阅读说明：本技术 曝光装置和曝光方法 (Exposure apparatus and exposure method ) 是由 奥山隆志 于 2020-11-25 设计创作，主要内容包括：本发明提供一种曝光装置和曝光方法。能够使曝光点均匀分散的新的多重曝光。在曝光装置(10)中,通过基于下述式(1)的上述间距(P)进行多重曝光动作。通过设定基准曝光点在单位曝光区域内的位置,使曝光点在多个曝光点线之间依次移动,从而使曝光点在主扫描方向(X)和副扫描方向(Y)上分散。其中,将固定的间距间隔设为P,将光调制元件的单位曝光区域设为C,将m设为2以上的整数,将n设为任意的整数,将u设为比m小的整数,将a设为比C小的值,满足P＝(n+u/m)C+a。(The invention provides an exposure apparatus and an exposure method. A new multiple exposure capable of uniformly dispersing the exposure points. In the exposure device (10), multiple exposure operations are performed by the pitch (P) based on the following formula (1). By setting the position of the reference exposure point within the unit exposure field, the exposure points are sequentially moved between the plurality of exposure point lines, thereby dispersing the exposure points in the main scanning direction (X) and the sub-scanning direction (Y). The fixed pitch interval is P, the unit exposure field 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, and P ═ n + u/m) C + a is satisfied.)

1. An exposure apparatus, comprising:

a light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged;

a scanning unit that relatively moves an exposure region of the light modulation element array, which is inclined at a predetermined inclination angle with respect to a main scanning direction, with respect to a subject to be depicted in the main scanning direction; and

an exposure control unit for performing a multiple exposure operation by adjusting the plurality of light modulation elements at predetermined pitch intervals,

the exposure control unit switches an exposure dot line of a predetermined exposure point among a plurality of exposure dot lines along the inclination angle in a predetermined unit exposure region for each exposure operation.

2. The exposure apparatus according to claim 1,

the exposure control unit sequentially switches between a plurality of exposure point lines arranged adjacent to each other.

3. The exposure apparatus according to claim 2,

the exposure control unit switches an exposure point line, in which an exposure point is separated from the predetermined unit exposure field in the next exposure operation, to an exposure point line, in which the exposure point is moved in the predetermined unit exposure field in the next exposure operation.

4. The exposure apparatus according to claim 3,

the exposure control unit performs multiple exposure operations at pitch intervals at which the exposure dot intervals of the exposure dot lines are equal to each other.

5. The exposure apparatus according to claim 4,

the exposure control unit performs multiple exposure operations at pitch intervals at which exposure point positions of adjacent exposure point lines along the main scanning direction are shifted.

6. The exposure apparatus according to claim 5,

the exposure control unit alternately switches the exposure dot lines between the 2k-1 th exposure dot line and the 2k th exposure dot line within the predetermined unit exposure region, where k is 1, 2, and ….

7. The exposure apparatus according to claim 4,

the exposure control unit performs a multiple exposure operation so that exposure point positions of adjacent exposure point lines along the main scanning direction are at the same pitch interval.

8. The exposure apparatus according to claim 7,

the exposure control unit sequentially switches the exposure point lines among a 3k-2 th exposure point line, a 3k-1 th exposure point line, and a 3 k-th exposure point line in the predetermined unit exposure region, where k is 1, 2, and ….

9. The exposure apparatus according to any one of claims 1 to 8,

if the predetermined pitch interval is P, the unit exposure field 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 can be represented by the following formula:

P＝(n+u/m)C+a。

10. an exposure method is characterized in that,

an array of light modulation elements in which a plurality of light modulation elements are two-dimensionally arranged is arranged,

tilting an exposure region of the light modulation element array at a predetermined tilt angle with respect to a main scanning direction, and relatively moving the exposure region with respect to a drawing target in the main scanning direction,

adjusting the plurality of light modulation elements at a predetermined pitch interval to perform a multiple exposure operation,

in the predetermined unit exposure region, an exposure dot line of a predetermined exposure point is switched between a plurality of exposure dot lines along the inclination angle for each exposure operation.

Technical Field

The present invention relates to an exposure apparatus for forming a pattern using an array of light modulation elements, and more particularly to multiple exposure.

