set in the unit exposure region E. Here, too, the same exposure point distribution as in FIG. 5 can be obtained. u represents the position of the reference exposure point when there are three or more exposure point lines.

As described above, according to the present embodiment, the exposure apparatus 10 performs the multiple exposure operation with the pitch interval P based on the above equation (1). By setting the position of the reference exposure point in the unit exposure area, the exposure points can be moved in order between the plurality of exposure point lines, so that the exposure points are scattered in the sub-scanning direction Y together with the main scanning direction X. It will be possible.

A reference exposure point different from the reference exposure point described above may be set, or the exposure point may be changed between four or more adjacent exposure point lines. Further, the exposure points may be changed between the exposure point lines that are not adjacent to each other.

The exposure apparatus 10 can be configured with a single exposure head, and the multiple exposure operation may be performed by a control configuration other than the controller 30. It is also possible to form a pattern with a light modulation element other than a micromirror.

10 Exposure device 22 DMD (light modulation element array)
30 controller (exposure control unit)

Claims (10)

An optical modulation element array in which a plurality of light modulation elements are arranged two-dimensionally,
A scanning unit that moves the exposure area of the light modulation element array, which is inclined at a predetermined tilt angle with respect to the main scanning direction, relative to the object to be drawn in the main scanning direction.
It is provided with an exposure control unit that modulates the plurality of light modulation elements at predetermined pitch intervals and performs a multiple exposure operation.
An exposure apparatus characterized in that the exposure control unit switches an exposure point line that determines an exposure point for each exposure operation between a plurality of exposure point lines along the inclination angle in a predetermined unit exposure region. The exposure apparatus according to claim 1, wherein the exposure control unit sequentially switches the exposure point lines among a plurality of exposure point lines arranged adjacent to each other. The exposure control unit switches the exposure point line whose exposure point moves within the predetermined unit exposure region in the next exposure operation to the exposure point line whose exposure point deviates from the predetermined unit exposure region in the next exposure operation. The exposure apparatus according to claim 1 or 2. The exposure apparatus according to any one of claims 1 to 3, wherein the exposure control unit performs a multiple exposure operation at pitch intervals at which the exposure point intervals of the exposure point lines are equal. The exposure apparatus according to claim 4, wherein the exposure control unit performs a multiple exposure operation at pitch intervals in which the exposure point positions along the main scanning direction of adjacent exposure point lines are deviated. The exposure control unit alternately alternates exposure point lines between the 2k-1 (k = 1, 2, ...) Th exposure point line and the 2kth exposure point line within the predetermined unit exposure region. The exposure apparatus according to claim 5, wherein the exposure apparatus is switched to. The exposure apparatus according to claim 4, wherein the exposure control unit performs a multiple exposure operation at exposure point positions along a main scanning direction of adjacent exposure point lines at the same pitch interval. The exposure control unit performs the 3k-2 (k = 1, 2, ...) Th-th exposure point line, the 3k-1st exposure point line, and the 3kth exposure point line in the predetermined unit exposure region. The exposure apparatus according to claim 7, wherein the exposure point lines are sequentially switched between the two. When the predetermined pitch interval is P, the unit exposure area of the light modulation element is C, m is an integer of 2 or more, n is an arbitrary integer, u is an integer smaller than m, and a is a value smaller than C, P is as follows. Expression

P = (n + u / m) C + a

The exposure apparatus according to any one of claims 1 to 8, wherein the exposure apparatus is represented by. A light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged is arranged.
A scanning unit that tilts the exposure area of the light modulation element array at a predetermined tilt angle with respect to the main scanning direction and moves the exposure area relative to the object to be drawn in the main scanning direction.
An exposure method in which the plurality of light modulation elements are modulated at predetermined pitch intervals to perform a multiple exposure operation.
An exposure method characterized in that, in a predetermined unit exposure region, an exposure point line that determines an exposure point is switched between a plurality of exposure point lines along the inclination angle for each exposure operation.

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