JP4884345B2 - Image processing device - Google Patents

Description

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

  In recent years, in order to reduce the variation in the characteristics of a film formed on a semiconductor wafer (hereinafter simply referred to as a wafer), the center position of the wafer and the orientation flat part or notch part in the vacuum chamber of the semiconductor manufacturing apparatus are used as a reference part. Improvement in reproducibility of the rotation position (rotation angle) of the wafer is strongly demanded.

  For example, in a vacuum chamber of a semiconductor manufacturing apparatus such as a sputtering apparatus, a shield is provided so as to cover the outer edge of the wafer film forming side in order to prevent sputter particles from entering the back surface side where the wafer film is not formed. Is provided. This shield tends to reduce the area of the portion covering the outer edge of the wafer in order to increase the number of semiconductor chips due to recent demands for improving production efficiency. In this way, when the area of the shield that covers the outer edge of the wafer is reduced, if the center position of the wafer is not accurately placed, a gap will be created between the shield and the wafer, and sputtered particles will wrap around the wafer backside, resulting in quality. There is a possibility that it will be a factor of deterioration, and conversely, the part of the wafer where the original film should be formed may be hidden behind the shield and the production efficiency may be reduced.

  In addition, in a semiconductor manufacturing apparatus that forms a film by introducing a reaction gas onto a wafer heated in a vacuum chamber, such as CVD (Chemical Vapor Deposition), the film forming surface must be heated unless the film forming surface of the wafer is uniformly heated. Processing irregularities occur in the film, and the film characteristics deteriorate. In order to eliminate this processing unevenness, the center position of the wafer must always be arranged at an appropriate position in the vacuum chamber, and the positional relationship between the wafer to be uniformly heated and the heater must be accurately reproduced.

  As described above, the accuracy of the wafer center position in the vacuum chamber of the semiconductor manufacturing apparatus and the rotation position of the wafer with reference to the orientation flat part, the notch part, etc. has a great influence on the quality of the semiconductor chip manufactured from the wafer. For this reason, a technique for correcting the position by measuring the wafer position in a vacuum chamber of a semiconductor manufacturing apparatus has been proposed.

  For example, Patent Document 1 discloses a vapor phase growth apparatus provided with an image processing apparatus that measures the position of a reaction system in a vacuum chamber by image processing. In this vapor phase growth apparatus, a reaction gas is introduced by heating a polygonal pyramidal susceptor, which is a substrate holding structure with a wafer attached to each outer surface, while rotating coaxially with its central axis in a bell-shaped reactor. As a result, a film is formed on the wafer. Further, this vapor phase growth apparatus is provided with an image pickup means, an image processing means, and a pressing position deviation correction means as means for measuring the position of the reaction system in the vacuum chamber and correcting the position.

  The image capturing means is an image capturing means for keeping the top of the susceptor within the field of view, and is provided outside the reactor via a viewport formed at the top of the reactor. The image processing means calculates the distance (susceptor misalignment) between the center of the top of the susceptor and the central axis of the reactor, using the image of the top of the susceptor captured by the image capturing means. The pressing-type misalignment correcting unit corrects the position by pressing the susceptor so as to eliminate the misalignment calculated by the image processing unit. By correcting the position shift of the susceptor by these means, in the vapor phase growth apparatus of Patent Document 1, the flow velocity distribution of the reaction gas becomes uniform between the reactor inner wall and the susceptor outer surface, and the film characteristics on the wafer are improved. Variation can be reduced.

  Patent Document 2 discloses a positioning method for determining a wafer position by performing image processing on an image obtained by imaging a plurality of points on the outer periphery of the wafer. Specifically, the observation field of view of the two-dimensional image processing apparatus is set at a plurality of locations on the wafer including notches or orientation flats (hereinafter referred to as orientation flats) of the wafer. A virtual position corresponding to the contact position with the reference pin of the contact type pre-alignment mechanism (rough positioning mechanism) is set in each observation field, and the wafer measurement point in each observation field is determined from the virtual position described above. The offset in the X direction, the offset in the Y direction, and the error of the rotational position of the wafer are obtained from the amount of positional deviation.

