JP5357617B2 - Exposure equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve throughput while micro patterns are formed, in an exposure apparatus using a spatial light modulator. <P>SOLUTION: A maskless exposure apparatus includes a DMD 24 and projection optical system 26 on its exposure head. The projection optical system 26 is provided with a first imaging optical system 28, an integrator 40 and a second imaging optical system 46. The integrator 40 provided with a fly-eye lenses 42 and 43 divides a pattern image into cell pattern images, and reduces them individually. A data correction section makes data areas corresponding to areas (divided areas) of a group of micro mirrors forming the cell pattern images into blocks, and it generates raster data consisting of a plurality of blocks. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a maskless exposure apparatus that directly draws a pattern using a spatial light modulator such as a DMD (Digital Micro-mirror Device), and more particularly to an exposure process in which the size of a beam spot is changed.

  In a maskless exposure apparatus equipped with a DMD or the like, an exposure operation is performed by controlling a light modulation device in which light modulation elements are two-dimensionally arranged in a matrix, and a pattern is directly formed on a drawing surface of a substrate. As a method for forming a two-dimensional high-accuracy pattern, a method of skewing the scanning direction with respect to the substrate is known, and by gradually shifting the spot position of the micromirror group in the same row in the sub-scanning direction. Then, an overlap exposure operation is performed on the same area (dot) (see, for example, Patent Document 1).

  The pattern image reflected on the DMD is enlarged / reduced by the imaging optical system, and the area size of the projection spot is enlarged / reduced on the exposure surface. However, when the spot size is enlarged, the MTF (Modulation Transfer Function) characteristic is lowered and the pattern resolution is lowered. In order to prevent a decrease in the MTF value, for example, a pair of fly-eye lenses (integrators) in which microlenses are two-dimensionally arranged so as to face DMD micromirrors are arranged. The mirror reflection image of the DMD is reduced for each cell image of each microlens, and a pattern image scattered at equal intervals with a predetermined spot size is formed (see Patent Document 2).

JP 2003-50469 A JP 2004-62155 A

  In recent years, there is a tendency that a drawing area where a pattern is to be formed is expanded in order to increase the size of a substrate such as a liquid crystal substrate or to improve production efficiency. On the other hand, in order to improve the performance of the arithmetic circuit, pattern miniaturization is required. In order to satisfy such a requirement, it is necessary to enlarge the entire light modulation device and reduce the size of the micromirror, but it is difficult to individually manufacture a light modulation device dedicated to the exposure apparatus.

  In Patent Document 2, since the micromirror and the microlens have a 1: 1 correspondence, the projection spot becomes minute by each microlens, and the pattern can be miniaturized. However, it is difficult to adjust the optical axis of each microlens according to a micromirror having a small size, and the optical system cannot be adjusted with high accuracy. Further, since the projection spot size is very small, the work time for performing the multiple exposure process increases, and the throughput cannot be improved.

  An exposure apparatus of the present invention is an exposure apparatus that forms a pattern using a spatial light modulation element such as a DMD, and is a light modulation element array in which a plurality of spatial light modulation elements that modulate light from a light source are two-dimensionally arranged. And scanning means for moving an area to be projected (hereinafter referred to as an exposure area) defined by the light modulation element array relative to the object to be drawn. For example, at least one DMD in which micromirrors are two-dimensionally arranged as spatial light modulation elements can be used as the light modulation element array.

  A light modulation element array such as a DMD or LCD guides illumination light from a light source to a drawing object according to a pattern, and selectively guides illumination light such as a micromirror or a liquid crystal element to the drawing object or the drawing object. It is constituted by a spatial light modulation element. The scanning unit may move the light modulation element array or the drawing object relatively, for example, the substrate may be moved in the scanning direction by a table driving mechanism or the like. As the scanning means, a step & repeat method of intermittently moving the exposure area intermittently or a continuous movement method of continuously moving the exposure area can be applied.

  An exposure apparatus of the present invention has a first optical system that forms an image of reflected light from a light modulation element array and forms a pattern image, and a plurality of microlenses that are two-dimensionally arranged. And a second optical system that individually reduces in units of partial images (hereinafter referred to as cell pattern images).

  The exposure apparatus further includes an exposure data generating unit that generates exposure data, and an exposure control unit that controls a plurality of spatial light modulation elements based on a relative position of the exposure area. By performing control according to the pattern (for example, ON / OFF control), a predetermined pattern is formed on the drawing object. For example, vector data input to the apparatus as pattern data is converted into raster data, and exposure data for controlling each light modulation element is generated from the raster data. The substrate on which the pattern is formed is subjected to development processing, etching or plating treatment, and then the photosensitive material is peeled off to manufacture the substrate.