Background

In a maskless exposure apparatus, pattern light is projected onto a substrate by an array of light modulation elements such as a DMD (Digital Micro-mirror Device) while moving a stage on which the substrate is mounted in a scanning direction. Here, the light modulation elements (micromirrors and the like) arranged in a two-dimensional shape are controlled so that pattern light is projected in accordance with the position of a projection area (exposure area) on the substrate on which the photoresist layer is formed, which is mounted on the stage.

In the case of a pattern resolution of the order of micrometers, it is necessary to form the pattern to be equal to or smaller than the projection size (cell size) of a micromirror or the like, and therefore, multiple exposure is performed in which exposure regions are overlapped and exposure is repeated (see, for example, patent documents 1 and 2). Here, the light modulation element array or the substrate mounting stage is arranged such that the exposure region is slightly inclined with respect to the main scanning direction without making the pitch interval of the exposure operation an integral multiple of the cell size.

If the pitch interval in the multiple exposure is P and the size of the unit exposure field (the field of the image of 1 mirror) of the micromirror is C, the multiple exposure is performed at a pitch interval P equal to a + a (a is an arbitrary integer, C > a). As a result, a plurality of exposure points (imaging center positions) are two-dimensionally distributed in a unit exposure field (a field of one mirror image) (see patent document 3).

Patent document 1: japanese patent No. 4203649

Patent document 2: japanese Kokai publication Hei-2004-514280

Patent document 3: japanese patent No. 4728536

In recent years, with the progress of higher sensitivity of photoresists and with the increase in light source output, the performance of optical systems has been improved, the throughput has been increased, and the number of shots per exposure field tends to be reduced. Therefore, the exposure points within the unit exposure field are not scattered and become uneven, and the pattern line width or profile may not reach the desired accuracy.

Therefore, a new multiple exposure capable of uniformly dispersing the exposure points is required.

Disclosure of Invention

An exposure apparatus of the present invention includes: a light modulation element array in which a plurality of light modulation elements are two-dimensionally arranged; a scanning unit that relatively moves an exposure region of the light modulation element array, which is inclined at a predetermined inclination angle with respect to a main scanning direction, with respect to a subject to be depicted in the main scanning direction; and an exposure control unit that performs multiple exposure operations by adjusting the plurality of light modulation elements at predetermined pitch intervals.

In the present invention, the exposure control unit switches the exposure line of the predetermined exposure point among the plurality of exposure lines along the inclination angle in the predetermined unit exposure region for each exposure operation. The "predetermined unit exposure field" is a field having a size corresponding to a projection field of one light modulation element when viewed from above the substrate. The "exposure dot line" indicates a line connecting the exposure dots in the oblique direction when viewed from above the substrate when the multiple exposure operation is performed at a predetermined pitch interval, and a plurality of exposure dot lines parallel to each other are defined on the substrate. The exposure control unit switches the exposure point lines for each exposure operation, thereby sequentially switching the exposure points to exposure points on different exposure point lines.

The exposure control unit can sequentially switch the exposure point lines between a plurality of exposure point lines arranged adjacently. The exposure control unit switches an exposure point line, in which an exposure point is separated from the predetermined unit exposure field in the next exposure operation, to an exposure point line, in which the exposure point is moved in the predetermined unit exposure field in the next exposure operation.

The exposure control unit can perform multiple exposure operations at pitch intervals at which the exposure dot intervals of the exposure dot lines are equal to each other. Alternatively, the exposure control unit may perform multiple exposure operations at pitch intervals that shift the positions of the exposure points along the main scanning direction of the adjacent exposure point lines. For example, the exposure control unit alternately switches the exposure dot lines between the 2k-1 th exposure dot line and the 2k nd exposure dot line in the predetermined unit exposure region, where k is 1, 2, and ….

On the other hand, the exposure control unit can perform multiple exposure operations at pitch intervals at which the exposure point positions along the main scanning direction of adjacent exposure point lines are the same. For example, the exposure control unit sequentially switches the exposure point lines among the 3k-2 rd exposure point line, the 3k-1 th exposure point line, and the 3k rd exposure point line in the predetermined unit exposure region, where k is 1, 2, and ….

