JP2010238970A - Method of estimating central position of disc member, and image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of highly precisely estimating the central position of a disc member, such as wafer. <P>SOLUTION: A image processing apparatus includes imaging cameras 2 which are disposed outside a transfer chamber 4 and take images of two spots containing the outline of a wafer 3 via view ports formed on the transfer chamber 4, and a measuring unit which determine estimation circles that are estimations of the outer circumference of the wafer 3, using pieces of arc information of the wafer 3 each extracted from each of the images taken by the imaging cameras 2, to estimate the central position of the wafer 3 from two estimation circles. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a center position estimation method and an image processing apparatus for measuring the center position of a semiconductor wafer in a vacuum chamber.

  In a semiconductor manufacturing apparatus, various processes are performed on a disk-shaped wafer in the process of manufacturing a semiconductor. At that time, it is important to accurately position the center position of the wafer in the apparatus. It is necessary to obtain the center position automatically. Conventionally, an entire wafer is imaged by an imaging camera, a circle that best fits the wafer shape is obtained from all edge information on the wafer circumference of the image by an image processing apparatus, and the center thereof is set as the center position of the wafer. However, in recent years, the wafer size has been steadily increasing, and the conventional method has required a large space and a large illumination means for imaging. Therefore, a technique has been proposed in which a part of the arc of the wafer is captured rather than the entire circumference of the wafer, a circle that best fits the wafer shape is obtained from the arc information of the arc image, and the center is estimated as the center position of the wafer. ing.

  For example, Patent Document 1 discloses a misalignment detection device that detects misalignment of a disk-shaped object having a direction recognition notch in the peripheral portion. This apparatus is provided with three contour detection sensors arranged so as to detect the positions of peripheral contours excluding direction recognition notches such as an orientation flat (orientation flat) portion and notch portion of the object to be processed. The amount calculation unit estimates the center position of the object to be processed based on the detection values of these three contour detection sensors, and obtains the deviation amount from the reference origin.

  Further, in Patent Document 2, a disk-shaped object to be processed that is carried into a processing unit by a transfer device is imaged at the unit entrance, and position information at a plurality of locations is detected from the arc shape of the outer periphery of the imaged object to be processed. Disclosed is a processing device that includes an imaging device and a calculation unit that calculates a virtual coordinate of a target object from position information of a plurality of locations, calculates center coordinates, and calculates positional deviation information of the target object with respect to the transport device. ing. Then, based on the calculated misregistration information, the transfer device carries the object to be processed at a predetermined position in the processing unit and carries it in.

JP 2002-43394 A JP 2008-306162 A

  In Patent Document 1, three contour detection sensors for detecting three points on the contour of a disk-shaped wafer are necessary. Also, since the points on the contour excluding the notch portion and orientation flat portion of the wafer are detected, if there is a chip on the wafer contour, the wafer contour cannot be detected accurately, and the measurement result There is a possibility that the center position is greatly shifted.

  Further, in Patent Document 2, a true circle is estimated based on a plurality of pieces of position information on a part of the arc around the wafer circumference, and the center of the estimated true circle is immediately determined as the center position of the wafer. Even a slight error in the upper position information has a large effect on the radius value error, and there is a problem that the center position of the wafer cannot be obtained with high accuracy. In addition, an actual wafer may have a shape close to a perfect circle but may not be a perfect circle but may be distorted.In addition, there may be a small chip in addition to the notch. The radius value error may be affected, and the center position may be greatly displaced.

  The present invention has been made to solve the above-described problems, and an object thereof is to estimate the center position of a disk-shaped member such as a wafer with high accuracy.

  The center position estimation method according to the first aspect of the present invention is the first method in which an image in which an arc of an arbitrary range of a disk-shaped member is imaged by an imaging means is defined with a coordinate position based on at least one axis in a predetermined direction. The first circular arc information is extracted from the first circular arc image, the first estimated circle is obtained based on the first circular arc information, and at least one of the arbitrary range of the disk-shaped member is captured by the imaging unit. An image in which arcs in different ranges are captured is defined as a second arc image that defines a position on coordinates with reference to one axis, and second arc information is extracted from the second arc image, A circle estimation step for obtaining a second estimated circle based on the arc information of the first and a first point on the coordinates, the maximum point on the first estimated circle or the maximum point on the second estimated circle as a first vertex Vertex calculation step and minimum on first estimated circle on coordinates Alternatively, a second vertex calculation step in which the minimum point on the second estimated circle is the second vertex, a midpoint between the first vertex and the second vertex is obtained, and the midpoint is the center position of the disk-shaped member And a center estimation step for estimating.

  In the center position estimation method according to the invention of claim 2, in the circle estimation step, a first estimated circle is obtained from an arc image having a large coordinate position among the first arc image and the second arc image, and the coordinate position is determined. The second estimated circle is obtained from an arc image with a small arc, and in the first vertex calculating step, the maximum point on the first estimated circle is set as the first vertex on the coordinates, and in the second vertex calculating step, the coordinates are displayed on the coordinates. The minimum point on the second estimated circle is the second vertex.

  In the center position estimation method according to the invention of claim 3, in the circle estimation step, it is assumed that one axis in a predetermined direction is the y axis, and an axis orthogonal to the predetermined one axis is the x axis. The first circular arc image and the second circular arc image captured with the coordinate positions substantially aligned are used.

  In the center position estimating method according to the invention of claim 4, in the center estimating step, the center position (x1, y1) and the radius r1 of the first estimated circle are calculated, and the center position (x2, y2) of the second estimated circle is calculated. y2) and the radius r2 are calculated, and the position ((x1 + x2) / 2, (y1 + r1 + y2-r2) / 2) is estimated as the center position of the disk-shaped member.

  The center position estimation method according to the invention of claim 5 extracts the first arc information from the first arc image by using the first arc image in which an arc of an arbitrary range of the disk-shaped member is imaged by the imaging means. Then, the first estimated circle is obtained based on the first arc information, and the second arc image obtained by imaging the arc of the disk-shaped member at least partially different from the arbitrary range is used by the imaging unit. Extracting a second arc information from the second arc image, obtaining a second estimated circle based on the second arc information, and a first existing on the first estimated circle. A point on the second estimated circle that intersects a straight line passing from the first vertex to the center of the first estimated circle by extracting a point in the arc image as the first vertex and the first vertex calculating step A second vertex calculation step as a second vertex and a midpoint between the first vertex and the second vertex It is made the center point from the center estimating step of estimating a center position of the disc-like member.

  According to a sixth aspect of the present invention, a center position estimation method extracts first arc information from a first arc image using a first arc image in which an arc of an arbitrary range of a disk-shaped member is imaged by an imaging means. Then, the first estimated circle is obtained based on the first arc information, and the second arc image obtained by imaging the arc of the disk-shaped member at least partially different from the arbitrary range is used by the imaging unit. Extracting a second arc information from the second arc image, obtaining a second estimated circle based on the second arc information, and a first existing on the first estimated circle. A first vertex calculation step that extracts one point in the arc image as a first vertex, and a second vertex that extracts one point in the second arc image existing on the second estimated circle A second vertex calculating step, a straight line passing from the first vertex to the center of the first estimated circle, The intersection of the straight line passing through the center of the second estimated circle from the apex, is made of a center estimating step of estimating a center position of the disc-like member.

