Exposure device and exposure method

Abstract

The invention provides an exposure apparatus and an exposure method. In the exposure device, multiple exposures are performed according to an exposure pitch of an exposure point distribution capable of forming a high-resolution pattern including a pattern along an inclined direction. The exposure device relatively moves in a state in which the exposure region (EA) is inclined by a minute angle [alpha] with respect to the main scanning direction (X direction), and during this period, multiple exposure operations are performed according to the pitch determined by the following formula. P = (n + u / m) C + a (1) a = (1 / (m2-b)) * (b / m) * C (2) where P is the pitch, C is the size (width) of the unit exposure region of the light modulation element, m is an integer of 2 or more, n is an arbitrary integer, and u is an integer smaller than m. And a represents a value less than C.

Description

Technical Field

[0001] The present invention relates to an exposure device for forming a pattern using an array of light modulating elements, and particularly to multiple exposure. Background Art

[0002] In a maskless exposure device, a stage carrying a substrate is moved along a scanning direction while a light pattern is projected onto the substrate using an array of light modulators, such as a DMD (Digital Micro-mirror Device). To form a pattern with a resolution below the projection size (cell size) of the micromirrors, the light modulator array is arranged so that the exposure areas are slightly tilted relative to the main scanning direction, and a multiple exposure operation is performed, repeatedly exposing the exposure areas while overlapping them (see, for example, Patent Documents 1 and 2).

[0003] To improve the resolution of the pattern, it is necessary to disperse multiple exposure points (shooting center positions) as evenly as possible over the projection area of ​​any micromirror (hereinafter referred to as a unit exposure area). For example, the spacing of the multiple exposure operation is determined according to a predetermined formula, and multiple exposure point lines are defined along the inclination angle of the exposure area relative to the main scanning direction. Then, multiple exposures are performed while sequentially switching the exposure points between the multiple exposure point lines (see Patent Document 3).

[0004] Patent Document 1: Japanese Patent No. 4273290

[0005] Patent Document 2: Japanese Patent No. 4273291

[0006] Patent Document 3: Japanese Patent Application Laid-Open No. 2021-157039

[0007] Regarding patterns, high resolution is required for patterns along the inclined direction, just like in the main scanning direction and the sub-scanning direction. However, as the patterns become smaller, it becomes difficult to form patterns (especially patterns along the inclined direction) with high precision even if the exposure spacing is simply determined so that the exposure points (shooting center positions) are dispersed in the unit exposure area.

[0008] Therefore, it is required to perform multi-exposure at an exposure pitch that allows for an exposure point distribution that can form a high-resolution pattern including a pattern along an oblique direction. Summary of the Invention

[0009] The exposure device of the present invention includes a light modulator array, which is a two-dimensional arrangement of multiple light modulators. The exposure area, which serves as the projection area of ​​the light modulator array, is tilted at a predetermined angle relative to the main scanning direction. For example, the arrangement of the light modulator array can be tilted at a slight angle relative to the main scanning direction. Furthermore, the exposure device includes a scanning unit that moves the exposure area relative to the object being drawn in the main scanning direction. For example, the scanning unit includes a stage for carrying the object being drawn, such as a substrate, and the exposure area is moved relative to the object being drawn by moving the stage carrying the substrate. Furthermore, the exposure device includes an exposure control unit that modulates the multiple light modulators at a predetermined pitch to perform multiple exposures. Furthermore, in the present invention, the pitch is determined to allow for a distribution of exposure points arranged along three non-perpendicular directions, with adjacent exposure points located at the vertices of a triangle with identical geometric properties.

[0010] The term "geometrically equal triangle" here refers to an exposure point distribution that forms a triangle with substantially equal or nearly equal geometric features between any two adjacent exposure points. For example, the spacing can be determined to form an exposure point distribution that forms the vertices of an equilateral triangle. The term "equilateral triangle" encompasses not only strictly geometrically defined equilateral triangles, i.e., triangles with equal sides and 60° internal angles, but also triangles that approximate equilateral triangles, with side lengths or included angles that differ within the acceptable range for an equilateral triangle.