As the pitch interval of the multiple exposure operation, for example, when the pitch interval is P, the unit exposure field 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, the following expression can be expressed:

P＝(n+u/m)C+a。

in an exposure method according to an aspect of the present invention, an exposure area of an array of light modulation elements in which a plurality of light modulation elements are two-dimensionally arranged is tilted at a predetermined tilt angle with respect to a main scanning direction, the exposure area is moved relative to a drawing target in the main scanning direction, the plurality of light modulation elements are adjusted at predetermined pitch intervals, and a multiple exposure operation is performed, and an exposure point line of a predetermined exposure point is switched between a plurality of exposure point lines along the tilt angle for each exposure operation in a predetermined unit exposure area.

Drawings

Fig. 1 is a block diagram of an exposure apparatus according to the present embodiment.

Fig. 2 is a diagram showing the arrangement of the exposure head with respect to the stage.

Fig. 3 is a view partially showing a pattern drawn on the substrate W.

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

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

Fig. 6 is a view showing a modification of the multiple exposure operation shown in fig. 5.

Description of the reference symbols

10: an exposure device;

22: DMD (light modulation element array);

30: a controller (exposure control unit).

Detailed Description

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

Fig. 1 is a block diagram of an exposure apparatus according to embodiment 1. Fig. 2 is a diagram showing the arrangement of the exposure head on the stage.

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

The exposure apparatus 10 includes a DMD22, an illumination optical system 23, and a projection optical system 25, and is provided with a plurality of exposure heads 18 (only 1 exposure head is shown in fig. 1) for projecting pattern light. As shown in fig. 2, the plurality of exposure heads 18 are staggered in the sub-scanning direction Y. The light source 20 is constituted by, for example, a discharge lamp (not shown), and is driven by a 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 grid conversion circuit 26, and the vector data is converted into grid data. The generated raster data is temporarily stored in a buffer (not shown), and then transmitted to the DMD drive circuit 24.

The DMD22 is an optical modulation element array in which micro mirrors are two-dimensionally arranged, and each micro mirror selectively switches the reflection direction of light by changing the posture. By controlling the posture of each mirror by the DMD drive circuit 24, light corresponding to the pattern is projected (imaged) onto the surface of the substrate W via the projection optical system 25. Thereby, a pattern image is formed on the substrate W.

The stage drive mechanism 15 moves the stage 12 in accordance with a control signal from the controller 30. The controller (exposure control unit) 30 controls the operation of the exposure apparatus 10, and outputs control signals 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 fixed speed, and the projection area (hereinafter referred to as exposure area) EA of the entire DMD22 moves relative to the substrate W in the main scanning direction X as the substrate W moves. As shown in fig. 2, the arrangement direction of the plurality of exposure heads 18 along the sub-scanning direction Y does not coincide with the sub-scanning direction Y, and is inclined by a predetermined angle α. Therefore, when stage 12 moves in the direction indicated by arrow a, exposure area EA becomes an area inclined by a predetermined angle α with respect to main scanning direction X, and moves relatively in main scanning direction X in an inclined state. In addition, in fig. 2, the inclination angle α is exaggeratedly depicted.

The controller 30 performs multiple exposures, i.e., an overlap exposure of the next exposure at a position overlapping with a part of the previous exposure area. The exposure operation is performed at predetermined pitch intervals, and each micromirror of the DMD22 is modulated according to the relative position (stage position) of the exposure area, thereby sequentially projecting light of a pattern to be drawn at the position of the exposure area. The entire substrate W is drawn by the plurality of exposure heads 18, and a pattern is formed on the entire substrate W. Alternatively, the stage 12 may be moved intermittently instead of continuously.

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

Fig. 3 is a view partially showing a pattern projected onto the substrate W. The main scanning direction X and the sub-scanning direction Y define a drawing coordinate system on the substrate W.

The pattern of 1 micromirror of the DMD22 is a square pattern along the width C of a square shaped micromirror. For example, C is 10 μm or less. In a multiple exposure operation requiring a double exposure, the exposure operation is repeated at a pitch interval not an integral multiple of C.

