JP2008028099A - Device and method for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for exposure which are capable of making exposure distribution uniform with a simple device configuration. <P>SOLUTION: The exposure device 1 projects an image pattern formed in a DMD2 onto a substrate on the basis of the image data formed through an image data forming unit 18. The intensity of light projected from the pixels of DMD2 onto the substrate is successively measured with a photodiode 11. The image data forming unit 18 determines the exposure time of the pixels so as to make the projected light volume of the every part of the image pattern spatially uniform on the basis of the ratio of the maximum value of intensity of received light to the intensity of received light of the projected light from the pixels, forms image pattern data where an image pattern varies with time so as to make spatially uniform the projected light volume of the every part of the image pattern with light projected thereto when exposure is carried out on the basis of the exposure time and the image pattern, forms an image pattern in DMD2 on the basis of the image pattern data, and projects it onto the substrate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and an exposure method.

  Conventionally, in an exposure apparatus, the distribution of the amount of light irradiated on the substrate surface is uneven due to the fact that the output light of the light source is not parallel light, the spatial nonuniformity of the light emitting part, the imperfection of the optical elements, etc. As a result, there was a problem that the exposure amount became non-uniform. There is also a problem that the intensity distribution of the output light of the light source fluctuates due to the environmental temperature or deterioration with time and affects the exposure intensity distribution.

  Therefore, in order to solve the problem of non-uniform exposure intensity distribution, an exposure apparatus that makes light from a light source uniform by an optical system has been proposed.

For example, Patent Literature 1 includes a diffractive optical element that forms light having a desired light intensity distribution on a predetermined surface, and angle distribution changing means that converts the angular distribution of light incident on the diffractive optical element into a desired distribution. An exposure apparatus including an illumination optical system is described. As the angle changing means, a collimator lens, an input lens, a fly-eye lens or a zoom lens is used. By controlling the angle of light incident on the diffractive optical element, a modified illumination is formed in the diffractive optical element, and the light source The output light is made uniform.
JP 2001-284240 A

  However, as in the exposure apparatus described in Patent Document 1, if it is intended to realize uniform output light of a light source only by an optical system, it is necessary to use a complicated optical system using a plurality of expensive lenses. There are problems that it is difficult to ensure and adjust the stability and that the manufacturing cost of the exposure apparatus increases.

  Further, in recent years, an exposure apparatus that forms a desired image pattern by a spatial light modulation means such as DMD (Digital Micro-mirror Device) and irradiates the surface of the substrate with this image pattern is used. It is possible to freely form an image pattern by the spatial light modulation means without requiring a photomask on which the pattern is written. Therefore, until now, the illumination light intensity distribution homogenization technique has been limited only to the improvement of the optical system, but in the exposure apparatus using the spatial light modulation means, the exposure intensity distribution can be obtained by devising the spatial light modulation means. Can be made uniform.

  The present invention has been made in view of the above circumstances, and an exposure apparatus and an exposure method that can make the exposure distribution uniform with a simple apparatus configuration without relying on an exposure intensity distribution uniformization method using an optical system. The purpose is to provide.

  In order to solve the above-mentioned problem, the invention according to claim 1 forms an image pattern by spatial light modulation means for spatially modulating the output light of the light source based on the image data created by the image data creation means. In an exposure apparatus configured to irradiate a pattern onto a substrate, the intensity of light projected onto the substrate from each pixel of the spatial light modulation unit is sequentially measured with a photodiode, and the image data creation unit includes: Based on the ratio between the maximum value of the received light intensity measured by the photodiode and the received light intensity of the projection light from each pixel of the spatial light modulation means, the projected light amount of each part of the image pattern on the substrate is spatially The exposure time for each of the pixels is determined so as to be uniform, and light is applied during exposure based on the exposure time and the image pattern to be formed on the substrate. The image pattern data that changes over time is generated so that the amount of light projected to each part of the image pattern to be projected is spatially uniform, and the spatial light modulator forms an image pattern based on the image pattern data The image pattern is irradiated onto the substrate.

