JP2013172046A - Substrate processing apparatus, and substrate processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform, in a configuration in which an image in a polar coordinate system obtained by photographing by imaging means a substrate that rotates while being supported by a rotary table is converted into an image in an orthogonal coordinate system, coordinate conversion regardless of displacement between an imaging area of the imaging means and the rotation center of the rotary table so as to precisely display the image of the substrate in the orthogonal coordinate system.SOLUTION: Coordinate conversion processing in which an image of a substrate W obtained by image processing means is converted from a polar coordinate system into an orthogonal coordinate system is performed on the basis of a displacement amount R0 between a rotation center Cr of a rotary table and an imaging area Ad. Accordingly, coordinate conversion from the polar coordinate system into the orthogonal coordinate system can be properly performed regardless of displacement between the imaging area Ad of imaging means and the rotation center Cr of the rotary table so as to precisely display the image of the substrate W in the orthogonal coordinate system.

Description

  The present invention relates to a substrate processing technique for executing processing on a substrate based on a result of imaging a substrate.

  Patent Document 1 describes an appearance inspection apparatus (substrate processing apparatus) having a configuration for imaging a substrate in order to perform appearance inspection (substrate processing) of the substrate. More specifically, this apparatus is provided with a rotary table that rotates while supporting a substrate on its upper surface, and a line sensor camera that images the substrate on the rotary table. The line sensor camera acquires an image for one line in the imaging area every time the substrate rotates by a predetermined amount along with the rotary table.

JP 2007-234932 A

  In this way, according to the method of sequentially acquiring an image for one line while changing the rotation amount, an image of the entire substrate is obtained in a polar coordinate system having the rotation angle and the distance (radial radius) from the rotation center as a coordinate axis. be able to. Based on this image, processing such as appearance inspection can be appropriately executed on the substrate. Incidentally, depending on the content of the processing to be performed on the substrate, it may be appropriate to represent the image of the substrate in the orthogonal coordinate system instead of the polar coordinate system. Therefore, it is conceivable to have a function of converting an image of a substrate from a polar coordinate system to an orthogonal coordinate system.

  However, the imaging area of the imaging means such as a line sensor camera may deviate from the rotation center of a rotation support unit such as a rotary table. In such a case, coordinate conversion from the polar coordinate system to the orthogonal coordinate system cannot be performed appropriately, and there is a possibility that the image of the substrate cannot be accurately represented in the orthogonal coordinate system.

  The present invention has been made in view of the above problems, and in an arrangement for converting an image in a polar coordinate system obtained by capturing an image of a substrate supported and rotated by a rotation support unit with an imaging unit to an orthogonal coordinate system, the imaging unit It is an object of the present invention to provide a technique capable of appropriately performing coordinate transformation regardless of the difference between the imaging region and the rotation center of the rotation support means and accurately representing an image of a substrate in an orthogonal coordinate system.

  In order to achieve the above object, the substrate processing apparatus according to the present invention includes a rotation support unit that rotates while supporting the substrate, and an imaging unit that is arranged so that the imaging region overlaps the substrate supported by the rotation support unit. And an image acquisition means for acquiring an image of the substrate expressed in a polar coordinate system by causing the imaging means to image the substrate in the imaging region while rotating the substrate by the rotation support means, and the rotation center of the rotation support means and imaging Based on the position information stored in the storage means, the storage means for storing the position information indicating the positional relationship with the region, and the coordinate conversion processing for converting the substrate image acquired by the image acquisition means from the polar coordinate system to the orthogonal coordinate system. It is characterized by comprising coordinate conversion means to be executed and substrate processing means for performing processing on the substrate based on the image of the substrate converted into the orthogonal coordinate system by the coordinate conversion means.

  In order to achieve the above object, the substrate processing method according to the present invention provides an image pickup means arranged so that the image pickup region thereof is overlapped with the substrate while rotating the rotation support means for supporting the substrate and rotating the substrate. Based on the image acquisition step of acquiring the image of the substrate represented in the polar coordinate system by imaging the substrate in the imaging region, and the positional information indicating the positional relationship between the rotation center of the rotation support means and the imaging region. Based on the coordinate conversion process for executing the coordinate conversion process for converting the image of the substrate acquired in the acquisition process from the polar coordinate system to the orthogonal coordinate system, and the image of the substrate converted to the orthogonal coordinate system in the coordinate conversion process. And a substrate processing step for performing processing.

  In the invention (substrate processing apparatus, substrate processing method) configured as described above, the coordinate conversion processing for converting the image of the substrate acquired by the image acquisition unit from the polar coordinate system to the orthogonal coordinate system is performed with the rotation center of the rotation support unit. This is executed based on position information indicating the positional relationship with the area. Therefore, coordinate conversion from the polar coordinate system to the Cartesian coordinate system can be performed appropriately and the image of the board can be accurately represented in the Cartesian coordinate system regardless of the difference between the imaging area of the imaging unit and the rotation center of the rotation support unit. It becomes.

  At this time, various types of image pickup means can be used. Therefore, the substrate processing apparatus may be configured such that the imaging unit has a linear imaging region in the orthogonal coordinate system.