[0011] Alternatively, the pitch can be determined to be a pitch that allows the exposure points to be distributed at the vertices of an isosceles triangle. The term "isosceles triangle" includes not only isosceles triangles in the strict geometric sense, but also triangles that are close to isosceles triangles in which the lengths of the sides or the angles between them vary within an acceptable range.

[0012] Considering improving the resolution of the pattern in the inclined direction, even if the exposure points are densely distributed, the spacing can be determined so that the exposure points are arranged in a direction inclined relative to the boundary of the unit exposure area of ​​the light modulator, that is, the exposure points are not arranged along the boundary of the unit exposure area.

[0013] Taking into account the fact that the exposure area is scanned in a state where it is tilted at a slight angle, the pitch can be determined so as to enable a multiple exposure operation using micromirrors arranged along the main scanning direction.

[0014] The exposure device may include a pitch setting unit for setting the pitch. The pitch setting unit may set the pitch from a plurality of pitches corresponding to a plurality of exposure point distributions having different distribution states.

[0015] The exposure method of the present invention includes the following steps: configuring a light modulator array, which is obtained by arranging multiple light modulators in two dimensions; tilting the exposure area of ​​the light modulator array at a specified tilt angle relative to the main scanning direction; moving the exposure area relative to the object to be drawn in the main scanning direction; and modulating the multiple light modulators according to a specified spacing to perform multiple exposure actions, wherein the spacing is determined to be a spacing that can form a distribution of exposure points arranged along three directions that are not perpendicular to each other and located at the vertex positions of a geometrically equal triangle between adjacent exposure points.

[0016] According to the present invention, in the exposure apparatus, multiple exposure can be performed at an exposure pitch that allows for an exposure point distribution that can form a high-resolution pattern including a pattern along an oblique direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a block diagram of the exposure apparatus of this embodiment.

[0018] Figure 2 It is a figure which shows the arrangement|positioning of an exposure head with respect to a stage.

[0019] Figure 3 Graph showing the distribution of exposure points within a unit exposure area.

[0020] Figure 4 A diagram showing a rhombic grid defined by the light spot distribution.

[0021] Figure 5 1 is a diagram illustrating a derivation process for determining the pitch of exposure point distribution.

[0022] Figure 6 : is a diagram showing an exposure point distribution having an isosceles triangle distance interval between mutually adjacent exposure points.

[0023] Label Description

[0024] 10: exposure device; 22: DMD (light modulation element array); E: unit exposure area; EA: exposure area; α: micro angle; P: pitch; ED: exposure point distribution. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0026] Figure 1 This is a block diagram of the exposure apparatus of this embodiment. Figure 2 It is a figure which shows the arrangement|positioning of an exposure head with respect to a stage.

[0027] The exposure device 10 is a maskless exposure device that forms a pattern by irradiating light onto a substrate (exposure target) W coated with or attached with a photosensitive material such as a photoresist. A stage 12 carrying the substrate W is arranged to be movable in a main scanning direction. A stage drive mechanism 15 moves the stage 12 in the main scanning direction X and the sub-scanning direction Y.

[0028] The exposure device 10 includes a DMD 22, an illumination optical system 23, a projection optical system 25, and a plurality of exposure heads 18 (in the Figure 1 Only one exposure head is shown in the figure). Figure 2 As shown, the plurality of exposure heads 18 are arranged in a staggered manner 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 driving unit 21 .

[0029] When CAD / CAM data consisting of vector data or the like is input to the exposure device 10, the vector data is sent to the 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 the DMD drive circuit 24.

[0030] The DMD 22 is a light modulation element array composed of tiny micromirrors arranged two-dimensionally. Each micromirror selectively switches the direction of light reflection by changing its posture. The DMD drive circuit 24 controls the posture of each mirror, projecting (imaging) light corresponding to a pattern onto the surface of the substrate W via the projection optical system 25. This forms a pattern image on the substrate W. Here, the projection magnification is set to 1x.