  An image processing apparatus according to a seventh aspect of the present invention provides a first circular arc in which an arc image of an arbitrary range of a disk-shaped member imaged by an imaging means is defined with a coordinate position based on at least one axis in a predetermined direction. In addition to an image, an arc image of a disc-shaped member imaged by the imaging means that is at least partially different from an arbitrary range is captured as a second arc image in which the position on the coordinates is defined with respect to one axis. The first arc information is extracted from the image input unit and the first arc image, the first estimated circle is obtained based on the first arc information, and the second arc information is obtained from the second arc image. A circle estimation unit that extracts and obtains a second estimated circle based on the second arc information, and a maximum point on the first estimated circle or a maximum point on the second estimated circle on the coordinates is the first And on the first estimated circle on the coordinates A vertex calculation unit having a small point or a minimum point on the second estimated circle as a second vertex, a midpoint between the first vertex and the second vertex, and a midpoint of the midpoint of the disk-shaped member And a center position estimating unit for estimating

  In the image processing device according to the invention of claim 8, the circle estimation unit obtains a first estimated circle from an arc image having a large coordinate position among the first arc image and the second arc image, and the coordinate position is The second estimated circle is obtained from the small arc image, and the vertex calculation unit sets the maximum point on the first estimated circle on the coordinates as the first vertex and the minimum point on the second estimated circle as the first point. The vertex of 2 is used.

  In the image processing apparatus according to the ninth aspect of the present invention, the circle estimation unit assumes that one axis in a predetermined direction is the y-axis, and an axis orthogonal to the predetermined one axis is the x-axis. The first arc image and the second arc image that are imaged with the coordinate positions substantially aligned are used.

  In the image processing device according to the tenth aspect, the circle estimation unit calculates the center position (x1, y1) and the radius r1 of the first estimated circle, and the center position (x2, y2) of the second estimated circle. ) And the radius r2, and the center position estimation unit estimates the position ((x1 + x2) / 2, (y1 + r1 + y2-r2) / 2) as the center position of the disk-shaped member.

  An image processing apparatus according to an eleventh aspect of the present invention uses an arc image of an arbitrary range of a disk-shaped member imaged by an imaging means as a first arc image, and an arbitrary range of the disk-shaped member imaged by an imaging means. And an image input unit that captures, as a second arc image, an arc image of a range that is at least partially different from the first arc information, and the first arc information is extracted from the first arc image, and the first arc information is extracted based on the first arc information. A circle estimation unit that obtains an estimated circle, extracts second arc information from the second arc image, and obtains a second estimated circle based on the second arc information, and exists on the first estimated circle A point in the first arc image is extracted as a first vertex, and a point on the second estimated circle that intersects the straight line passing through the center of the first estimated circle from the first vertex is the first vertex. A vertex calculation unit as two vertices, and a midpoint between the first vertex and the second vertex, The middle point is obtained so as to include a central position estimation unit that estimates a center position of the disc-like member.

  An image processing apparatus according to a twelfth aspect of the present invention provides an arc image of an arbitrary range of a disk-shaped member imaged by an imaging unit as a first arc image, and an arbitrary range of the disk-shaped member imaged by an imaging unit. And an image input unit that captures, as a second arc image, an arc image of a range that is at least partially different from the first arc information, and the first arc information is extracted from the first arc image, and the first arc information is extracted based on the first arc information. A circle estimation unit that obtains an estimated circle, extracts second arc information from the second arc image, and obtains a second estimated circle based on the second arc information, and exists on the first estimated circle One point in the first arc image is extracted as the first vertex, and one point in the second arc image existing on the second estimated circle is extracted as the second vertex. A vertex calculation unit, a straight line passing from the first vertex to the center of the first estimated circle, and the second vertex From in which the intersection of the straight line passing through the center of the second estimation circle, and so and a center position estimation unit that estimates a center position of the disc-like member.

  According to the first and seventh aspects of the invention, the first and second estimated circles are obtained from the first and second arc images, and the maximum point on the first or second estimated circle is determined on the coordinates. Since the first vertex and the minimum point on the first or second estimated circle is the second vertex, the midpoint between the first and second vertices is estimated as the center position of the disk-shaped member. The error of the radius value of the estimated circle can be suppressed, and the center position can be estimated with high accuracy.

  According to the inventions of claim 2 and claim 8, the maximum point on the estimated circle estimated from the arc image with a large coordinate position is the first vertex, and the minimum point on the estimated circle estimated from the arc image with a small coordinate position As the second vertex, the midpoint between the first and second vertices is estimated as the center position of the disc-shaped member, so that the radius error of the estimated circle can be further suppressed, and the center position is more accurate. Can be estimated.

  According to the third and ninth aspects of the present invention, since the first and second arc images that are imaged with the coordinate positions on the x-axis substantially aligned are used, x at the center positions of the two estimated circles. The axial displacement hardly occurs, and the estimation accuracy of the center position of the disc-shaped member in the x-axis direction can be improved.

  According to the invention of claim 4 and claim 10, the center position (x1, y1) and radius r1 of the first estimated circle are calculated, and the center position (x2, y2) and radius r2 of the second estimated circle are calculated. And the position ((x1 + x2) / 2, (y1 + r1 + y2-r2) / 2) is estimated as the center position of the disk-shaped member, so that it is simple from the center position and radius of the two estimated circles, and The center position of the disk-shaped member can be estimated with high accuracy.

  According to the invention of claim 5 and claim 11, one point in the first arc image existing on the first estimated circle is set as the first vertex, and the second point existing on the second estimated circle Since one point in the arc image is extracted as the second vertex and the midpoint between the first and second vertices is estimated as the center position of the disk-shaped member, the radius error of the estimated circle is suppressed. The center position can be estimated with high accuracy.

  According to the invention of claim 6 and claim 12, one point in the first arc image existing on the first estimated circle is defined as a first vertex, and the center of the first estimated circle from the first vertex. Since the point on the second estimated circle that intersects the straight line passing through is the second vertex, and the midpoint between the first and second vertices is estimated as the center position of the disk-shaped member, the radius of the estimated circle The value error can be suppressed, and the center position can be estimated with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows roughly the image processing apparatus by Embodiment 1 of this invention, and the semiconductor manufacturing apparatus using the same. It is a block diagram which shows the structure of the image processing apparatus in FIG. It is a figure for demonstrating the example of a wafer position measurement in a transfer chamber. FIG. 4 is a side view of the transfer chamber in FIG. 3. It is a figure explaining the structure for imaging two places of a wafer outer periphery. It is a figure for demonstrating the position measurement using the one part image of a wafer outer periphery. 4 is a flowchart showing a flow of wafer center position estimation processing by the image processing apparatus according to the first embodiment; 5 is a diagram for explaining wafer center position estimation processing by the image processing apparatus according to the first embodiment; FIG. It is a figure for demonstrating the wafer center estimation process by the center position estimation part. It is a figure for demonstrating the other example of the center position estimation process of a wafer. It is a figure for demonstrating the other example of the center position estimation process of a wafer. It is a figure for demonstrating the other example of the center position estimation process of a wafer. It is a figure for demonstrating the wafer position measurement in the conveyance position of a process chamber.

