JP4897432B2 - Exposure method and exposure apparatus - Google Patents

Description

  The present invention relates to an exposure method and an exposure apparatus, and more specifically, uses a spatial light modulator in which a large number of spatial light modulation elements are two-dimensionally arranged, and modulates light emitted from a light source by the spatial light modulator. The present invention relates to an exposure method and an exposure apparatus that form an exposure pattern on an object by projecting the bright and dark pattern formed on the object.

Conventionally, as an exposure apparatus, a light source, a DMD (digital micromirror device: spatial light modulator) that modulates light emitted from the light source to form a light / dark pattern, and a light / dark pattern formed by the DMD are targeted. An image forming optical system that forms an image on an object is known (for example, Patent Document 1).
JP 2006-133432 A

The DMD micromirrors are two-dimensionally arranged, and an exposure pattern similar to the light and dark pattern formed by the DMD is formed on the object. Therefore, according to the conventional exposure method, the following problems have occurred.
For example, considering the case where a linear pattern is included in the exposure pattern, there is no problem when the linear pattern extends corresponding to the arrangement direction (two directions orthogonal) of the micromirror. When the linear pattern does not correspond to the arrangement direction of the micromirror, that is, when the linear pattern is inclined with respect to the arrangement direction of the micromirror, the edge of the linear pattern is There has been a problem that smooth exposure cannot be performed.

  The present invention has been made in view of such problems, and an object thereof is to provide an exposure method and an exposure apparatus capable of smoothly exposing a pattern edge.

The exposure method according to claim 1 is obtained by using a spatial light modulator in which a large number of spatial light modulation elements are two-dimensionally arranged, and modulating light emitted from a light source by the spatial light modulator. An exposure method for forming an exposure pattern on an object by projecting a light and dark pattern onto the object,
A desired exposure pattern is set after two-dimensionally dividing a pixel corresponding to each of the spatial light modulation elements in the exposure region into a plurality of sub-pixels;
Causing the spatial light modulation element corresponding to the pixel to perform exposure in the plurality of sub-pixels belonging to each of the pixels;
A plurality of the sub-pixels belonging to the pixel corresponding to the spatial light modulation element at a central portion of the spatial light modulation element can be exposed in units of sub-pixels.
A light image from each of the spatial light modulation elements is sequentially scanned and projected onto each of the plurality of sub-pixels belonging to the pixel that corresponds to the spatial light modulation element, and
Each spatial light modulation element is switched on and off in accordance with light and darkness on the desired exposure pattern in the sub-pixel onto which the light image is projected, and necessary exposure is performed for each sub-pixel. It is characterized by that.

  The exposure method according to claim 2 is the exposure method according to claim 1, wherein the scanning of the optical image is interposed in an optical path between the spatial light modulator and the object. It is characterized by making it carry out by.

  An exposure method according to a third aspect is the exposure method according to the first aspect, wherein the optical image is scanned by relative movement of the spatial light modulator and the object.

  The exposure method according to claim 4 is the exposure method according to any one of claims 1 to 3, wherein the spatial light modulator uses a DMD in which the spatial light modulator is composed of a micromirror. It is characterized by that.

The exposure apparatus according to claim 5 includes a spatial light modulator in which a large number of spatial light modulation elements are two-dimensionally arranged, and is obtained by modulating light emitted from a light source by the spatial light modulator. An exposure apparatus that forms an exposure pattern on an object by projecting the pattern onto the object,
Pattern setting means for setting a desired exposure pattern on a screen in which pixels corresponding to each of the spatial light modulation elements in an exposure region are two-dimensionally divided into a plurality of sub-pixels;
The central portion of the spatial light modulator is configured to be capable of exposing the plurality of sub-pixels belonging to the pixel corresponding to the spatial light modulator in a sub-pixel unit, from each of the spatial light modulators. A light image is simultaneously scanned on the object, and a light image from each of the spatial light modulation elements is applied to each of the plurality of sub-pixels belonging to the pixel corresponding to the spatial light modulation element. Optical image scanning means for sequentially guiding;
Switching means for switching on / off of each of the spatial light modulation elements so that a light image from the spatial light modulation element corresponds to light and darkness on the desired exposure pattern in the sub-pixel on which the light image is projected; ,
It is characterized by providing.

