JP2009086015A - Maskless exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a maskless exposure apparatus superior in energy efficiency by facilitating adjustment. <P>SOLUTION: The maskless exposure apparatus is formed by: arranging to incline at an angle of θ to a Y direction moving a stage 4 a rectangular spatial optical modulator arranging to juxtapose m micro mirrors 21 having p of length of one side in a row direction by mutually spacing gaps g and n micro mirrors in a line direction orthogonal to the row direction; and positioning a second spatial optical modulator 2B in an X direction orthogonal to the Y direction to a first spatial optical modulator 2A by setting an imperfect region of the second spatial optical modulator 2B inclined at the angle of θ to the Y direction to the imperfect region in which the number of the micro mirrors 21 of the Y direction arranged on the first spatial optical modulator 2A is not sufficient for the number of times k of overlapping necessary for exposure so that the sum s of the number of the micro mirrors 21 of the Y direction of the first and second spatial optical modulators 2A, 2B exceeds the number of times k of overlapping necessary for exposure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a maskless exposure apparatus that draws a pattern on a work such as a printed circuit board by turning on and off a micromirror of a spatial light modulator.

FIG. 4 is a block diagram of a conventional maskless exposure apparatus.
In the LD array 1, semiconductor lasers 11 are two-dimensionally arranged. The laser light output from the semiconductor laser 11 is shaped into a circular cross section by the cylindrical lens array 100 and is incident on the integrator 13 as parallel light by the condenser lens 12. The light transmitted through the integrator 13 passes through the condenser lens 14, is reflected by the mirror 15, and irradiates the spatial light modulator (DMD) 2. The spatial light modulator 2 has m micromirrors 21 each having a length of p arranged side by side with a gap g arranged in the column direction and n in the row direction perpendicular to the column direction, and the outer shape is rectangular. It is. The micromirrors 21 are individually controlled on and off. The laser light reflected by the micromirror 21 is incident on the surface of the workpiece 5 through the projection lens 3. The diffuser 16 that is rotationally driven by the motor 161 is a modulator that changes the wavefront of the laser light, and prevents the occurrence of interference fringes. The control circuit 6 controls the semiconductor laser 11, the motor 161, all the micromirrors 21 and the stage 4.

  With the above configuration, the spatial light modulator 2 is irradiated with laser light, the stage 4 is moved in the Y direction, and the micromirrors are individually controlled to be turned on / off so that the laser light reflected by the micromirrors is on the stage 4. A desired pattern can be drawn on the workpiece 5 by making it incident on the surface of the workpiece 5 (Patent Document 1).

  By the way, in the spatial light modulators that are currently available, m square micromirrors 21 each having a side length p of about 16 μm are arranged side by side in the column direction and n in the row direction perpendicular to the column direction. ing. In order to perform continuous exposure, the influence of the gap g (g is about 1 μm) between the adjacent micromirrors 21 must be eliminated. Furthermore, it is necessary to shorten the drawing interval in order to improve the resolution. Therefore, the spatial light modulator 2 is arranged at an angle θ with respect to the Y direction. Also, since the range that can be drawn with one spatial light modulator is usually smaller than the width of the exposure area on the work, a plurality of spatial light modulators are arranged in the X direction. When the spatial light modulator 2 is rectangular, the inclination of the spatial light modulator 2 with respect to the X axis is also θ.

  Next, an angle θ for tilting the DMD 2 with respect to the Y axis will be described.

  In order to make the exposure result uniform, the position to be exposed is usually exposed by a plurality of mirrors 21. For example, if DMD2 in which mirrors 21 are arranged in N rows in the vertical direction is used and the number of overlapping points is k, DMD2 is at an angle θ with respect to the moving direction of workpiece 6, where θ = tan−1 (k / N). Just tilt.

  By the way, the number of mirrors M arranged in a commercially available DMD is, for example, m = 1024 in the column direction and n = 768 in the row direction. Therefore, even if the column direction is arranged parallel to the X axis, the width that can be exposed with one DMD is about 16 mm. Therefore, by arranging a plurality of DMDs side by side in the X direction, the number of scans (the number of movements in the Y-axis direction) is reduced, and the work efficiency is improved.

Next, how to arrange DMDs will be described.
FIG. 5 is an explanatory diagram of how the conventional DMDs 2 are arranged, and schematically shows adjacent portions of two DMDs 2. Here, the number of micromirrors 21 indicated by dots is six (that is, six rows) in the row direction, and the number of overlapping points k is two.