  In the configuration using such an image pickup unit, the linear image pickup region rotates relatively around the rotation center of the rotation support unit in the orthogonal coordinate system. At this time, if the imaging area and the rotation center of the rotation support means are deviated, the imaging area is rotated from the rotation center of the rotation support means while keeping a distance corresponding to the deviation amount.

  Therefore, the coordinate conversion means performs coordinate conversion processing based on the result of specifying the locus of the imaging region that rotates relatively around the rotation center at a certain distance from the rotation center in the orthogonal coordinate system based on the position information. Thus, the substrate processing apparatus may be configured. In other words, by specifying the locus of the imaging region from the position information in this way, it is possible to accurately grasp which location the data acquired by the imaging means in the imaging region is captured. It is possible to appropriately execute the coordinate conversion process.

  At this time, the coordinate conversion means corresponds to the distance in the radial direction in the polar coordinate system from the contact point where the imaging area is in contact with the virtual circle whose radius is a fixed distance from the center of rotation to any point on the imaging area. In addition, the substrate processing apparatus may be configured to execute the coordinate conversion process by making the angle of the imaging region correspond to the angle in the polar coordinate system. As a result, it is possible to appropriately execute the above-described coordinate conversion process by accurately associating the polar coordinate system with the orthogonal coordinate system.

  Note that the coordinate conversion process from the polar coordinate system to the orthogonal coordinate system can be executed by converting an image in the conversion target range from the end of the substrate to the rotation center expressed in the polar coordinate system into the orthogonal coordinate system. However, in this case, the imaging region may straddle the rotation center in the radial direction in the polar coordinate system, and may protrude from the conversion target range. In such a case, an image at a location outside the conversion target range may be mixed into the captured image of the imaging unit, and coordinate conversion processing from the polar coordinate system to the orthogonal coordinate system may not be performed properly.

  Therefore, the coordinate conversion unit specifies the conversion target range from the edge of the substrate to the center of rotation, and excludes the image outside the conversion target range from the image of the substrate acquired by the image acquisition unit from the target of the coordinate conversion process. In the above, the substrate processing apparatus may be configured to execute the coordinate conversion process on the image within the conversion target range. In such a configuration, an image at a location outside the conversion target range is excluded from the target of the coordinate conversion process, and therefore the coordinate conversion process from the polar coordinate system to the orthogonal coordinate system can be appropriately performed.

  At this time, the storage unit stores distance information indicating a distance corresponding to one pixel of the imaging unit, and the coordinate conversion unit specifies the conversion target range based on the distance information stored by the storage unit. An apparatus may be configured. Such a configuration can accurately specify the conversion target range based on the distance information indicating the distance corresponding to one pixel of the image pickup means, and thus more appropriately performs the coordinate conversion processing from the polar coordinate system to the orthogonal coordinate system. It can be performed and is preferable.

  Various processes can be considered for the substrate processing means to execute on the substrate. Therefore, the substrate processing means may be configured to execute the inspection of the substrate as a process on the substrate. As a more specific example, in a substrate processing apparatus that performs processing on a semiconductor substrate on which a plurality of dies are formed, the substrate processing means compares the dies with each other and identifies a defective die. The substrate processing apparatus may be configured to perform the inspection on the substrate.

  Various substrate shapes are also conceivable. Therefore, the present invention may be applied to a substrate processing apparatus that performs processing on a circular substrate. As described above, the present invention for acquiring an image in the polar coordinate system can be particularly preferably applied to a substrate processing apparatus that performs processing on a circular substrate.

  According to the present invention, coordinate conversion from the polar coordinate system to the orthogonal coordinate system is appropriately performed regardless of the deviation between the imaging region of the imaging unit and the rotation center of the rotation support unit, and the image of the substrate is accurately obtained in the orthogonal coordinate system. Can be represented.

It is a side view which illustrates schematic structure of the substrate processing apparatus concerning embodiment of this invention. It is a top view which shows typically the positional relationship of a light irradiation means and an imaging means. It is sectional drawing which showed the principal part cross section of the light irradiation means typically. It is the top view which showed typically the optical path from a light irradiation means to an imaging means. It is the figure which showed typically the content of the image process performed by the coordinate transformation process from a polar coordinate system to a rectangular coordinate system. It is the top view which showed typically the positional relationship of the center of a board | substrate, and the rotation center of a turntable. It is a schematic diagram which expands and shows the edge of the board | substrate in the image which the image processing means acquired. It is a figure which shows typically the content of the coordinate conversion process which converts a coordinate from a polar coordinate system to a rectangular coordinate system. It is the figure which showed the formula showing each coefficient of the formula of the tangent drawn on the virtual circle.

  FIG. 1 is a side view illustrating a schematic configuration of a substrate processing apparatus according to an embodiment of the invention. In the figure and the drawings shown below, an XYZ orthogonal coordinate system with the Z axis as the vertical axis is shown as appropriate. The substrate processing apparatus 1 is a substrate inspection apparatus that inspects a substrate W based on a result of imaging a substrate such as a circular semiconductor wafer (hereinafter referred to as a substrate W). Specifically, the substrate processing apparatus 1 includes a turntable 2 that supports the substrate W, a light irradiation unit 3 that irradiates the substrate W with light, an imaging unit 4 that images the substrate W, and power supply and signal processing. The electrical system 5 which bears is equipped with the schematic structure arrange | positioned in the detection unit 10. FIG.