  For example, one measurement point by the two-dimensional image processing apparatus is set at one notch portion of the wafer and two locations at the other outer peripheral portion, and the wafer position is detected by detecting the position of the wafer at these three measurement points. A position and a two-dimensional position can be specified. On the other hand, two measurement points by the two-dimensional image processing apparatus are set in the orientation flat part of the wafer and one in the other outer peripheral part, and the wafer rotation is detected by detecting the position of the wafer at these three measurement points. A position and a two-dimensional position can be specified.

  Furthermore, the positional deviation detection device disclosed in Patent Document 3 includes three contour detection sensors arranged to detect edge positions excluding the notch portion and orientation flat portion of the wafer, and detection values of the three contour detection sensors. And a deviation amount calculation unit for obtaining a deviation amount between the center position of the wafer and the reference origin. In the misregistration detection apparatus of Patent Document 3, by detecting the positions of three points on the contour of the wafer with three contour detection sensors, the presence or absence of misalignment of the wafer without being affected by wafer manufacturing errors and thermal expansion and contraction. In addition, the amount of displacement can be obtained.

JP-A-8-264461 Japanese Patent Laid-Open No. 9-186061 JP 2002-43394 A

  In Patent Document 1, the top of the susceptor is imaged through the viewport provided at the top of the reactor. However, depending on the processing executed in the reactor, the reactant may adhere to the window material of the viewport and imaging may become impossible. There is. In addition, in the configuration in which the view port is provided in the reactor, it is not possible to perform processing that is easily affected by ambient light.

  In recent years, in addition to a so-called batch type semiconductor manufacturing apparatus in which a plurality of wafers are processed at once in a reactor as in Patent Document 1, a single-wafer type semiconductor manufacturing apparatus is widely used. This single wafer transfer semiconductor manufacturing apparatus includes a process chamber for performing film formation processing on a wafer and a transfer chamber provided with a robot arm for wafer transfer. The robot arm moves from the transfer chamber to the process chamber. Processing is performed by transferring wafers one by one.

  The wafer conveyance accuracy by the robot arm of the transfer chamber strongly affects the accuracy of the center position and rotation position of the wafer in the process chamber. For this reason, a single wafer transfer semiconductor manufacturing apparatus needs to be able to inspect and correct misalignment by measuring the center position and rotation position of a wafer transferred by a robot arm. However, in Patent Document 1, since only the image of the top of the susceptor is used, it cannot be directly applied to a single wafer transfer semiconductor manufacturing apparatus.

  Further, in Patent Document 2, since the position of the wafer is measured by imaging the notch part or orientation flat part of the wafer and other measurement points of the outer peripheral part, it is applicable to a semiconductor manufacturing apparatus of single wafer transfer. is there. However, in order to image the measurement points of the notch part or orientation flat part of the wafer and other outer peripheral parts, a plurality of viewports or large-diameter viewports that provide an observation visual field including these measurement points are required.

  Further, the positional deviation detection apparatus of Patent Document 3 requires three contour detection sensors for detecting three points on the wafer contour. In addition, since the points on the contour excluding the notch portion and orientation flat portion of the wafer are detected, if there is a chip or the like on the wafer contour, the wafer contour cannot be detected accurately, and the measurement result There is a possibility that the center position of will be greatly shifted.

  The present invention has been made to solve the above-described problems. In a single wafer transfer semiconductor manufacturing apparatus for transferring wafers one by one, the center position and rotation position (rotation angle) of the wafer are accurately determined. An object of the present invention is to obtain an image processing apparatus capable of measuring and confirming a positional deviation.

The image processing apparatus according to the present invention is used for the following vacuum processing apparatus, and the vacuum processing apparatus includes a processing chamber for processing a processing target and a processing target transport mechanism. And a transfer vacuum chamber for loading and unloading the processing object. In the image processing apparatus used for measuring the position of the processing object of the vacuum processing apparatus, at least the contour of the processing object is installed via a viewport provided outside the transfer vacuum chamber and provided in the transfer vacuum chamber. One imaging camera that captures an image including a line, a plurality of contour position data indicating points on the contour line of the processing object extracted from the image captured by the imaging camera, and 3 of the contour position data After obtaining a relational expression indicating the contour of the object to be processed using points, a deviation between each contour position data and the relational expression indicating the contour is obtained, and the maximum value of the deviation amount is larger than a predetermined value. with case obtaining a relational expression indicating a new profile by changing the combination of the three points of the contour position data, when the maximum value of the shift amount is less than the predetermined value, the Those comprising measuring means for measuring the position of the processing object based on the engagement equation.

