JP2015142036A - Exposure device and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine a pattern formation position/exposure position in a maskless exposure device.SOLUTION: An exposure device including a DMD has a light-shielding part 40 having slits ST1 to ST2 formed at an equal distance and installed above a single photosensor PD, and projects a position detection pattern string PT comprising a plurality of bar-like patterns PL1 to PL4 parallel to a sub scanning direction Y while an exposure area makes relative displacement through the light-shielding part 40. The exposure device detects a half value of a light quantity signal output from a photosensor PD, calculates an exposure position from an intermediate position of the output of a trigger signal, and corrects the exposure position.

Description

  The present invention relates to a maskless exposure apparatus that forms a pattern using a light modulation element array, and more particularly to position detection of a pattern projected on a substrate or the like.

  In a maskless exposure apparatus, pattern light is projected onto a substrate by a light modulation element array such as DMD (Digital Micro-mirror Device) while moving a stage on which the substrate is mounted along the scanning direction. There, a light modulation element such as a micromirror arranged in a two-dimensional manner is used to detect the position of a projection area (exposure area) on a substrate placed on a stage and project pattern light according to the position. Control.

  When a fine pattern is formed on the order of a micrometer, it is necessary to accurately detect the position of the substrate and project the pattern light without misalignment. However, due to a change in temperature of the DMD or the like, there may be a deviation in the projection position of the pattern light and an error in the pattern formation position.

  In order to prevent this, a plurality of optical sensors such as photodiodes are arranged beside the stage to correct the exposure position (see Patent Document 1). In this case, a plurality of slits are formed near the drawing surface, and a specific micromirror is turned on when the projection area of the DMD passes through a slit wider than the spot light size. Then, the light amount change of the spot light when passing through the slit is detected, and the position where the half value of the maximum light amount is detected is calculated as the drawing position.

JP 2007-271867 A

  When the light amount is measured based on the spot light from one micromirror, the intensity of the spot light is weak, so noise generated in the photosensor affects the light amount measurement. In addition, since the slit width is wide with respect to the spot light size, the position of the spot light becomes unstable due to fluctuations in the light source, and it is difficult to accurately detect the exposure position.

  Therefore, in a maskless exposure apparatus, accurate two-dimensional position detection is required using a photosensor such as a photodiode.

  The exposure apparatus of the present invention moves a light modulation element array in which a plurality of light modulation elements are arranged in a matrix and an exposure area, which is a projection area by the light modulation element array, relative to the object to be drawn along the main scanning direction. And a scanning control unit that controls a plurality of light modulation elements according to the relative position of the exposure area, and an exposure control unit that projects pattern light onto the drawing object.

  In addition, the exposure apparatus includes a light shielding unit in which at least one slit is formed along the drawing surface of the drawing object, a photometric unit that receives light transmitted through the slit, and a position calculation that calculates an exposure position from the output of the photometric unit. A part. The photometry unit can be configured by, for example, a photosensor, and a single photosensor arrangement or a photosensor arrangement for each scanning band can be configured.

  In the present invention, the exposure control unit projects the light of the position detection pattern having a width in the main scanning direction wider than the width of the slit in the main scanning direction while the exposure area moves relative to the light shielding unit at a predetermined speed. Then, the position calculation unit calculates the exposure position from the continuous light quantity distribution by the light quantity output from the photometry part continuously and in time series. A continuous light quantity distribution is derived from a series of time-series outputs from the photometry unit, and the distribution characteristics follow the output value. The position calculation unit calculates the exposure position based on the light amount distribution during the passage of the pattern slits at a constant speed, for example, instead of the spot-like and static light amount.

  It is desirable to configure the pattern light and the slit so that the continuous light quantity distribution corresponds to the spatial light quantity distribution of the pattern light. The exposure position can be obtained from the light amount distribution in correspondence with the exposure amount of the photosensitive material or the like.