  The turntable 2 has a plurality of suction holes opened on the upper surface on which the substrate W is placed, and sucks and holds the substrate W by sucking each suction hole by a suction means (not shown). To do. The turntable 2 receives the rotational driving force from the motor M2 provided in the detection unit 10 and rotates around the Z axis while holding the substrate W.

  The light irradiation means 3 is disposed at a position above the substrate W held horizontally on the turntable 2 and on one side in the X-axis direction with respect to the vertical line Lv passing through the center Cw of the substrate W. The On the other hand, the imaging means 4 is disposed at a position above the substrate W held horizontally on the turntable 2 and on the other side in the X-axis direction with respect to the vertical line Lv. That is, the light irradiation means 3 and the imaging means 4 are arranged on the opposite sides with respect to the vertical axis Lv passing through the center Cw of the substrate W. The light emitted from the light irradiation unit 3 and incident on the substrate W at the incident angle α1 is specularly reflected (α1 = α2) at the reflection angle α2 on the substrate W and then travels to the imaging unit 4.

  At this time, when a semiconductor wafer having a diameter of 300 [mm], which is currently mainstream, is used as the substrate W, the incident angle α1 at which light is incident on the substrate W is 20 degrees to 45 degrees. The same applies to the case where a next-generation type larger-sized substrate, specifically, a 450 [mm] semiconductor wafer is used as the substrate W.

  The imaging means 4 includes an optical system 41 that reflects light regularly reflected from the substrate W at a reflection angle α2, and a photoelectric conversion unit 42 that detects the light reflected by the optical system 41 and converts it into an electrical signal. The optical system 41 has a configuration in which a rectangular mirror 411 having a rectangular shape is held by a holding plate 412, and regular reflection light from the substrate W is reflected by the mirror 411 and guided to the photoelectric conversion unit 42. . The photoelectric conversion unit 42 is composed of, for example, a line sensor camera. The line sensor camera includes a line sensor element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), an amplifier, a drive circuit, an A / D (Analog / Digital) converter, a memory, an input / output circuit, a connection. A well-known line sensor camera including an image lens (imaging lens) and a housing can be used.

  Thus, after the light emitted from the light irradiation means 3 is reflected by the substrate W, it enters the imaging means 4. In this way, an image of the substrate W can be taken by the imaging means 4. Subsequently, more specific configurations of the light irradiation unit 3 and the imaging unit 4 will be described.

  FIG. 2 is a plan view schematically showing the positional relationship between the light irradiation means and the imaging means. FIG. 3 is a cross-sectional view schematically showing a main part cross section of the light irradiation means. FIG. 4 is a plan view schematically showing an optical path from the light irradiation means to the imaging means. In FIG. 4, the photoelectric conversion unit 42 is illustrated so as to be shifted with respect to the optical system 41 in order to show the optical path. However, actually, as shown in FIGS. 1 and 2, the photoelectric conversion unit 42 is an optical system. 41 is disposed immediately above.

  The light irradiation means 3 has a configuration in which a cylindrical light source 31 that is long in the Y-axis direction is covered in the circumferential direction by a hollow cylindrical support member 32 that is also long in the Y-axis direction. A slit S32 (FIG. 3) extending in the Y-axis direction is opened in the cylindrical support member 32 toward the substrate W on the turntable 2. Light emitted from the light source 31 is applied to the substrate W via the slit S32. Is done. As a result, the substrate W is irradiated with light in a straight line extending in the Y-axis direction. Further, in the gap between the cylindrical support member 32 and the light source 31, a reflective material 31a is provided so as to cover the light source 31 from the opposite side of the slit S32. As a result, light emitted from the light source 31 in the direction opposite to the slit S32 is reflected by the reflector 31a to the slit S31. As a result, it is possible to increase the amount of light that passes through the slit S32 and to ensure a sufficient amount of light that is applied to the substrate W.

  As shown in FIG. 2, the light source 31 is disposed closer to one side in the Y-axis direction with respect to the center Cw of the substrate W on the turntable 5, and one end thereof is one side wall 10 a of the detection unit 10. It is fixed to. On the other hand, the other end of the light source 31 is connected to an LED (Light Emitting Diode) via a connecting portion 33, a connecting tube 34, and an optical fiber 35. More specifically, one end of the connecting tube 34 is connected to the end (the other end) of the light source 31 via the connecting portion 33, and the other end of the connecting tube 34 is fixed to the other side wall 10 b of the detection unit 10. ing. Then, on the outside of the detection unit 10, the end (the other end) of the connecting tube 34 is connected to the LED 36 via the optical fiber 35. Therefore, after the light from the LED 36 is guided by the optical fiber 35, it reaches the light source 31 through the connecting tube 34 and the connecting portion 33 and is emitted from the light source 31.

