JP2009003173A - Illuminance measuring device for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminance measuring device for exposure capable of accurately and easily measuring integral illuminance in an objective portion for exposure. <P>SOLUTION: The illuminance measuring device 10 for exposure includes a light source 11, a spatial light-modulating element (digital micro-mirror device (DMD)) 12 modulating light emitting from the light source, a condenser lens 13 where the whole light exiting from the DMD enters, a single photo-electron converter (PD) 14 where the converged light through the condenser lens enters, and a controller 17. The controller 17 calculates, from a light detection signal of the PD 14, the integral illuminance (data of luminous energy necessary for exposure in an exposure device) in an objective portion on an exposure surface to be irradiated with light by use of the DMD 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for performing an exposure process without using a pattern mask, and in particular, in a device that performs an exposure process using a spatial light modulator, obtains data on the amount of light required for the exposure. The present invention relates to an exposure illuminance measuring apparatus adapted to do so.

  2. Description of the Related Art Conventionally, various apparatuses for performing image exposure with a light beam modulated according to image data using a spatial light modulator such as DMD (Digital Micro-mirror Device) or LCD (Liquid Crystal Device) have been proposed. . For example, DMD is a trademark for optical and electronic integrated devices using micromirrors developed by Texas Instruments, Inc. of the United States, where hundreds of thousands of micromirrors are integrated on CMOS SRAM cells to reflect light from the light source. The reflection type light modulation device controls the direction of the reflected light. When a digital signal is written in the DMD SRAM cell, the individual micromirrors are electromechanically controlled by the digital signal and tilt so as not to collide with each other at a predetermined angle. At this time, a part of the micromirror necessary for projecting the image is tilted to the “on” state, and a part of the micromirror that is not necessary is tilted to the “off” state. Therefore, when light is applied to the mirror surface, only the light hitting the “on” micromirror is reflected in a predetermined direction.

  Thus, the light reflected in the predetermined direction can be used for the exposure process. For example, Patent Document 1 describes an example thereof. In the exposure apparatus described in Patent Document 1, pattern data corresponding to a pattern to be exposed is created, input to an DMD as an electrical signal, and each mirror is tilted in accordance with the pattern data. By irradiating light onto the resist and projecting each reflected light onto the resist, exposure is performed in a shape corresponding to the pattern data.

  By scanning such DMD in a certain direction along the exposure surface, exposure along the scanning line is performed. Since the DMD micromirrors are generally arranged in a matrix so that the row arrangement direction and the column arrangement direction are orthogonal to each other, in actual exposure, such DMD is inclined with respect to the scanning direction. It is arranged. With this scanning mode, the scanning lines are closely spaced during scanning, and the same scanning line is overlapped and exposed (multiple exposure) by different micromirror arrays, so that the resolution is improved and high-definition exposure can be realized. Because. A technique related to such multiple exposure is described in Patent Document 2, for example.

  In addition, in such an exposure apparatus using DMD, the amount of light required to perform the exposure, that is, the integrated illuminance at the corresponding portion of the exposure surface to be irradiated with light using DMD is measured in advance. In general, the exposure process is performed based on the measured light quantity (data). When detecting the integrated illuminance at the exposure target location, in the conventional technique, as illustrated in FIG. 7, a plurality of photodiodes (hereinafter also simply referred to as “PD”) are arrayed corresponding to one DMD 1. The light emitted from each micromirror of the DMD 1 is detected by each PD using the PD array 2 arranged in a shape, and an analog signal (light detection signal) corresponding to the amount of light detected by each PD is detected by the switch 3. After sequentially switching and selecting, the selected photodetection signal is amplified through the amplifier 4 and converted into a digital signal through the A / D converter 5. Then, the controller 6 calculates the illuminance from the total illuminance detected by each PD. The integrated illuminance of light irradiated to the exposure target location was obtained.

In the example of FIG. 7, for simplicity of explanation, a case where there is one DMD 1 is shown. However, actually, a plurality of DMDs are arranged in a predetermined arrangement form, The PD array 2 is provided in the connection form as shown in FIG.
JP-A-10-112579 Japanese Patent Laid-Open No. 2004-9595

  As described above, in the exposure apparatus using the conventional DMD, it is necessary to measure the integrated illuminance of the exposure target portion in advance (FIG. 7).