[0031] The stage drive mechanism 15 moves the stage 12 based on a control signal from the controller 30. The controller (exposure control unit) 30 controls the operation of the exposure device 10 and outputs control signals to the stage drive mechanism 15 and the DMD drive circuit 24 based on stage position information sent from the position detection unit 27. An XY coordinate system is defined for the substrate W mounted on the stage 12, with the main scanning direction being X and the sub-scanning direction being Y.

[0032] 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 moves relatively on the substrate W along the main scanning direction X as the substrate W moves. Figure 2 As shown, the arrangement direction of the plurality of exposure heads 18 along the sub-scanning direction Y is not consistent with the sub-scanning direction Y, but is tilted at a small predetermined angle α (hereinafter referred to as the small angle). Therefore, when the stage 12 moves in the direction indicated by the arrow A, the exposure area EA becomes an area tilted at the small angle α relative to the main scanning direction X, and moves relatively in the main scanning direction X in an inclined state. Figure 2In FIG, the small angle α is exaggerated.

[0033] The controller 30 performs multiple exposures, i.e., overlapping exposures where the next exposure overlaps a portion of the previous exposure area. Exposures are performed at a predetermined pitch, modulating the micromirrors of the DMD 22 according to the relative positions of the exposure areas (stage positions) to sequentially project light representing the pattern to be drawn at the locations of the exposure areas. Multiple exposure heads 18 draw the entire substrate W, forming a pattern across the entire substrate W. Alternatively, the stage 12 may be moved intermittently rather than continuously. The memory 32 stores programs for controlling the controller 30.

[0034] In this embodiment, the spacing is determined so that when plotting the mirror center points (shooting center positions, hereinafter referred to as exposure points) during exposure when performing a multiple exposure operation, i.e., modulating each micromirror at a predetermined spacing, the distribution becomes a distribution in which adjacent exposure points are arranged in three non-perpendicular directions with equal spacing between them. Furthermore, the spacing between exposure points and the direction in which the exposure points are arranged can be set and selected. This is described below.

[0035] Figure 3 : is a diagram showing the exposure point distribution of a unit exposure area.

[0036] Here, the projection area of ​​a single micromirror of the DMD 22, i.e., the unit exposure area E, is a square pattern having a width C, according to the square-shaped micromirrors. For example, C is set to be less than 10 μm. Furthermore, the DMD 22 has a matrix arrangement with a predetermined number of micromirrors (e.g., 3840 × 2160) arranged in a longitudinal direction corresponding to the sub-scanning direction Y and a transverse direction corresponding to the main scanning direction X.

[0037] Since the projection area of ​​the DMD 22, i.e., the exposure area EA, is tilted at a slight angle α relative to the main scanning direction X, the exposure point (center position of imaging) EP of each micromirror also moves in a direction tilted at the slight angle α, consistent with the direction of movement of the exposure area EA. Therefore, when a unit exposure area E is defined on the substrate W, while the multiple exposure operation is performed at a predetermined pitch, the exposure point EP of the micromirror 22 that reaches a position capable of irradiating the unit exposure area E with a pattern shifts in the sub-scanning direction Y. Specifically, the exposure point EP shifts in the sub-scanning direction Y by an integer multiple of the pitch.

[0038] Here, the inclination angle β of the line (here, represented by label L1) on which the exposure points EP are arranged when the exposure area EA advances in the main scanning direction X and shifts along the sub-scanning direction Y is greater than the small angle α of the exposure area EA relative to the main scanning direction X, that is, the small angle of the unit exposure area E of each micromirror relative to the main scanning direction X (β>α).

[0039] The exposure points EP are regularly distributed in the unit exposure area E so as to be aligned along the line L1 and the lines L2 and L3. Specifically, any three adjacent exposure points are spaced at equal distances from each other. Figure 3 The three exposure points P0, P1, and P2 shown are equidistant from each other and form the vertices of an equilateral triangle. The three lines L1, L2, and L3 along which the exposure points EP are arranged are not perpendicular to each other and are not parallel to the boundary of the unit exposure area E or the main scanning direction X or the sub-scanning direction Y.

[0040] Figure 4 1 is a diagram showing a rhombic lattice (hexagonal lattice) defined based on the above-mentioned exposure point distribution.