  Thus, the light emitted from the light irradiation means 3 is directed to the image pickup means 4 after being irradiated onto the substrate W in a straight line extending in the Y-axis direction. That is, as indicated by a broken line in FIG. 4, the light emitted from the light irradiation means 3 is specularly reflected by the substrate W on the turntable 2, then further reflected by the optical system 41 and incident on the photoelectric conversion unit 42. To do. Here, assuming that an area where light incident on the photoelectric conversion unit 42 is reflected by the substrate W is an imaging area Ad, the imaging area Ad overlaps the range from the end of the substrate W to the center Cw. At this time, the imaging region Ad has a linear shape slightly longer than the radius of the substrate W, and protrudes on both sides of the range Ar from the end of the substrate W to the center Cw. In FIG. 4, the range where the imaging region Ad protrudes to the substrate center Cw side with respect to this range At is denoted by reference sign ΔAr. Then, the light reflected by the imaging region Ad is reduced and imaged on the light receiving unit of the photoelectric conversion unit 42. In this way, the imaging unit 4 captures an image of the substrate W for one line in the imaging region Ad.

  The above is the outline of the mechanical configuration of the substrate processing apparatus 1. Next, returning to FIG. 1, the electrical configuration of the substrate processing apparatus 1, that is, the configuration of the electrical system 5 will be described. The electrical system 5 executes image processing on the control unit 51 that controls each part of the substrate processing apparatus 1, the power source 52 that supplies power to each part of the substrate processing apparatus 1, and the imaging result of the imaging unit 4. Image processing means 53.

  In particular, the control unit 51 acquires the image of the substrate W by causing the imaging unit 4 to appropriately execute the imaging operation while rotating the drive motor M2 to control the rotation operation of the turntable 2. Specifically, the control unit 51 performs a process for causing the imaging unit 4 to perform imaging for one line for one rotation of the substrate W each time the rotation table 2 is rotated to rotate the substrate W by a predetermined angle. Then, an image of the entire substrate W is acquired.

  Further, the image processing unit 53 sequentially receives an image for one line imaged at every predetermined rotation angle by the imaging unit 4, so that the polar coordinate system having the rotation angle and the distance (radial radius) from the rotation center as a coordinate axis. The image of the substantially whole board | substrate W represented by is acquired (image acquisition process). Then, the image processing means 53 can execute the inspection of the substrate W based on the acquired image in the built-in evaluation unit 531.

  Various inspections can be performed as the inspection at this time. To give a specific example, when performing a pass / fail inspection of the edge bead removal line on the substrate W from which the edge bead has been removed by applying a resist film, an image of the substrate W expressed in a polar coordinate system may be used. Preferred. This is because, when the substrate W is represented in the polar coordinate system, the shape of the removal line in which the edge bead is properly removed is substantially straight, whereas the shape of the removal line in which the edge bead is not properly removed is out of the straight line. Therefore, it is possible to easily check the quality of the edge bead removal line simply by confirming the shape of the edge bead removal line.

  Depending on the type of inspection, it may be preferable to represent the image of the substrate W in the orthogonal coordinate system rather than the polar coordinate system. To give a specific example, a substrate expressed in an orthogonal coordinate system is used when a semiconductor substrate W on which a plurality of dies are formed is compared with each other and an inspection for specifying a defective die is performed. It is preferable to use an image of W. Because, when the substrate W is represented in an orthogonal coordinate system, each die basically has the same shape and pattern, while an abnormal die is different in shape and pattern compared to other normal dies, This is because a defective die can be easily identified simply by comparing the shapes and patterns of the dies.

  Therefore, the image processing unit 53 includes a coordinate conversion unit 532 that executes an image conversion process for converting an image of the substrate W from a polar coordinate system to an orthogonal coordinate system, and a memory 533 that stores information necessary for the coordinate conversion process. Have. Next, the coordinate conversion process will be described.

  FIG. 5 is a diagram schematically showing the contents of the image processing executed in the coordinate conversion processing from the polar coordinate system to the orthogonal coordinate system. In the figure and the drawings described below, polar coordinate axes represented by a rotation angle θ and a distance (moving radius) ρ from the rotation center are appropriately shown. As described above, the image processing unit 53 receives an image for one line every time the substrate W rotates by a predetermined rotation angle, thereby acquiring an image of the entire substrate W expressed in the polar coordinate system. That is, the image IM1 acquired by the image processing unit 53 is an image expressed in a polar coordinate system as shown in the column “Image acquired by the image processing unit” in FIG. In the same column, the left end of the image IM1 corresponds to the substantial rotation center, and the right end of the image IM1 corresponds to the end of the substrate W. The same applies to the image IM2 in the columns of “substrate placement error correction image” and “conversion target range image” described later.

  Incidentally, the substrate W is ideally placed so that its center Cw coincides with the rotation center of the turntable 2. However, since there is actually a limit on the placement accuracy of the substrate W, as shown in FIG. 6, a placement deviation occurs such that the center Cw of the substrate W and the rotation center Cr of the turntable 2 are shifted from each other.

