Substrate processing apparatus and substrate processing method

Abstract

This technology provides efficient transfer of image data while maintaining the accuracy of alignment mark detection. [Solution] The exposure apparatus 1 comprises a second stage 25, an imaging unit 50, a compression unit 60, and a control unit 70. The second stage 25 holds a substrate W having alignment marks M. The imaging unit 50 captures the alignment marks M of the substrate W held by the second stage 25 and acquires image data D. The compression unit 60 compresses the image data D acquired by the imaging unit 50 according to predetermined conditions. The control unit 70 detects the position of the alignment marks M based on the image data D compressed by the compression unit 60. The compression unit 60 compresses the image data D of the alignment marks M that the control unit 70 does not use for position detection of the alignment marks M.

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to substrate processing apparatus and substrate processing methods. [Background technology]

[0002] Conventionally, exposure apparatuses are known for directly exposing patterns onto the upper surface of substrates, such as semiconductor substrates and printed circuit boards, in order to manufacture such substrates. In this type of exposure apparatus, alignment marks formed on the substrate are detected, and the exposure on the substrate is aligned based on the position of the alignment marks. For example, Patent Document 1 describes detecting alignment marks by performing a template matching process between a template image stored in a memory unit and a real image acquired by a CCD camera. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-214816 [Overview of the project] [Problems that the invention aims to solve]

[0004] Increasing the number of alignment marks can contribute to improving alignment accuracy. Similarly, increasing the camera resolution can also contribute to improving alignment accuracy. However, in both cases, there was a technical challenge: the increase in image data led to an increase in the amount of data transferred to the image processing unit.

[0005] The objective of the present invention is to provide a technology that can efficiently transfer image data while maintaining the accuracy of alignment mark detection. [Means for solving the problem]

[0006] To solve the above problems, the first embodiment is a substrate processing apparatus comprising: a stage for holding a substrate having alignment marks; an imaging unit for capturing images of the alignment marks on the substrate held on the stage and acquiring multi-tone image data; a compression unit for compressing the image data acquired by the imaging unit according to predetermined conditions; and an image processing unit for detecting the position of the alignment marks based on the image data compressed by the compression unit, wherein the compression unit compresses the image data that the image processing unit does not use for detecting the position of the alignment marks.

[0007] The second embodiment is a substrate processing apparatus according to the first embodiment, wherein the compression unit determines whether the grayscale value shown by the image data is within a predetermined threshold range, and compresses the image data that is outside the threshold range.

[0008] A third embodiment is a substrate processing apparatus according to the second embodiment, wherein the compression unit compresses the image data outside the threshold range into 1 bit information by converting the grayscale value indicated by the image data to a first value if it is less than the lower limit of the threshold range, and to a second value if it exceeds the upper limit of the threshold range.

[0009] A fourth embodiment is a substrate processing apparatus according to the third embodiment, wherein the compression unit converts the image data in a first distribution region in the grayscale value distribution shown by a series of image data, in which the grayscale value exceeds the lower limit but falls below the lower limit without exceeding the upper limit, into the first value.

[0010] The fifth embodiment is a substrate processing apparatus according to the third or fourth embodiment, wherein the compression unit converts the image data in a second distribution region in which the grayscale value distribution shown by a series of image data exceeds the upper limit without falling below the lower limit, after the grayscale value has fallen below the upper limit, into the second value.

[0011] The sixth embodiment is a substrate processing apparatus according to any of the first to fifth embodiments, wherein the image processing unit detects the position of the alignment mark by shape matching.

[0012] The seventh aspect is the substrate processing apparatus according to any one of the first to sixth aspects, further comprising an exposure head that emits light to the substrate.

[0013] The eighth aspect is a substrate processing method, comprising: an image data acquisition step of imaging an alignment mark formed on the substrate held on a stage to acquire multi-tone image data; a compression step of compressing the image data acquired in the image data acquisition step according to a predetermined condition; and a position detection step of detecting a position of the alignment mark based on the image data compressed in the compression step, wherein the compression step includes a step of compressing image data of the alignment mark that is not used for position detection of the alignment mark in the position detection step.

Effect of the Invention

[0014] According to the first to eighth aspects, transfer of image data can be improved by compressing image data in an area not used for alignment mark detection.

