Exposure apparatus and exposure method

Abstract

To perform a multiple exposure action capable of effectively dispersing exposure spots in an exposure apparatus.SOLUTION: An exposure apparatus 10 includes a DMD 22. An exposure area EA of the DMD 22 relatively moves to a substrate W in a state of slanting to a main scanning direction X by a fine angle α. An exposure center point (shot center point, hereinafter referred to as an exposure point) when each micro mirror is modified by a predetermined pitch is defined on a line (hereinafter referred to as an exposure point line ) having an angle that is an inclination angle different from an inclination angle α with respect to the main scanning angle of the exposure area EA and is larger than the inclination angle α. A multiple exposure action is performed while selectively switching a plurality of exposure point lines.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an exposure apparatus that forms a pattern using an optical modulation element array, and particularly relates to multiple exposures.

Background Art

[0002] In a maskless exposure apparatus, while moving a stage on which a substrate is mounted along a scanning direction, pattern light is projected onto the substrate by an optical modulation element array such as a DMD (Digital Micro-mirror Device). In order to form a pattern with a resolution equal to or less than the projection size (cell size) of the micromirror, the optical modulation element array is arranged so that the exposure area is slightly inclined with respect to the main scanning direction, and a multiple exposure operation is performed in which the exposure area is overlapped and exposed repeatedly (see, for example, Patent Document 1).

[0003] In order to disperse a large number of exposure points (shot center positions) as uniformly as possible with respect to the projection size of the micromirror, a multiple exposure operation for switching exposure point lines is performed (see Patent Document 2). Therein, the pitch of the exposure operation is determined based on a predetermined formula, and a plurality of exposure point lines are defined along the inclination angle of the exposure area with respect to the main scanning direction. Then, multiple exposures are performed while sequentially switching the exposure points between the plurality of exposure point lines.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] For reasons such as increasing the resolution of patterns along the sub-scanning direction and increasing the resolution of the diagonal line pattern, the tilt angle of the exposure area with respect to the main scanning direction is usually set to a small angle. In order to scatter exposure points (shot center positions) over the entire area of one mirror image region (hereinafter referred to as a unit exposure region), it is necessary to set a large pitch for the multiple exposure operation, and the relative movement distance of the substrate between shots becomes long. Therefore, a wide range of micromirrors are used until the number of exposure times required for exposure of the unit exposure region is reached. This may prevent throughput improvement.

[0006] For example, when the pattern image of the entire DMD is divided by a branching optical system (division optical system) and the divided pattern images are projected onto different scanning band regions along the sub-scanning direction, if the relative movement distance between shots is set long, the number of multiple exposures for the unit exposure region is limited, and it is difficult to disperse the exposure points. Also, when forming the divided pattern image, there is a possibility of a limit in the number of pattern divisions.

[0007] Therefore, it is required to execute a multiple exposure operation capable of effectively dispersing the exposure points.

Means for Solving the Problem

[0008] The exposure apparatus of the present invention includes an optical modulation element array in which a plurality of optical modulation elements are two-dimensionally arranged, a scanning unit that relatively moves the exposure area of the optical modulation element array, which is tilted at a predetermined tilt angle with respect to the main scanning direction, in the main scanning direction with respect to the object to be drawn, and an exposure control unit that modulates the plurality of optical modulation elements at a predetermined pitch and performs a multiple exposure operation. The tilt angle can be set as a small angle, for example, 5 degrees or less. And the exposure control unit switches the exposure point line that determines the exposure points for each exposure operation between a plurality of exposure point lines along a tilt angle larger than the tilt angle in a predetermined unit exposure region.

[0009] The "predetermined unit exposure area" refers to an area having a size corresponding to the projected area of one light modulation element as viewed from above the substrate, and is inclined at an angle corresponding to the inclination angle of the exposure area with respect to the main scanning direction. Also, the "exposure point line" represents a line connecting exposure points along the inclination angle direction as viewed from above the substrate when the multi-exposure operation is performed at a predetermined pitch, and a plurality of exposure point lines parallel to each other are defined on the substrate.

[0010] By switching the exposure point line for each exposure operation, the exposure points are sequentially switched to the exposure points on different exposure point lines. The pitch of the multi-exposure operation can be determined so that the multi-exposure operation using micromirrors arranged in parallel along the main scanning direction is performed. That is, it can be determined to use the micromirrors parallel to the micromirror that shoots the first exposure point (herein referred to as the reference exposure point) with respect to a certain unit exposure area. Also, the pitch can be determined to select and use some of the micromirrors from among the series of parallel micromirrors.