  FIG. 6 is a plan view schematically showing the positional relationship between the center of the substrate and the rotation center of the rotary table. As shown in the figure, the center Cw of the substrate and the rotation center Cr of the turntable 2 are shifted by a shift amount ΔC. Therefore, the distance from the end of the circular substrate W to the rotation center Cr is the maximum value (= Rw + ΔC) obtained by adding the deviation amount ΔC to the diameter Rw of the substrate W, and the minimum value obtained by subtracting the deviation amount ΔC from the diameter Rw of the substrate W. It fluctuates sinusoidally between values (= Rw−ΔC). As a result, in the “image acquired by the image processing means” column of FIG. 5 and the image IM1 acquired by the image processing means 53 as shown in FIG. 7, the edge of the substrate W is not linear but has an amplitude ΔC. It will wave sinusoidally.

  FIG. 7 is a schematic diagram showing an enlarged end of the substrate in the image acquired by the image processing means. In FIG. 7, the fluctuation period of the substrate W is represented by a symbol T, and the fluctuation center line (so-called zero cross line) of the substrate W is represented by a symbol Lzc. As described above, the substrate W fluctuates sinusoidally with the amplitude ΔC around the fluctuation center line Lzc. At this time, in the ideal case where there is no deviation between the substrate center Cw and the rotation center Cr and the deviation amount ΔC is zero, the end of the substrate W coincides with the fluctuation center line Lzc. In other words, by performing an operation of aligning the edge of the substrate W with the fluctuation center line Lzc, an image of the substrate W corresponding to the case where there is no deviation between the substrate center Cw and the rotation center Cr can be generated. Specifically, the coordinate conversion unit 532 obtains an amount Δρz in which the end (θn, ρz + Δρz) of the n-th line data D (n) is shifted from the position ρz of the fluctuation center line Lzc, and determines the line data Dn. A process of shifting in the ρ direction by (−Δρz) is executed for each line data D (1), D (2),. As a result, as shown in the column “Substrate placement deviation correction image” of FIG. 5, an image IM2 of the substrate W corresponding to the case where there is no deviation between the substrate center Cw and the rotation center Cr is generated. In the image IM2, since the right end is aligned in a straight line, the left end is a curve L1 that vibrates sinusoidally.

  Thus, after correcting the mounting displacement of the substrate W, the coordinate conversion unit 532 performs coordinate conversion from the polar coordinate system to the orthogonal coordinate system for the image of the conversion target range At from the end of the substrate W to the rotation center Cr. Execute the process. Incidentally, the amount of rotation of the turntable 2 rotated in acquiring the image IM1 is not just one rotation, but is usually slightly more than one rotation. Therefore, the images IM1 and IM2 include extra images that are more than one rotation of the substrate W. Therefore, in order to appropriately perform the coordinate conversion process, it is preferable to remove this extra image. Corresponding to this, in the coordinate conversion processing here, the range between the end of the substrate W and the rotation center Cr in the ρ direction and the rotation period T of the substrate W in the θ direction is the conversion target range. Identified.

  As shown in FIG. 6, the imaging region Ad in which the imaging unit 4 acquires an image for one line protrudes from the rotation center Cr by a distance ΔAd. In other words, in the radial direction ρ (the direction in which the linear imaging region Ad extends) in the polar coordinate system, the imaging region Ad extends beyond the conversion target range At across the rotation center Cr. For this reason, the image IM2 includes an image at a location outside the conversion target range At. In such a state, if the coordinate conversion process is performed on the assumption that the entire image IM2 corresponds to the image in the conversion target range At, partial distortion occurs in the image converted into the orthogonal coordinate system. As a specific example, distortion occurs such that a pattern to be represented by a straight line is partially bent or interrupted.

  Therefore, as shown in the column “conversion target range” in FIG. 5, the coordinate conversion unit 532 performs an operation of specifying the conversion target range At of the rotation center Cr from the end of the substrate W on the image IM2. Incidentally, in the polar coordinate system, the position of the rotation center Cr is a curve L2 that sinusoidally vibrates in the same shape as the curve L1 around the virtual straight line Lr that is a distance of the substrate radius Rw from the end of the substrate W toward the rotation center Cr. appear. Accordingly, a range on the right side of the curve L2 and between the rotation periods T is specified as the conversion target range At.

  However, the distance Px corresponding to one pixel of the imaging unit 4 in the radial axis direction ρ varies depending on the positional relationship between the imaging unit 4 and the substrate W. Therefore, in order to identify which part is the image of the conversion target range At on the image captured by the imaging unit 4, a position away from the edge of the substrate W by the substrate radius Rw is estimated and fluctuated at the position. In estimating the curve L2 to be performed, the value of the distance Px is required. On the other hand, in this embodiment, a distance Px corresponding to one pixel of the imaging means 4 in the radial axis direction ρ is obtained in advance as distance information and stored in the memory 533, and the coordinate conversion unit 532 By dividing the radius Rw of W by the distance Px, the number of pixels corresponding to the radius Rw is obtained, and a curve L2 sine-oscillated at a position away from the edge of the substrate W by the number of pixels is estimated (that is, the rotation center Cr Estimate position). As a result, the conversion target range At is accurately specified. Then, the coordinate conversion unit 532 performs a coordinate conversion process on the image IM2 of the substrate W in the conversion target range At thus specified. At this time, as described above, the conversion target range At has a length corresponding to the rotation period T in the θ direction.