  In the present invention, a first optical system and a second optical system are provided as an optical system that performs reduction projection in units of reflected light of each micromirror. The pattern image of the reflected light is divided into microlens sizes by the first optical system and the second optical system, and the cell pattern image is individually reduced. As a result, the pattern image is formed on the drawing object in such a manner that cell pattern images reduced at predetermined intervals (hereinafter referred to as reduced cell pattern images) are scattered.

  The first optical system may be formed while enlarging / reducing the pattern image by the reflected light, or can form the pattern image at the same magnification. The size of the pattern image may be determined based on the exposure area size of the drawing object, the size of the light modulation element array, and the like. For example, the first optical system includes an imaging optical system that enlarges the magnification of the entire pattern image.

  On the other hand, the second optical system includes an imaging optical system that individually reduces each cell pattern image while dividing the entire pattern image into cell pattern images corresponding to the microlens size. For example, the second optical system is configured by an integrator optical system including a microlens array group (for example, two microlens arrays) in which a plurality of microlenses are arranged to face each other.

  In the present invention, the arrangement of the microlenses is not 1: 1 corresponding to the arrangement of the spatial light modulation elements, but the spatial light modulation element area forming the cell pattern image corresponds to the microlens. That is, a single cell pattern image is formed by reflected light from a series of spatial light modulation elements (hereinafter referred to as a spatial light modulation element group) that are adjacent to each other in a predetermined number (two or more).

  This spatial light modulation element group is determined in consideration of the entrance pupil of the microlens, that is, the power performance. For example, the spatial light modulation element group may be configured in the maximum area where light is incident on the entrance pupil of the microlens, or may be configured with less than that. When a data area (hereinafter referred to as a block) corresponding to the spatial light modulation element group is a data unit, the pattern data corresponding to the pattern image is composed of a plurality of blocks according to the arrangement of the microlenses.

  In order to execute the exposure operation based on the correspondence between the data block and the microlens, the exposure data generation unit of the present invention uses the spatial light modulation element group that forms the cell pattern image from the pattern data corresponding to the pattern image. Are converted into pattern data composed of blocks corresponding to the above, and exposure data of each block is generated as spot data. That is, a pattern is formed using an illumination spot (hereinafter referred to as a unit exposure area) composed of a spatial light modulation element group as an illumination unit. Then, the exposure control means controls the plurality of spatial light modulation elements according to the exposure data of each block based on the relative position of the exposure area.

  In the present invention, the exposure area during the exposure operation can be enlarged by enlarging the pattern image with the first optical system or the like. On the other hand, the size of each reduced cell pattern image can be adjusted by the enlargement and reduction magnification of the first optical system and the second optical system. According to this, the size of the cell pattern image can be set to a size capable of forming a fine pattern within the exposure area enlarged by the first optical system. In particular, by defining the light modulation element group according to the microlens size, the required pattern accuracy, etc., it is possible to project illumination spots scattered at an arbitrary pitch and size.

  Therefore, the conflicting technical problem of reducing the size of each reduced cell pattern image (illumination spot) is improved while improving the throughput even under the exposure conditions of exposure to a large substrate and formation of a fine pattern. be able to. Exposure data generation processing and exposure control for executing such an exposure operation are executed.

  Further, by making the scanning direction (main scanning direction) oblique with respect to the arrangement direction of the reduced cell pattern image, it is possible to irradiate a pattern between unit exposure areas arranged at a predetermined interval. As a result, the entire irradiation surface can be irradiated with light in a single scan, and it is possible to realize fine pattern formation and improved throughput.

  For accurate pattern formation, it is desirable to make exposure amounts as equal as possible in the sub-scanning direction. The scanning means may relatively move the exposure area according to a predetermined tilt angle so that the exposure amount is equal in the sub-scanning direction.

For example, the size along the sub-scanning direction of the unit exposure area corresponding to the reduced cell pattern image is A, the pitch along the sub-scanning direction between the adjacent unit exposure areas is B, and the scanning direction between the adjacent unit exposure areas is When the pitch along the line is C, the inclination angle is θ, the number of unit exposure areas arranged along the scanning direction is N, and the number of overlaps of a predetermined reduced cell pattern image is n, the inclination angle θ satisfies the following expression: What is necessary is just to comprise.

tan θ = B / N × C
N × A = B × n

  The boundary portion between adjacent spatial light modulation element groups may or may not be clearly defined in accordance with the microlens boundary, that is, the light incident boundary. The number of spatial light modulation elements constituting the spatial light modulation element group depends on the size of the microlens. Therefore, in order to divide the spatial light modulation element array as evenly as possible without leaving the spatial light modulation elements, the number of arrangements of the spatial light modulation element groups should follow the common divisor of the number of arrangements in the spatial light modulation elements. It should be configured. In this case, the microlens is sized according to a common divisor.