  An image processing apparatus according to the present invention includes an imaging camera that captures an image including at least a contour line of a processing object conveyed to a position of a processing chamber, and a measuring unit is positioned at the position of the processing chamber captured by the imaging camera. Using the contour position data of the processing object extracted from the conveyed processing object image, a relational expression indicating the contour of the processing target is obtained, and the position of the processing target is measured based on this relational expression. is there.

  The image processing apparatus according to the present invention compares the position measurement results of the processing object measured by the measuring means at the same position in the transfer vacuum chamber before being transferred into the processing chamber and after being transferred out of the processing chamber. A misalignment inspection means for inspecting misalignment is provided.

  In the image processing apparatus according to the present invention, the positional deviation inspection means compares the position information of the processing object aligned by the aligner device provided in the vacuum processing apparatus and the position measurement result of the processing object by the measuring means. This is to inspect the misalignment.

  The image processing apparatus according to the present invention provides a position measurement result or displacement of a processing object by a measuring unit as operation correction data for the transport mechanism, with respect to a control device that controls the operation of the transport mechanism provided in the vacuum processing apparatus. Communication control means for transmitting the result of the positional deviation inspection by the inspection means is provided.

  In the image processing apparatus according to the present invention, the processing object has a disk shape in which a reference portion is formed on the outer periphery, and the contour position of the processing object extracted from the image captured by the imaging camera by the measuring unit A circle estimation means for obtaining a relational expression indicating the contour circle of the processing object using the data, a center position measuring means for calculating the center position of the processing object based on the relational expression obtained by the circle estimation means, Rotation that calculates the angle formed by the first reference line that passes through the center position and the reference portion obtained by the position measuring means and the second reference line that passes through the center position and a predetermined reference position as the rotation position of the processing object. And an angle measuring means.

  In the image processing apparatus according to the present invention, the measurement unit obtains a relational expression that approximates the entire contour of the processing object using the contour position data extracted from the image including a part of the contour line of the processing object, The position of the processing object is measured based on the relational expression.

  In the image processing apparatus according to the present invention, the measurement unit obtains a relational expression indicating the contour of the processing target using the contour position data extracted from the image including the entire contour of the processing target, and based on the relational expression. The position of the processing object is measured.

  The image processing apparatus according to the present invention includes transmission illumination means for illuminating from the back side of the processing object, and the measurement means is imaged from the surface side of the processing object illuminated by the transmission illumination means by the imaging camera. The position of the processing object is measured using the obtained image.

  The image processing apparatus according to the present invention includes a transmission illumination unit that provides illumination from the front side of the processing object, and the measurement unit is imaged from the back side of the processing object that is illuminated by the transmission illumination unit by the imaging camera. The position of the processing object is measured using the obtained image.

  According to the present invention, one image pickup camera that is installed outside the transfer vacuum chamber and picks up an image including at least the outline of the processing object via the view port provided in the transfer vacuum chamber, and the image pickup camera A measuring unit that obtains a relational expression indicating the outline of the processing target using the contour position data of the processing target extracted from the image captured in step, and measures the position of the processing target based on the relational expression. Therefore, there is an effect that the position of the wafer can be accurately measured and the positional deviation can be confirmed.

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 is a single wafer transfer semiconductor manufacturing apparatus in which the center position of the wafer 3 and the rotation position (rotation) of the wafer 3 with respect to the orientation flat part or notch part are used. Corner). 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 (measurement unit) 14, a communication control unit (communication control unit) 19, and a positional deviation inspection unit (positional deviation inspection unit) 20. Prepare. 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 the 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, a circle estimation unit ( A circle estimation unit) 16, a center position measurement unit (center position measurement unit) 17, and a rotation angle measurement unit (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, and the entire wafer 3 described later with reference to FIGS. 6 and 9 is captured. In the case of an image, an image including the outer circumference circle of the wafer 3 is cut out from 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 center position measurement unit 17 measures 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 is measured by the notch or orientation flat part on the outer periphery of the wafer 3 specified from the position measurement image, the relational expression indicating the circle obtained by the circle estimation unit 16, and the center position measurement 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) Using Image Capturing Part of Wafer Perimeter FIG. 3 is a diagram for explaining an example of wafer position measurement in the transfer chamber. As in FIG. 1, the transfer chamber 4 is shown through the transfer chamber 4 from above. 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. When a part of the outer periphery of the wafer 3 is placed in the field of view a, the rotational position of the wafer 3 is set in advance so that the notch part, orientation flat part or other reference point on the outer periphery enters the field of view a. .