[0015] According to the substrate processing apparatus of the second aspect, transfer of image data can be improved by compressing image data outside the threshold range.

[0016] According to the substrate processing apparatus of the third aspect, image data outside the threshold range can be significantly compressed, so that the transfer efficiency of image data can be further improved.

[0017] According to the fourth aspect and the substrate processing apparatus of the fourth aspect, image data in unnecessary distribution regions that do not contribute to position detection of the alignment mark can be compressed, so that data transfer efficiency can be further improved.

[0018] According to the substrate processing apparatus of the sixth aspect, the alignment mark can be specified with high accuracy by shape matching. Brief Description of the Drawings

[0019] [Figure 1]1 is a perspective view showing the overall configuration of an exposure apparatus according to an embodiment. [Figure 2] It is a block diagram related to image data processing. [Figure 3] It is a diagram showing an alignment mark. [Figure 4] It is a control block diagram of the exposure apparatus. [Figure 5A] It is a diagram showing a first gradation value distribution. [Figure 5B] It is a diagram showing another example of setting a threshold range. [Figure 6A] It is a diagram showing a second gradation value distribution. [Figure 6B] It is a diagram showing a third gradation value distribution. [Figure 7] It is a diagram showing a timing chart related to transmission of image data. DESCRIPTION OF EMBODIMENTS

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the constituent elements described in this embodiment are merely illustrative, and are not intended to limit the scope of the present invention only thereto. In the drawings, for ease of understanding, the dimensions and numbers of respective parts may be exaggerated or simplified as necessary.

[0021] In FIG. 1 and each subsequent drawing, an XYZ orthogonal coordinate system is defined to explain the positional relationship of elements. Here, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction. In the following description, in the Z-axis direction, the +Z direction is vertically upward, and the -Z direction is vertically downward.

[0022] <1. Embodiment> Figure 1 is a perspective view showing the overall configuration of the exposure apparatus 1 according to the embodiment. The exposure apparatus 1 is a substrate processing apparatus that irradiates light onto the upper surface of a substrate W coated with a photosensitive material to draw a pattern on the upper surface of the substrate W without a mask. The substrate W is, for example, a printed circuit board or a semiconductor substrate. For example, in the manufacturing process of a printed circuit board, the process of forming a layer on the upper surface of the substrate W in another apparatus and the process of exposing a pattern on the upper surface of the substrate W in this exposure apparatus 1 are repeatedly performed. This produces a multilayer printed circuit board.

[0023] The exposure apparatus 1 comprises a base 10, a gantry 15, a first stage 21, a first moving mechanism 23, a second stage 25, a second moving mechanism 27, an exposure unit 40, an imaging unit 50, a compression unit 60 (see Figure 2), and a control unit 70.

[0024] The base 10 is a support base that supports each element of the exposure apparatus 1, such as the gantry 15 and the first stage 21. The base 10 has a flat, plate-like shape that extends along the horizontal plane. The base 10 is made of a stone material such as granite. The base 10 is fixed to the factory floor. The base 10 is rectangular in shape when viewed from above. The long side of the base 10 is parallel to the Y-axis direction. The short side of the base 10 is parallel to the X-axis direction.

[0025] The gantry 15 is fixed to the upper surface of the base 10. The gantry 15 has a pair of legs 151 and a bridging portion 152. The pair of legs 151 are spaced apart in the X-axis direction. Each leg 151 extends upward (+Z direction) from the upper surface of the base 10. The bridging portion 152 connects the upper ends of the legs 151 in the X-axis direction. A through-hole 18 is formed between the upper surface of the base 10 and the gantry 15, through which the substrate W can pass in the Y-axis direction.

[0026] The first stage 21 is movable along the Y-axis. The first stage 21 has a flat, plate-like shape. In a top view, the shape of the first stage 21 is rectangular, smaller than the base 10. The first stage 21 is positioned above the base 10 in a substantially horizontal position.