  The exposure data processing apparatus of the present invention forms a pattern image by forming a light modulation element array in which a plurality of spatial light modulation elements that modulate light from a light source are two-dimensionally arrayed and light reflected by the light modulation element array. And a second optical system having a plurality of two-dimensionally arranged microlenses and individually reducing a pattern image in units of cell pattern images formed by each microlens. It is a data processing apparatus of the apparatus, and is incorporated in the exposure apparatus or configured separately from the exposure apparatus.

  Then, the exposure data processing device includes raster conversion processing means for converting vector data corresponding to the pattern image into raster data, and raster data as data corresponding to a predetermined number of spatial light modulation element groups forming a reduced cell pattern image. Exposure data generating means for converting into raster data composed of blocks as areas and generating exposure data for each block as spot data is provided.

  The exposure data processing method of the present invention converts vector data corresponding to a pattern image into raster data, and the raster data is converted into a data area corresponding to a predetermined number of spatial light modulation element groups forming a reduced cell pattern image. It is converted to raster data composed of a certain block, and exposure data of each block is generated as spot data.

  According to the present invention, it is possible to improve the throughput while forming a fine pattern.

It is the perspective view which showed typically the drawing apparatus which is 1st Embodiment. Is a diagram illustrating an internal structure of the exposure head 20 _1. 3 is a block diagram of a drawing control unit provided in the drawing apparatus 10. FIG. FIG. 6 is a diagram showing pattern image conversion in the projection optical system 26. It is the figure which showed the arrangement | sequence of a unit exposure area. It is the figure which showed the inclination angle at the time of scanning, and the locus | trajectory which a unit area passes. It is the figure which showed the projection pattern in an exposure process.

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

  FIG. 1 is a perspective view schematically showing a drawing apparatus according to the first embodiment.

  A drawing apparatus (exposure apparatus) 10 is a maskless exposure apparatus that forms a pattern by irradiating light onto a substrate SW coated or affixed with a photosensitive material such as a photoresist. 14. An XY stage mechanism (not shown here) that supports the drawing table 18 is mounted on the base 14, and a substrate SW is installed on the drawing table 18.

  In the drawing apparatus 10, an exposure operation is executed and controlled by a drawing control unit (not shown here). An input device such as a monitor and a keyboard (both not shown) is connected to the drawing control unit, and drawing processing is performed according to the operation of the operator.

A gate-like structure 12 is juxtaposed eight exposure heads 20 ₁ to 20 ₈ to form a pattern on the surface of the substrate SW is. In addition, a CCD sensor 19 for detecting the deformation state of the substrate SW is disposed toward the substrate. Exposure head 20 _1, lamp, DMD (Digital Micro-mirror Device ), provided with the projection optical system (not shown here), other exposure head ₂₀ 2-20 ₈ has a similar configuration.

  The rectangular substrate SW is a substrate for an electronic circuit such as a silicon wafer, a printed substrate, a dry film, a glass substrate, or a copper-clad laminate, and is in a blank state that has been subjected to processing such as pre-baking and photoresist coating. Is mounted on the drawing table 18. The substrate SW, that is, the drawing table 18, defines an XYZ coordinate system orthogonal to each other, and the drawing table 18 is movable along the X and Y directions. The drawing table 18 is rotatable around the Z axis, and the substrate feed direction is adjusted. Here, the Y direction is defined as the main scanning direction (scanning direction), and the X direction is defined as the sub-scanning direction.

Figure 2 is a diagram showing the internal configuration of the exposure head 20 _1.

The ultra-high pressure mercury lamp 35 installed on the support 21 emits illumination light that is ultraviolet light, and the illumination light is guided to the illumination optical system 32 by the reflector 38. Light shaped into parallel light by the illumination optical system 32 is guided to the DMD 24 ₁ through the mirrors 25 and 27. The DMD 24 ₁ is a light modulation device in which micro rectangular micromirrors of several μm to several tens of μm are two-dimensionally arranged in a matrix, and here, is constituted by 1024 × 768 micromirrors. The micromirror is disposed on an integral memory cell such as an SRAM cell.

In DMD 24 _1, based on the control signal stored in the memory cell (exposure data), the micromirrors are selectively ON / OFF control, respectively. The light reflected by the micromirror in the ON state is guided to the projection optical system 26 held by the holding frames 22 and 23 via the mirror 27.

  The projection optical system 26 includes a first imaging optical system 28, an integrator 40, and a second imaging optical system 46. The first imaging optical system 28 forms an image of light corresponding to the pattern by the DMD 24 and enlarges the entire pattern image at a predetermined magnification. The integrator 40 has a structure in which two fly-eye lens arrays 42 and 43 are provided in a sleeve 41, and each fly-eye lens array includes a plurality of convex-flat microlenses that are two-dimensionally arranged in close contact with each other. The microlenses of the fly-eye lens arrays 42 and 43 are arranged to face each other.