[0011] The exposure control unit can sequentially switch the exposure point line between a plurality of adjacent exposure point lines. Also, the exposure control unit can switch the exposure point line where the exposure point moves within the predetermined unit exposure area in the next exposure operation to the exposure point line where the exposure point moves outside the predetermined unit exposure area in the next exposure operation.

[0012] The exposure control unit can perform the multi-exposure operation at a pitch such that the exposure point intervals of each exposure point line are equal. Alternatively, the exposure control unit can also perform the multi-exposure operation at a pitch such that the exposure point positions along the main scanning direction of adjacent exposure point lines are shifted.

[0013] Another aspect of the exposure method of the present invention is an exposure method in which an optical modulation element array in which a plurality of optical modulation elements are two-dimensionally arranged is disposed, the exposure area of the optical modulation element array is inclined at a predetermined inclination angle with respect to the main scanning direction, and the exposure area is relatively moved in the main scanning direction with respect to an object to be drawn. The exposure method includes a scanning unit and an exposure method that modulates the plurality of optical modulation elements at a predetermined pitch and performs a multi-exposure operation. In a predetermined unit exposure area, an exposure point line that determines an exposure point is switched for each exposure operation between a plurality of exposure point lines along an inclination angle larger than the inclination angle.

Effect of the Invention

[0014] According to the present invention, in an exposure apparatus, it is possible to execute a multi-exposure operation capable of effectively dispersing exposure points.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a block diagram of an exposure apparatus according to the present embodiment. FIG. 2 is a diagram showing the arrangement of an exposure head with respect to a stage.

[0018] The exposure apparatus 10 is a maskless exposure apparatus that forms a pattern by irradiating light onto a substrate (exposure target) W coated or attached with a photosensitive material such as photoresist. A stage 12 on which the substrate W is mounted is installed so as to be movable along the main scanning direction. A stage drive mechanism 15 moves the stage 12 along the main scanning direction X and the sub-scanning direction Y.

[0019] 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 that project pattern light (only one exposure head is shown in FIG. 1). As shown in FIG. 2, the plurality of exposure heads 18 are arranged in a staggered pattern along 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 drive unit 21.

[0020] When CAD / CAM data composed of vector data or the like is input to the exposure apparatus 10, the vector data is sent to a raster conversion circuit 26 and converted into raster data. The generated raster data is temporarily stored in a buffer memory (not shown) and then sent to a DMD drive circuit 24.

[0021] The DMD 22 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 its attitude. By controlling the attitude of each mirror by a 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. Here, the projection magnification is set to 1×.

[0022] The stage drive mechanism 15 moves the stage 12 in accordance with a control signal from a 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. For the substrate W mounted on the stage 12, an X-Y coordinate system with the main scanning direction as X and the sub-scanning direction as Y is defined.

[0023] During the exposure operation, the stage 12 moves at a constant speed, and the entire projection area (hereinafter referred to as the exposure area) EA of the DMD 22 relatively moves along the main scanning direction X over the substrate W as the substrate W moves. As shown in FIG. 2, the plurality of exposure heads 18 are inclined by a minute predetermined angle α (hereinafter referred to as the minute angle) such that the arrangement direction along the sub-scanning direction Y thereof 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 the minute angle α with respect to the main scanning direction X, and relatively moves in the main scanning direction X in the inclined state. Note that in FIG. 2, the minute angle α is exaggeratedly drawn.

[0024] The controller 30 executes multiple exposure, that is, overlapping exposure in which the next exposure is performed at a position overlapping a partial area of the previous exposure area. The exposure operation is performed according to a predetermined pitch, 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. Note that the stage 12 may move intermittently instead of continuously. The memory 32 stores a program for controlling the controller 30 and the like.

[0025] In the present embodiment, the exposure center point (shot center position, hereinafter referred to as the exposure point) when each micromirror is modulated at a predetermined pitch is defined on a line having an inclination angle different from the minute angle α with respect to the main scanning direction X of the exposure area EA and having an angle larger than the minute angle α (hereinafter referred to as the exposure point line). Then, the multiple exposure operation is performed while selectively switching a plurality of exposure point lines. Hereinafter, this will be described in detail.

[0026] FIG. 3 is a diagram showing an example of the distribution of exposure points along the exposure point line with respect to the unit exposure area.

[0027] The pattern formed by one micromirror of DMD22 is a rectangular pattern with a width C according to the square micromirror. For example, C is 10 μm or less. In the multiple exposure operation with overlapping exposure, the exposure operation is repeated at a pitch that is not an integer multiple of C.