  The exposure apparatus according to claim 6 is the exposure apparatus according to claim 5, wherein the scanning unit includes a tilt mirror interposed in an optical path between the spatial light modulator and the object. It is characterized by being.

  The exposure apparatus according to claim 7 is the exposure apparatus according to claim 5, wherein the scanning unit includes a moving unit that relatively moves one of the spatial light modulator and the object with respect to the other. It is characterized by being.

  An exposure apparatus according to an eighth aspect is the exposure apparatus according to any one of the fifth to seventh aspects, wherein the spatial light modulator includes a DMD in which the spatial light modulator is composed of a micromirror. And

  According to the first to fourth aspects of the present invention, the optical image from each spatial light modulation element is sequentially scanned into each of the plurality of sub-pixels belonging to the pixel corresponding to the spatial light modulation element. The spatial light modulator is switched on / off in accordance with the brightness on the desired brightness / darkness pattern in the subpixel on which the optical image is projected. Can be exposed. Therefore, for example, even when the exposure pattern includes a linear pattern and the linear pattern does not correspond to the arrangement direction of the micromirrors, the pattern edge can be exposed smoothly.

  According to the fifth to eighth aspects of the present invention, the optical image from each spatial light modulation element is sequentially scanned into each of the plurality of sub-pixels belonging to the pixel corresponding to the spatial light modulation element. The spatial light modulator can be switched on / off in accordance with the brightness on the desired light / dark pattern in the sub-pixel on which the optical image is projected. Can be exposed. Therefore, for example, even when the exposure pattern includes a linear pattern and the linear pattern does not correspond to the arrangement direction of the micromirrors, the pattern edge can be exposed smoothly.

First, an exposure apparatus that performs the exposure method according to the present invention will be described.
FIG. 1 shows a part of the configuration of the exposure apparatus, and FIG. 2 shows a control block of the exposure apparatus. Here, it should be noted that in FIG. 1, for convenience of illustration, the size and distance of each component do not correspond to actual ones.

  The exposure apparatus 100 shown here includes a light source 110, a DMD (digital micromirror device) 120, which is one of the spatial light modulators, and imaging optics that forms an image of a light / dark pattern formed by the DMD 120 on an object. A system 130, a tilt mirror 140 for scanning a light and dark pattern on the object, and a stage 160 for placing the object 150 are provided.

  Here, as the light source 110, it is possible to use a known light source that is generally used in combination with DMD. For example, as the light source 110, a metal halide lamp, a xenon lamp, a halogen lamp, a light emitting diode, a laser, or other light sources can be used.

  The DMD 120 includes a micromirror array unit in which a large number of micromirrors (spatial light modulation elements) that reflect and modulate light emitted from the light source 110 are two-dimensionally arranged. The angles of the micromirrors constituting the micromirror array unit can be adjusted independently. By adjusting the angle of each micromirror, a micromirror pattern is formed, and a light / dark pattern is formed when light is applied to the micromirror pattern.

  The imaging optical system 130 is composed of a plurality of lenses. In the embodiment, the collimator lens 131 and the imaging lens 132 are configured, but the present invention is not limited to this. The configuration of the imaging lens 130 is not limited as long as it can project the optical image of each micromirror of the DMD 120 onto the object 150 on a one-to-one basis.

  The tilt mirror 140 is a biaxial tilt mirror, and can be tilted forward and backward about each axis corresponding to the arrangement direction (two directions orthogonal) of the DMD 120 when viewed optically. It is configured. By controlling the tilt of the tilt mirror 140, a light image from each micro mirror of the DMD 120 can be scanned on the object 150.

  Examples of the object 150 include those that require a lithography process, such as a semiconductor substrate and a liquid crystal substrate.

  Further, the stage 160 is not limited, but a three-axis stage of X, Y, and θ is installed.

Next, the electrical configuration of the exposure apparatus 1 will be described with reference to FIG.
As shown in the figure, the exposure apparatus 1 includes a control unit 210. An input unit 220, a storage unit 230, a light source driving unit 240, a DMD driving unit 250, a tilt mirror driving unit 260 and a stage driving unit 270 are connected to the control unit 210. Although not shown, the exposure apparatus 1 can include a display unit such as a display.

  The storage unit 230 stores an exposure processing program and various data necessary for the exposure processing. The control unit 210 executes various processing programs stored in the storage unit 230.