[0041] by Figure 3 The exposure points EP in the distribution state shown as a plane lattice (grid) of lattice points can be determined as an orthorhombic lattice G. The orthorhombic lattice G here is determined by analogy with the lattice of a repeating pattern in the crystal structure of metals, etc., and is obtained by connecting lattice points arranged in three directions that are not perpendicular to each other.

[0042] In particular, the rhombus lattice G here defines the positions of the lattice points according to the distance between adjacent lattice points to form an equilateral triangle. Hereinafter, this planar lattice is referred to as a hexagonal lattice. In a hexagonal lattice, shapes are represented using equilateral triangles as units, and various shapes can be expressed by connecting the lattice points.

[0043] Similar to the hexagonal lattice structure of a metal crystal structure, the hexagonal lattice G as a plane lattice can arrange lattice points densely compared to a square lattice composed of two mutually perpendicular lines. In particular, when forming a figure with lines along an inclined direction as the outline, more lattice points can be arranged. For example, it is possible to draw Figure 4 The figure of the regular hexagon PP along the arc of the circle CP is shown.

[0044] Therefore, by conducting Figure 3 The multiple exposure operation with the exposure point distribution shown can form a high-precision pattern in the main scanning direction X, the sub-scanning direction Y, and the oblique direction relative to the main scanning direction X and the sub-scanning direction Y. Figure 3 The pitch of the exposure point distribution shown can be determined, for example, as follows.

[0045] Figure 5 is a diagram illustrating a derivation process for determining the pitch of exposure point distribution.

[0046] Here, the pitch of the multiple exposure operation is determined by the following equation. Here, let P be the pitch, let C be the size (width) of the unit exposure area of ​​the light modulator, let m be an integer greater than 2, let n be an arbitrary integer, and let u be an integer less than m. Furthermore, a represents a value less than C.

[0047] P = (n + um) CC + a (1)

[0048] Furthermore, assuming that a multiple exposure action is performed using micromirrors arranged along the main scanning direction (X direction), by continuously using a portion of the above-mentioned micromirrors while performing the multiple exposure action according to the pitch P of the multiple exposure action, an exposure point distribution is formed that can achieve exposure in which the exposure points are dispersed within the entire range of the unit exposure area E.

[0049] exist Figure 3 In the exposure point distribution ED shown, the lines L1, L2, and L3 along which the exposure points EP are arranged are all inclined relative to the boundary line of the unit exposure area E. In the above formula (1), by setting a = 0, an exposure point distribution is determined in which the exposure points EP are arranged along the boundary line of the unit exposure area E. In contrast, by setting a value other than 0, the arrangement direction of the exposure points EP is inclined relative to the boundary line of the unit exposure area E.

[0050] exist Figure 5 (A) shows the exposure point distribution when n = 1, m = 8, u = 1, and a = 0 are substituted into the above formula (1) (here, this is an exposure point distribution different from the actual exposure point distribution, so it is represented by the symbol E0). In this case, regarding the pitch P of the multi-exposure operation, according to the above formula (1), P = 1.125C. The exposure point distribution E0 is regularly arranged along the line (exposure point line) L30, which is along the boundary line of the unit exposure area E (≈ the sub-scanning direction (Y direction)). The number of exposure point lines L30 corresponds to the value of m (= 8).

[0051] On the other hand, through the multiple exposure operation, the exposure points EP are arranged along multiple lines (exposure point lines) while being shifted along the sub-scanning direction (Y direction) at an inclination angle β relative to the square unit exposure area E. The number of exposure point lines L10 along the inclination angle β is equal to the number of exposure point lines L30 (=8).

[0052] When a≠0 is set, the exposure points EP are not arranged along the exposure point line L30 (≈sub-scanning direction (Y direction)), and each time a multiple exposure operation is performed, the exposure points are shifted by the value of a in the main scanning direction (X direction), and the shift amount is gradually accumulated in the unit exposure area E. Figure 5 In (A), the exposure point at this time is indicated by symbol EP', and one exposure point line where the exposure points EP' are arranged is indicated by symbol L'.