  By the way, it is ideal that the imaging area Ad in which the imaging unit 4 acquires an image for one line coincides with the rotation center Cr of the turntable 2, but in practice, it is shifted from the rotation center Cr. There are many. As described above, when the imaging region Ad is deviated from the rotation center Cr, if the coordinate conversion process is executed without considering this deviation amount, partial distortion occurs in the image converted into the orthogonal coordinate system. As a specific example, distortion occurs such that a pattern to be represented by a straight line is partially bent or interrupted. Therefore, in this embodiment, the shift amount R 0 between the imaging area Ad and the rotation center Cr is obtained in advance as position information indicating the positional relationship between the imaging area Ad and the rotation center Cr and stored in the memory 533. Then, the coordinate conversion unit 532 performs a coordinate conversion process based on the deviation amount R0. This will be described in detail below.

  FIG. 8 is a diagram schematically showing the contents of coordinate conversion processing for converting coordinates from a polar coordinate system to an orthogonal coordinate system. In the figure, the positional relationship between the rotation center Cr of the turntable 2 and the imaging region Ad in the orthogonal coordinate system is shown. Although a plurality of imaging areas Ad are shown, this does not indicate that the plurality of imaging areas Ad actually exist, and the imaging areas Ad that rotate and move relative to the substrate W are rotated differently. This is shown for each angle.

  As described above, when the substrate W is rotated by a predetermined angle, an image for one line is executed by the imaging unit 4, whereby an almost entire image of the substrate W is acquired. In such a configuration, the linear imaging region Ad relatively rotates around the rotation center Cr of the turntable 2. At this time, if the imaging region Ad and the rotation center Cr are shifted by the shift amount R0, the imaging region Ad rotates while being spaced from the rotation center Cr of the turntable 2 by the shift amount R0. In other words, the imaging region Ad rotates while being in contact with the virtual circle Ce having the radius R0 centered on the rotation center Cr.

  Therefore, the coordinate conversion unit 532 specifies such a locus of the imaging region Ad based on the deviation amount R0 stored in the memory 533. In this way, by identifying the locus of the imaging region Ad from the deviation amount R0, it is possible to accurately grasp which location the data acquired by the imaging unit 4 by capturing in the imaging region Ad is captured. Can do. Specifically, it is understood that the line data for one line corresponding to the rotation angle θ is data captured in the imaging region Ad that is rotated by the angle θ around the rotation center Cr at a distance R0 from the rotation center Cr. it can.

  Then, the coordinate conversion unit 532 associates an arbitrary point in the polar coordinate system with a point in the orthogonal coordinate system based on the locus of the imaging region Ad thus specified, and performs image conversion processing from the polar coordinate system to the orthogonal coordinate system. Run. That is, the distance from the contact point at which the imaging area Ad contacts the virtual circle Ce to an arbitrary point on the imaging area Ad is associated with the distance in the radial direction ρ in the polar coordinate system, and the angle of the imaging area Ad is the polar coordinate system. Is associated with the angle θ. As a result, the polar coordinate system and the orthogonal coordinate system are accurately associated with each other.

Specifically, in the Cartesian coordinate system, an expression of a tangent drawn from an arbitrary point (xj, yj) with respect to a virtual circle Ce having a radius R0 centered on the rotation center Cr (xk, yk) is expressed as ax + by + c = 0.
In other words, each of the coefficients a, b, and c is represented by each equation shown in FIG. Here, FIG. 9 is a diagram showing an equation representing each coefficient of the tangent equation drawn on the virtual circle. Therefore, the coordinate conversion unit 532 performs coordinate conversion processing by mapping to the corresponding point in each point orthogonal coordinate system of the polar coordinate system using the formula shown in FIG. 9 (coordinate conversion process). As a result, as shown in the column “Image in Cartesian Coordinate System” in FIG. 5, an image IM3 of the substrate W expressed in the Cartesian coordinate system is obtained. Note that an image is not acquired because the imaging region Ad does not pass within the range of the virtual circle Ce. Therefore, in the image IM3 of the substrate W in the orthogonal coordinate system, the virtual circle Ce appears as an invisible circle lacking an image. Then, the evaluation unit 531 of the image processing unit 53 performs an inspection such as identifying an abnormal die among a plurality of dies formed on the substrate W, for example, based on the image of the substrate W expressed in the orthogonal coordinate system. Execute (substrate processing step).

  As described above, in this embodiment, the coordinate conversion processing for converting the image of the substrate W acquired by the image processing means 53 from the polar coordinate system to the orthogonal coordinate system is performed by the rotation center Cr of the turntable 2 and the imaging region Ad. This is executed based on the deviation amount R0. Therefore, coordinate conversion from the polar coordinate system to the orthogonal coordinate system is appropriately performed regardless of the deviation between the imaging area Ad of the imaging means 4 and the rotation center Cr of the rotary table 2, and the image IM3 of the substrate W is accurately obtained in the orthogonal coordinate system. It is possible to express

  In this embodiment, the coordinate conversion unit 532 specifies the locus of the imaging region Ad that rotates relative to the rotation center Cr at a distance R0 (a constant distance) from the rotation center Cr in the orthogonal coordinate system. Based on the above, coordinate conversion processing is executed. In this way, by specifying the trajectory of the imaging area Ad based on the distance R0 indicating the amount of deviation between the imaging area Ad and the rotation center Cr, the data acquired by the imaging means 4 by imaging in the imaging area Ad is It is possible to accurately grasp whether or not the place is imaged, and it is possible to appropriately execute the coordinate conversion process.