  The integrator 40 divides the enlarged pattern image formed by the first imaging optical system 28 into a plurality of minute pattern images (hereinafter referred to as cell pattern images) according to the size of the microlens, and each cell at a predetermined magnification. Reduce the pattern image individually. The light of the reduced cell pattern image (reduced cell pattern image) passes through the second imaging optical system 46 and is irradiated onto the substrate SW. As a result, reduced pattern images that are two-dimensionally arranged at predetermined intervals are formed on the substrate SW.

  As the exposure method, a multiple exposure method based on a step & repeat method is applied here. That is, the drawing table 18 intermittently moves along the Y direction, and the micromirrors are ON / OFF controlled at predetermined exposure pitch time intervals accordingly. As the substrate SW moves along the scanning direction Y, the projection area defined by the entire DMD 24, that is, the exposure area, moves relative to the substrate SW.

  The substrate SW is disposed on the drawing table 18 in a state in which the substrate SW is directed obliquely by a minute angle with respect to the scanning direction Y. Therefore, when the drawing table 18 moves along the scanning direction Y, the exposure area moves relative to the longitudinal direction of the substrate SW in an oblique direction.

  The raster scanning is continued while the exposure area by each exposure head relatively moves along the scanning direction Y, whereby a pattern is formed on the entire substrate. When the drawing process is completed, a development process, etching or plating, a resist stripping process, and the like are performed, and a substrate on which a pattern is formed is manufactured.

  FIG. 3 is a block diagram of a drawing control unit provided in the drawing apparatus 10.

  The drawing control unit 30 is connected to an external workstation (not shown) and includes an exposure control unit 52. The exposure control unit 52 controls the drawing process and outputs a control signal to each circuit such as the DMD driving circuit 59, the read address control circuit 57, and the drawing table control circuit 61. A program for controlling the drawing process is stored in advance in a ROM (not shown) in the exposure control unit 52.

  Pattern data input from a workstation (not shown) to the exposure control unit 52 is vector data (CAD / CAM data) having position information of a drawing pattern, and as position coordinate data based on an XY coordinate system. expressed. The vector data input to the raster conversion unit 51 is converted into raster data which is two-dimensional dot data (ON / OFF data) of a pattern.

  The raster data input to the data correction unit 53 is converted into a reduced cell pattern image, that is, raster data composed of blocks corresponding to the microlens size of the integrator 40 (hereinafter referred to as block raster data). The data correction unit 53 is configured as an exposure data generation processing unit in units of blocks.

  Each block represents one spot data, that is, ON / OFF data. The correspondence relationship between the reduced cell pattern image and the raster data before conversion is determined in advance from the enlargement / reduction magnification and the coordinate conversion characteristics of the first imaging optical system 28, the integrator 40, and the second imaging optical system 46. The generated block raster data is stored in the buffer memory 58.

During scanning, block raster data is sequentially read from the buffer memory 38 at a predetermined timing according to the relative position of the exposure area. Based on the relative position information of the exposure area, the control signal for ON / OFF control of the micromirror in blocks, is output from the DMD drive circuit 59 to the DMD 24 ₁ to 24 ₈ of the exposure heads ₂₀ 1 to 20 _8. A pattern is formed by exposure control by such processing of the exposure control unit 52 and the DMD drive circuit 59. The relative position of the exposure area is detected based on predetermined coordinate conversion and enlargement / reduction magnification.

  The drawing table control circuit 61 controls an XY stage mechanism 56 equipped with a motor (not shown) via the drive circuit 54, thereby controlling the moving speed of the drawing table 18, the substrate feed direction, and the like. The position detection sensor 55 detects the position of the drawing table 18, that is, the relative position of the exposure area with respect to the drawing table 18.

FIG. 4 is a diagram showing pattern image conversion in the projection optical system 26. The enlargement / reduction of the pattern image will be described with reference to FIG. Incidentally, describes a pattern image by DMD 24 ₁ of the exposure head, the code is referred to as "24" or less.

  Here, the micromirror of the DMD 24 is divided by a 64 × 64 divided area B. Since the 768 × 1024 micromirrors are arranged in a matrix, the DMD 24 includes 12 × 16 divided areas along the row direction (scanning direction Y) and the column direction (sub-scanning direction). The divided area at the left corner is M0 (1, 1), and the address of the divided area is expressed as M0 (k, j) (1 ≦ k ≦ 12, 1 ≦ j ≦ 16) along the row and column directions.

  The first imaging optical system 28 forms an image of the pattern light formed by the DMD 24 at the focal point T1 (imaging position) and enlarges the pattern image at an enlargement magnification N0. As a result, left and right and upside-down inverted enlarged pattern images are formed at the imaging position T1 of the first imaging optical system 28.