  A second aspect of the present invention is the exposure apparatus according to the first aspect, wherein the image data creating means expresses a luminance level in each pixel of the image pattern data expressed in gradation in binary numbers, and Image pattern data is generated such that the exposure time distributed by bit weighting is turned on according to the gradation of each pixel.

  According to a third aspect of the present invention, there is provided an exposure method in which an image pattern is formed on a spatial light modulation means for spatially modulating the output light of a light source based on the created image data, and the substrate is irradiated with the image pattern. Then, the light intensity projected on the substrate from each pixel of the spatial light modulator is sequentially measured by a photodiode, and the maximum value of the received light intensity measured by the photodiode and each of the spatial light modulators Based on the ratio of the projection light from the pixel to the received light intensity, the exposure time in each pixel is determined so that the projected light quantity of each part of the image pattern on the substrate is spatially uniform, and the exposure time Based on the image pattern to be formed on the substrate, the image pattern changes over time so that the amount of light projected from each part of the image pattern to which light should be projected during exposure is spatially uniform. That the image pattern data to generate the image pattern data based on the form an image pattern on the spatial light modulating means, and then irradiating the image pattern on the substrate.

  The invention according to claim 4 is the exposure method according to claim 3, wherein the luminance level in each pixel of the image pattern data expressed in gradation is expressed by a binary number and distributed by weighting each bit. Image pattern data is generated such that the exposure time is turned on according to the gradation of each pixel.

  According to the first or third aspect of the invention, based on the ratio between the intensity of light projected from each pixel of the DMD and its maximum value, the amount of light projected on the entire exposure surface is spatially uniform. The exposure time for each pixel can be determined. Based on the exposure time of each pixel and the image pattern to be formed on the substrate, the amount of light projected from the DMD pixel to which light is projected changes over time so that light is projected upon exposure. Such image pattern data can be generated. In the image pattern data, among the pixels of the DMD, the pixel with low light intensity on the exposure surface has a long exposure time, and the pixel with high light intensity has a short exposure time so that the projection light amount on the entire exposure surface is spatially uniform. It is to become. Thereby, it is possible to make the exposure distribution uniform with a simple apparatus configuration without using a complicated optical system using a plurality of expensive lenses.

  According to the second or fourth aspect of the present invention, the luminance level of the image pattern data is expressed by a binary number, and the ON / OFF of each pixel is controlled by the exposure time allocated by the weighting of each bit. Since the number of times of driving each mirror of the DMD is significantly reduced as compared with a method in which one frame time is evenly distributed, the processing speed can be increased.

(Device configuration)
The exposure apparatus 1 according to the present embodiment forms an image pattern on a DMD (Digital Micro-mirror Device) 2 as a spatial light modulation unit based on predetermined image data, and the image pattern is supported on a stage 3. It irradiates the top.

  As shown in FIG. 1, the exposure apparatus 1 includes a light source 4, a collimator lens 5, mirrors 6 and 7, DMD 2, mirror 8, relay lens 9, objective lens 10 and stage 3, and has an exposure distribution. At the time of measurement, a photodiode (Photodiode) 11 is placed on the stage 3.

  Among these, the light source 4 is comprised by a laser, LED, etc., and outputs the light for exposure at the time of the exposure of a board | substrate, and a measurement.

  The collimator lens 5 shapes the output light from the light source 4 into parallel light, and the mirrors 6 and 7 allow the transmitted light from the collimator lens 5 to enter the DMD 2.

  Further, the DMD 2 is formed as a single panel by laying fine mirror elements on a semiconductor element in a lattice shape, and the output light of the light source 4 is changed by changing the inclination angle of each mirror independently. Can be turned on / off.