  However, as illustrated in FIG. 7, when the light emitted from the DMD 1 is incident on each PD of the PD array 2, the number of mirrors constituting the DMD 1 is larger than the number of PDs constituting the PD array 2. Therefore, depending on the arrangement relationship of each PD with respect to the DMD 1, not all of the light reflected by each mirror of the DMD 1 is incident on each PD (without leakage). That is, a part of the light reflected by each mirror of DMD 1 (light indicated by “ND” in FIG. 7) leaks through the gap between the PDs without entering the light receiving surface of any PD. Inconvenience can occur. The leaked light is originally a light amount that should be detected by any PD, but an error (variation) occurs in the integrated illuminance of the exposure target portion by the amount of light that has not been detected.

  In other words, in a conventional apparatus configuration in which a plurality of PDs (PD arrays) are provided for one DMD, the integrated illuminance corresponding to the spot (exposure area) on the exposure surface cannot be accurately measured. There was a problem.

  Further, in an exposure apparatus in which a stage for supporting an exposure object and an exposure head with a built-in DMD are disposed so as to be relatively movable, a total of a mirror near the left end and a mirror near the right end of the DMD as the DMD moves. Area (for example, portions indicated by ST2 and ST3 in FIG. 6A), or between the DMD adjacent to the right end of one DMD and the vicinity of the left end of the other DMD between adjacent DMDs. In an area where the total illuminance by the mirror is required (for example, a portion indicated by ST1 in FIG. 6B), it is caused by a positional deviation of the DMD with respect to the scanning direction or a positional deviation of each PD with respect to the DMD There is also a problem that the integrated illuminance in the area varies. The areas (ST1, ST2, ST3) where the total illuminance is required are also referred to as “stitch areas” for convenience in the following description.

  Further, in the conventional configuration (FIG. 7), it is difficult to detect the integrated illuminance at the exposure target location even if one of the micromirrors constituting the DMD 1 is broken. For example, when any one of the mirrors of the DMD 1 is set to the “ON” state, the mirror reflects the light that is not detected by any PD (light indicated by “ND” in FIG. 7). In the case of the arrangement, the reflected light is not detected even though it is functioning normally, so that the amount of light is not reflected in the illuminance that should be integrated.

  In addition, in order to accurately measure the integrated illuminance at the exposure target location, the controller 6 corrects the variation in illuminance between the PDs in the PD array 2 and between the PD arrays 2 corresponding to each DMD 1. It was necessary to correct the illuminance variation of the image, and the correction process was difficult.

  The present invention has been created in view of the problems in the prior art, and an object thereof is to provide an exposure illuminance measuring apparatus capable of accurately and easily measuring the integrated illuminance at an exposure target location.

  In order to solve the above-mentioned problems of the prior art, according to the present invention, there is provided an exposure illuminance measuring apparatus adapted to acquire data on the amount of light required for performing exposure in an exposure apparatus, comprising: a light source; A spatial light modulation element that modulates the light emitted from the light source, a condensing lens that receives all the light emitted from the spatial light modulation element, and a single light that is incident on the light converged through the condensing lens. One photoelectric conversion element, and a control means for calculating an integrated illuminance of the portion of the exposure surface to be irradiated with light from the light detection signal of the photoelectric conversion element using the spatial light modulation element. An exposure illuminance measuring apparatus is provided.

  According to the illuminance measuring apparatus for exposure according to the present invention, since all the light emitted from the spatial light modulation element (for example, DMD) is incident on the condenser lens, the conventional technique (FIG. 7) is used. As seen, there is no inconvenience that some of the light reflected by each mirror of the DMD leaks through the gaps between the PDs in the PD array. That is, the light reflected by each pixel portion (each micromirror in the case of DMD) can be detected through the condenser lens without omission, so that there is an error (variation) in the integrated illuminance at the exposure target location. ) Does not occur, and it is possible to accurately measure the integrated illuminance of light striking the location.