[0053] Here, considering that the slope of the line L' where the exposure points EP' are arranged changes according to the value of a, the number of exposure point lines L10 and the number of exposure point lines L30 (=8) along the tilt angle β in the square unit exposure area E are equal, it can be achieved by adjusting the value of a. Figure 3 The exposure point distribution ED shown is an exposure point distribution ED in which the distances between three adjacent exposure points are equal to form an equilateral triangle.

[0054] Specifically, a perpendicular bisector passing through the midpoint of the adjacent exposure point lines along the sub-scanning direction (Y direction) is drawn to find the intersection of two exposure points arranged along the tilt angle β. Figure 5 (B) shows an enlarged view of Figure 5 The intersection of the four exposure points in (A) is represented by the symbol p, when exposure points N1, N2, N9, and N10 are set. Furthermore, although exposure point N2 deviates from exposure point line L30 when a≠0, this value is sufficiently small compared to the value of pitch P, so the value of a is determined assuming that exposure point N2 is located on exposure point line L30.

[0055] The intersection point of the line segment connecting the exposure point N1 at the lower left end of the unit exposure area E and the intersection point p with the upper side of the unit exposure area E is defined as q. When arranging the exposure points ED along this exposure point line (indicated by the reference numeral LL1), the number of exposure point lines from the left side of the unit exposure area E is defined as b. Figure 5 In (C), b=3.

[0056] When an exposure point line LL2 is determined that is parallel to the exposure point line LL1 and has an exposure point located at the upper right end of the unit exposure area E, Figure 5 The position of the exposure point (reference symbol PP) in the case of a=0 shown in (A) is the last exposure position in the unit exposure area E. The exposure point PP is Figure 5 The exposure point distribution E0 of (A) is (m 2 -b) exposure points.

[0057] Here, in Figure 5 The exposure point distribution E0 shown in (A) is (m 2-b) The position of the next exposure point PQ of the exposure point PP is the position of the upper right end of the unit exposure area E. Therefore, when the exposure point lines LL1 and LL2 are defined, Figure 5 d shown in (D) can be expressed as (b / m)×C.

[0058] for Figure 5 The exposure point N2 shown in (B) is shifted by a value a (≠0) in the main scanning direction (X direction). For the exposure points determined sequentially, the shift amount along the main scanning direction (X direction) gradually accumulates according to the number of multiple exposure operations. Therefore, the following formula can be used to calculate the realization Figure 3 The value of a for the exposure point distribution shown.

[0059] a (1(m2-b))×(b / m))×C(2)

[0060] exist Figure 5 Here, b=3, m=8, and therefore a=0.006C.

[0061] The exposure point distribution ED obtained based on the pitch P of the multiple exposure operation described above is an exposure point distribution in which the distances between three adjacent exposure points are substantially equal, forming a plane lattice point distribution in the shape of an equilateral triangle. As described above, the pitch P is determined based on a geometric approximation, so in a strict sense, the exposure point distribution obtained will not be exactly the same as the plane lattice point distribution forming an equilateral triangle.

[0062] However, considering that the exposure point distribution ED that can improve the pattern accuracy is obtained under conditions (restrictions) such as the size of the micromirror and the number of exposure point lines being an integer, and that the spacing is derived on the software installed in the exposure device, it can be said that an exposure point distribution of exposure points with geometric distance intervals of an "equilateral triangle shape" is created, that is, an exposure point distribution that is similar to the hexagonal lattice of the crystal structure of a metal as an analogy.

[0063] The above-mentioned pitch P is used as a calculation formula to obtain the exposure point distribution having the distance intervals between the vertices of the "equilateral triangle shape" between adjacent exposure points. Figure 5 The spacing P obtained in the experiment is the same as the number of exposure points on the exposure point line when a=0 is set (in Figure 5 This is because, depending on the value of the small angle α of the unit exposure area E relative to the main scanning direction X, it may not be possible to derive Figure 5 In this case, the pitch P of the exposure point distribution is calculated so that three adjacent exposure points have a distance interval between the vertices of an "isosceles triangle shape".

[0064] Figure 6: is a diagram showing an exposure point distribution having an isosceles triangle distance interval between mutually adjacent exposure points.