If the exposure point N1 at which the pattern S1 is formed is taken as the exposure start point, the next exposure point N2 is moved in the sub-scanning direction Y by an amount equivalent to the inclination angle α of the exposure area EA with respect to the main scanning direction X. The pattern S1 and the pattern S2 resulting from the successive exposures are shown in fig. 3. The DMD22 has a structure in which a predetermined number of micromirrors (for example, 3840 × 2160) are arranged in the vertical direction corresponding to the sub-scanning direction Y and in the horizontal direction corresponding to the main scanning direction X, and the patterns S1 and S2 are exposed by the micromirrors arranged in the horizontal direction along the main scanning direction X. When the exposure action is repeated at fixed pitch intervals, the position of the subsequent exposure point on the exposure point line L1 extending from the exposure point N1 at the inclination angle α can be determined.

On the other hand, since a plurality of micromirrors are arranged in the lateral direction of the DMD22, the next pattern may be formed on the opposite side of the main scanning direction X from the exposure start point (the (-X direction)). In fig. 3, a pattern S3 of the exposure point N3 as an exposure start point and a pattern S4 of the next exposure point N4 are shown. The exposure point N4 of the pattern S4 is located on an exposure point line L3 different from the exposure point line L2 extending from the exposure point N3 at the inclination angle α.

In addition, when an area on the substrate having a size corresponding to the projection area of one micromirror is used as a unit exposure area, in order to make the pattern resolution of exposure equal to or smaller than the size of the unit exposure area, it is necessary to perform multiple exposures at a pitch equal to or smaller than the unit exposure area to disperse the exposure points, but the first exposure point (hereinafter referred to as a reference exposure point) in a certain unit exposure area is not necessarily located at the end of the unit exposure area, and the position thereof may be arbitrarily set.

For example, instead of the unit exposure field E1 in which the reference exposure point N5 is set as the end point of the square region as in the conventional art, a unit exposure field E2 in which the middle point of the square region is set as the reference exposure point N6 may be defined. Then, by adjusting the exposure pitch, the next exposure point of the reference exposure point N6 is not defined on the exposure point line L4 extending in the direction of the inclination angle α from the reference exposure point N6, but is defined on the exposure point line L5, and the exposure point line L5 is parallel to L4 and is positioned in the unit exposure field E2.

While the exposure area EA is relatively moved, if the exposure point (irradiation center position) located in the unit exposure area is located on one exposure point line at each exposure timing, the exposure operation can be repeated while sequentially changing the exposure point lines. This makes it possible to narrow the interval between adjacent exposure points in the sub-scanning direction Y, unlike the main scanning direction X in which the pitch interval is fixed.

In the present embodiment, the pitch interval of the exposure operation is determined by the following equation. Here, the pitch interval is P, the size (width) of the unit exposure field 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. In addition, 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 dot rows.

Here, the intermediate point at which the end edge 2 of the unit exposure field E is equally divided in the main scanning direction X is set as the reference exposure point N1. Then, an exposure operation is performed at a pitch interval P so that the exposure point is alternately moved between the adjacent 2 exposure dot lines. Specifically, in formula (1), m is 2 and u is 1.

When the exposure operation is performed on the reference exposure point N1 (see fig. 4 a) and then the pitch interval P is advanced, a new exposure point N2 is set at a position a away from the end edge of the unit exposure field E on the opposite side of the reference exposure point N1 in the main scanning direction X. The next exposure operation is performed on the exposure point N2 on the exposure point line L1 which is not located at the exposure point N1. The exposure point line L1 is not subjected to exposure without adjusting the micromirrors (see fig. 4B).

When the pitch distance interval P is further advanced, an exposure operation is performed at an exposure point N3 located on the exposure point line L11 (see fig. 4C). By repeating this operation each time the pitch interval P is advanced, the exposure point is transferred between the exposure dot lines L1 and L2. Fig. 4 (D) shows exposure points N1 to N9 defined in time series.

The exposure point N5 on the exposure dot line L1 is located at the end of the unit exposure field E, and the next exposure point on the exposure dot line L1 is offset from the unit exposure field E. Meanwhile, the exposure points N7 are distributed at the other end of the unit exposure field E. In the subsequent exposure operation, the exposure point line L1 is switched to the exposure point line L3 extending from the exposure point N7, and an exposure operation is performed in which the exposure point is alternately moved between the exposure point line L2 and the exposure point line L3. Since the exposure operation is performed at the distance interval 2a at the exposure point on each exposure point, the exposure points are separated from each other by the distance interval 2a in the main scanning direction X.