  Further, in the prior art (FIG. 7), the signals detected by each PD in the PD array are sequentially switched by a switch and taken into the controller, and the integrated illuminance at the relevant location is obtained by summing the illuminance by each PD. There is a disadvantage that it takes time to measure the integrated illuminance. However, in the present invention, since the condensing lens is used instead of the PD array, the exposure object to be irradiated with light using the spatial light modulation element. The integrated illuminance at the location can be easily measured.

  Other structural features of the illuminance measuring apparatus for exposure according to the present invention and advantageous advantages based on the features will be described in detail with reference to embodiments of the invention described later.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows a part of the configuration of an exposure illuminance measuring apparatus according to an embodiment of the present invention. In the exposure illuminance measuring apparatus 10 according to the present embodiment, a stage that supports an exposure target and an exposure head that includes a spatial light modulation element that modulates incident light according to image data, as described later, are relative to each other. It is assumed that it is used by being incorporated in an exposure apparatus arranged so as to be movable.

  The exposure illuminance measuring apparatus 10 according to the present embodiment includes a light source unit 11, a digital micromirror device (DMD) 12 as a spatial light modulation element, a condenser lens 13, and a photoelectric conversion element as illustrated. Photodiode (PD) 14, an amplifier 15 for amplifying an analog signal (photodetection signal) corresponding to the amount of light detected by the PD 14, and an A for converting the photodetection signal amplified through the amplifier 15 into a digital signal A / D converter 16 and a controller 17 for processing a digital signal output from the A / D converter 16 are provided. Further, a plurality of units (number corresponding to the number of exposure heads to be described later) are provided with each member of 11 to 17 as one unit, and each unit is provided in parallel. Further, the signal processed by each controller 17 is input to the main controller 18, and each unit (exposure illuminance measuring apparatus 10) is controlled by the main controller 18. The configurations and operations of the members 11 to 14, the controllers 17, and the main controller 18 will be described later.

  Next, an exposure apparatus incorporating the apparatus 10 will be described with reference to the configuration (external appearance) shown in FIG.

  As shown in the figure, the exposure apparatus 50 includes a flat stage 52 that holds an exposure object 51 such as a wiring board by adsorbing to the surface. Two guides 55 extending along the stage moving direction are provided on the upper surface of the thick plate-like support base 54 supported by the four legs 53, and the stage 52 has a longitudinal direction in the stage. It arrange | positions so that it may face the moving direction, and is supported by the guide 55 so that a reciprocation is possible. Further, the exposure apparatus 50 is provided with a stage driving unit (described later) for driving the stage 52 along the guide 55.

  A “U” -shaped gate 56 is provided at the center of the support base 54 so as to straddle the movement path of the stage 52, and each end of the gate 56 is formed on both side surfaces of the support base 54. It is fixed. A scanner 57 is provided on one side of the gate 56, and a plurality (two in the illustrated example) that detect the end portions (front end and rear end) of the exposure target 51 in the moving direction are provided on the other side. The detection sensor 58 is provided. The scanner 57 and the detection sensor 58 are respectively attached to the gate 56 and fixedly arranged above the moving path of the stage 52. That is, the stage 52 that supports the exposure target object 51 and the scanner 57 that scans the exposure target object 51 are provided so as to be movable relative to each other. The scanner 57 and the detection sensor 58 are connected to a control unit (described later) that controls them, and are controlled so that they can be exposed at a predetermined timing when exposure is performed by an exposure head described later.

  Further, the condensing lens 13 characterizing the present invention is arranged in a region different from the region where the exposure target 51 is mounted on the stage 52 (in the example shown, the left end portion on the stage 52). . The condenser lenses 13 are provided corresponding to the number of exposure heads to be described later. Each condenser lens 13 is arranged so that the corresponding exposure head is aligned by the movement of the stage 52. Further, although not shown in FIG. 2, one photodiode (PD) for detecting light converged through the corresponding condenser lens 13 is provided on the light emission side of each condenser lens 13. ing.