[0065] Here, the small angle α of the unit exposure area E with respect to the main scanning direction (X direction) is Figure 5 Specifically, in Figure 5 The exposure point distribution shown is a multiple exposure operation using 64 (=8×8) micro mirrors in the same row. When n=1, m=8, and u=1, the small angle α=1 / 72. Figure 6 In FIG. 1 , a multiple exposure operation is performed using 48 (=8×6) micromirrors in the same row continuously. When n=1, m=8, and u=1, the small angle α=1 / 54.

[0066] and Figure 5 Similarly, the pitch P of the multiple exposure operation is obtained. Here, the number of exposure points on the exposure point line L30 when a=0 is set to m' (in Figure 6 In the case of 6 exposure points, the (m×m′-b)th exposure point becomes the final exposure point, and thus is obtained by the following formula.

[0067] a (1(m×m'-b))×(b / m)×C(3)

[0068] Although Figure 6 The exposure point distribution shown is similar to Figure 5 The exposure point distribution shown is not uniform, but it can create a pattern with good precision (especially in the oblique direction) compared to an exposure point distribution with vertices of a simple triangle that is not an equilateral triangle or an isosceles triangle.

[0069] As described above, according to the exposure apparatus of this embodiment, the exposure area EA moves relative to the main scanning direction (X direction) while being tilted at a slight angle α. During this time, multiple exposures are performed according to the pitch calculated using the above equation. By performing multiple exposures according to an exposure point distribution in which exposure points are distributed at the vertices of an equilateral triangle or an isosceles triangle, a pattern with high precision can be formed.

[0070] Furthermore, an exposure point distribution can be formed at the vertex positions of triangles other than regular triangles and isosceles triangles. In this case, the exposure point distribution is formed so that the exposure points are arranged at the vertex positions of triangles that are considered to be congruent, that is, triangles that have the same geometric properties.

[0071] In addition, it is also possible to configure the operator to be able to appropriately select and set Figure 5 、 Figure 6The exposure point distribution shown or other exposure point distributions. For example, the controller 30 may be configured to set an arbitrary exposure point distribution based on an input operation from an operator.

Claims

1. An exposure device, characterized in that: The exposure device comprises: A light modulator array is a two-dimensional array of multiple light modulators. a scanning unit that moves an exposure area of ​​the light modulation element array, which is tilted at a predetermined angle with respect to a main scanning direction, relative to an object to be drawn in the main scanning direction; as well as an exposure control unit for modulating the plurality of light modulators at a predetermined pitch to perform a multiple exposure operation, The pitch is determined so as to allow exposure points to be distributed in three directions that are not perpendicular to each other and with vertices of geometrically equal triangles located between adjacent exposure points.

2. The exposure device according to claim 1, wherein The pitch is determined to be a pitch that enables exposure points to be distributed at vertex positions of an equilateral triangle shape or an isosceles triangle shape.

3. The exposure device according to claim 1, wherein The pitch is determined so as to achieve an exposure dot distribution in which the exposure dots are arranged in a direction oblique to the boundary of the unit exposure region of the light modulation element.

4. The exposure device according to claim 1, wherein The exposure device further includes a pitch setting unit for setting the pitch. The pitch setting unit sets a pitch from among a plurality of pitches corresponding to a plurality of exposure point distributions having different distribution states.

5. The exposure apparatus according to any one of claims 1 to 4, wherein The pitch is determined so as to enable a multiple exposure operation using micromirrors arranged along the main scanning direction.

6. An exposure method comprising the following steps: Arranging a light modulator array, wherein the light modulator array is obtained by arranging a plurality of light modulators in a two-dimensional manner; Inclining the exposure area of ​​the light modulation element array at a predetermined angle relative to the main scanning direction; moving the exposure area relative to the object to be drawn in the main scanning direction; and The plurality of light modulators are modulated at a predetermined pitch to perform a multiple exposure operation. It is characterized by: The pitch is determined to be a pitch that allows exposure points to be distributed in three directions that are not perpendicular to each other and with vertices of geometrically equal triangles located between adjacent exposure points.

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