  The slit can be formed, for example, along the sub-scanning direction, and the position detection pattern can be formed as a bar-shaped pattern along the sub-scanning direction. The width of the slit along the main scanning direction can be set to 0.1 to 0.5 times the width of the bar-shaped pattern along the main scanning direction.

  A plurality of slits can be formed along the main scanning direction, and the exposure position can be calculated for each slit. In this case, the exposure control unit can project the light of a plurality of position detection patterns as a pattern row along the main scanning direction. At this time, the interval between the plurality of slits is the interval between the plurality of position detection patterns. What is necessary is just to project a pattern row | line so that it may become wider.

  On the other hand, it is possible to define two light receiving areas in the photometry unit and output them separately. In this case, the exposure control unit projects different first position detection patterns and second position detection patterns on the first photometry area and the second photometry area as patterns to be projected onto the exposure area. The photometry unit detects and outputs the light amount corresponding to the first position detection pattern and the second position detection pattern from the first and second photometry areas.

  For example, the exposure operation control unit projects a bar-shaped pattern along the sub-scanning direction as a first position detection pattern, and projects a bar-shaped pattern inclined with respect to the main scanning direction as a second position detection pattern. Is possible.

  An exposure method according to another aspect of the present invention is configured to move an exposure area by a light modulation element array in which a plurality of light modulation elements are arranged in a matrix, relative to an object to be drawn along a main scanning direction. A plurality of light modulation elements are controlled in accordance with the position, pattern light is projected onto the drawing object, at least one slit is formed along the drawing surface of the drawing object, and light transmitted through the slit is received and photometry is performed. An exposure method for calculating an exposure position from an output of a portion, and projecting light of a position detection pattern having a main scanning direction width wider than a main scanning direction width of the slit while the exposure area relatively moves the light shielding portion, The exposure position is calculated from the continuous light quantity distribution according to the time series output of the photometry unit.

  According to the present invention, a pattern forming position / exposure position can be accurately determined in a maskless exposure apparatus.

It is a block diagram of the exposure apparatus which is 1st Embodiment. It is the figure which showed the light-shielding part and the position detection pattern row | line | column. It is the schematic side view which showed arrangement | positioning of a photo sensor and a light-shielding part. It is the graph which showed time-sequential light quantity distribution when one bar-shaped pattern light passes through one slit. It is a timing chart at the time of exposure position detection. It is the figure which showed the photo sensor and position detection pattern row | line in 2nd Embodiment. It is the figure which showed the relationship between deviation | shift amount and a measured value.

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

  FIG. 1 is a block diagram of an exposure apparatus according to the first embodiment.

  The exposure apparatus (drawing apparatus) 10 is a maskless exposure apparatus that forms a pattern by irradiating light onto a substrate W to which a photosensitive material such as a photoresist is applied or pasted, and a stage 12 on which the substrate W is mounted is provided. It is installed so as to be movable along the scanning direction. The stage drive mechanism 15 can move the stage 12 along the main scanning direction X and the sub-scanning direction Y.

  The exposure apparatus 10 includes a plurality of exposure heads that project pattern light (only one exposure head 18 is shown here), and the exposure head 18 includes a DMD 22, an illumination optical system, and an imaging optical system (all not shown). Prepared). The light source 20 is constituted by a discharge lamp (not shown), for example, and is driven by a light source driving unit 21.

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

  The DMD 22 is a light modulation element array (light modulator) in which minute micromirrors are two-dimensionally arranged, and each micromirror selectively switches the light reflection direction by changing the posture. By controlling the posture of each mirror by the DMD driving circuit 24, light corresponding to the pattern is projected onto the surface of the substrate W through the imaging optical system.

  The stage drive mechanism 15 moves the stage 12 in accordance with a control signal from the controller 30. The stage drive mechanism 15 includes a linear encoder (not shown), and measures the position of the stage 12 and feeds it back to the controller 30.