[0027] The first moving mechanism 23 is a mechanism for moving the first stage 21 in the Y-axis direction relative to the base 10 and the gantry 15. The first moving mechanism 23 is a linear motor mechanism having a pair of guide rails and a linear motor. The pair of guide rails are rails for guiding the first stage 21 in the Y-axis direction. The pair of guide rails are provided on the upper surface of the base 10 at intervals in the X-axis direction and extend linearly along the Y-axis direction. The linear motor has a stator provided on the upper surface of the base 10 and a mover fixed to the lower surface of the first stage 21. When a drive signal is supplied to the linear motor from the control unit 70, the mover moves along the stator in the Y-axis direction due to the magnetic attractive and repulsive forces generated between the stator and the mover. As a result, the first stage 21 moves in the Y-axis direction relative to the base 10. Note that the drive source of the first moving mechanism 23 is not limited to a linear motor. The first moving mechanism 23 may be, for example, a mechanism that converts the rotational motion of a servo motor into linear motion using a ball screw.

[0028] The second stage 25 is movable along the X-axis. The second stage 25 has a flat, plate-like shape. In a top view, the shape of the second stage 25 is a smaller rectangle than that of the first stage 21. The second stage 25 is positioned above the first stage 21 in a substantially horizontal position.

[0029] The second moving mechanism 27 is a mechanism for moving the second stage 25 in the X-axis direction relative to the first stage 21. The second moving mechanism 27 is a linear motor mechanism having a pair of guide rails and a linear motor. The pair of guide rails are arranged on the upper surface of the first stage 21 at intervals in the Y-axis direction. Each guide rail extends linearly along the X-axis direction. The pair of guide rails are rails for guiding the second stage 25 in the X-axis direction. However, the second moving mechanism 27 is not limited to a linear motor mechanism, and may be, for example, a ball screw mechanism.

[0030] The substrate W is supported on the upper surface of the second stage 25 in a substantially horizontal position. The second stage 25 may have chuck pins for fixing the substrate W and a plurality of suction holes for adsorbing the substrate W. The exposure apparatus 1 moves the substrate W in the Y-axis direction (main scanning direction) and the X-axis direction (sub-scanning direction), respectively, by operating the first moving mechanism 23 and the second moving mechanism 27.

[0031] The exposure unit 40 is a unit that exposes the substrate W supported by the second stage 25. The exposure unit 40 has four exposure heads 41. The multiple exposure heads 41 are fixed to the bridging portion 152 of the gantry 15. The multiple exposure heads 41 are arranged at equal intervals along the X-axis. Each exposure head 41 has a spatial light modulation element to form a desired pattern on the substrate W. As the spatial light modulation element, for example, a GLV (Grating Light Valve) (registered trademark) or a DMD (Digital Micromirror Device) can be used. A GLV is a diffraction grating type spatial light modulator that uses a minute diffraction grating structure to control the diffraction of laser light, thereby adjusting the transmittance and reflectance of the light and forming a patterned light. A DMD uses a minute mirror array to change the direction of light reflection by tilting individual mirrors and forming a patterned light.

[0032] The exposure unit 40 spatially modulates the laser light supplied from the light source 43 to form patterned light, which is then irradiated onto the substrate W. The light source 43 can be, for example, a laser oscillator, an LED (Light Emitting Diode), or a mercury lamp. The laser light from the light source 43 is converted into linear laser light by the illumination optical system 45 and guided to the spatial light modulator of the exposure head 41. The illumination optical system 45 includes, for example, a collimator lens that converts the light from the light source 43 into parallel light, and a cylindrical lens that converts it into linear light.

[0033] The exposure apparatus 1 alternately performs a main scanning process and a sub-scanning process. In the main scanning process, the exposure apparatus 1 moves the substrate W in the Y-axis direction while multiple exposure heads 41 emit pattern light. In the main scanning process, the exposure apparatus 1 moves the substrate W relative to the multiple exposure heads 41 in the Y-axis direction. This draws a pattern in a striped area. In the sub-scanning process, the substrate W is moved a predetermined distance in the X-axis direction to position the substrate W at the starting position of the next exposure. The exposure apparatus 1 exposes the entire surface of the substrate W by repeating these main scanning and sub-scanning processes.

[0034] The imaging unit 50 images the alignment marks M formed on the substrate W supported by the second stage 25 and acquires image data including the alignment marks M. The imaging unit 50 is attached to the bridging portion 152 of the gantry 15. The imaging unit 50 performs imaging based on a drive signal from the control unit 70.