  The first fly-eye lens 42 of the integrator 40 is installed at the imaging position T1 of the first imaging optical system 28. The arrangement of the micro lenses 42M in the first fly-eye lens 42 corresponds to the arrangement of the divided areas B in the DMD 24, and the 12 × 16 micro lenses 42M are two-dimensionally arranged.

  The size of the divided area B, that is, the 64 × 64 micromirror region is defined based on the size of each microlens. That is, the cross-sectional area of the light beam passing through each microlens corresponds to the cross-sectional area of the light beam reflected in the 64 × 64 micromirror region, and a microlens cell pattern image is formed by the reflected light of the 64 × 64 micromirror. The Therefore, the pattern image enlarged by the first imaging optical system 28 is divided into 12 × 16 cell pattern images by the first fly-eye lens 42.

  Since the pattern image formed by the first imaging optical system 28 is an inverted image, the position of the cell pattern image is also inverted. For example, the cell pattern image of the divided area M0 (1, 1) located at the lower left corner in the DMD 24 is moved to the upper right corner by the first imaging optical system 28. In FIG. 4, a cell pattern image corresponding to the divided area M0 (1, 1) is represented as M1 (12, 16).

  The second integrator 43 has a plurality of microlenses 43M arranged in the same array as the first integrator 42, and is arranged at a position separated from the first integrator 42 by a predetermined interval M. The light that has passed through each microlens of the first fly-eye lens 42 enters the microlens at the corresponding position of the second fly-eye lens 43.

  The first fly-eye lens 42 functions as a field lens and a condenser lens, and propagates an image between the opposing microlenses of the first and second fly-eye lenses 42 and 43. On the other hand, the second fly-eye lens 43 functions as a relay lens. Therefore, the light of each cell pattern image formed by the first fly-eye lens 42 passes through the second microlens and forms an image at the focal point (imaging position) T2 of the first fly-eye lens 42.

  Furthermore, the second fly's eye lens 43 individually reduces the cell pattern image of each microlens, and a reduced cell pattern image is formed at the imaging position T2. The position of the second fly-eye lens 43 with respect to the first fly-eye lens 42 causes a cell pattern image having a reduction magnification N1 to be formed at the imaging position T2 with respect to the cell pattern image formed at the first imaging position T1.

  The second imaging optical system 46, which is a telecentric optical system, does not enlarge or reduce the reduced cell pattern image formed at the imaging position T2, but forms the reduced cell pattern image at the focal point (imaging position) T3 as it is. At this time, each reduced cell pattern image is formed as an inverted image at the imaging position T3. The imaging position T3 corresponds to the surface position of the substrate SW, and a reduced cell pattern image is formed on the substrate SW. By disposing the second imaging optical system 21, a distance interval WD between the projection optical system 26 and the substrate SW is secured.

As described above, the projection optical system 26 enlarges the pattern image as a whole by the first imaging optical system 28, and then the cell pattern corresponding to the microlenses 42M and 43M of the first and second fly-eye lenses 42 and 43. Form an image and reduce it individually. As a result, a series of reduction cell pattern image CP ₀ formed in the exposure area EA in the exposure operation of a point is made in a two-dimensional array image together provided a predetermined distance.

  Since the reduced cell pattern image becomes a single projection spot, the exposure data sent to the micromirror during scanning is switched to ON / OFF data in units of blocks. Therefore, data correction processing based on the projection position for each block is performed on the raster data obtained from the vector data. In the data correction process (block exposure data generation process), exposure data is generated based on the coordinate conversion by the integrator 40, and the substrate SW is skewed with respect to the Y direction twice. Corresponding block raster data is generated.

  FIG. 5 shows the arrangement of unit exposure areas. FIG. 6 is a diagram showing an inclination angle during scanning and a trajectory passing through a unit area. FIG. 7 is a diagram showing a projection pattern in the exposure process. The tilt angle during scanning will be described with reference to FIGS.

As shown in FIG. 5, when an exposure operation is performed at a certain point, a reduced cell pattern image is formed according to the arrangement of 12 × 16 unit exposure areas. As described above, in the DMD 24, 768 micromirrors are two-dimensionally arranged along the scanning direction and 1024 micromirrors along the sub-scanning direction. A cell group composed of 64 × 64 micromirrors is defined as a unit exposure area EPA ₀ in accordance with the microlens arrangement of the first and second fly's eye lenses 42 and 43.