  The position detection unit 28 is installed near the end of the stage 12 and includes a single photosensor PD and a pulse signal generation unit 29. Above the position detection unit 28, a light blocking unit 40 that partially transmits light is provided. The position calculator 27 calculates the exposure position, that is, the position of the substrate W (stage 12) relative to the exposure head, based on the signal sent from the position detector 28.

  During the exposure operation, the stage 12 moves along the scanning direction X at a constant speed. A projection area (hereinafter referred to as an exposure area) by the entire DMD 22 relatively moves on the substrate W as the substrate W moves. The exposure operation is performed according to a predetermined exposure pitch, and the micromirror is controlled to project pattern light in accordance with the exposure pitch.

By adjusting the control timing of each micromirror of the DMD 22 according to the relative position of the exposure area, the light of the pattern to be drawn is sequentially projected at the position of the exposure area. Then, a pattern is formed on the entire substrate W by drawing the entire substrate W with a plurality of exposure heads including the exposure head 18.

  As an exposure method, not only a continuous movement method that moves at a constant speed, but also step and repeat movements that move intermittently are possible. Also, multiple exposure (overlap exposure) in which the projection area at the time of exposure shot is partially overlapped is possible.

  In the stage before starting the exposure operation, correction processing relating to the exposure start position is performed in order to form a pattern at an accurate position. While moving the stage 12 at a constant speed, light of a pattern for position detection is projected. The controller 30 corrects the exposure start position based on the position information sent from the position calculation unit 27.

  Hereinafter, detection and correction of the exposure position will be described with reference to FIGS.

  FIG. 2 is a diagram showing a light shielding portion and a position detection pattern sequence. FIG. 3 is a schematic side view showing the arrangement of the photosensor and the light shielding portion.

  A slit area ST is formed along the main scanning direction X in the light shielding portion 40 disposed above the light source side of the single rectangular photosensor PD. Here, the slit area ST is perpendicular to the main scanning direction X, that is, sub-scanning. Six bar-shaped slits ST1 to ST6 parallel to the direction Y are formed at equal intervals with a slit pitch SP. The size of the light-shielding part 40 is larger than the entire size of the photosensor PD, and the photosensor PD arranged directly below the light-shielding part 40 receives only light that has passed through the slit ST.

  The photosensor PD that detects the light intensity / light quantity is held by a support mechanism 60 that supports the substrate W, and supports both ends of the light-shielding portion 40 parallel to the light-receiving surface PS of the photosensor and the drawing surface of the substrate W. The mechanism 50 is supported by a support mechanism 60 that supports the substrate W. The support mechanism 60 is attached to the stage 12. As the stage 12 moves, the exposure area passes through the light shielding unit 40.

  When the exposure position is detected, the light of the position detection pattern row PT is projected as pattern light. The position detection pattern row PT is a pattern row in which a plurality of bar-shaped patterns perpendicular to the main scanning direction X, that is, parallel to the sub-scanning direction Y are arranged. Here, four bar-shaped patterns arranged at equal intervals with the pattern pitch PP. It is comprised by PL1, PL2, PL3, PL4. The light of the position detection pattern row PT is scanned toward the light shielding unit 40.

  Each pattern width K of the bar-shaped patterns PL1, PL2, PL3, PL4 is wider than the slit width Z of each of the slits ST1 to ST6 formed in the light shielding part 40. The pattern pitch PP is also wider than the slit width Z. Therefore, after one bar-shaped pattern has completely passed through one slit at a predetermined speed, the next bar-shaped pattern starts to pass through the slit. The overall width PW along the main scanning direction X of the position detection pattern row PT is smaller than the slit pitch SP. For this reason, when the last bar-shaped pattern PL4 of the position detection pattern row PT finishes passing through one slit, for example, at a constant speed, the first bar-shaped pattern PL1 starts passing the next slit.