Embodiment 1 FIG.
FIG. 1 is a diagram schematically showing the configuration of an image processing apparatus according to Embodiment 1 of the present invention and a semiconductor manufacturing apparatus using the same, and describes the internal configuration of the transfer chamber 4 through the top. . As shown in FIG. 1, the image processing apparatus 1 according to the first embodiment estimates the center position of a wafer (disk-shaped member) 3 in a single wafer transfer semiconductor manufacturing apparatus. The semiconductor manufacturing apparatus includes a transfer chamber (transfer vacuum chamber) 4, a process chamber (processing chamber) 5, a load / unload device 6, and a control device 8.

  The transfer chamber 4 is provided with a robot arm (transfer mechanism) 9 for transferring the wafer 3, and the robot arm 9 is used to load / unload the wafer 3 into / from the process chamber 5 and load / unload apparatus 6. The wafer 3 is transferred between them. In addition, view ports are provided at the upper and lower portions of the transfer chamber 4.

  In the example of FIG. 1, the imaging camera 2 is attached to the outside of the transfer chamber 4 via a view port provided at the top of the transfer chamber 4. In addition, transmitted illumination, which will be described later with reference to FIG. 2, is attached to the outside of the transfer chamber 4 through a view port provided in the lower part of the transfer chamber 4. This transmitted illumination can illuminate a part of the outer periphery of the wafer 3 located in the field of view a of the imaging camera 2 from directly below through the lower viewport. Thereby, the imaging camera 2 can capture an image of a part of the outer periphery of the wafer 3 illuminated with transmission illumination from directly below from above, via the upper viewport. FIG. 1 shows a case where the transfer camera 4 is provided with an imaging camera 2 and transmitted illumination corresponding to each process chamber 5 and the load / unload device 6. Thereby, each imaging camera 2 can image the wafer 3 in the visual field a.

  The process chamber 5 is provided for each type of vacuum processing such as sputtering, PVD (Physical Vapor Deposition), etcher, and CVD, and the vacuum processing is performed on the wafer 3 carried in from the transfer chamber 4. The process chamber 5 is not provided with a view port for the reason of avoiding ambient light. The transfer chamber 4 and the process chamber 5 are in a vacuum state by an exhaust system (not shown).

  The load / unload device 6 is a device that transfers the wafer 3 to and from the transfer chamber 4, and includes a wafer aligner (aligner device) 7 and a robot arm (transfer mechanism) 10 for transferring the wafer 3. . The wafer aligner 7 has an edge sensor that detects an edge portion of the wafer 3 and a rotation holding portion that adjusts the rotation direction of the wafer 3, and the rotation position (rotation angle) of the wafer 3 with respect to the orientation flat portion and the notch portion. Then, the center position of the wafer 3 is aligned (positioned) to an appropriate position. The control device 8 controls the transfer operation of the wafer 3 by the robot arms 9 and 10 according to the measurement result of the image processing device 1.

  FIG. 2 is a block diagram showing the configuration of the image processing apparatus in FIG. In FIG. 2, the image processing apparatus 1 includes an image data acquisition unit 12, a storage unit 13, a measurement unit 14, a communication control unit 19, and a misregistration inspection unit 20. The image data acquisition unit 12 is a component that functions as an interface with the imaging camera 2 and acquires image data captured by the imaging camera 2. The storage unit 13 stores the image data acquired by the image data acquisition unit 12.

  The measurement unit 14 is a component that measures the center position and rotation position (rotation angle) of the wafer 3 using the image data of the wafer 3 captured by the imaging camera 2, and includes an image cutout unit 15 and a circle estimation unit 16. A vertex calculation unit 16a, a center position estimation unit 17, and a rotation angle measurement unit 18. The image cutout unit 15 cuts out an image necessary for position measurement of the wafer 3 from the image data picked up by the image pickup camera 2. For example, in the case of an image captured within the field of view a shown in FIG. 1, an image including a part of the outer periphery of the wafer 3 is cut out from the captured image. The image data acquisition unit 12 or the image cutout unit 15 as the image input unit includes coordinate information indicating which coordinate position on the xy coordinate axis plane where the wafer 3 is present in the captured image.

  The circle estimation unit 16 obtains a relational expression indicating a circle corresponding to the outer periphery (contour) of the wafer 3 using the position measurement image cut out by the image cutout unit 15. The vertex calculation unit 16a calculates a vertex on the circle using a relational expression indicating a circle corresponding to the outer periphery of the wafer 3 obtained by the circle estimation unit 16. The center position estimation unit 17 estimates the center position of the wafer 3 using a relational expression indicating a circle corresponding to the outer periphery of the wafer 3 obtained by the circle estimation unit 16. The rotation angle measurement unit 18 measures the notch or orientation flat on the outer periphery of the wafer 3 identified from the position measurement image, the relational expression indicating the circle obtained by the circle estimation unit 16, and the center position estimation unit 17. Using the center position of the wafer 3, the rotation position (rotation angle) of the wafer 3 with respect to the notch portion or orientation flat portion is measured.

  The communication control unit 19 is a component that functions as an interface with the control device 8, and the position measurement result of the wafer 3 by the measurement unit 14 and the positional deviation amount of the wafer 3 obtained by the positional deviation inspection unit 20. Send. The positional deviation inspection unit 20 inspects the positional deviation from the position of the wafer 3 aligned by the wafer aligner 7 with respect to the position measurement result of the wafer 3 by the measurement unit 14.

  Note that the image data acquisition unit 12, the storage unit 13, the measurement unit 14, the communication control unit 19, and the misregistration inspection unit 20 described above store an image processing program in accordance with the spirit of the present invention on the CPU mounted on the image processing apparatus 1. By executing the program and controlling its operation, it can be realized as a specific means in which software and hardware cooperate.

Next, the operation will be described.
First, under the control of the control device 8, the load / unload device 6 uses the robot arm 10 to take out the wafer 3 from, for example, a wafer holding shelf (not shown) and transport it to the wafer aligner 7. The wafer aligner 7 detects an orientation flat portion or a notch portion of the wafer 3 using an edge sensor, and aligns the rotation position (rotation angle) of the wafer 3 and the center position of the wafer 3 with respect to the detected position. . Thereafter, the wafer 3 is transferred from the wafer aligner 7 to the transfer chamber 4 using the robot arm 10. In the image processing apparatus 1 according to the first embodiment, the following position measurement of the wafer 3 is performed in the transfer chamber 4.

(1) Position measurement of wafer 3 in transfer chamber 4 (1-1) When using an image obtained by capturing an arc of a position facing across the wafer center FIG. 3 illustrates an example of wafer position measurement in the transfer chamber It is a figure and the internal structure is described through the transfer chamber 4 through the top like FIG. FIG. 4 is a side view of the transfer chamber in FIG. 3, and shows the side walls in order to show the internal configuration of the transfer chamber 4. As shown in FIG. 4, the imaging camera 2 is attached to the outside of the transfer chamber 4 via the view port 4a. The transmitted illumination 11a is attached to the outside of the transfer chamber 4 through the view port 4b. 3 and 4, the same reference numerals are given to the components corresponding to those shown in FIG.