  While the feeding direction of the substrate SW is inclined with respect to the longitudinal direction of the substrate, the arrangement direction of the exposure areas coincides with the reference direction when the substrate SW is not inclined. Therefore, the scanning direction is directed obliquely with respect to the arrangement direction of the reduced cell pattern images. When the exposure operation is performed by setting the exposure interval to be equal to or less than the pitch interval of the unit exposure area or the distance between the front and back as the exposure pitch, the position of each unit exposure area, that is, the projection position of the reduced cell pattern image gradually follows the sub-scanning direction. Shift. FIG. 5 shows a line KM in which the unit exposure area moves according to one reduced pattern image.

  Therefore, when the multiple exposure operation is executed in accordance with the relative movement of the exposure area, the reduced cell pattern is sequentially projected onto the substrate SW without a gap. Furthermore, in the present embodiment, the exposure amount along the sub-scanning direction is configured to be uniform in the oblique scanning. Hereinafter, conditions for uniformizing the exposure dose will be described.

  FIG. 6 shows two rows of reduced cell pattern images along the scanning direction. However, to simplify the description, only eight reduced cell pattern images along the scanning direction are considered. The upper (A row) reduced cell pattern images A1 to A8 and the lower (B row surface) reduced cell pattern images B1 to B8 correspond to unit exposure areas at certain exposure points, respectively. (Hereinafter, A1 to A8 and B1 to B8 are selectively handled as unit exposure areas or reduced cell pattern images as appropriate).

  The size of the unit exposure area (reduced cell pattern image) is defined as A, the pitch interval along the sub-scanning direction as B, the pitch interval along the scanning direction as C, and the tilt angle of the substrate SW with respect to the scanning direction as θ. The number of unit exposure areas along the scanning direction (referred to as the number of cell patterns) is defined as N. In FIG. 6, N = 8.

  In order for the exposure amount to be constant on the Z line along the sub-scanning direction, two conditions must be satisfied. The first condition is to make the overlapping of the reduced cell pattern images along the sub-scanning direction uniform so that the exposure amount at the pitch interval B in the sub-scanning direction does not vary. In order to satisfy this condition, the end points of each of a series of unit exposure areas arranged in the scanning direction must pass through the Z line at equal pitch intervals.

Since the pitch interval B along the sub-scanning direction represents the distance between the centers of adjacent cell pattern images, the pitch interval B is obtained by the following equation.

B = DS × N0 × MB (1)

Here, DS represents the micromirror size, N0 represents the magnification of the first imaging optical system 28, and MB represents the number of micromirrors along the scanning direction. The exposure pitch is determined to be 1 / k (k is an integer) of the pitch interval C of the unit exposure areas along the scanning direction. Therefore, on the Z line, the light of the reduced cell pattern image in the unit exposure areas A1 to A8 and B1 to B8 is projected when passing through the Z line.

  The unit exposure area A8 at the end point in the scanning direction of the A line is closest to the reduced cell pattern image formed in the unit exposure area B1 when passing on the Z line, compared to the other unit exposure areas A1 to A7. . On the other hand, when the unit exposure area B2 passes on the Z line, the ratio of overlapping with the reduced cell pattern image formed in the unit exposure area B1 is the highest compared to the other unit exposure areas B3 to B7.

  Therefore, a reduced cell pattern image when the unit exposure area A1 is on the Z line, a reduced cell pattern image when the unit exposure area B1 is on the Z line, and a reduced cell when the unit exposure area B2 is on the Z line Pattern images are formed in order overlapping in the sub-scanning direction.

In order to equalize the exposure amount by the reduced cell pattern image of the A row and the exposure amount by the reduced cell pattern image of the B row along the Z line without a step at the boundary portion, the unit exposure area A8 is the Z line. Regarding the interval b between the reduced cell pattern image and the reduced cell pattern image B1 when passing over, and the interval a between the reduced cell pattern image and the reduced cell pattern image B1 when the unit exposure area B2 passes over the Z line, It is necessary to satisfy the following formula.

a = b (2)

Since the equation (2) is established, the following relational equation is established between the pitch interval B in the sub-scanning direction and the number N of cell patterns in the scanning direction.

B = N × a (3)

Further, when the reduced cell pattern images B1 and B2 are compared, the scanning inclination angle θ and the interval a satisfy the following relational expression.

tan θ = a / C (4)

Therefore, the following conditional expressions are obtained between the inclination angle θ and the pitch intervals B and C by the expressions (3) and (4). The first condition is satisfied by this conditional expression.

tan θ = (B / N) × C (5)

  Next, a second condition for equalizing the exposure amount on the Z line will be described. Under the second condition, the amount of exposure on the Z line needs to be the same at any point. This condition is satisfied when the overlap of the exposure areas is equal.

Here, if the number of overlaps of unit exposure areas that pass during scanning with respect to a certain reduced cell pattern image is n (integer), the following conditional expression must be satisfied.

A / a = n (6)

In FIG. 6, n = 4 is set.