  In particular, in this embodiment, the distance from the contact point at which the imaging area Ad contacts the virtual circle Ce to an arbitrary point on the imaging area Ad corresponds to the distance in the radial direction ρ in the polar coordinate system, and the angle of the imaging area Ad. Is associated with the angle θ in the polar coordinate system, coordinate conversion processing is executed. As a result, it is possible to appropriately execute the above-described coordinate conversion process by accurately associating the polar coordinate system with the orthogonal coordinate system.

  Incidentally, as described above, there is a case where the imaging region Ad straddles the rotation center Cr in the radial direction ρ in the polar coordinate system and protrudes from the conversion target range At. In such a case, an image at a place outside the conversion target range At may be mixed into the captured image At of the imaging unit 4 and the coordinate conversion process from the polar coordinate system to the orthogonal coordinate system may not be performed properly.

  On the other hand, in this embodiment, the conversion target range At from the end of the substrate W to the rotation center Cr is specified, and the image outside the conversion target range At among the images of the substrate W acquired by the image acquisition unit. Is excluded from the target of the coordinate conversion process, and the coordinate conversion process is executed on the image within the conversion target range At. In such a configuration, an image at a place outside the conversion target range At is excluded from the target of the coordinate conversion process, and therefore the coordinate conversion process from the polar coordinate system to the orthogonal coordinate system can be appropriately performed.

  In particular, in this embodiment, the distance Px corresponding to one pixel of the imaging unit 4 is stored in the memory 533, and the coordinate conversion unit 532 specifies the conversion target range At based on the distance Px stored in the memory 533. . Such a configuration is preferable because the conversion target range At can be accurately specified, so that the coordinate conversion process from the polar coordinate system to the orthogonal coordinate system can be performed more appropriately.

  In addition, the present invention for acquiring an image in a polar coordinate system can be particularly preferably applied to the substrate processing apparatus 1 that performs processing on a circular substrate W as in this embodiment.

  Thus, in this embodiment, the substrate processing apparatus 1 corresponds to the “substrate processing apparatus” of the present invention, the rotary table 2 corresponds to the “rotation support means” of the present invention, and the imaging means 4 corresponds to “ The image processing unit 53 corresponds to the “image acquisition unit” of the present invention, the memory 533 corresponds to the “storage unit” of the present invention, and the coordinate conversion unit 532 corresponds to the “image conversion unit” of the present invention. The evaluation unit 531 corresponds to the “substrate processing means” of the present invention. Further, the shift amount R0 between the imaging region Ad and the rotation center Cr corresponds to “position information” of the present invention, and the distance Px corresponding to one pixel of the imaging means 4 corresponds to “distance information” of the present invention. The imaging area Ad corresponds to the “imaging area” of the present invention, and the conversion target range At corresponds to the “conversion target range” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the inspection is performed on the substrate W based on the image of the substrate W expressed in the orthogonal coordinate system has been described. However, the processing performed by the substrate processing apparatus 1 on the substrate W is not limited to substrate inspection. Therefore, also for the substrate processing apparatus 1 that executes a process of applying a resist to the substrate W while rotating the substrate W, and the substrate processing apparatus 1 that executes a process of removing edge beads of the substrate W while rotating the substrate W. The present invention can be applied.

  In the above embodiment, the method for obtaining the distance Px corresponding to one pixel of the imaging unit 4 and the method for obtaining the deviation amount R0 between the imaging region Ad and the rotation center Cr have been particularly described. Various methods can be adopted as the method. An example is as follows.

  As described above, when an image at a location outside the conversion target range At is captured and coordinate conversion processing is performed, distortion occurs in the image represented by the orthogonal coordinate system. Therefore, in the above embodiment, an image in the conversion target range At is specified based on the distance Px corresponding to one pixel of the imaging unit 4. At this time, if the distance Px is not a correct value, the conversion target range At cannot be accurately specified, and the image represented by the orthogonal coordinate system is distorted. Therefore, when determining the distance Px, the relationship between the value of the distance Px and the image distortion can be used.

  That is, for example, the image IM1 of the test substrate W on which a linear test pattern is formed is acquired in the polar coordinate system as described above. Then, the image IM1 is converted into the image IM3 in the orthogonal coordinate system via the image IM2 in the manner described above. By executing this operation a plurality of times while changing the value of the distance Px, a plurality of images IM3 having different degrees of distortion of the test pattern can be obtained. Then, the value of the distance Px used for acquiring the image IM3 with the smallest distortion of the test pattern can be obtained as indicating the correct distance Px.

  Further, as described above, when the coordinate conversion process is performed without considering the shift amount R0 between the imaging region Ad and the rotation center Cr, distortion occurs in the image represented by the orthogonal coordinate system. Therefore, in the above-described embodiment, based on the trajectory of the imaging region Ad obtained from the deviation amount R0, which location the data acquired by the imaging unit 4 by capturing in the imaging region Ad is captured. I know. At this time, if the deviation amount R0 is not a correct value, it is impossible to accurately grasp where the captured data is, and the image represented by the orthogonal coordinate system is distorted. Therefore, when obtaining the shift amount R0, the relationship between the value of the shift amount R0 and the distortion of the image can be used.