  The input unit 220 includes a keyboard, a mouse, a scanner, a touch panel, a switch, and the like. From the input unit 220, the user can input and set data related to the exposure process based on a command from the control unit 210 made according to the processing program stored in the storage unit 230. For example, the user can input and set desired exposure pattern data. In other words, the input unit 220 and the control unit 210 function as a pattern setting unit for setting exposure pattern data in the storage unit 230 in cooperation with the processing program stored in the storage unit 230.

  The light source driving unit 240 is for turning on and off the light source 110 based on a command from the control unit 210 made in accordance with a processing program stored in the storage unit 230.

  The DMD driving unit 250 is for operating each micromirror of the DMD 120 on and off based on a command from the control unit 210 made in accordance with a processing program stored in the storage unit 230. In other words, the DMD driving unit 250 and the control unit 210 function as switching means for switching on / off of each micromirror of the DMD 120 in cooperation with the processing program and exposure data stored in the storage unit 230. . Here, the state in which the micromirror is on means a state in which the micromirror is tilted so that the light reflected by the micromirror is projected onto the object 150, and the state in which the micromirror is off means that the micromirror is off. A state in which the micromirror is tilted so that the light reflected by the mirror is not projected onto the object 150.

  The tilt mirror drive unit 260 is for changing the tilt angle by operating the tilt mirror 140 about two axes based on a command from the control unit 210 made in accordance with a processing program stored in the storage unit 230. It is. In other words, the tilt mirror driving unit 260 and the control unit 210 cooperate with a processing program stored in the storage unit 230 to control the direction, order, and speed of scanning by the tilt mirror 140. Function as.

  The stage driving unit 270 moves the stage 160 in the X-axis and Y-axis directions or rotates about the θ-axis based on a command from the control unit 210 made according to a processing program stored in the storage unit 230. Is for.

  Next, an exposure method performed by the exposure apparatus 1 according to this embodiment will be described in comparison with a conventional example. Here, in order to make the explanation easy to understand, an exposure method in the case of using DMD in which micromirrors are arranged in 5 rows and 5 columns will be described.

FIG. 3A shows a schematic diagram of a DMD 120 in which micromirrors are arranged in 5 rows and 5 columns. In the figure, row numbers a to e and column codes 1 to 5 are shown to identify the micromirrors.
FIG. 3B shows an exposure area exposed by the DMD 120. The figure shows a ′ to e ′ row numbers and 1 ′ to 5 ′ column numbers for specifying regions (pixels) exposed by each micromirror of the DMD 120.
Here, if the micromirror located in i row and j column is represented as (i, j) micromirror and the micromirror located in i ′ row and j ′ column is represented as (i ′, j ′) pixel, (a, j) 1) micromirror, (a, 2) micromirror,..., (C, 3) micromirror,..., (E, 5) micromirrors are (a ′, 1 ′) pixels, ( a ′, 2 ′) pixels,..., (c ′, 3 ′) pixels,..., (e ′, 5 ′) pixels corresponding to positions, and each pixel corresponds to a position corresponding micro. It is exposed by a mirror.
Based on the above, a case will be considered in which an oblique line pattern (bright pattern) extending in a direction intersecting the pixel arrangement direction on the object 150 is viewed optically.

First, a conventional exposure method will be described.
In this conventional exposure method, the inclination of the micromirror corresponding to the oblique line pattern to be exposed and the inclination of the other micromirrors are changed. That is, the micromirror corresponding to the oblique line pattern to be exposed is turned on, and the other micromirrors are turned off. An example is shown in FIG. In the figure, the white micromirror is in an on state, and a light image from the on-state micromirror is a bright portion of a light-dark pattern. On the other hand, the shaded micromirrors are in an off state, and the light image from the micromirrors in the off state is a dark portion of a light / dark pattern.
In this way, the inclination of each micromirror is adjusted, and a light / dark pattern formed by the entirety of each micromirror is projected onto the object once to form an exposure pattern. FIG. 4B shows an exposure pattern obtained by this conventional exposure method. In the figure, white pixels correspond to bright portions of the exposure pattern, and hatched pixels correspond to dark portions of the exposure pattern.
According to this conventional exposure method, the micromirror pattern, that is, the light / dark pattern formed by the DMD 120 is similar to the light / dark pattern, that is, the exposure pattern, formed on the object. In this case, the degree of miniaturization of the exposure pattern is limited by the configuration (size) of the micromirror and the resolution of the optical system. For example, when forming an exposure pattern including a hatched pattern or a circular pattern, smoothing of the edge is performed. There is also a limit to the degree of.