  Further, a controller 12 (see FIG. 3) is electrically connected to the DMD 2 so that ON / OFF of each mirror can be controlled. As a result, as shown in FIG. 2, when measuring the exposure distribution, light is projected from each pixel of the DMD 2 while sequentially turning on the mirrors at predetermined positions.

  Here, one mirror provided in the DMD 2 corresponds to one pixel, and the controller 12 can also turn on the mirror for each pixel. However, when the change in the luminance distribution on the substrate is smooth, for example, The light intensity distribution on the exposure surface may be measured with 16 × 16 pixels as a minimum unit. As a result, the processing speed of the exposure distribution measurement is increased and the output signal of the photodiode 11 is increased, so that a sufficient S / N ratio can be obtained.

  Further, at the time of exposure, a mirror at a predetermined position is sequentially turned on / off to form a desired image pattern, and an image pattern is formed on the substrate by this image pattern.

  In this embodiment, the DMD 2 is used as the spatial light modulation unit, but a liquid crystal panel, a light emitting diode array, a magneto-optical effect, or the like can be used as the spatial light modulation unit.

  Further, the mirror 8 causes the projection light from the DMD 2 to enter the relay lens 9, and the relay lens 9 converts the light emitted from the point on the DMD 2 into parallel light. The objective lens 10 condenses the light transmitted through the relay lens 9 on the surface of the substrate or the photodiode 11.

  As the stage 3, various stages such as 2-axis, 3-axis, and 6-axis can be used. A stage driving unit 13 (see FIG. 3) is electrically connected to the stage.

  The photodiode 11 is placed on the stage 3 at the time of measuring the exposure distribution, and sequentially measures the intensity of light projected from each pixel of the DMD 2 onto the substrate. This makes it possible to detect the exposure intensity distribution on the substrate. It is possible to use a two-dimensional light receiving element such as a CCD for measuring the light intensity distribution, but in this case, it is necessary to correct the sensitivity unevenness of the two-dimensional light receiving element in advance. In this embodiment, it is not necessary to consider such sensitivity unevenness of the light receiving element, and highly accurate measurement can be performed.

  Further, a control device 14 such as a personal computer is connected to the exposure apparatus 1 via a network that can communicate with each other, and various instruction signals are transmitted to each component of the exposure apparatus 1.

(Control configuration)
Next, FIG. 3 shows a control block diagram of the exposure apparatus 1 according to the present embodiment.

  As shown in FIGS. 1 and 3, the exposure apparatus 1 includes a control device 14. The control unit 15 included in the control device 14 includes a CPU (Central Processing Unit), a RAM (Random Access Memory) composed of a rewritable semiconductor element, and a ROM (Read Only Memory) composed of a nonvolatile semiconductor memory. The processing program recorded in the ROM is expanded in the RAM, and this processing program is executed by the CPU.

  As shown in FIG. 3, an input unit 16 and a storage unit 17 are connected to the control unit 15. Furthermore, the controller 14 is connected to the light source 4, the controller 12 that controls the DMD 2, the stage drive unit 13 that drives the stage 3, the photodiode 11, and the image data creation unit 18.

  The light source 4 is turned on / off by the control unit 15.

  The input unit 16 includes a keyboard, a mouse, a touch panel, and the like, and outputs an instruction signal based on an instruction input by a user to the control unit 15.

  The storage unit 17 is a recording memory including a semiconductor memory and has a recording area for recording information input from the input unit 16. The storage unit 17 may be, for example, a built-in memory such as a flash memory, a removable memory card or a memory stick, or a magnetic recording medium such as a hard disk or a floppy (registered trademark) disk. .

  The controller 12 functions as a control unit of the DMD 2 and controls ON / OFF of each mirror provided in the DMD 2. As a result, when measuring the exposure distribution, the mirrors at predetermined positions are sequentially turned on one pixel at a time, and light is projected from each pixel of the DMD 2. At the time of exposure, on the basis of the image pattern data created by the image data creation unit 18, a mirror at a predetermined position is sequentially turned on / off to form a desired image pattern, and an image pattern is formed on the substrate by this image pattern. It is like that.