  First, the wafer 3 is transferred by the robot arm 9 in the transfer chamber 4, and a part of the outer periphery of the wafer 3 is put in the field of view a of the imaging camera 2. Next, the illumination power source (not shown) is activated to turn on the transmissive illumination 11a, and a part of the outer periphery of the wafer 3 located in the field of view a of the imaging camera 2 is directly below via the lower viewport 4b. Give lighting from. Thereafter, a part of the outer periphery of the wafer 3 illuminated by the transmission illumination 11a is imaged by the imaging camera 2 from directly above via the upper viewport 4a.

  The image data acquisition unit 12 of the image processing apparatus 1 acquires image data obtained by imaging a part of the outer periphery of the wafer 3 (a part of the outline of the wafer 3) from the imaging camera 2 and stores it in the storage unit 13. The image cutout unit 15 of the measurement unit 14 takes in the image data from the storage unit 13 and cuts out an image necessary for measuring the position of the wafer 3 from the image data. Here, a partial image including a part of the outer periphery of the wafer 3 is cut out from the image captured in the visual field a.

  Subsequently, the robot arm 9 puts a part of the outer periphery of the wafer 3 imaged previously, and the other part facing the center position in the field of view a of the imaging camera 2. Thereafter, the other part of the outer periphery of the wafer 3 illuminated by the transmission illumination 11a is imaged from directly above the view port 4a in the same manner as before, and a partial image including the other part of the outer periphery of the wafer 3 is cut out. It is.

FIG. 5 is a diagram illustrating a configuration for imaging two locations on the outer periphery of the wafer. FIG. 5A shows a part of the outer periphery (hereinafter referred to as the first arc 3 a) in the field of view a of the wafer 3 indicated by a solid line, which is imaged by the imaging camera 2, and then the wafer 3 is moved by the robot arm 9. Then, the other part of the outer periphery (hereinafter referred to as the second arc 3b) entering the field of view a of the wafer 3 indicated by a broken line is imaged by the imaging camera 2. The direction in which the wafer 3 is moved is on a coordinate axis in one direction as indicated by an arrow in the figure.
The configuration for imaging the first arc 3a and the second arc 3b may be a configuration other than that shown in FIG. 5A. For example, as shown in FIG. 5B, the position of the wafer 3 remains fixed. In this case, the imaging camera 2 and its visual field a may be moved for imaging, or as shown in FIG. 5 (c), two visual fields a are created by the two imaging cameras 2, and the first arc 3a and You may make it image the 2nd circular arc 3b at once.

  FIG. 6 is a diagram for explaining position measurement using an image of a part of the outer periphery of the wafer. FIG. 6A shows an edge image of the first arc 3a of the wafer 3, and FIG. b) shows an edge image of the second arc 3b facing the first arc 3a with the center position of the wafer 3 in between. By using the transmitted illumination 11a, as shown in FIGS. 6 (a) and 6 (b), the image in the field of view a shadows the portion of the transmitted illumination 11a as black and passes through the illumination of the transmitted illumination 11a. The portion appears white and an edge portion on the outer periphery of the wafer 3 is emphasized.

  As a result, the edge portion is not blurred due to the influence of the material of the wafer 3 and the circuit pattern formed on the wafer 3 as in the case of reflected illumination, and stable position measurement can be performed. The image cutout unit 15 extracts the first arc image 21a including the first arc 3a on the outer periphery of the wafer 3 as shown in FIG. 6A from the image picked up in the field of view a, and FIG. 6B. A second arc image 21b including the second arc 3b on the outer periphery of the wafer 3 as shown in FIG.

FIG. 7 is a flowchart showing the flow of the wafer center position estimation process performed by the image processing apparatus according to the first embodiment. Details of the process of estimating the wafer center position will be described with reference to FIG.
First, when the first circular arc image 21a and the second circular arc image 21b are input from the image cutout unit 15, the circle estimation unit 16 inputs the first circular arc image 21a and the second circular arc image 21b for each pixel column. Scanning is performed to extract the contours of the first arc 3a and the second arc 3b to create each arc information (step ST1).

  Next, the circle estimation unit 16 performs an approximate calculation such as a least square method using each obtained arc information, and in the two-dimensional coordinate system set on the wafer transfer surface of the transfer chamber 4, the entire contour of the wafer 3 is obtained. Each approximate circle to be approximated is obtained (step ST2). Thereafter, the circle estimation unit 16 obtains a deviation between the arc information and the estimated circle, and determines whether or not the maximum deviation amount is equal to or less than a predetermined value (step ST3). At this time, when the maximum value of the deviation amount is larger than the predetermined value, the process returns to step ST1 and the above-described processing is repeated. By performing this process for each of the first arc image 21a and the second arc image 21b, the first estimated circle is obtained from the arc information of the first arc image 21a, and the first estimated circle is obtained from the arc information of the second arc image 21b. Obtain 2 estimated circles. The above steps ST1 to ST3 are circle estimation steps.

  The circle estimation unit 16 repeats the processing from step ST1 to step ST3 until the estimated circle with the smallest deviation amount between the arc information and the estimated circle is obtained, so that it is the most reliable as the circle corresponding to the outer periphery of the wafer 3. Can be estimated as two circles of the first and second estimated circles. Information regarding the circle corresponding to the outer periphery of the wafer 3 thus obtained is sent from the circle estimation unit 16 to the vertex calculation unit 16a and the rotation angle measurement unit 18.

  The wafer 3 is not necessarily a perfect circle, and there may be a circle estimation error factor such as chipping or slight distortion. Therefore, in the image processing apparatus 1 according to the first embodiment, the center position of the wafer 3 is estimated using two estimated circles obtained from two arc images. First, the vertex calculation unit 16a calculates the coordinates of the first and second vertices from the equations of the first and second estimated circles corresponding to the outer periphery of the wafer 3 (step ST4).

  FIG. 8 is a diagram for explaining the wafer center position estimation process. In FIG. 8, the robot arm 9 moves the wafer 3 in the y-axis direction with respect to the fixed imaging camera 2, and the imaging camera 2 aligns the coordinate positions on the x-axis so that the first arc 3 a and the second arc are aligned. It is assumed that the first arc image 21a and the second arc image 21b are acquired by imaging 3b. Further, it is assumed that the movement of the robot arm 9 is controlled so that a straight line connecting the first arc 3a and the second arc 3b passes over the center position assumed at the time of imaging of the wafer 3 indicated by a solid line.

  In the first estimated circle 22a estimated on the basis of the first arc image 21a, the vertex calculation unit 16a sets the maximum point on the y-axis as the first vertex 23a (first vertex calculation step), In the second estimated circle 22b estimated on the basis of the arc image 21b, the point on the y-axis that is the smallest is taken as the second vertex 23b (second vertex calculation step). In FIG. 8, in order to facilitate the explanation of the center position estimation process according to the first embodiment, estimated circles 22a and 22b in which errors in circle estimation are emphasized are illustrated.