[0028] In DMD22, a matrix array is formed in which a predetermined number of micromirrors are arranged along the vertical direction corresponding to the sub-scanning direction Y and the horizontal direction corresponding to the main scanning direction X (for example, 3840×2160). During the exposure operation, pattern light is projected onto the substrate W according to the arrangement of the micromirrors for a predetermined area of the substrate W. FIG. 3 shows the exposure points of some micromirrors of DMD22, that is, the shot center positions (see reference symbol CP).

[0029] Since the exposure area EA, which is the projection area of DMD22, is inclined by a small angle α with respect to the main scanning direction X, the shot center positions of each micromirror also move in a direction inclined by the small angle α in accordance with the moving direction of the exposure area EA. Therefore, when a certain unit exposure area is defined on the substrate W, while the multiple exposure operation is performed at a predetermined pitch, the exposure points of the micromirrors 22 that reach positions where the unit exposure area can be irradiated with a pattern shift in the sub-scanning direction Y. Specifically, they shift in the sub-scanning direction Y by a value that is an integer multiple of the pitch value (assuming cosα≒1).

[0030] In an example shown in FIG. 3, when the multiple exposure operation is performed with the pitch set to 1.54C, the exposure points of the micromirrors M1 to M7 with respect to the unit exposure area E are shown. Here, taking the exposure point CP of the micromirror M1 as the middle position of the bottom side and defining a unit exposure area E with this as the first exposure point (hereinafter also referred to as the reference exposure point) (hereinafter, the reference exposure point is represented by the reference symbol N1). The width (size) of the unit exposure area E is equal to the size C of the micromirror here.

[0031] The multi-exposure operation is performed at a pitch of 1.54C, and the exposure area EA moves relatively while tilted at a small angle α. Therefore, among the micromirrors M2 to M7 arranged in parallel in the horizontal direction (row direction) of DMD22 with respect to the unit exposure area E, some of the micromirrors M3, M4, M6, and M7 reach positions where exposure points (shot center positions) are included within the unit exposure area E during the process of repeating the exposure operation. Here, the exposure points of the micromirrors M3, M4, M6, and M7 are represented by the symbols N2, N3, N4, and N5, respectively.

[0032] According to the multi-exposure operation with a pitch of 1.54C, after the exposure operation at the reference exposure point N1, the exposure operation is next performed at the exposure point N2, and then the exposure operations are performed in the order of the exposure points N3, N4, and N5. Between the exposure point lines L1 and L2, the exposure operations of moving the exposure points to different exposure point lines are repeated. The reference exposure point N1 and the exposure points N3, N5 are located on the exposure point line L1, and the exposure points N2, N4 are located on the exposure point line L2.

[0033] The exposure point lines L1 and L2 are lines defined according to the pitch of the multi-exposure operation and are tilted with respect to the unit exposure area E. The tilt angle β is larger than the small angle α, which is the tilt angle of the exposure area EA (β > α).

[0034] When the exposure operation is further performed on the exposure point line L1, the exposure point moves out of the unit exposure area E. Instead, the exposure operation within the unit exposure area E is performed by a micromirror on which an exposure point (shot center position) is located on a new exposure point line L3 that fits within the unit exposure area E. Thereafter, the exposure points shift in order between the exposure point line L2 and a new exposure point line (not shown) defined on the opposite side of the exposure point line L1, and the multi-exposure operation is performed in order between a plurality of exposure point lines.

[0035] In this way, by performing an exposure operation in which the exposure point moves between a plurality of exposure point lines, it becomes possible to distribute a large number of exposure points within the unit exposure area E along the sub-scanning direction Y. Further, while the exposure point positions along the main scanning direction X of adjacent exposure point lines are shifted, all the exposure points on the same exposure point line are separated from each other along the exposure point line by the same distance interval. As a result, within the unit exposure area E, the exposure points can be dispersed (scattered) as uniformly as possible.

[0036] FIG. 4 is a diagram showing another example of the exposure point distribution within the unit exposure area E. Here, a multiple exposure operation with a pitch of 1.217C is performed. However, in FIG. 4, an area where the reference exposure point is located at the lower left corner of the region is defined as the unit exposure area E.

[0037] As shown in FIG. 4, within the unit exposure area E, exposure points are distributed along five exposure point lines L1 to L6. An exposure operation is performed while switching the exposure points between the exposure point lines L1 to L6, and a multiple exposure operation based on a non-biased exposure point distribution is performed. Specifically, the exposure points repeatedly shift in the order of exposure point lines L1, L2, L3, L4, L5, L1, L2, ···. Further, as the exposure points on the exposure point line L5 move out of the unit exposure area E, exposure points along a new exposure point line L6 are distributed within the unit exposure area E, and the exposure points shift between the exposure point lines L1, L2, L3, L4, and L6.