  The stage drive unit 13 adjusts the position of light incident on the surface of the substrate by controlling the vertical movement and inclination of the stage 3 on which the substrate is placed during exposure.

  The photodiode 11 sequentially measures the intensity of light projected on the substrate from each pixel of the DMD 2 and transmits an output signal as a measurement result to the image data creation unit 18. FIG. 4 shows an example of the light intensity distribution on the substrate corresponding to each pixel of the DMD 2.

  The image data creation unit 18 functions as image data creation means, and has a ratio between the maximum value of the received light intensity measured by the photodiode 11 and the received light intensity of the projection light from each pixel of the DMD 2. Based on this, the exposure time in each pixel of the DMD 2 is determined such that the amount of light projected on each part of the image pattern on the substrate is spatially uniform. In addition, the image data creation unit 18 makes the projected light quantity of each part of the image pattern to which light should be projected during exposure be spatially uniform based on the determined exposure time and the image pattern to be formed on the substrate. Image pattern data whose image pattern changes over time is generated and transferred to the controller 12.

Specifically, when receiving the output signal of the photodiode 11, the image data creation unit 18 detects light intensity I (x, y) as shown in FIG. 4 from the output signal corresponding to each pixel of the DMD 2. In the example of FIG. 4, the light intensity of each of the area (A) and the area (B) is I _A and I _B , respectively.

Further, the image data creating unit 18 performs exposure based on the ratio between the maximum value I _max of the light intensity in the exposure area and the light intensity I (x, y) corresponding to each pixel of the DMD 2 measured by the photodiode 11. The exposure time of each pixel for making the exposure amount uniform over the entire surface is obtained. That is, _assuming that the optimum exposure time for a pixel having a light intensity of I _max is T _m , the exposure time T (x, y) for each pixel is obtained by the following equation (1).

  Based on the exposure time of each pixel and the image pattern to be formed on the substrate, the amount of light projected from each pixel of the DMD 2 to which light is to be projected at the time of exposure is temporally uniform. Image pattern data that changes is generated.

  Here, the image pattern data that changes with time so that the amount of light projected from the DMD 2 is spatially uniform is the exposure time in each pixel of the image pattern adjusted according to the light intensity distribution on the substrate. Image pattern data. That is, among the pixels of DMD 2 to which light is to be projected at the time of exposure, a pixel corresponding to a region having a low light reception intensity has a long exposure time, and a pixel corresponding to a region having a high light reception intensity has a short exposure time. Data. This exposure time can be adjusted by the time for turning on / off the mirror of the DMD 2.

  Further, the image data creating unit 18 transfers the generated image pattern data to the controller 12. When the controller 12 forms a desired image pattern on the DMD 2 based on the image pattern data generated in this way and forms an image pattern on the substrate using this image pattern, each pixel of the DMD 2 to which light is to be projected at the time of exposure. The projection light quantity becomes spatially uniform, and the exposure distribution is made uniform.

  At this time, the image data creation unit 18 expresses the luminance level in each pixel of the image pattern data expressed in gradation in binary numbers, and sets the exposure time allocated by weighting each bit according to the gradation of each pixel. The image pattern data to be lit up is generated and transferred to the controller 12.

  Specifically, first, the image data creating unit 18 expresses desired image pattern data in gradation, converts the gradation level into a binary number, and distributes the exposure time T by weighting each bit. For example, when the gradation is represented by 6 bits (0 to 63), the exposure time allocated to each bit from the most significant bit (MSB) to the least significant bit (LSB) is T / 2 and T / 4, respectively. , T / 8, T / 16, T / 32, and T / 64, and the gradation can be expressed by transferring six images divided for each bit, while the exposure time T is divided evenly. In the case of expression, since 63 image transfers are required with T / 63 as the minimum exposure unit, image transfer weighted for each bit can realize faster exposure processing.