  As shown in FIGS. 3 and 4B, the scanner 57 includes a plurality of exposure heads HD arranged in a matrix. In the illustrated example, 14 exposure heads HDmn (m = 1 to 3, n = 1 to 5) arranged in a matrix of 3 rows and 5 columns are provided. However, four exposure heads HD31 to HD34 are arranged in the third row in relation to the width of the exposure object 51. Each exposure head HD (HDmn) is provided with a light source unit 11 and a DMD 12 as will be described later. An exposure area A (Amn) by each exposure head HD (HDmn) has a rectangular shape with a short side in the sub-scanning direction as shown in the figure, and is inclined at a predetermined angle with respect to the sub-scanning direction. As the stage 52 moves, a strip-shaped exposed region B is formed on the exposure target 51 for each exposure head HD.

  Further, as shown in FIGS. 4A and 4B, each of the exposure heads HD11 to HD15, HD21 to HD25, and HD31 to HD34 in each row is adjacent to a strip-shaped exposed region B (portion indicated by hatching). Are arranged so as to partially overlap the exposed region B to be shifted by a predetermined interval in the arrangement direction. Regions that partially overlap each exposed region B correspond to stitch areas ST1, ST2, and ST3. By adopting such an arrangement, for example, a portion that cannot be exposed between the exposure area A11 of the first row and the exposure area A12 is exposed by the exposure area A21 of the second row and the exposure area A31 of the third row. Can do. The same applies to the second and subsequent lines. That is, joints (stitch areas) between a plurality of exposure heads HD11 to HD15, HD21 to HD25, and HD31 to HD34 arranged in the main scanning direction (direction orthogonal to the sub-scanning direction) are controlled by a small amount of exposure position control. Can be connected without steps.

  Next, the electrical configuration of the exposure apparatus 50 (FIG. 2) incorporating the exposure illuminance measuring apparatus 10 (FIG. 1) will be described with reference to the block configuration shown in FIG.

  In FIG. 5, reference numeral 20 denotes a control unit that controls the entire exposure apparatus 50 (FIG. 2), and includes each controller 17 and main controller 18 shown in FIG. The control unit 20 temporarily stores image data creation unit 21 that creates binary image data (exposure image data) for exposure based on input image data, and image data created by the image data creation unit 21. The image buffer 22 to be stored, the DMD driver 23 for controlling the driving of the DMD 12 based on the image data of the image buffer 22, and the driving of the light source unit 11 having a laser diode (LD) as a light source are controlled. The LD driver 24, a stage drive unit 25 that controls the movement of the stage 52, and a position measurement unit 26 that measures the position and displacement of the stage 52 (relative displacement between the exposure head HD and the stage 52) are connected. ing.

  The exposure head HD includes a light source unit 11 and a DMD 12 as shown. The light source unit 11 is configured in the form of an LD array in which a plurality of light emitting sources (LDs) are two-dimensionally arranged, and the amount of light emitted from each LD is based on control from the control unit 20 as an LD driver. 24 is controlled individually. The DMD 12 is configured by arranging a plurality of micromirrors in a matrix on the substrate as described above, and each mirror (corresponding to a pixel) is a control signal supplied from the control unit 20 via the DMD driver 23. In response to the angle, the angle of the mirror surface (reflection surface) is individually controlled (light modulation). Although not shown, the DMD driver 23 includes a data processing unit and a mirror drive control unit. In this data processing unit, each exposure head HD (FIG. 3, FIG. 3) is based on the image data input from the image buffer 22. A control signal for driving and controlling each micromirror in the region to be controlled by the DMD 12 is generated every time FIG. Based on the generated control signal, the mirror drive control unit controls the angle of the reflection surface of each micromirror of the DMD 12 to “on” or “off” for each exposure head HD.

  Further, as described above, the stage 52 that is controlled to move by the stage drive unit 25 based on the control from the control unit 20 is different from the predetermined region (the region on which the exposure object 51 (FIG. 2) is mounted). The condensing lens 13 is disposed in the area (1). The condenser lenses 13 are provided corresponding to the number of exposure heads HD (FIG. 3), and are arranged such that the corresponding exposure heads are aligned by the movement of the stage 52. Thus, all the light emitted from the DMD 12 built in the exposure head HD is incident. That is, the condenser lens 13 can detect the light reflected by the individual micromirrors constituting the DMD 12 without leaking.