  FIG. 4 is a graph showing a time-series light amount distribution when one bar-shaped pattern light passes through one slit. FIG. 5 is a timing chart when the exposure position is detected. In the following, description will be made with respect to the slit ST6 and the bar-shaped pattern PL1.

  When the light of the position detection pattern row PT passes through the light shielding portion 40 at a constant speed, a signal (hereinafter referred to as a light amount signal) output from the photosensor PD when the bar-shaped pattern PL1 passes through the slit ST6 is time-series. Changes continuously. As described above, this is because the slit width Z is shorter than the pattern width K of the bar-shaped pattern PL1.

  As shown in FIG. 4, the light intensity distribution / light quantity distribution GD along the main scanning direction X of the bar-shaped pattern PL1 is substantially expressed by a Gaussian distribution. Therefore, the amount of light gradually decreases around the peak value. As a result, the time series distribution (hereinafter referred to as the light quantity signal distribution) AL of the light quantity detected by the photosensor PD is also substantially Gaussian, and the time series light quantity signal distribution AL and the spatial light quantity distribution GD are similar to each other. It has a general correlation. However, the light quantity signal distribution AL here represents a locus obtained by continuously plotting the light quantity signal values detected according to the slit width Z with respect to the movement of the stage 12.

  In order for the light amount signal distribution AL and the light amount distribution GD to have a similar relationship, the slit width Z needs to be shorter than the bar-shaped pattern width K. By making it sufficiently short, the chevron shape of the light amount signal distribution AL becomes the light amount distribution GD. It becomes closer to the Yamagata shape. Here, the slit width Z is set to 0.1 to 0.5 times the bar-shaped pattern width K. In order to achieve such a ratio, either or both of the setting of the region of the micromirror for projecting the light of the bar-shaped pattern PL1 and the adjustment of the slit width Z are performed.

  Regarding the measurement of the exposure position, the projection position of the bar-shaped pattern PL1 can be detected in the process of continuous scanning by obtaining the center position of the light quantity signal distribution AL and measuring the position as the exposure position. As a specific detection method, the trigger signal is output from the pulse signal generator 29 when the light amount signal passes / strides a predetermined threshold value. In consideration of the fact that the exposure amount of the photosensitive material on the substrate W is calculated based on the half value of the light intensity, the threshold value is set as the threshold value here in the light intensity distribution GD of the bar-shaped pattern PL1.

  Since the light amount signal distribution AL is a distribution that continuously decreases from a continuous increase in the light amount, two trigger signals are output when the bar-shaped pattern PL1 passes through the slit ST6 as shown in FIG. The middle of the two trigger signal output timings is obtained as an exposure position corresponding to the peak position of the light amount distribution AL of the bar-shaped pattern PL1.

  Although the light amount signal distribution when the bar-shaped pattern PL1 passes through the slit ST6 has been described, the same light amount signal distribution is obtained when the other bar-shaped patterns PL2 to PL4 pass through the slit ST6, and the trigger signal is the same. Are output at regular time intervals.

  Furthermore, the time interval from when the position detection pattern row PT finishes passing through the first slit ST6 to when it starts to pass through the next slit ST5 is the same as the time interval during which light of two bar-shaped patterns passes through one slit ST6. The scanning speed and the slit pitch SP are determined so that Therefore, the trigger signal is output at a constant time interval PPt while the position detection pattern row PT passes through all the slits ST1 to ST6. The position calculation unit 27 sequentially calculates the exposure position from the intermediate value of the two adjacent trigger signal output timings.

  The controller 30 sequentially calculates the difference between the exposure position calculated from the trigger signal and the preset standard exposure position. As the standard exposure position, the position coordinates of the center point of the slit are stored and set in advance.

  After calculating correction values for all detected exposure position coordinates, the average value is obtained. The exposure position is corrected by this average value. When actual drawing processing is performed, drawing is started by shifting the exposure position by the correction value. Here, the exposure position is corrected as the reference position of the substrate W for each of the plurality of exposure heads.