[0035] Figure 2 is a block diagram relating to the processing of image data. The imaging unit 50 includes an image sensor 51 and an AD converter 53. The image sensor 51 is a semiconductor device having a plurality of photodetectors that convert light into electrical signals, and is specifically an image sensor such as a CCD (Charge-Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor). The image sensor 51 is a line sensor in which a plurality of photodetectors are arranged in the X-axis direction.

[0036] The AD converter 53 converts the electrical signal output by the image sensor 51 into image data, which is multi-gradation digital data. In this embodiment, since the image including the alignment mark M is acquired as a grayscale image, the AD converter 53 converts the electrical signal from the image sensor 51 into 8-bit data with 256 gradations, where black is 00h and white is ffh. The imaging unit 50 outputs the acquired image data to the compression unit 60. Thus, the process in which the imaging unit 50 images the alignment mark M of the substrate W held in the second stage 25 and acquires multi-gradation image data corresponds to the "image data acquisition process".

[0037] The compression unit 60 compresses the image data input from the imaging unit 50 according to predetermined conditions (compression process). Then, the compression unit 60 transmits the compressed image data to the control unit 70 (image processing device). The conditions under which the compression unit 60 performs compression will be described later.

[0038] Figure 3 shows an alignment mark M. The alignment mark M shown in Figure 3 is cross-shaped, but it may be of other shapes. The alignment mark M is formed, for example, by etching or laser processing. When imaging the alignment mark M, the control unit 70 moves the substrate W in the X-axis direction so that the alignment mark M is within the imaging area of ​​the imaging unit 50. Then, the control unit 70 moves the substrate W in the Y-axis direction and images the alignment mark M when it passes directly below the imaging unit 50 (see Figure 3). If multiple alignment marks M are formed at different positions in the X-axis direction, the control unit 70 sequentially moves the substrate W to the position of each alignment mark M. The control unit 70 repeats the operation of moving the substrate W in the X-axis direction and then in the Y-axis direction, so that all alignment marks M are imaged by the imaging unit 50.

[0039] The imaging unit 50 may also have a light source for illuminating the object. Furthermore, the exposure apparatus 1 may have a moving mechanism for moving the imaging unit 50 in the X-axis direction. Such a moving mechanism could be, for example, a linear motor mechanism or a ball screw mechanism. The exposure apparatus 1 may comprise a plurality of imaging units 50 arranged in the X-axis direction. The imaging unit 50 may have a two-dimensional image sensor instead of a line sensor.

[0040] Figure 4 is a control block diagram of the exposure apparatus 1. The control unit 70 is a unit for controlling the operation of each part of the exposure apparatus 1. As shown in Figure 4, the control unit 70 is a computer equipped with a processor 71 such as a CPU (Central Processing Unit) and memory 72 such as RAM (Random Access Memory) or ROM (Read Only Memory). The memory 72 may also have an auxiliary storage device such as a hard disk drive.

[0041] The control unit 70 is electrically connected to the first moving mechanism 23, the second moving mechanism 27, the exposure unit 40, the imaging unit 50, and the compression unit 60, and is also communicatively connected to them.

[0042] Memory 72 stores the detection program P1 and the exposure program P2. The detection program P1 and the exposure program P2 may be recorded on a recording medium readable by the control unit 70, which is a computer. The processor 71 performs position detection of the alignment mark M by executing the detection program P1 (position detection step). The processor 71 also performs exposure processing by executing the exposure program P2.

[0043] In this embodiment, the control unit 70 applies shape matching to the position detection of the alignment mark M. Specifically, it detects edge portions in the image data transmitted from the compression unit 60 where the gradation value (luminance value) changes abruptly, and extracts these gradation value change portions as edge information. Based on the obtained edge information, the control unit 70 compares the features in the image with a pre-prepared template Tm1 (see Figure 3) representing the outline of the alignment mark M, and identifies the most similar region. The control unit 70 then acquires the position of the identified region (for example, the centroid coordinates of the region) as the position of the alignment mark M.