The center position estimation unit 17 obtains a midpoint between the first vertex 23a and the second vertex 23b calculated by the vertex calculation unit 16a, and estimates the midpoint as the coordinates of the center position 24 of the wafer 3 (step ST5). , Center estimation step). FIG. 9 is a diagram for explaining the wafer center position estimation processing by the center position estimation unit 17, and the portion related to the first estimated circle 22a in FIG. 8 is extracted as FIG. 9A, and FIG. A portion related to the second estimated circle 22b is extracted and shown in FIG. First, the center position estimating unit 17 calculates the center position (x1, y1) and radius r1 of the first estimated circle, and calculates the center position (x2, y2) and radius r2 of the second estimated circle 22b. At this time, the coordinate position of the first vertex 23a is (x1, y1 + r1), and the coordinate position of the second vertex 23b is (x2, y2-r2). Subsequently, the center position estimation unit 17 calculates the coordinates ((x1 + x2) / 2, (y1 + r1 + y2−r2) / 2) of the center position 24 of the wafer 3.
As described above, the maximum point on the y-axis of the wafer 3 and the first vertex 23a which is the maximum on the y-axis of the first estimated circle 22a substantially coincide with each other, and the minimum point on the y-axis of the wafer 3 Since the second vertex 23b that is the smallest on the y-axis of the second estimated circle 22b substantially matches, the actual center position of the wafer 3 and the estimated center position 24 substantially match.

(1-2) When using an image obtained by capturing an arc at a position shifted from the center of the wafer When there is an estimation error in the estimated circle, the shape of the estimated circle and the wafer 3 are well matched within the range of the arc image. As the distance from the image increases, the error of the estimated circle increases, the shape of the wafer 3 does not match, and the deviation increases. For this reason, in the example shown in FIG. 8 of (1-1) above, imaging is performed in advance so that the first arc image 21a includes the maximum point of the wafer 3 and the second arc image 21b includes the minimum point of the wafer 3. The visual field a of the camera 2 is adjusted to improve the accuracy of center position estimation. However, the center position 24 of the wafer 3 can be estimated even if the field of view a is adjusted so that the maximum and minimum points are not included in the arc image.

  FIG. 10 is a diagram for explaining the center position estimation process of the wafer, and shows a case where the maximum point and the minimum point of the wafer 3 are not included in the arc image. As shown in FIG. 10, when an arc of a position slightly deviated from the maximum point and the minimum point of the wafer 3 is imaged, the first estimated circle 22a is displaced from the wafer 3 as the distance from the first arc image 21a increases. Increase. The vertex calculation unit 16a selects the maximum point of the first estimated circle 22a as the first vertex 23a, but there is a slight deviation from the maximum point of the wafer 3, and similarly the second vertex 23b is selected as the second vertex 23b. The estimated circle 22b of 2 is slightly deviated from the minimum point of the wafer 3. Therefore, the estimated center position 24 is also shifted. From this, the estimation error of the center position 24 can be suppressed as the visual field a for capturing the first arc image 21a and the second arc image 21b is closer to the maximum point and the minimum point of the wafer 3.

(1-3) When using an image obtained by imaging an arc at an arbitrary position on the outer periphery of the wafer 1
The image processing apparatus 1 can also estimate the center position 24 of the wafer 3 by another method. FIG. 11 is a diagram for explaining the wafer center position estimation processing. As shown in FIG. 11, when the first arc image 21a and the second arc image 21b are acquired from arbitrary outer peripheral positions of the wafer 3, the vertex calculation unit 16a is included in the range of the first arc image 21a. One point is extracted from the arc to be taken as the first vertex 23a. Next, the vertex calculation unit 16a sets a second point on the second estimated circle 22b that intersects with a straight line passing from the first vertex 23a to the center of the first estimated circle 22a (broken cross in FIG. 11). Let apex 23b of. As described above, in the method (1-3), the vertex is not necessarily the maximum point and the minimum point of the wafer 3, and the center position estimation accuracy is not affected even if the vertex is not the maximum point or the minimum point.
Similarly to the above (1-1), the center position estimation unit 17 obtains a midpoint between the first vertex 23a and the second vertex 23b calculated by the vertex calculation unit 16a, and uses this midpoint as the center position 24 of the wafer 3. Estimate the coordinates.

  In the case of this estimation method, the first arc image 21a and the second arc image 21b may be captured at arbitrary positions, but the center with respect to the arc sandwiched between the first vertex 23a and the second vertex 23b. If the angle is adjusted to be within 90 degrees, the estimation error of the center position 24 can be suppressed. Further, this estimation method will be described in (1-1) with reference to FIG. 8 when the first arc image 21a and the second arc image 21b are at positions facing each other across the center position of the wafer 3. The estimation method is substantially the same.

(1-3) When using an image obtained by imaging an arc at an arbitrary position on the outer periphery of the wafer 2
Furthermore, the center position 24 of the wafer 3 can be estimated by another method. FIG. 12 is a diagram for explaining the wafer center position estimation process. As shown in FIG. 12, when the first arc image 21a and the second arc image 21b are acquired from arbitrary outer peripheral positions of the wafer 3, the vertex calculation unit 16a is included in the range of the first arc image 21a. One point is extracted from the circular arc shape to be the first vertex 23a. Similarly, the vertex calculation unit 16a extracts one point from the arc shape included in the range of the second arc image 21b and sets it as the second vertex 23b. The center position estimator 17 includes a straight line passing from the first vertex 23a to the center of the first estimated circle 22a (broken line in FIG. 12), and the center of the second estimated circle 22b from the second vertex 23b ( An intersection point with a straight line passing through a cross-dotted line in FIG. 12 is obtained, and this intersection point is estimated as a coordinate of the center position 24 of the wafer 3.

  In the case of this estimation method, the first arc image 21a and the second arc image 21b may be captured at arbitrary positions, but the center with respect to the arc sandwiched between the first vertex 23a and the second vertex 23b. If the angle is adjusted to be within 90 degrees, the estimation error of the center position 24 can be suppressed. Further, in this estimation method, the first arc image 21a and the second arc image 21b are located at positions facing each other across the center position of the wafer 3, that is, as shown in FIG. 8 of (1-1). Since the straight line passing through the center of the first estimated circle 22a from the first vertex 23a and the straight line passing through the center of the second estimated circle 22b from the second vertex 23b do not intersect at one point, the center position 24 cannot be estimated.

  The coordinate data of the center position 24 of the wafer 3 is sent from the center position estimation unit 17 to the rotation angle measurement unit 18, the communication control unit 19, and the misalignment inspection unit 20. The rotation angle measurement unit 18 calculates the rotation angle θ of the wafer 3 (the rotation position of the wafer 3 with reference to the notch 22 with respect to a predetermined reference position) using information on the estimated circle having the center position 24. Since a known method may be used as the calculation method of the rotation angle θ, a detailed description of the rotation angle measurement unit 18 is omitted.

  The rotation angle θ of the wafer 3 obtained in this way is sent from the rotation angle measurement unit 18 to the communication control unit 19 and the misregistration inspection unit 20 as a position measurement result of the wafer 3 by the measurement unit 14. In the communication control unit 19, the information about the center position of the wafer 3 acquired from the center position estimation unit 17 and the information about the rotation position of the wafer 3 acquired from the rotation angle measurement unit 18 are used as the position measurement result of the wafer 3 by the measurement unit 14. Transmit to the control device 8.

  For example, an appropriate wafer position is registered in the control device 8 in advance, and whether the wafer 3 is misaligned by comparing the appropriate wafer position with the position measurement result of the wafer 3 by the measurement unit 14. Determine. If the wafer 3 is misaligned, the controller 8 controls the robot arm 9 (or robot arm 10) to correct the center position of the wafer 3, or returns to the wafer aligner 7 to include the rotational position. Align the position.