[0038] Similar to the exposure point distribution in FIG. 3, while the exposure point positions along the main scanning direction X of adjacent exposure point lines are shifted, all the exposure points on the same exposure point line are separated from each other along the exposure point line by the same distance interval.

[0039] The inclination angle β of the exposure point lines L1 to L6 is larger than the minute angle α in FIG. 3. This is due to setting the pitch so as to set more exposure point lines within the unit exposure area E.

[0040] By appropriately determining the pitch of the multiple exposure operation to a value that is not an integral multiple in this way, within the unit exposure area E, it is possible to disperse as many exposure points as evenly as possible without bias. Regarding the pitch, it is possible to calculate the pitch by multiplying a non-integral real value by C and then adding a value smaller than the real value (herein referred to as the adjustment value). For example, a value one digit smaller or with fewer digits than that can be defined as the adjustment value.

[0041] For example, when the variable multiplied by C is "M", M is a real number greater than or equal to 1 (excluding integral multiples) with one decimal digit, and when the adjustment value to be added is "m", m can be defined as a value with two decimal digits or less. By appropriately selecting the value of the adjustment value, it becomes possible to change the inclination angle β of the exposure point line, and the distribution state of the exposure points can be made into a desired distribution state.

[0042] In order to perform the multiple exposure operation using the micromirrors in the same column (same row), from the perspective of throughput improvement, it is possible to achieve the number of exposure times until reaching photosensitivity under the condition that the relative movement distance of the substrate W is short. Therefore, the pitch can be determined according to the sensitivity of the substrate W, and the multiple exposure operation can be executed. On the other hand, it is not necessarily the case that adjacent micromirrors are continuously defined as exposure points within the unit exposure area E. According to the set pitch of the multiple exposure operation, while using the micromirrors selected from a series of parallel micromirrors, in other words, while selecting the micromirrors in a form of thinning out, the exposure operation is performed at the exposure points within the unit exposure area E.

[0043] Note that it may be configured as an exposure apparatus provided with a split optical system disclosed in Japanese Patent Application Laid-Open No. 2012-247711 and Japanese Patent Application Laid-Open No. 2017-083676. In this case, the micromirrors are ON / OFF controlled according to each split pattern. Also in the multiple exposure operation using such a split optical system, while using micromirrors in a relatively close arrangement relationship, it is possible to disperse more exposure points as evenly as possible without bias with respect to the unit exposure area.

Explanation of Reference Numerals

[0044] 10 Exposure apparatus 22 DMD (Optical modulation element array) E unit exposure area EA exposure area α minute angle (tilt angle)

Claims

1. An optical modulation element array in which a plurality of optical modulation elements are two-dimensionally arranged, a scanning unit that relatively moves the exposure area of the optical modulation element array, which is inclined at a predetermined inclination angle with respect to the main scanning direction, in the main scanning direction with respect to the object to be drawn, and an exposure control unit that modulates the plurality of optical modulation elements at a predetermined pitch and performs a multi-exposure operation, wherein the exposure control unit switches an exposure point line that determines exposure points for each exposure operation among a plurality of exposure point lines along an inclination angle larger than the inclination angle in a predetermined unit exposure area. An exposure apparatus characterized by this.

2. The exposure apparatus according to claim 1, wherein the exposure control unit sequentially switches the exposure point lines among a plurality of adjacent exposure point lines.

3. The exposure apparatus according to claim 1, wherein the exposure control unit switches an exposure point line where the exposure points move within the predetermined unit exposure area in the next exposure operation with an exposure point line where the exposure points deviate from the predetermined unit exposure area in the next exposure operation.

4. The exposure apparatus according to claim 1, wherein the exposure control unit performs a multi-exposure operation with a pitch such that the exposure point intervals of each exposure point line are equal.

5. The exposure apparatus according to claim 4, wherein the exposure control unit performs a multi-exposure operation with a pitch such that the exposure point positions along the main scanning direction of adjacent exposure point lines are shifted.

6. The exposure apparatus according to any one of claims 1 to 5, wherein the pitch is determined so that a multi-exposure operation using micromirrors arranged in parallel along the main scanning direction is performed.

7. An optical modulation element array in which a plurality of optical modulation elements are two-dimensionally arranged is disposed, the exposure area of the optical modulation element array is inclined at a predetermined inclination angle with respect to the main scanning direction, a scanning unit that relatively moves the exposure area in the main scanning direction with respect to the object to be drawn, and an exposure method that modulates the plurality of optical modulation elements at a predetermined pitch and performs a multi-exposure operation, wherein in a predetermined unit exposure area, an exposure point line that determines exposure points is switched for each exposure operation among a plurality of exposure point lines along an inclination angle larger than the inclination angle. An exposure method characterized by this.

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