  Further, one photodiode (PD) 14 is provided on each light exit side (inside the stage 52) of each condenser lens 13. As a result, each PD 14 detects the light converged through the corresponding condenser lens 13 and outputs an analog signal (light detection signal) corresponding to the detected light amount.

  The light detection signals output from the PDs 14 are amplified through the amplifiers 15 (FIG. 1), converted into digital signals through the A / D converter 16, and then input to the controllers 17 in the control unit 20. The controller 17 includes the same functional blocks (arithmetic unit such as CPU, memory, etc.) as a general microprocessor and the like. As processing related to the present invention, a signal corresponding to the amount of light detected by the corresponding PD 14 From the (photodetection signal), the integrated illuminance at the corresponding portion of the exposure surface to be irradiated with light is calculated using the corresponding DMD 12. In this calculation, the arithmetic unit compares it with a desired reference value that has been created in advance as the integrated illuminance at that location, and calculates a correction value corresponding to the difference based on the comparison. The accumulated illuminance data reflecting the correction value in this way is input to the main controller 18 (in the control unit 20).

  The main controller 18 includes an arithmetic unit such as a CPU, a memory, and the like, similarly to each controller 17, and a display unit (see FIG. 5) that displays the integrated illuminance of the exposure target portion calculated by each controller 17 on the screen. (Not shown). The main controller 18 is basically for controlling the entire exposure apparatus 50 (FIG. 2). In particular, as a process related to the present invention, based on the integrated illuminance data calculated by each controller 17, the LD While controlling the light irradiation amount (light emission amount of each LD) of each light source unit 11 via the driver 24, a control signal for changing the light modulation state of each DMD 12 according to the exposure information is generated. Each mirror (corresponding to a pixel) is individually controlled (optically modulated) via the DMD driver 23.

  As described above, according to the exposure illuminance measuring apparatus 10 according to the present embodiment (see FIGS. 1 and 5), all the light emitted from the DMD 12 as the spatial light modulation element is incident on the condenser lens 13. Inconvenience as seen in the prior art (FIG. 7) (some of the light reflected by each mirror of the DMD leaks through the gap between the PDs in the PD array) Inconvenience) does not occur, and the light reflected by each micromirror of the DMD 12 can be detected without omission by the condensing lens 13 and the corresponding PD 14. As a result, since there is no error (variation) in the integrated illuminance of the spot on the exposure surface to be irradiated with light using the DMD 12, it is possible to accurately measure the integrated illuminance of light falling on the spot. .

  Further, in the prior art (FIG. 7), the signals detected by each PD in the PD array are sequentially switched by a switch and the illuminance of each PD is obtained from the signals taken into the controller to obtain the integrated illuminance at that location. However, in the apparatus configuration according to the present embodiment (FIG. 1), the condensing lens 13 is used in place of the conventional PD array. The integrated illuminance at the target location can be easily measured.

  Further, when the integrated illuminance of the stitch area is measured only by the DMD with the relative movement of the exposure head HD (DMD 12) with respect to the stage 52 (for example, the integrated illuminance of the stitch areas ST2 and ST3 as shown in FIG. In the case of measuring) and when measuring the integrated illuminance of the same stitch area using the adjacent DMD (for example, measuring the integrated illuminance of the stitch area ST1 as shown in FIG. 6B), With the above configuration (the condensing lens 13 and the corresponding PD 14), there is no variation in the integrated illuminance of the area, so that the integrated illuminance of light falling on the area can be accurately measured.

  In the prior art (FIG. 7), even if one of the mirrors constituting the DMD is broken and always emits light, it is difficult to detect the failure. On the other hand, in the present embodiment, even if one of the mirrors constituting the DMD 12 is broken by the combination of the condenser lens 13 and the corresponding PD 14 described above, the emitted illuminance due to the failed part is completely turned off. The failure can be detected by detecting.