Next, an exposure method according to this embodiment will be described.
First, each of the pixels corresponding to each micromirror in the exposure area is two-dimensionally divided into a plurality of sub-pixels. In the embodiment, each pixel is divided into sub-pixels of 4 rows and 4 columns for convenience of explanation. Then, a desired exposure pattern is set on a screen composed of the subpixels as a whole. This process is shown in FIGS. In this way, since the image corresponding to the exposure area is composed of a large number of sub-pixels, it is possible to set a desired exposure pattern that is fine and has a smooth pattern edge.
Next, exposure at each pixel, that is, (a ′, 1 ′) to (e ′, 5 ′) is applied to a micromirror corresponding to the pixel, that is, (a, 1) to (e, 5) micromirror. Let them bear. In actual exposure, the light images from each of the (a, 1) to (e, 5) micromirrors are (a ′, 1 ′) to (e ′, 5) corresponding to the micromirrors. ') Sequentially scan and project each of the 16 sub-pixels belonging to the pixel. At the same time, each of the micromirrors (a, 1) to (e, 5) is switched on / off in accordance with the brightness on the desired brightness / darkness pattern in the sub-pixel onto which the optical image is projected. For example, if the sub-pixel onto which the optical image is projected is a bright part on the desired exposure pattern, the inclination of the micro-mirror is adjusted so that the light from the micro-mirror responsible for the exposure of the sub-pixel reaches the sub-pixel. If the sub-pixel on which the light image is projected is a dark part on the desired exposure pattern, light from the micro-mirror responsible for the exposure of the sub-pixel does not reach the sub-pixel. Adjust the inclination of the micromirror (micromirror is off).

  This exposure method will be described more specifically with reference to FIG. Here, a case where (b ′, 5 ′) pixels are exposed by a (b, 5) micromirror will be described as a representative example. That is, in actuality, each of the sub-pixels of (a ′, 1 ′) to (e ′, 5 ′) pixels is simultaneously exposed by the (a, 1) to (e, 5) micromirrors. However, one of them will be described as an example.

Although not particularly limited, first, the light image from the (b, 5) micromirror is projected onto the sub-pixel at the upper left corner among the 16 sub-pixels belonging to the (b ′, 5 ′) pixel. In this case, since the subpixel is a dark portion on the desired exposure pattern, (b, 5) the inclination of the micromirror is adjusted so that the light from the micromirror does not reach the subpixel (the micromirror is off).
Next, the tilt mirror 140 is operated (b, 5), and the light image from the micromirror is projected onto the right subpixel. Also in this case, since the subpixel is a dark part on the desired exposure pattern, (b, 5) the inclination of the micromirror is adjusted so that the light from the micromirror does not reach the subpixel (micromirror). Is off).
Next, the tilt mirror 140 is operated (b, 5), and the optical image from the micromirror is further projected onto the right subpixel. In this case, since the sub-pixel is a bright portion on the desired exposure pattern, the (b, 5) micromirror is turned on so that the light from the (b, 5) micromirror reaches the sub-pixel. deep.
Thereafter, as shown in FIG. 6, (b, 5) the optical image from the micromirror is scanned, and at the same time, the subpixel on which the optical image is projected corresponds to the light and darkness on the desired exposure pattern (b, 5). Switches the micromirror on / off.

  When exposure is performed in units of sub-pixels, the light of the micromirror responsible for the exposure of the sub-pixels hits the sub-pixels that form the neighboring sub-pixels and the neighboring pixels, but the light energy distribution is a Gaussian distribution. Therefore, the sub-pixel may be exposed for a predetermined time at a place where the energy is maximized.

  When the exposure of one exposure area is completed as described above, the next exposure area is exposed by the step-and-repeat method.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary.

  For example, in the above embodiment, the optical image from the micromirror is scanned by the tilt mirror 140, but the optical image is scanned by moving the stage 160 on which the object 150 is placed relative to the DMD 120. You may do it. In this case, instead of the tilt mirror driving unit 260, a driving unit (for example, a motor) suitable for moving the DMD 120 or the stage 160 is required.

  In the above embodiment, the DMD is taken as an example of the spatial light modulator, but a spatial light modulator using liquid crystal or other spatial light modulators can be used. In this case, instead of the DMD driving unit 250, a driving unit suitable for a spatial light modulator using liquid crystal or other spatial light modulator is required.