  As described above, according to the first embodiment, in the exposure apparatus 10 provided with the DMD 22, the light shielding unit 40 in which the slits ST1 and ST2 are formed at equal intervals is provided above the single photosensor PD, and the exposure area is set. While the light shielding unit 40 is relatively moved, a position detection pattern row PT composed of a plurality of bar-shaped patterns PL1 to PL4 parallel to the sub-scanning direction Y is projected. Then, the half value of the light amount signal output from the photosensor PD is detected, and the exposure position is calculated from the output intermediate position of the trigger signal and corrected.

  Since the photosensor only receives light that has passed through the slit, the influence of noise such as leakage light can be suppressed. Since the light amount signal distribution detected in time series has a shape corresponding to the light intensity distribution of the pattern light, the exposure position corresponding to the peak position can be detected accurately by detecting the half value of the light amount distribution. Can do.

  In addition, the pattern light passes through multiple slits, and the average value is calculated based on the relative amount of movement, so that the effects of light source fluctuations and photosensor sensitivity irregularities can be suppressed. Can do. Furthermore, when the plurality of bar-shaped patterns pass through the plurality of slits, the parameter of the average value is expanded, and the exposure position is accurately measured.

  The bar-shaped pattern of the position detection pattern row may not be perpendicular to the main scanning direction, the pattern shape is determined in accordance with the slit forming direction, and the width of the slit in the main scanning direction so as to obtain the above-described continuous light amount distribution, The width of the pattern light in the main scanning direction may be determined. Moreover, it is also possible to use one bar-like pattern as a position detection pattern instead of the pattern row. As for the photo sensor, it is also possible to install a photo sensor for each scanning band.

  Next, a second embodiment will be described with reference to FIGS. In the second embodiment, the photosensor is divided into two light quantity detection regions, and a two-dimensional exposure position is detected in the main scanning direction (X direction) and the sub-scanning direction (Y direction). Other configurations are substantially the same as those in the first embodiment.

  FIG. 6 is a diagram illustrating a photosensor and a position detection pattern sequence according to the second embodiment.

  The photosensor PD1 is equally divided into two along the main scanning direction, and first and second photometric areas AP1 and AP2 are respectively defined. Here, the division means that the photosensor PD is configured to have two light receiving parts, and one light receiving element may be electrically divided into two light receiving parts, or two independent light receiving parts. You may comprise so that a light receiving element may be provided adjacently. In the photosensor PD1, the amount of light is detected separately in each region. Then, the first position detection pattern row PT1 is projected onto the first photometry area AP1, and the position detection pattern row PT2 is projected onto the second photometry area AP2.

  As in the first embodiment, a plurality of slits SU1 parallel to the sub-scanning direction Y are formed at equal intervals in a half region corresponding to the first photometric region AP1 of the light shielding unit 400. The first position detection pattern row PT1 is also composed of a plurality of bar-shaped patterns parallel to the sub-scanning direction Y, as in the first embodiment.

  On the other hand, slits SU2 inclined at a predetermined angle with respect to the main scanning direction X are formed at equal intervals in the remaining half of the light shielding unit 400 corresponding to the second photometric area AP2. The second position detection pattern row PT2 is also configured as a pattern row inclined by the same inclination angle. Here, the inclination angle is set to −45 degrees with respect to the main scanning direction X.

  When the exposure position is detected, the first and second position detection pattern rows PT1 and PT2 are projected. At this time, in each of the first photometry area AP1 and the second photometry area AP2, a light quantity signal distribution that is continuous in time series and corresponds to a Gaussian distribution is obtained, and the trigger signal is the first photometry area AP1, the second photometry area AP1, and the second photometry area AP2. Are output from each of the two photometric areas AP2.

  For the first photometric area AP1, the exposure position along the main scanning direction X and its correction value are calculated as in the first embodiment. On the other hand, the exposure position detected in the second photometric area AP2 includes a positional deviation in the main scanning direction X and the sub-scanning direction Y. However, by using the positional deviation in the main scanning direction X obtained in the first execution area AP2, it is possible to obtain the biaxial deviation amount.