  That is, as in the case of the distance Px, for example, the image IM1 of the test substrate W on which a linear test pattern is formed is acquired in the polar coordinate system as described above. Then, the image IM1 is converted into the image IM3 in the orthogonal coordinate system via the image IM2 in the manner described above. By executing this operation a plurality of times while changing the value of the deviation amount R0, a plurality of images IM3 having different degrees of distortion of the test pattern can be obtained. Then, the value of the deviation amount R0 used for obtaining the image IM3 with the smallest distortion of the test pattern can be obtained as indicating the correct deviation amount R0.

  Further, in the above-described embodiment, the case where the placement deviation of the substrate W occurs has been described. However, the present invention can also be applied to the substrate processing apparatus 1 in which the placement accuracy of the substrate W is very high and there is almost no placement displacement of the substrate W. In this case, the correction process of the substrate placement deviation (that is, the process of converting the image IM1 into the image IM2) can be omitted.

  Further, the shape of the substrate W is not limited to the circular shape. Therefore, the present invention can also be applied to the substrate processing apparatus 1 that processes a substrate W other than a circle.

  The present invention can be used in a substrate processing apparatus that performs processing on a substrate based on a result of converting an image of a substrate W expressed in a polar coordinate system into an orthogonal coordinate system.

DESCRIPTION OF SYMBOLS 1 ... Substrate processing apparatus 2 ... Rotary table 3 ... Light irradiation means 4 ... Imaging means 51 ... Control means 53 ... Image processing means 531 ... Evaluation part 532 ... Coordinate conversion part 533 ... Memory W ... Substrate R0 ... Imaging area Ad and rotation center Deviation amount from Cr Px: Distance corresponding to one pixel of the imaging means 4 Ad: Imaging area At: Conversion target range

Claims (10)

Rotation support means for rotating while supporting the substrate;
Imaging means arranged so that its imaging region overlaps the substrate supported by the rotation support means;
Image acquisition means for acquiring an image of the substrate represented in a polar coordinate system by causing the imaging means to image the substrate in the imaging region while rotating the substrate by the rotation support means;
Storage means for storing position information indicating a positional relationship between the rotation center of the rotation support means and the imaging region;
Coordinate conversion means for executing a coordinate conversion process for converting the image of the substrate acquired by the image acquisition means from a polar coordinate system to an orthogonal coordinate system based on the position information stored in the storage means;
A substrate processing apparatus comprising: a substrate processing unit configured to perform processing on the substrate based on the image of the substrate converted into an orthogonal coordinate system by the coordinate conversion unit.   The substrate processing apparatus according to claim 1, wherein the imaging unit includes the linear imaging region in an orthogonal coordinate system.   The coordinate conversion unit is configured to convert the coordinate based on a result of specifying a trajectory of the imaging region that is relatively rotated around the rotation center at a certain distance from the rotation center in the orthogonal coordinate system based on the position information. The substrate processing apparatus of Claim 2 which performs a process.   The coordinate conversion means is a radial distance in a polar coordinate system from a contact point where the imaging region is in contact with a virtual circle having a radius of the fixed distance with the rotation center as a center to an arbitrary point on the imaging region. The substrate processing apparatus according to claim 3, wherein the coordinate conversion process is executed by making the angle of the imaging region correspond to an angle in a polar coordinate system.   The coordinate conversion unit specifies a conversion target range from an end of the substrate to the center of rotation, and among the images of the substrate acquired by the image acquisition unit, images outside the conversion target range are subjected to the coordinate conversion process. The substrate processing apparatus according to claim 1, wherein the coordinate conversion process is performed on an image within the conversion target range after being excluded from the target. The storage means stores distance information indicating a distance corresponding to one pixel of the imaging means,
The substrate processing apparatus according to claim 5, wherein the coordinate conversion unit specifies the conversion target range based on the distance information stored in the storage unit.   The substrate processing apparatus according to claim 1, wherein the substrate processing unit executes inspection of the substrate as processing on the substrate. The substrate processing apparatus according to claim 7, wherein processing is performed on the semiconductor substrate on which a plurality of dies are formed.
The substrate processing apparatus is a substrate processing apparatus that performs an inspection on the substrate to identify defective dies by comparing dies with each other.   The substrate processing apparatus according to claim 1, wherein processing is performed on the circular substrate. A polar coordinate system by causing the imaging means arranged so that the imaging region overlaps the substrate to image the substrate in the imaging region while rotating the substrate by rotating a rotation support unit that supports the substrate. An image acquisition step of acquiring an image of the substrate represented by:
Based on position information indicating the positional relationship between the rotation center of the rotation support means and the imaging region, a coordinate conversion process is performed to convert the image of the substrate acquired in the image acquisition step from a polar coordinate system to an orthogonal coordinate system. A coordinate transformation process;
A substrate processing method comprising: a substrate processing step of performing processing on the substrate based on the image of the substrate converted into an orthogonal coordinate system in the coordinate conversion step.

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