  In the above description, the case where the position measurement is performed on the wafer 3 before being loaded into the process chamber 5 has been shown. However, at the same position of the transfer chamber 4 before being loaded into the process chamber 5 and after unloading from the process chamber 5. The center position and rotation position of the wafer 3 may be measured. In this case, the misalignment inspecting unit 20 acquires the measurement result of the wafer position before and after the wafer 3 is loaded into the process chamber 5 from the measuring unit 14 and compares them to inspect the misalignment. When this positional deviation is large, there is a possibility that the center position of the wafer 3 in the process chamber 4 is not at an appropriate place, that is, processing irregularity of the wafer 3 may occur. For this reason, when the positional deviation is large, an alarm may be transmitted from the image processing apparatus 1 to the control apparatus 8.

  By transmitting the inspection result (position displacement amount or the like) to the control device 8 as correction data, the position displacement before and after the wafer 3 is loaded into the process chamber 5 can be corrected. In this way, by measuring the position of the wafer 3 before and after the vacuum processing and correcting the positional deviation, various vacuum processing can be continuously performed on the same wafer 3 with good position reproducibility.

(2) Misalignment Inspection in the Transport Process of the Wafer 3 Positionally Corrected by the Wafer Aligner 7 First, the misalignment inspection unit 20 includes the center position of the wafer 3 aligned by the wafer aligner 7 by the load / unload apparatus 6 and The rotation position (rotation angle) is acquired, and the center position and rotation position (rotation angle) of the wafer 3 measured by the measurement unit 14 in the transfer chamber 4 are acquired as described in (1) above. Thereafter, the misalignment inspection unit 20 compares the position of the wafer 3 aligned by the wafer aligner 7 with the measurement result by the measurement unit 14, and determines the measurement unit 14 from the position of the wafer 3 aligned by the wafer aligner 7. It is determined how much the measurement result by the position shifts.

  Here, when the measurement result by the measurement unit 14 does not coincide with the position of the wafer 3 aligned by the wafer aligner 7, the misalignment inspection unit 20 determines that the misalignment has occurred in the wafer transfer process in the transfer chamber 4. Then, the amount of displacement is calculated. The calculation result of the misregistration amount is transmitted from the misregistration inspection unit 20 to the control device 8 via the communication control unit 19.

  When receiving the calculation result of the positional deviation amount from the image processing apparatus 1, the control device 8 controls the robot arm 9 (or the robot arm 10) to correct the center position of the wafer 3 so as to eliminate this positional deviation. Then, the wafer aligner 7 is returned to align the position including the rotational position. By doing so, it is possible to correct the positional deviation in the process of transporting the wafer 3.

(3) Measurement of wafer position at the transfer position of the process chamber When a view port is provided in the process chamber 5 where vacuum processing such as film formation processing on the wafer is performed, depending on the vacuum processing executed inside the process chamber 5 The processing material may adhere to the window material of the viewport, or the result of the vacuum processing may be affected by disturbance light incident inside through the viewport. For this reason, a configuration in which a view port is not provided in the process chamber 5 has become a trend. On the other hand, it is important to confirm whether or not a positional deviation occurs between the transfer chamber 4 and the process chamber 5 before the wafer 3 is transferred, in order to improve the position reproducibility of the wafer 3.

  Therefore, before the process chamber 5 is assembled, the wafer 3 is transferred to the position of the process chamber 5 by the robot arm 9 of the transfer chamber 4 using the image processing apparatus 1 according to the first embodiment. The position measurement is performed, and it is confirmed whether or not a positional deviation has occurred before the wafer 3 is transferred to the process chamber 5.

  FIG. 13 is a view for explaining the wafer position measurement at the transfer position of the process chamber. Similarly to FIG. 1, the transfer chamber 4 is seen through from above and its internal configuration is described. In FIG. 13, the same reference numerals are assigned to the components corresponding to those shown in FIG. In the example shown in FIG. 13, only a cylindrical structure part serving as a side wall of the process chamber 5 is connected to the transfer chamber 4, and a lid-like flange to which an upper configuration in the process chamber 5 is attached to the cylindrical structure part; The position of the wafer 3 is measured before the bottom plate-like flange to which the lower structure is attached is attached.

  The imaging camera 2 is arranged on the opening side of the upper part of the cylindrical structure part of the process chamber 5 to which the lid-like flange is attached, and the transmitted illumination is provided in the lower opening of the cylindrical structure part to which the bottom plate-like flange is attached. Deploy.

  As shown in FIG. 13, the wafer 3 is transferred to the process chamber 5 before assembling using the robot arm 9. At this transfer position, the portions corresponding to the first arc and the second arc of the wafer 3 are positioned in the field of view a of the imaging camera 2, and the center position measuring unit is processed in the same procedure as described in the above (1). 17 estimates the center position using images obtained by imaging the first arc and the second arc of the wafer 3. The position measurement result obtained in this way is sent from the image processing device 1 to the control device 8. Thereby, the conveyance accuracy of the robot arm 9 can be inspected.

  Thus, using the position measurement result in the stage transferred to the process chamber 5 together with the position measurement result in the transfer chamber 4 shown in the above (1), it is confirmed whether the wafer 3 is transferred to an appropriate position. However, when the positional deviation is large, it is possible to realize wafer transfer with stable positional accuracy in the transfer system in the semiconductor manufacturing apparatus by correcting the defect of the transfer system (for example, robot arm). It is possible to improve the quality of the semiconductor manufactured by using it.

  As described above, according to the first embodiment, the image processing apparatus 1 uses the coordinates of an arc image of an arbitrary range of the wafer 3 captured by the imaging camera 2 on the basis of at least the y axis in a predetermined direction. The first arc image 21a defining the position and the arc image of a range at least partially different from the arbitrary range of the wafer 3 imaged by the imaging camera 2 are displayed on the coordinates with respect to the y-axis. The first arc information is extracted from the image data acquisition unit 12 and the image cutout unit 15 to be captured as the prescribed second arc image 21b and the first arc image 21a, and the first arc information is extracted based on the first arc information. While obtaining the estimated circle 22a, extracting the second arc information from the second arc image 21b and obtaining the second estimated circle 22b based on the second arc information, on the coordinates, First guess The maximum point on the circle 22a or the maximum point on the second estimated circle is the first vertex 23a, and the minimum point on the first estimated circle 22a or the minimum point on the second estimated circle 22b is the second vertex. And a center position estimating unit 17 for obtaining a midpoint between the first vertex 23 a and the second vertex 23 b and estimating the midpoint as the center position 24 of the wafer 3. It was configured as follows. For this reason, it is possible to suppress an error in the radius value of the estimated circle and to estimate the center position 24 of the wafer 3 with high accuracy.

  In addition, according to the first embodiment, the circle estimation unit 16 obtains the first estimated circle 22a from the arc image having a large coordinate position among the first arc image 21a and the second arc image 21b, and The second estimated circle 22b is obtained from the arc image with a small coordinate position, and the vertex calculation unit 16a sets the maximum point on the first estimated circle 22a as the first vertex 23a on the coordinates, and the second estimate. The minimum point on the circle 22b is configured as the second vertex 23b. For this reason, since the maximum point and the minimum point included in the arc image in which the estimation error of the estimated circle is small are the first vertex and the second vertex, the radius value error of the estimated circle can be further suppressed, and the center position of the wafer 3 can be suppressed. 24 can be estimated with higher accuracy.