From equation (3), equation (5) can be expressed as a relational expression of N and B as follows.

A = B × n / N (7)

In FIG. 6, N = 8 and A / B = 1/2.

  When the expression (7) is satisfied, the lengths of the scanning trajectories passing through the predetermined reduced cell pattern image are the same. In the line L3 shown in FIG. 6, when scanning is performed for the distance of the exposure area, the unit exposure area A8 passes through the reduced cell pattern image formed by the unit exposure areas B1, B2, A7, and A8. The total LL of the lengths L31, L32, L33, and L34 at this time is the same in any scanning locus. For example, the total LL is obtained also in the scanning lines L1 and L2 shown in FIG.

  When the expressions (5) and (7) are satisfied, the exposure amount on the Z line is equal at any point. The pitch intervals B and C depend on the size of the DMD and the enlargement magnification of the first imaging optical system 28, and the size A of the reduced cell pattern image follows the reduction magnification of the integrator 40. Therefore, the condition of the tilt angle θ can be determined according to the characteristics of the DMD 24 and the projection optical system 26 of the exposure apparatus.

According to this embodiment, in a mask-less exposure apparatus, an exposure head 20 ₁ to DMD 24 _1, the projection optical system 26 is provided. The projection optical system 26 includes a first imaging optical system 28, an integrator 40, and a second imaging optical system 46. First imaging optical system 28 forms the pattern image of the reflected light in the DMD 24 _1.

The integrator 40 having a fly-eye lens 42, 43 are arranged two-dimensionally combined plurality of microlenses on DMD 24 ₁ micromirror array divides the pattern image to the cell pattern image, reduced separately. Therefore, a two-dimensional array of reduced cell pattern images spaced apart from each other by a predetermined distance along the scanning direction and the sub-scanning direction is formed.

  On the other hand, in the data correction unit 53, the raster data of the micromirror group forming the cell pattern image, that is, the micromirror group corresponding to the microlens size is handled as a lump of data according to the area (divided area) of the micromirror group. Raster data composed of a plurality of blocks is generated using the data area as a block.

Scanning direction, while scanning the unit exposure areas of a two-dimensional array spaced a predetermined distance from each other along the sub-scanning direction, and sends the exposure data (ON / OFF data) to DMD 24 ₁ formed in blocks. Further, the feeding direction of the substrate SW is inclined with respect to the arrangement direction of the unit exposure areas, and the inclination angle is determined so as to satisfy the above formula. As a result, the reduced cell pattern image is formed on the entire substrate SW without any defects, and the exposure amount along the sub-scanning direction becomes uniform.

  In the present embodiment, the microlens size does not correspond to one micromirror size, but is configured to form a cell pattern image by light from a plurality of micromirror groups. Then, the pattern is projected using the reflected light from the micromirror group as a spot unit. In the raster data, the exposure data of the block corresponding to the micromirror group is generated as spot data.

  The enlargement magnification of the entire pattern image and the reduction magnification of the cell pattern image in the projection optical system 26 can be adjusted in consideration of the substrate size and the like. Therefore, in the exposure operation for a large substrate such as a liquid crystal substrate, an exposure operation with a large spot size can be executed. As a result, the throughput is improved. Further, since the microlens size is larger than the micromirror size, the optical axis of the projection optical system 26 can be easily adjusted.

  On the other hand, since an exposure area in which a plurality of unit exposure areas are arranged at intervals is defined, the reduced cell pattern image can be ordered more finely by appropriately setting the reduction, enlargement magnification, inclination angle when scanning, etc. The fine pattern can be formed without reducing the throughput.

  In particular, since the exposure amount along the sub-scanning direction can be made uniform by setting the tilt angle based on the optical performance of the integrator, the shape characteristics of the DMD, etc., the exposure amount can be adjusted by adjusting the scanning angle during the exposure operation. Can be adjusted.

  The integrator 40 may be constituted by three or more fly-eye lenses. Further, the first imaging optical system 28 can be configured to reduce the pattern image or not to enlarge or reduce the pattern image.

  The number of mirrors constituting the micromirror group may be determined in consideration of equalizing the number of each microlens, for example, a common divisor of the number of micromirror arrays. The microlens size of the integrator 40 may be set according to the micromirror arrangement. However, when the microlens size is determined in advance, the area size of the micromirror group, that is, the block size of the exposure data may be determined accordingly. Good.

  In addition, the maximum number of mirrors incident on the microlens may be configured, but a cell pattern image may be formed by the following mirrors depending on the pattern accuracy or the like. In this case, the block of raster data is also determined according to the area where the cell pattern image is formed.