As a result of performing the exposure operation while alternately switching the exposure point lines between the 2k-1(k is an integer of 1 or more) th exposure point line and the 2 k-th exposure point line from below in the unit exposure field E, the exposure point positions in the main scanning direction X in the adjacent exposure point lines are shifted from each other, and a multiple exposure operation in which the exposure points are distributed at more positions in the sub-scanning direction Y can be performed. Therefore, a pattern in which the exposure amount is uniformly dispersed while the number of exposures (the number of exposure point distributions) in the unit exposure field E is suppressed can be formed.

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

Here, one division point at which the edge of the unit exposure field E is divided into three equal parts in the main scanning direction X is set as the reference exposure point N1. Then, the exposure operation is performed at a pitch interval P at which the exposure points are alternately transferred between 3 exposure point lines arranged adjacently. Specifically, in formula (1), m is 3 and u is 1.

When the reference exposure point N1 has performed the exposure operation (see fig. 5 a) and then has advanced by the pitch interval P, the exposure point N2 is set in the unit exposure field E at a position separated from another divided position equally dividing the edge 3 of the unit exposure field E by the distance a in the main scanning direction X. The next exposure operation is performed at the 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.

When the pitch interval P is further advanced, the exposure point N3 is set at a position separated from the end of the unit exposure field E by a distance a in the main scanning direction X. An exposure operation is performed at the exposure point N3 (see fig. 5C). No exposure operation is performed on exposure point line L1 and exposure point line L2. Such an exposure operation of sequentially moving the exposure points to different exposure point lines is repeated between the exposure point lines L1 to L3. Fig. 5 (D) shows exposure points N1 to N9 defined in time series.

The exposure point N5 on the exposure dot line L1 is located at the end of the unit exposure field E, and the next exposure point on the exposure dot line L1 is offset from the unit exposure field E. On the other hand, when advancing by 2 pitch intervals P, the exposure points N8 are distributed at the other end of the unit exposure field E. In the subsequent exposure operation, the exposure point line L1 is switched to the exposure point line L4 extending from the exposure point N8, and an exposure operation is performed in which the exposure points are sequentially shifted between the exposure point line L2 and the exposure point line L3. The exposure points along each exposure line are equally spaced apart by a distance interval 3 a.

In this way, as a result of performing the exposure operation for sequentially switching the exposure dot lines among the 3k-2 rd exposure dot line, the 3k-1 th exposure dot line, and the 3k th exposure dot line in the unit exposure field E, the exposure dots are distributed at more positions in the sub-scanning direction Y, and a multiple exposure operation with an average exposure amount can be performed.

Fig. 6 is a diagram showing a modification of the multiple exposure operation shown in fig. 5.

Here, the exposure operation is performed at a pitch interval P where m is 3 and u is 2 defined in the formula (1). As shown in fig. 5 (a), the reference exposure point N1 is located on the main scanning direction X side when the edge of the unit exposure field E is divided into three equal parts. Each time the pitch interval P advances, an exposure point N2 and an exposure point N3 are set in the unit exposure field E. The same distribution of exposure points as in fig. 5 can be obtained here. u denotes the position of the reference exposure point in the case where there are 3 or more exposure point lines.

As described above, according to the present embodiment, the exposure apparatus 10 performs the multiple exposure operation at the pitch interval P based on the above expression (1). The exposure points can be dispersed in the main scanning direction X and the sub-scanning direction Y by sequentially moving the exposure points between the plurality of exposure point lines by setting the positions of the reference exposure points within the unit exposure field.

A reference exposure point different from the reference exposure point may be set, or an exposure point may be transferred between 4 or more exposure point lines arranged adjacently. Also, the exposure points may be transferred between non-adjacent exposure point lines.

The exposure apparatus 10 may be configured as a single exposure head, or may be configured to perform multiple exposure operations by a control mechanism other than the controller 30. Light modulation elements other than micromirrors may also be used to form the pattern.