  In addition, according to the first embodiment, the circle estimation unit 16 uses the first arc image 21a captured with the coordinate positions on the x-axis substantially aligned in the two-dimensional xy coordinates set on the wafer transfer surface, and The second arc image 21b is used. For this reason, the shift of the center position of the two estimated circles in the x-axis direction hardly occurs, and the estimation accuracy of the center position 24 of the wafer 3 in the x-axis direction can be improved.

  Further, according to the first embodiment, the circle estimation unit 16 calculates the center position (x1, y1) and radius r1 of the first estimated circle 22a, and the center position (x2) of the second estimated circle 22b. , Y2) and the radius r2, and the center position estimating unit 17 is configured to estimate the position ((x1 + x2) / 2, (y1 + r1 + y2-r2) / 2) as the center position of the disk-shaped member. Therefore, the center position 24 of the wafer 3 can be easily estimated with high accuracy from the center positions and radii of the two estimated circles.

  Further, according to the first embodiment, the image processing apparatus 1 uses the arc image of the arbitrary range of the wafer 3 imaged by the imaging camera 2 as the first arc image 21 a and the image processing apparatus 1 images the image processing apparatus 1. The image data acquisition unit 12 and the image cutout unit 15 that capture the arc image of the wafer 3 in a range that is at least partially different from the arbitrary range as the second arc image 21b, and the first arc information from the first arc image 21a. The first estimated circle 22a is obtained based on the first arc information, and the second arc information is extracted from the second arc image 21b, and the second arc information is extracted based on the second arc information. The circle estimation unit 16 for obtaining the estimated circle 22b, and extracting one point in the first arc image 21a existing on the first estimated circle 22a to be the first vertex 23a, and from the first vertex 23a First estimated circle 2 a vertex calculator 16a having a point on the second estimated circle 22b intersecting with a straight line passing through the center of a as a second vertex 23b, and a midpoint between the first vertex 23a and the second vertex 23b, A center position estimation unit 17 that estimates the midpoint as the center position 24 of the wafer 3 is provided. For this reason, the radius value error of the estimated circle can be suppressed, and the center position 24 of the wafer 3 can be estimated with high accuracy.

  Further, according to the first embodiment, the image processing apparatus 1 uses the arc image of the arbitrary range of the wafer 3 imaged by the imaging camera 2 as the first arc image 21 a and the image processing apparatus 1 images the image processing apparatus 1. The image data acquisition unit 12 and the image cutout unit 15 that capture the arc image of the wafer 3 in a range that is at least partially different from the arbitrary range as the second arc image 21b, and the first arc information from the first arc image 21a. The first estimated circle 22a is obtained based on the first arc information, and the second arc information is extracted from the second arc image 21b, and the second arc information is extracted based on the second arc information. The circle estimation unit 16 for obtaining the estimated circle 22b, and extracting one point in the first arc image 21a existing on the first estimated circle 22a to be the first vertex 23a, and the second estimated circle 22b The second existing above A vertex calculation unit 16a that extracts one point in the arc image 21b and sets it as the second vertex 23b, a straight line passing through the center of the first estimated circle 22a from the first vertex 23a, and the second vertex 23b The center position estimator 17 for estimating the intersection point with the straight line passing through the center of the second estimated circle 22b and the center position 24 of the wafer 3 is provided. For this reason, the radius value error of the estimated circle can be suppressed, and the center position 24 of the wafer 3 can be estimated with high accuracy.

  In the first embodiment, the semiconductor manufacturing apparatus having the wafer aligner 7 has been described as an example. However, when the positional accuracy within the range adjustable by the robot arm 9 is allowed, the image processing apparatus 1 is used. Since the desired position of the wafer 3 can be corrected based on the measurement result obtained by the above, it is possible to omit the wafer aligner 7 in addition to the misalignment inspection unit 20.

  In the first embodiment, the configuration has been described in which the imaging camera 2 is attached to the viewport side provided in the upper part of the transfer chamber 4 and the transmission illumination 11 is attached to the viewport side provided in the lower part of the transfer chamber 4. The imaging camera 2 may be attached to the lower viewport side of the transfer chamber 4 and the transmission illumination 11 may be attached to the upper viewport side of the transfer chamber 4.

Furthermore, in the first embodiment, the case where the present invention is applied to a single-wafer type semiconductor manufacturing apparatus has been described. However, the application of the present invention is not limited to a single-wafer type semiconductor manufacturing apparatus.
Moreover, although the case where the semiconductor wafer was used as the object of center position estimation was shown in the first embodiment, the present invention is not limited to this, and any disk-shaped member may be used.

DESCRIPTION OF SYMBOLS 1 Image processing apparatus 2, 2a Imaging camera 3 Wafer 3a, 3b 1st, 2nd circular arc 4 Transfer chamber 4a, 4b Viewport 5 Process chamber 6 Load / unload apparatus 7 Wafer aligner 8 Control apparatus 9 Robot arm 10 Robot arm 11 Transmitted illumination 12 Image data acquisition unit (image input unit)
13 storage unit 14 measurement unit 15 image cutout unit (image input unit)
16 circle estimation unit 16a vertex calculation unit 17 center position estimation unit 18 rotation angle measurement unit 19 communication control unit 20 misalignment inspection unit 21a, 21b first and second circular arc images 22a, 22b first and second estimation circles 23a , 23b First and second vertices 24 Center position

Claims (12)