10 Drawing device (exposure device)
24 _{1 to} 24 ₈ DMD (light modulation element array)
30 Drawing Controller SW Substrate 26 Projection Optical System 28 First Imaging Optical System (First Optical System)
40 Integrator (second optical system)
46 Second imaging optical system 42, 43 Fly eye lens (micro lens array)
51 Raster Conversion Unit 52 Exposure Control Unit (Exposure Control Unit)
53 Data correction unit (exposure data generation means)
56 XY stage mechanism (scanning means)
59 DMD drive circuit (exposure control means)
61 Drawing table control circuit (scanning means)
EA exposure area EPA ₀ unit exposure area

Claims (9)

A light modulation element array in which a plurality of spatial light modulation elements that modulate light from a light source are two-dimensionally arranged;
Scanning means for moving the exposure area defined by the light modulation element array relative to the drawing object;
A first optical system that forms an image of reflected light from the light modulation element array and forms a pattern image;
A second optical system having a plurality of two-dimensionally arranged microlenses , dividing a pattern image into cell pattern images corresponding to the microlens size, and individually reducing the cell pattern image in units of two or more The second optical element in which the plurality of microlenses are two-dimensionally arranged so that one cell pattern image is formed by the reflected light of the spatial light modulation element group including the number of spatial light modulation elements according to the microlens size. The system,
Exposure data that converts pattern data corresponding to a pattern image, which is raster data, into pattern data composed of blocks that are data areas corresponding to the spatial light modulation element group , and generates exposure data for each block as spot data Generating means;
Exposure control means for controlling the plurality of spatial light modulators according to exposure data of each block based on the relative position of the exposure area ;
The second optical system includes two microlens arrays in which a plurality of microlenses are arranged opposite to each other;
The exposure data generation means generates exposure data for each block based on the correspondence between the reduced cell pattern image and the pattern data before conversion, which is determined from the coordinate conversion characteristics of the second optical system. An exposure apparatus characterized by the above.   The exposure apparatus according to claim 1, wherein the scanning unit relatively moves the exposure area along a direction inclined with respect to an arrangement direction of reduced reduced cell pattern images on the drawing object.   3. The exposure apparatus according to claim 2, wherein the scanning unit relatively moves the exposure area according to a predetermined inclination angle so that the exposure amount is equal in the sub-scanning direction. The size along the sub-scanning direction of the unit exposure area corresponding to the reduced cell pattern image is A, the pitch along the sub-scanning direction between the adjacent unit exposure areas is B, and the scanning direction between the adjacent unit exposure areas is along the scanning direction. When the pitch is C, the inclination angle is θ, the number of arrangement of unit exposure areas along the scanning direction is N, and the number of overlaps of a predetermined reduced cell pattern image is n, n and θ satisfy the following formulas. 4. An exposure apparatus according to claim 3, wherein

tan θ = B / N × C
N × A = B × n   The exposure apparatus according to claim 1, wherein the number of arrangements of the spatial light modulation element groups follows a common divisor of the number of arrangements in the spatial light modulation elements. 6. The exposure apparatus according to claim 1, wherein an area size of the spatial light modulation element group is determined according to a predetermined microlens size .   The exposure apparatus according to claim 1, wherein the first optical system includes an imaging optical system that enlarges a magnification of a pattern image. The exposure apparatus according to claim 1, further comprising an imaging optical system that forms the reduced cell pattern image on the surface of the drawing object without being enlarged or reduced. A light modulation element array in which a plurality of spatial light modulation elements that modulate light from a light source are two-dimensionally arranged, and a scanning unit that moves an exposure area defined by the light modulation element array relative to a drawing object When,
A first optical system that forms an image of reflected light from the light modulation element array and forms a pattern image;
A second optical system having a plurality of two-dimensionally arranged microlenses and individually reducing a pattern image in units of cell pattern images;
Exposure data generating means for converting pattern data corresponding to a pattern image into pattern data composed of blocks which are data areas corresponding to the spatial light modulation element group, and generating exposure data of each block as spot data;
Exposure control means for controlling the plurality of spatial light modulators according to exposure data of each block based on the relative position of the exposure area;
The scanning unit relatively moves the exposure area along a direction inclined with respect to an arrangement direction of the reduced reduced cell pattern image on the drawing object,
The scanning means relatively moves the exposure area according to a predetermined inclination angle so that the exposure amount becomes equal in the sub-scanning direction,
The size along the sub-scanning direction of the unit exposure area corresponding to the reduced cell pattern image is A, the pitch along the sub-scanning direction between the adjacent unit exposure areas is B, and the scanning direction between the adjacent unit exposure areas is along the scanning direction. When the pitch is C, the inclination angle is θ, the number of arrangement of unit exposure areas along the scanning direction is N, and the number of overlaps of a predetermined reduced cell pattern image is n, n and θ satisfy the following formulas. A featured exposure apparatus.

tan θ = B / N × C
N × A = B × n

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