[0044] As shown in Figure 3, when the alignment mark M is imaged, a tonal value distribution H is obtained from the series of image data. In this tonal value distribution H, the alignment mark M has high tonal values ​​(high brightness), while the other parts have low tonal values ​​(low brightness). Here, as shown in Figure 3, if there is a foreign object 9 such as a stain within the alignment mark M, a decrease in tonal value occurs at the corresponding location. However, in shape matching, the shape of the alignment mark M is detected by the change in tonal value using the template Tm1, so the position of the alignment mark M can be detected without being affected by the foreign object 9.

[0045] The compression unit 60 compresses the image data of the alignment mark M acquired by the imaging unit 50 that the control unit 70 (image processing unit) does not use for position detection of the alignment mark M. For example, in position detection by shape matching, information other than changes in the grayscale value of the edge portion is basically unnecessary. Therefore, the compression unit 60 compresses the image data that does not correspond to the edge portion. Specifically, the compression unit 60 determines whether the grayscale value of the image data is within a predetermined threshold range, and if the grayscale value is outside the threshold range, it compresses the image data. More specifically, if the grayscale value of the image data is outside the threshold range, the compression unit 60 compresses the image data from 8 bits to 1 bit of information.

[0046] Figure 5A shows the first grayscale value distribution H1. As shown in Figure 5A, the compression unit 60 compresses the grayscale value of the image data to the lower limit of the threshold range L. min If it is less than 0b, it is converted to 0b (the first value), which is 1 bit information. On the other hand, the grayscale value of the image data is the upper limit of the threshold range L max If it exceeds a certain value, the image data is converted to 1b (the second value), which is 1 bit of information.

[0047] As described above, by keeping the image data used for detecting the position of alignment marks M uncompressed and compressing only the image data not used for detecting the position of alignment marks M, it is possible to improve the transfer efficiency of image data without reducing the accuracy of detecting the position of alignment marks M.

[0048] Particularly, in the case of shape matching, by setting image data within a preset threshold range to be uncompressed, information about edge portions necessary for detecting the alignment mark M can be retained. On the other hand, by compressing image data outside the threshold range, the data amount of regions other than the edge portions can be reduced. Therefore, the transfer efficiency of image data can be improved without reducing the position detection accuracy of the alignment mark M by shape matching.

[0049] Further, by compressing image data into 1-bit information, the amount of image data can be greatly reduced. Thereby, the transfer efficiency of image data can be greatly improved.

[0050] FIG. 5B is a diagram showing another example of setting a threshold range. It is not essential that both the lower limit L min and the upper limit L max are set in advance. In FIG. 5B, only the lower limit L min is set, and the upper limit L of the threshold range max is the maximum grayscale value (ffh). In this case, the compression unit 60 compresses only image data not exceeding the lower limit L min into 0b. Although not shown in the figure, when only the upper limit L max is set, the lower limit of the threshold range is set to the minimum grayscale value (00h). In this case, the compression unit 60 may be configured to compress only image data exceeding the upper limit L max into 1b.

[0051] The compression unit 60 may analyze the shape of the grayscale value distribution to compress the image data. FIG. 6A is a diagram showing a second grayscale value distribution H2. This grayscale value distribution H2 includes a distribution region A1 that, after the grayscale value exceeds the lower limit L min , does not exceed the upper limit L max , and falls below the lower limit L min . The grayscale values of the image data in the distribution region A1 are within the threshold range. However, the compression unit 60 may compress the image data in this distribution region A1 into 0b (a first value). The distribution region A1 corresponds to a "first distribution region".

[0052] Figure 6B shows the third grayscale value distribution H3. In this grayscale value distribution H3, the grayscale value is the upper limit L max After falling below the lower limit L min Without falling below the upper limit L max It includes a distribution region A2 that exceeds [a certain value]. The grayscale values ​​of the image data in distribution region A2 are within the threshold range. However, the compression unit 60 may compress the image data within this distribution region A2 to 1b (the second value). Distribution region A2 corresponds to the "second distribution region".

[0053] Distribution regions A1 and A2 represent errors within the alignment mark M caused by foreign objects 9 shown in Figure 3, or by factors such as lighting brightness, and are unnecessary for position detection of the alignment mark M. Therefore, by compressing the image data of distribution regions A1 and A2, which contain such errors, data transfer efficiency can be further improved without reducing the accuracy of position detection of the alignment mark M.