  As shown in the drawing, since there is only one micromirror 21 in the exposure lines D, E, and F parallel to the Y direction in which the X coordinate of the DMD 2A is D, E, and F, it can be exposed only once. Therefore, the exposure line a at the end of the DMD 2B is arranged on the extension line of the exposure line D, that is, coaxially, the exposure line b is coaxial with the exposure line E, and the exposure line c is coaxial with the exposure line F. DMD2B is arranged in the X direction. The reason why the DMD 2A and the DMD 2B are shifted in the Y direction is because the respective frame portions are sufficiently larger than the length p of one side of the micromirror 21, and cannot be disposed close to each other. Hereinafter, in the spatial light modulator, an area where the number of micromirrors 21 in the Y direction (exposure line direction) satisfies the number of overlaps k required for exposure is referred to as “complete area”, and the number of micromirrors 21 in the exposure line direction is An area that is less than the number of overlapping times k necessary for exposure is referred to as an “incomplete area”.

  In order to perform exposure without unevenness, it is necessary to uniformly irradiate the exposure surface with light. Therefore, conventionally, the amount of laser light incident on the surface of the workpiece 5 is measured using an illuminometer, a photodiode, or the like, and supplied to each semiconductor laser 11 so that the amount of light falls within a predetermined range. The current value and the position and angle of the optical components from the LD array 1 to the imaging optical system are adjusted.

There is also a technique for making the amount of light incident on the workpiece uniform by reducing the number of micromirrors used for exposure or reducing the on-time of the micromirror so that the amount of light is the smallest (Patent Document 2).
JP 2004-039871 A JP 2005-203697 A

  However, in the case of the technique disclosed in Patent Document 1, it takes a long time to adjust the position of an optical component or the like in order to equalize the amount of light at the portion exposed by the two spatial light modulators.

  Further, in the case of the technique disclosed in Patent Document 2, the amount of light can be made uniform efficiently, but the energy efficiency has deteriorated. In addition, a specific method for aligning a plurality of spatial light modulators in the X direction is not disclosed.

  An object of the present invention is to provide a maskless exposure apparatus that solves the above-described problems, is easy to adjust, and is excellent in energy efficiency.

  FIG. 6 is a diagram showing the relationship between a conventional exposure line and light quantity, where the horizontal axis represents the position in the X direction and the vertical axis represents the light quantity.

  The present inventor is troublesome in adjusting the light amount of the portion exposed by the two spatial light modulators, as shown in the figure, the light amount supplied near both ends of the spatial light modulator is smaller than that in the central portion. I found out that it was a little. Based on this result, the present invention is a rectangular spatial light modulation in which m micromirrors each having a side length of p are arranged side by side with a gap g and n in the column direction and n in the row direction perpendicular to the column direction. The stage is tilted at an angle θ with respect to the Y direction in which the stage moves, and the spatial light modulator is irradiated with light, the stage is moved, and the micromirrors are individually turned on / off to control the micromirrors. In a maskless exposure apparatus that draws a desired pattern on the work by making the light reflected by the light incident on the surface of the work on the stage, the Y direction arranged in the first spatial light modulator The incomplete area of the second spatial light modulator tilted at an angle θ with respect to the Y direction is applied to the incomplete area where the number of the micromirrors is less than the number of overlapping times k necessary for exposure. First The sum S of the number of the micromirrors of the first and second spatial light modulators exceeds the number of overlappings k required for exposure so that the second spatial light modulator is the first spatial light modulator. The positioning is performed in the X direction perpendicular to the Y direction.

  Since the energy of the laser beam output from a light source such as a semiconductor laser can be used effectively, the processing efficiency can be improved. In addition, since the amount of light supplied to the workpiece can be easily made uniform, the adjustment time can be shortened.

  FIG. 1 is a block diagram of a maskless exposure apparatus according to the present invention. Components having the same or the same functions as those in FIG.

  The controller unit 60 outputs drawing data of the pattern to be exposed to the driver circuit 65. The driver circuit 65 converts the given data and outputs a control data signal (ON / OFF signal for each micromirror 21) to the DMD 2. Of the light incident on the DMD 2, the light reflected by the on-state micromirror 21 is incident on the projection optical system, and the light incident on the off-state micromirror 21 is reflected outside the projection optical system. The reflected light of the micromirror 21 is shaped into individual spots by the optical system and irradiated onto the workpiece 5 on the stage 4. The position of the stage 4 is precisely controlled by the movement control device 80 according to a command from the controller unit 60.

  The controller unit 60 includes a sequence control unit 60a, a drawing data control unit 60b, a position control unit 60c, and a correction value calculation unit 60d. A series of operation control of the maskless exposure apparatus, DMD2 control, stage 4 position control, image processing Correction control based on inputs from the device 70 and the optical camera 75 is performed.

  FIG. 2 is an explanatory diagram of how the DMDs 2 are arranged in the present invention. DMD 2A and DMD 2B are the same as those in FIG. Further, the overlapping point number k is set to 2.