  FIG. 7 is a diagram showing the relationship between the deviation amount and the measured value. If the amount of deviation in the main scanning direction X is A, the amount of deviation in the sub-scanning direction Y is B−A because the pattern inclination angle is 45 degrees. Therefore, the difference between the value of the exposure position in the main scanning direction X calculated for the second photometry area AP2 and the value of the exposure position in the main scanning direction X calculated for the first photometry area AP1 ( By taking B-A), the exposure position can be corrected for the X and Y axes.

  Note that it is possible to form an inclined slit and project an inclined position detection pattern row also in the area of the light shielding portion corresponding to the first photometric area. In this case, the shift amount may be obtained from the biaxial exposure position in each region.

10 Exposure Equipment 22 DMD (Light Modulation Element Array)
27 Position calculation unit 28 Position detection unit (photometry unit)
30 controller (exposure controller)
40 Light-shielding part PD Photo sensor

Claims (9)

A light modulation element array in which a plurality of light modulation elements are arranged in a matrix, and
A scanning unit that relatively moves the exposure area by the light modulation element array along the main scanning direction with respect to the drawing object;
An exposure control unit that controls the plurality of light modulation elements according to a relative position of the exposure area, and projects pattern light onto the drawing object;
A light-shielding portion in which at least one slit is formed along the drawing surface of the drawing object;
A photometric unit that receives light transmitted through the slit;
A position calculation unit that calculates an exposure position from the output of the photometry unit,
The exposure control unit projects light of a position detection pattern having a main scanning direction width wider than the main scanning direction width of the slit while the exposure area relatively moves the light shielding unit,
An exposure apparatus, wherein the position calculation unit calculates an exposure position from a continuous light amount distribution according to a time series output of the photometry unit.   The exposure apparatus according to claim 1, wherein the continuous light amount distribution corresponds to a spatial light amount distribution of pattern light. The slit is formed along the sub-scanning direction;
The exposure apparatus according to claim 1, wherein the position detection pattern has a bar-shaped pattern along the sub-scanning direction.   4. An exposure apparatus according to claim 3, wherein the width of the slit along the main scanning direction is 0.1 to 0.5 times the width of the bar-shaped pattern along the main scanning direction.   5. The exposure apparatus according to claim 1, wherein a plurality of slits are formed along the main scanning direction. The exposure control unit projects light of a plurality of position detection patterns along the main scanning direction,
6. The exposure apparatus according to claim 5, wherein an interval between the plurality of slits is wider than an interval between the plurality of position detection patterns. The photometry section has first and second photometry areas divided along the main scanning direction, and detects the amount of light for each of the first and second photometry areas;
The exposure control unit projects a first position detection pattern and a second position detection pattern, which are different from each other within an exposure area, onto the first photometry area and the second photometry area, respectively. The exposure apparatus according to claim 1.   The exposure operation control unit projects a bar-shaped pattern along the sub-scanning direction as the first position detection pattern, and projects a bar-shaped pattern inclined with respect to the main scanning direction as the second position detection pattern. The exposure apparatus according to claim 5. Move the exposure area by the light modulation element array in which a plurality of light modulation elements are arranged in a matrix, relative to the object to be drawn along the main scanning direction,
Controlling the plurality of light modulation elements according to the relative position of the exposure area, projecting pattern light onto the drawing object,
Forming at least one slit along a drawing surface of the drawing object;
Receiving light transmitted through the slit,
An exposure method for calculating an exposure position from an output of the photometry unit,
While the exposure area moves relative to the light shielding portion, the light of a position detection pattern having a main scanning direction width wider than the main scanning direction width of the slit is projected,
An exposure method, wherein an exposure position is calculated from a continuous light amount distribution according to a time series output of the photometry unit.

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