Using an arc image obtained by imaging a part of the disk-shaped member by the imaging means, arc information indicating the outline of the arc is extracted to obtain an estimated circle, and the center position of the disk-shaped member is estimated using the estimated circle Center position estimation method,
An image in which an arc of an arbitrary range of the disk-shaped member is imaged by the imaging unit is defined as a first arc image that defines a coordinate position with respect to at least one axis in a predetermined direction. 1 arc information is extracted to obtain a first estimated circle based on the first arc information, and the imaging means captures an arc of a disc-shaped member in a range that is at least partially different from the arbitrary range. Based on the second arc information, the second arc information is extracted from the second arc image, the second arc image defining a coordinate position with respect to the one axis. A circle estimation step for obtaining a second estimated circle,
On the coordinates, a first vertex calculation step in which a maximum point on the first estimated circle or a maximum point on the second estimated circle is a first vertex;
A second vertex calculation step using the minimum point on the first estimated circle or the minimum point on the second estimated circle on the coordinates as a second vertex;
Center position estimation of a disk-shaped member characterized by comprising a center estimation step of obtaining a midpoint between the first vertex and the second vertex and estimating the midpoint as the center position of the disk-shaped member. Method. The center position estimation method according to claim 1,
In the circle estimation step, a first estimated circle is obtained from an arc image having a large coordinate position among the first arc image and the second arc image, and a second estimated circle is obtained from the arc image having a small coordinate position. ,
In the first vertex calculation step, the maximum point on the first estimated circle is the first vertex on the coordinates,
In the second vertex calculation step, a center position estimation method for a disk-shaped member, wherein the minimum point on the second estimated circle is the second vertex on the coordinates. In the center position estimation method according to claim 1 or 2,
In the circle estimation step, it is assumed that one axis in a predetermined direction is a y-axis, an axis orthogonal to the predetermined one axis is an x-axis, and the first image is captured with the coordinate positions on the x-axis substantially aligned. The center position estimation method of a disk-shaped member characterized by using the circular arc image and the second circular arc image. In the center position estimation method according to claim 3,
In the center estimation step, the center position (x1, y1) and radius r1 of the first estimated circle are calculated, and the center position (x2, y2) and radius r2 of the second estimated circle are calculated to obtain the position (( x1 + x2) / 2, (y1 + r1 + y2-r2) / 2) is estimated as the center position of the disk-shaped member. Using an arc image obtained by imaging a part of the disk-shaped member by the imaging means, arc information indicating the outline of the arc is extracted to obtain an estimated circle, and the center position of the disk-shaped member is estimated using the estimated circle Center position estimation method,
Based on the first arc information, first arc information is extracted from the first arc image using a first arc image in which an arc of an arbitrary range of the disk-shaped member is imaged by the imaging means. A first estimated circle is obtained, and the second arc image is obtained by using a second arc image obtained by imaging an arc of a disc-shaped member at least partially different from the arbitrary range by the imaging means. Extracting a second arc information from the circle and obtaining a second estimated circle based on the second arc information;
A first vertex calculation step of extracting one point in the first arc image existing on the first estimated circle as a first vertex;
A second vertex calculation step in which a point on the second estimated circle that intersects with a straight line passing through the center of the first estimated circle from the first vertex is a second vertex;
Center position estimation of a disk-shaped member characterized by comprising a center estimation step of obtaining a midpoint between the first vertex and the second vertex and estimating the midpoint as the center position of the disk-shaped member. Method. Using an arc image obtained by imaging a part of the disk-shaped member by the imaging means, arc information indicating the outline of the arc is extracted to obtain an estimated circle, and the center position of the disk-shaped member is estimated using the estimated circle Center position estimation method,
Based on the first arc information, first arc information is extracted from the first arc image using a first arc image in which an arc of an arbitrary range of the disk-shaped member is imaged by the imaging means. A first estimated circle is obtained, and the second arc image is obtained by using a second arc image obtained by imaging an arc of a disc-shaped member at least partially different from the arbitrary range by the imaging means. Extracting a second arc information from the circle and obtaining a second estimated circle based on the second arc information;
A first vertex calculation step of extracting one point in the first arc image existing on the first estimated circle as a first vertex;
A second vertex calculation step of extracting one point in the second arc image existing on the second estimated circle as a second vertex;
The intersection of a straight line passing from the first vertex to the center of the first estimated circle and a straight line passing from the second vertex to the center of the second estimated circle is estimated as the center position of the disk-shaped member. The center position estimation method of the disk-shaped member characterized by comprising the center estimation step to perform. Image processing for obtaining an estimated circle by extracting arc information indicating the outline of the arc using the arc image of the disc-like member imaged by the imaging means, and estimating the center position of the disc-like member using the estimated circle A device,
An arc image in an arbitrary range of the disk-shaped member imaged by the imaging unit is used as a first arc image that defines a position on coordinates with reference to at least one axis in a predetermined direction, and is captured by the imaging unit. An image input unit that captures an arc image of a range that is at least partially different from the arbitrary range of the disk-shaped member as a second arc image that defines a position on coordinates with respect to the one axis;
First arc information is extracted from the first arc image, a first estimated circle is obtained based on the first arc information, and second arc information is extracted from the second arc image. A circle estimation unit for obtaining a second estimated circle based on the second arc information;
On the coordinates, the maximum point on the first estimated circle or the maximum point on the second estimated circle is set as the first vertex, and the minimum point on the first estimated circle on the coordinates Or a vertex calculation unit having a minimum point on the second estimated circle as a second vertex;
An image processing apparatus comprising: a center position estimation unit that obtains a midpoint between the first vertex and the second vertex and estimates the midpoint as a center position of the disk-shaped member. The image processing apparatus according to claim 7.
The circle estimation unit obtains a first estimated circle from an arc image having a large coordinate position among the first arc image and the second arc image, and obtains a second estimated circle from the arc image having a small coordinate position. ,
The vertex calculation unit is characterized in that, on the coordinates, the maximum point on the first estimated circle is the first vertex, and the minimum point on the second estimated circle is the second vertex. An image processing apparatus. The image processing apparatus according to claim 7 or 8,
The circle estimation unit assumes that one axis in a predetermined direction is a y-axis, and an axis orthogonal to the predetermined one axis is an x-axis, and the first image is obtained with the coordinate positions on the x-axis being substantially aligned. An image processing apparatus using the arc image and the second arc image. The image processing apparatus according to claim 9.
The circle estimation unit calculates the center position (x1, y1) and radius r1 of the first estimated circle, calculates the center position (x2, y2) and radius r2 of the second estimated circle,
The center position estimation unit estimates the position ((x1 + x2) / 2, (y1 + r1 + y2-r2) / 2) as the center position of the disk-shaped member. Image processing for obtaining an estimated circle by extracting arc information indicating the outline of the arc using the arc image of the disc-like member imaged by the imaging means, and estimating the center position of the disc-like member using the estimated circle A device,
An arc image of an arbitrary range of the disk-shaped member imaged by the imaging unit is used as a first arc image, and at least a part of the disk-shaped member imaged by the imaging unit is different from the arbitrary range. An image input unit that captures an arc image as a second arc image;
First arc information is extracted from the first arc image, a first estimated circle is obtained based on the first arc information, and second arc information is extracted from the second arc image. A circle estimation unit for obtaining a second estimated circle based on the second arc information;
One point in the first circular arc image existing on the first estimated circle is extracted as a first vertex, and a straight line passing from the first vertex to the center of the first estimated circle; A vertex calculation unit that intersects a point on the second estimated circle as a second vertex;
An image processing apparatus comprising: a center position estimation unit that obtains a midpoint between the first vertex and the second vertex and estimates the midpoint as a center position of the disk-shaped member. Image processing for obtaining an estimated circle by extracting arc information indicating the outline of the arc using the arc image of the disc-like member imaged by the imaging means, and estimating the center position of the disc-like member using the estimated circle A device,
An arc image of an arbitrary range of the disk-shaped member imaged by the imaging unit is used as a first arc image, and at least a part of the disk-shaped member imaged by the imaging unit is different from the arbitrary range. An image input unit that captures an arc image as a second arc image;
First arc information is extracted from the first arc image, a first estimated circle is obtained based on the first arc information, and second arc information is extracted from the second arc image. A circle estimation unit for obtaining a second estimated circle based on the second arc information;
One point in the first circular arc image existing on the first estimated circle is extracted as a first vertex, and in the second circular arc image existing on the second estimated circle A vertex calculation unit that extracts one point as a second vertex;
The intersection of a straight line passing from the first vertex to the center of the first estimated circle and a straight line passing from the second vertex to the center of the second estimated circle is estimated as the center position of the disk-shaped member. An image processing apparatus comprising: a center position estimating unit that performs the processing.

Images