  In the present invention, the number of overlapping points k at the end of DMD 2 is set to be larger than a specified value. That is, as shown in the figure, the DMD 2B exposure line d is coaxial with the DMD 2A exposure line D, the DMD 2B exposure line e is coaxial with the DMD 2A exposure line E, and the DMD 2B exposure line f is coaxial with the DMD 2A exposure line F. The DMDs 2B are arranged in the X direction so as to be arranged respectively. In this case, the number of overlapping points k is 3 in the exposure lines D, E, and F. With the above arrangement, the number of overlapping points k in the exposure lines A, B, and C is also 3.

  Next, the exposure procedure of the present invention will be described.

  Prior to exposure, the amount of light at each point in the exposure area with the micromirrors 21 turned on is integrated for each exposure line. And when the light quantity of two DMD2 edge parts adjacent to a X direction is larger than the number of overlapping points 2, it carries out as follows. That is, for example, if the amount of light in the exposure line A is 1.5 times that in the exposure line in the complete region, one of the three micromirrors 21 is not turned on. Alternatively, the on time of all three micromirrors 21 is set to 2/3 of the on time of the other micromirrors 21.

  As described above, since the light amount for each exposure line is aligned, exposure is performed in the same manner as in the prior art. Since the amount of light of all the exposure lines is almost the same, exposure unevenness hardly occurs. In this case, since the light quantity of the micromirror 21 only in the adjacent part of the DMD 2 where the number of overlapping points k is larger than the others is limited, the energy loss is small.

  Although the case where the overlap point k is 2 has been described here, since the overlap point k is normally 5 to 10, for example, the light amount in the incomplete region is 10 to 20% of the desired light amount. Can be adjusted.

  FIG. 3 is a diagram showing the relationship between the exposure line and the light quantity in the present invention, where (a) shows a state immediately after the light quantity measurement, (b) shows a state after the light quantity adjustment, and (c) shows a conventional case shown for comparison. It is.

  As shown in the figure, the number of micromirrors 21 included in the exposure line formed by the incomplete region of the first spatial light modulator and the incomplete region of the second spatial light modulator is set to the overlap point in the complete region. As a result of being larger than the number, the amount of light in this region is greater than the amount of light in the complete region. However, some of the micromirrors 21 may not be turned on, or all of the micromirrors 21 may be turned on so that the amount of light in the exposure line in the region is substantially the same as the exposure line in the complete region. By adjusting the time, the amount of light can be made almost the same as the others.

It is a block diagram of the maskless exposure apparatus which concerns on this invention. It is explanatory drawing of how to arrange DMD2 in this invention. It is a figure which shows the relationship between the exposure line and light quantity in this invention. It is a block diagram of the conventional maskless exposure apparatus. It is explanatory drawing of how to arrange the conventional DMD. It is a figure which shows the relationship between the conventional exposure line and light quantity.

Explanation of symbols

2A First spatial light modulator 2B Second spatial light modulator 4 Stage 21 Micromirror Y Stage movement direction (exposure line direction)
θ Angle of the spatial light modulators 2A and 2B with respect to the Y direction

Claims (3)

In the Y direction in which the stage moves, a rectangular spatial light modulator is arranged in which m micromirrors each having a length of p are arranged in the column direction and n in the row direction perpendicular to the column direction with a gap g therebetween. The spatial light modulator is disposed at an angle θ, and the spatial light modulator is irradiated with light and the stage is moved, and the micromirrors are individually turned on and off to reflect the light reflected by the micromirrors on the stage. In a maskless exposure apparatus configured to draw a desired pattern on the workpiece by being incident on the surface of the workpiece,
The second space inclined at an angle θ with respect to the Y direction in an incomplete region in which the number of the micromirrors in the Y direction arranged in the first spatial light modulator is less than the number of overlaps k required for exposure. In the incomplete region of the light modulator, the sum s of the number of the micromirrors in the Y direction of the first and second spatial light modulators exceeds the number of overlapping times k necessary for exposure, and the second A maskless exposure apparatus, wherein the spatial light modulator is positioned in an X direction perpendicular to the Y direction with respect to the first spatial light modulator.   The amount of light when all the micromirrors in the incomplete area are on is measured in advance for each exposure line, and the measured amount of light is measured by the micromirrors in the Y direction arranged in the spatial light modulator. When the number exceeds the allowable range of the light amount of the exposure line in the complete area that satisfies the number of overlapping times k necessary for exposure, the micromirror that is not turned on on the exposure line in the incomplete area is defined. The maskless exposure apparatus according to claim 1.   The amount of light when all the micromirrors in the incomplete area are on is measured in advance for each exposure line, and the measured amount of light is measured by the micromirrors in the Y direction arranged in the spatial light modulator. If the number is q times the light quantity r of the exposure line in the complete area satisfying the number of overlapping times k necessary for exposure (where q> r), the micro on the exposure line at the time of drawing in the incomplete area 2. The maskless exposure apparatus according to claim 1, wherein the on-time of the mirror is set to r / q of the on-time of the micromirror on the exposure line in the complete region.

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