It is a figure which shows a part of structure of the optical system of the exposure apparatus used for the exposure method of embodiment. It is a block diagram which shows the control structure of exposure apparatus. FIG. 4A is a schematic diagram of a DMD in which micromirrors are arranged in 5 rows and 5 columns, and FIG. 4B is a diagram showing an image corresponding to an exposure area exposed by the DMD. It is a figure for demonstrating the conventional exposure method, The figure (A) is explanatory drawing of the micromirror pattern of DMD, The figure (B) is a figure which shows the exposure pattern obtained by the exposure method. It is a figure for demonstrating the exposure method of embodiment, Comprising: It is a figure which shows the setting procedure of a desired exposure pattern. It is a figure for demonstrating the exposure method of embodiment, Comprising: It is a figure which shows the exposure procedure of a sub pixel.

Explanation of symbols

100 Exposure Device 110 Light Source 120 DMD
130 imaging optical system 140 tilt mirror 150 exposure object 160 stage 210 control unit 220 input unit 230 storage unit 240 light source driving unit 250 DMD driving unit 260 tilt mirror driving unit 270 stage driving units (a, 1) to (e, 5) ) Micromirrors (a ′, 1 ′) to (e ′, 5 ′) Pixels on the exposure area

Claims (8)

By using a spatial light modulator in which a large number of spatial light modulation elements are two-dimensionally arranged, and projecting a light and dark pattern obtained by modulating light emitted from a light source by the spatial light modulator onto an object An exposure method for forming an exposure pattern on the object,
A desired exposure pattern is set after two-dimensionally dividing a pixel corresponding to each of the spatial light modulation elements in the exposure region into a plurality of sub-pixels;
Causing the spatial light modulation element corresponding to the pixel to perform exposure in the plurality of sub-pixels belonging to each of the pixels;
A plurality of the sub-pixels belonging to the pixel corresponding to the spatial light modulation element at a central portion of the spatial light modulation element can be exposed in units of sub-pixels.
A light image from each of the spatial light modulation elements is sequentially scanned and projected onto each of the plurality of sub-pixels belonging to the pixel that corresponds to the spatial light modulation element, and
Each spatial light modulation element is switched on and off in accordance with light and darkness on the desired exposure pattern in the sub-pixel onto which the light image is projected, and necessary exposure is performed for each sub-pixel. An exposure method characterized by the above.   The exposure method according to claim 1, wherein the optical image is scanned by a tilt mirror interposed in an optical path between the spatial light modulator and the object.   The exposure method according to claim 1, wherein the optical image is scanned by relative movement of the spatial light modulator and the object.   4. The exposure method according to claim 1, wherein the spatial light modulator uses a DMD in which the spatial light modulator is composed of a micromirror. 5. A spatial light modulator having a large number of spatial light modulation elements arranged two-dimensionally, and projecting a light and dark pattern obtained by modulating light emitted from a light source by the spatial light modulator onto an object; An exposure apparatus for forming an exposure pattern on an object,
Pattern setting means for setting a desired exposure pattern on a screen in which pixels corresponding to each of the spatial light modulation elements in an exposure region are two-dimensionally divided into a plurality of sub-pixels;
The central portion of the spatial light modulator is configured to be capable of exposing the plurality of sub-pixels belonging to the pixel corresponding to the spatial light modulator in a sub-pixel unit, from each of the spatial light modulators. A light image is simultaneously scanned on the object, and a light image from each of the spatial light modulation elements is applied to each of the plurality of sub-pixels belonging to the pixel corresponding to the spatial light modulation element. Optical image scanning means for sequentially guiding;
Switching means for switching on / off of each of the spatial light modulation elements so that a light image from the spatial light modulation element corresponds to light and darkness on the desired exposure pattern in the sub-pixel on which the light image is projected; ,
An exposure apparatus comprising:   The exposure apparatus according to claim 5, wherein the scanning unit includes a tilt mirror interposed in an optical path between the spatial light modulator and the object.   The exposure apparatus according to claim 5, wherein the scanning unit includes a moving unit that moves one of the spatial light modulator and the object relative to the other.   The exposure apparatus according to claim 5, wherein the spatial light modulator includes a DMD in which the spatial light modulation element includes a micromirror.

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