FIG. 5 shows a method of controlling the exposure time by the controller 12, taking as an example the case where I _A / I _B = 1.4 in the light intensity distribution shown in FIG. 4 assuming gradation expression with 6-bit resolution. It is a concrete representation. When the optimum exposure time at the light intensity I _A in the region (A) is T _m , the exposure time in the region (B) is T _m × I _A / I _B from the above equation (1), and this time is expressed as a 6-bit floor. If the maximum tone value is 63, the gradation of the area (A) is 63 / 1.4 = 45 (101101 in binary notation). Therefore, the pixels of the small area of the light intensity on the exposure plane (B) during the exposure time _{T m × I A / I B} , while the state of always ON, while the for pixels larger region of the light intensity (A) By setting the time weighted to the second bit and the fifth bit to OFF, and setting the other times to ON, the exposure amount on the substrate can be made uniform.

(Exposure method)
Next, the exposure method of the present invention using the exposure apparatus 1 according to this embodiment will be described.

  First, the photodiode 11 is placed on the stage 3 and the light intensity distribution on the exposure surface is measured.

  When the control unit 15 turns on the light source 4 to output exposure light, the collimator lens 5 shapes the output light of the light source 4 into parallel light, and the mirrors 6 and 7 cause the transmitted light of the collimator lens 5 to enter the DMD 2. .

  Subsequently, when the controller 12 sequentially turns on the mirror of the DMD 2 by one pixel at a time, the mirror 8 causes the projection light from the DMD 2 to enter the relay lens 9, and the relay lens 9 converts the light emitted from the point on the DMD 2 into parallel light. The objective lens 10 condenses the light transmitted through the relay lens 9 on the surface of the photodiode 11.

  Subsequently, the photodiode 11 sequentially measures the intensity of light projected from each pixel of the DMD 2 and transmits an output signal as a measurement result to the image data creation unit 18.

  Next, an exposure substrate is placed on the stage 3.

  Subsequently, the control unit 15 turns on the light source 4, the collimator lens 5 shapes the output light of the light source 4 into parallel light, and the mirrors 6 and 7 cause the transmitted light of the collimator lens 5 to enter the DMD 2.

  Next, the image data creation unit 18 projects the image pattern portions on the substrate based on the ratio between the maximum value of the received light intensity measured by the photodiode 11 and the received light intensity of the projection light from each pixel of the DMD 2. The exposure time for each pixel of the DMD 2 is determined so that the amount of light is spatially uniform. Then, based on the determined exposure time and the image pattern to be formed on the substrate, the image pattern changes over time so that the amount of light projected from each part of the image pattern to which light is projected during exposure is spatially uniform. Image pattern data is generated and transferred to the controller 12.

  At this time, the image data creation unit 18 expresses the luminance level in each pixel of the image pattern data expressed in gradation in binary numbers, and sets the exposure time allocated by weighting each bit according to the gradation of each pixel. Then, image pattern data that is lit up is generated and transferred to the controller 12.

  The controller 12 forms a desired image pattern on the DMD 2 based on the image pattern data generated by the image data creation unit 18 so that the exposure amount on the substrate is uniform. Subsequently, the mirror 8 causes the projection light from the DMD 2 to enter the relay lens 9, the relay lens 9 collimates the light emitted from the point on the DMD 2, and the objective lens 10 transmits the light transmitted through the relay lens 9 to the substrate surface. Condensate. Thereby, the substrate surface is uniformly exposed.

  As described above, according to the exposure apparatus 1 and the exposure method according to the present embodiment, the amount of light projected on the substrate is spatially uniform based on the ratio between the intensity of light projected from each pixel of the DMD 2 and its maximum value. The exposure time for each pixel can be determined. Then, based on the exposure time of each pixel and the image pattern to be formed on the substrate, the amount of light projected from each pixel of the DMD 2 to which light is projected changes over time so that light is projected upon exposure. Such image pattern data can be generated. In this image pattern data, pixels with low light intensity of the image pattern on the substrate of DMD2 have a long exposure time, and pixels with a high light intensity have a short exposure time to spatially equalize the amount of light projected on the exposure surface. To do. Thereby, it is possible to make the exposure distribution uniform with a simple apparatus configuration without using a complicated optical system using a plurality of expensive lenses.