  In the prior art (FIG. 7), it is necessary to correct both the illuminance variation between the PDs in the PD array and the illuminance variation between the PD arrays corresponding to each DMD. The above-described configuration (the condensing lens 13 and the corresponding PD 14) corrects only the illuminance variation between the PDs 14 corresponding to the DMDs 12, thereby making it possible to accurately measure the integrated illuminance.

  In the above-described embodiment, the case where the DMD 12 is used as the spatial light modulation element has been described as an example. However, the gist of the present invention (all the light emitted from the spatial light modulation element is incident on the condenser lens, Of course, the form of the spatial light modulator is not limited to DMD, as is clear from the fact that the light converged through the optical lens is detected by a single photoelectric conversion element (PD). In short, any element having a function of modulating the incident light according to image data and emitting the modulated light is sufficient. For example, a transmissive spatial light modulator such as a liquid crystal shutter array can be used. In this liquid crystal shutter array, a plurality of liquid crystal cells (pixel portions) capable of blocking transmitted light in response to control signals are arranged in a matrix on a substrate.

It is a block diagram which shows typically a part of structure of the illumination intensity measuring apparatus for exposure which concerns on one Embodiment of this invention. It is a perspective view which shows the external appearance of the exposure apparatus incorporating the apparatus of FIG. It is a perspective view which shows the structure of the scanner in the exposure apparatus of FIG. It is a figure which shows the relationship between the arrangement | sequence of the exposure area by each exposure head in FIG. 3, and an exposure area | region. FIG. 3 is a block diagram showing an electrical configuration in the exposure apparatus of FIG. 2. It is a figure for demonstrating an example of the effect acquired by the illumination intensity measuring apparatus for exposure of FIG. It is a figure for demonstrating the problem concerning the illumination intensity measurement for exposure in the conventional exposure apparatus.

Explanation of symbols

10: Illuminance measuring device for exposure,
11 ... Light source unit,
12 ... DMD (spatial light modulator),
13 ... Condensing lens,
14 ... PD (photoelectric conversion element),
17 ... Controller (control means),
20 ... control unit (each controller / main controller),
50. Exposure apparatus,
51. Object to be exposed,
52 ... Stage,
57 ... Scanner,
A (Amn) ... exposure area,
B: Exposed area,
HD (HDmn) ... exposure head,
ST1, ST2, ST3 ... Stitch area.

Claims (5)

An illuminance measuring apparatus for exposure adapted to acquire data on the amount of light required to perform exposure in the exposure apparatus,
A light source;
A spatial light modulator for modulating light emitted from the light source;
A condensing lens for entering all the light emitted from the spatial light modulator;
A single photoelectric conversion element on which light converged through the condenser lens is incident;
An illuminance measurement for exposure, comprising: a control means for calculating an integrated illuminance of the portion of the exposure surface to be irradiated with light from the light detection signal of the photoelectric conversion element using the spatial light modulation element apparatus. When the illuminance measuring apparatus for exposure is used by being incorporated in an exposure apparatus in which a stage for supporting an exposure object and an exposure head are arranged to be relatively movable,
The light source and the spatial light modulator are provided in the exposure head,
The exposure illuminance measurement apparatus according to claim 1, wherein the condenser lens and the photoelectric conversion element are arranged in a region different from a region where the exposure object is mounted on the stage. The light source, the spatial light modulation element, the condenser lens, the photoelectric conversion element, and the control means comprise a plurality of units as one unit,
A plurality of exposure heads in the plurality of units are arranged at a predetermined interval with respect to the exposure object so that a band-shaped exposure target area by the exposure head partially overlaps a band-shaped exposure target area by an adjacent exposure head The illuminance measuring apparatus for exposure according to claim 2, wherein:   The spatial light modulation element is a micromirror device in which a plurality of micromirrors each capable of changing the angle of a reflecting surface in response to a control signal are arranged in a matrix on a substrate. Item 1. An illuminance measuring apparatus for exposure according to Item 1.   2. The liquid crystal shutter array according to claim 1, wherein the spatial light modulator is a liquid crystal shutter array in which a plurality of liquid crystal cells capable of blocking transmitted light in response to a control signal are arranged in a matrix on a substrate. An illuminance measuring apparatus for exposure described in 1.

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