[0054] Figure 7 is a timing chart for transmitting image data. As shown in Figure 7, the compression unit 60 transmits the image data D, along with a clock signal CK, a data recognition signal S, and an enable signal E, to the control unit 70. The image data D is transmitted using a serial communication method. That is, the image data D is transmitted bit by bit in chronological order using a single communication line. Uncompressed image data D is transmitted in 8 bits, and compressed image data D is transmitted in 1 bit.

[0055] The clock signal CK, data recognition signal S, and enable signal E are transmitted to the image data D using a parallel communication method. The clock signal CK functions as a synchronization signal for the image data. In one cycle of the clock signal CK, one bit of the image data D is transmitted to the control unit 70. The data recognition signal S is a signal for identifying one pixel of the image data D. The data recognition signal S transitions between a high level and a low level at the timing of the switching of the image data D. The enable signal E is a signal that indicates that valid data is being transmitted. When the image data D is compressed, the period of the data recognition signal S becomes shorter than when it is uncompressed. Therefore, the control unit 70 can determine whether the image data D is compressed or uncompressed based on the period of the data recognition signal S. <2. Variant Example> Although embodiments have been described above, the present invention is not limited to those described above, and various modifications are possible.

[0056] In the above embodiment, shape matching is applied to detect the position of the alignment mark M, but other methods may also be applied. For example, the centroid position of the alignment mark M may be determined by finding the centroid of the edges on both sides from the slope of the gradation value change corresponding to the edges on both sides of the alignment mark M.

[0057] Although this invention has been described in detail, the above description is illustrative in all respects, and the invention is not limited thereto. It is understood that countless variations not illustrated can be conceived without falling outside the scope of this invention. The components described in each of the above embodiments and variations can be combined or omitted as appropriate, as long as they do not contradict each other. [Explanation of symbols]

[0058] 1: Exposure apparatus (substrate processing apparatus) 40: Exposure area 50: Imaging Unit 60: Compression section 70: Control Unit (Image Processing Unit) M: Alignment mark W: Circuit board

Claims

1. A substrate processing apparatus, A stage for holding a substrate having alignment marks, An imaging unit that captures the alignment marks of the substrate held on the stage and acquires multi-tone image data, A compression unit that compresses the image data acquired by the imaging unit according to predetermined conditions, An image processing unit that detects the position of the alignment marks based on the image data compressed by the compression unit, Equipped with, The compression unit compresses the image data that the image processing unit does not use for detecting the position of the alignment marks, as part of the substrate processing apparatus.

2. A substrate processing apparatus according to claim 1, The compression unit determines whether the grayscale values ​​shown by the image data are within a predetermined threshold range, and compresses the image data that is outside the threshold range, in a substrate processing apparatus.

3. A substrate processing apparatus according to claim 2, The compression unit compresses the image data outside the threshold range into 1-bit information by converting the grayscale value of the image data to a first value if it is less than the lower limit of the threshold range, and to a second value if it exceeds the upper limit of the threshold range.

4. A substrate processing apparatus according to claim 3, The compression unit is a substrate processing apparatus that converts the image data in a first distribution region, in the grayscale value distribution shown by a series of image data, where the grayscale value exceeds the lower limit but does not exceed the upper limit and falls below the lower limit, into a first value.

5. A substrate processing apparatus according to claim 3, The compression unit is a substrate processing apparatus that converts the image data in a second distribution region in which the grayscale value of a series of image data falls below the upper limit and then exceeds the upper limit without falling below the lower limit into the second value.

6. A substrate processing apparatus according to claim 1, The image processing unit is a substrate processing device that detects the position of the alignment marks by shape matching.

7. A substrate processing apparatus according to any one of claims 1 to 6, An exposure head that emits light onto the substrate, A substrate processing device further equipped with these features.

8. A substrate processing method, Image data acquisition step: Captures alignment marks formed on the substrate held on the stage to acquire multi-tone image data. A compression step is performed to compress the image data acquired in the image data acquisition step according to predetermined conditions. A position detection step, based on the image data compressed by the compression step, detects the position of the alignment marks. Includes, A substrate processing method comprising the compression step of compressing the image data of the alignment marks that is not used for position detection of the alignment marks in the position detection step.

Images