  In addition, the brightness level of the image pattern data is expressed in binary, and the number of times each mirror of the DMD is driven is greatly reduced by controlling the ON / OFF of each pixel according to the exposure time allocated by weighting each bit. Therefore, the processing speed can be increased.

  As described above in detail, according to the exposure apparatus and the exposure method of the present invention, it is possible to make the exposure distribution on the substrate uniform with a simple apparatus configuration without relying on a complicated uniformization method using an optical system. It becomes.

It is a whole block diagram of the exposure apparatus which concerns on this embodiment. It is a conceptual diagram which shows control of DMD which concerns on this embodiment. It is a block diagram which shows the functional structure of the exposure apparatus which concerns on this embodiment. It is an example of the light intensity distribution on a board | substrate measured with the photodiode which concerns on this embodiment. It is an example of the conceptual diagram which shows control of the exposure time by the controller which concerns on this embodiment.

Explanation of symbols

1 Exposure device 2 DMD
3 Stage 4 Light source 5 Collimator lens 6, 7 Mirror 8 Mirror 9 Relay lens 10 Objective lens 11 Photo diode 12 Controller 13 Stage drive unit 14 Controller 15 Control unit 16 Input unit 17 Storage unit 18 Image data creation unit

Claims (4)

In an exposure apparatus configured to form an image pattern by a spatial light modulation unit that spatially modulates output light of a light source based on image data created by the image data creation unit, and to irradiate the image pattern on a substrate ,
The intensity of light projected on the substrate from each pixel of the spatial light modulator is sequentially measured with a photodiode,
The image data creation means is configured to generate an image pattern on the substrate based on a ratio between the maximum value of the received light intensity measured by the photodiode and the received light intensity of the projection light from each pixel of the spatial light modulation means. The exposure time in each pixel is determined so that the amount of light projected from each part is spatially uniform, and light should be projected during exposure based on the exposure time and the image pattern to be formed on the substrate. Generating image pattern data in which the image pattern changes over time so that the amount of light projected from each part of the image pattern is spatially uniform;
An exposure apparatus characterized in that the spatial light modulator forms an image pattern based on the image pattern data and irradiates the image pattern onto a substrate.   The image data creation means expresses the luminance level in each pixel of the image pattern data expressed in gradation in binary numbers, and lights the exposure time allocated by weighting each bit according to the gradation of each pixel. 2. The exposure apparatus according to claim 1, wherein the image pattern data is generated. An exposure method for forming an image pattern on a spatial light modulator that spatially modulates output light of a light source based on the created image data, and irradiating the image pattern on a substrate,
The intensity of light projected on the substrate from each pixel of the spatial light modulator is sequentially measured with a photodiode,
Based on the ratio between the maximum value of the received light intensity measured by the photodiode and the received light intensity of the projection light from each pixel of the spatial light modulation means, the projected light amount of each part of the image pattern on the substrate is spatially The exposure time in each of the pixels is determined so as to be uniform, and based on the exposure time and the image pattern to be formed on the substrate, the projection light quantity of each part of the image pattern to be projected at the time of exposure Generate image pattern data that changes the image pattern over time so that is uniform in space,
An exposure method comprising: forming an image pattern on the spatial light modulator based on the image pattern data, and irradiating the image pattern on a substrate.   Image pattern data that expresses the luminance level in each pixel of the image pattern data expressed in gradation in binary numbers and lights up the exposure time allocated by weighting of each bit according to the gradation of each pixel. 4. The exposure method according to claim 3, wherein the exposure method is generated.

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