  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.

  FIG. 5 is a diagram for explaining position measurement using an image of a part of the outer periphery of the wafer. FIG. 5A shows an edge image of a part of the outer periphery of the wafer 3, and FIG. FIG. 5 shows a measurement process of the rotational position of the wafer 3 using the edge image in FIG. By using the transmitted illumination 11a, as shown in FIG. 5 (a), an image in the field of view a has a black shadow on the portion that blocks the illumination of the transmitted illumination 11a, and a portion that passes through the illumination of the transmitted illumination 11a appears white. The edge portion on the outer periphery of the wafer 3 becomes an emphasized image.

  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. In the image cutout unit 15, an image 21 a including a part of the outer periphery of the wafer 3 as shown in FIG. 5A is extracted from the image captured in the field of view a, and is output to the circle estimation unit 16. In the example of FIG. 5, it is assumed that the notch 22 on the outer periphery of the wafer 3 is captured in the image 21a.

FIG. 6 is a flowchart showing the flow of wafer position measurement processing by the image processing apparatus according to the first embodiment, and details of wafer position measurement will be described with reference to this figure.
First, when the image estimation unit 16 receives the image 21a from the image cutout unit 15, the circle estimation unit 16 scans the image 21a for each column of pixels and extracts an edge position (step ST1).

  Next, the circle estimation unit 16 performs an approximate calculation such as a least square method using the obtained edge position data, 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 (step ST2). Thereafter, the circle estimation unit 16 obtains a deviation between each edge position data and the approximate circle, and determines whether or not the maximum value of the deviation amount is a predetermined value or less (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.

  In order to obtain an approximate circle from the edge position of the wafer 3, at least three edge positions are required. In Patent Document 3, three edge positions are detected using three contour detection sensors, and a circle corresponding to the outer periphery of the wafer is estimated. On the other hand, the circle estimation unit 16 can obtain an approximate circle by using all edge positions constituting the edge portion (contour line) included in the image 21a.

  For example, consider a case where a digital camera having 1280 pixels in the horizontal direction is used as the imaging camera 2 and an edge portion composed of 1280 pixels is extracted from the edge image 21a. Even in this case, the method of Patent Document 3 uses only one circle because three edge positions are used. On the other hand, the circle estimation unit 16 can obtain a maximum of 426 circles by extracting three edge positions from 1280 edge coordinates.

  The circle estimation unit 16 repeats the processes from step ST1 to step ST3 until the approximate circle with the smallest deviation amount between the edge position data and the approximate circle is obtained, so that the circle is most reliable as the circle corresponding to the outer periphery of the wafer 3. One high-quality circle can be estimated. 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 center position measurement unit 17 and the rotation angle measurement unit 18.

  The center position measurement unit 17 calculates the coordinates of the center position a1 of the wafer 3 from a circle formula corresponding to the outer periphery of the wafer 3, as shown in FIG. The coordinate data of the center position a1 of the wafer 3 is sent from the center position measurement unit 17 to the rotation angle measurement unit 18, the communication control unit 19, and the misalignment inspection unit 20.

  On the other hand, the rotation angle measurement unit 18 compares the many edge position data obtained in step ST1 with the approximate circle, and obtains the position of the notch part (reference part) 22 from the edge part included in the image 21a (step ST4). ). For example, the edge portion of the wafer 3 included in the image 21 a is scanned along the approximate circle corresponding to the outer periphery of the wafer 3 input from the circle estimation unit 16, and a portion deviating from the edge portion, for example, a recessed portion is notched 22. Extract as

  Subsequently, the rotation angle measurement unit 18 uses the approximate circle formula of the wafer 3 input from the circle estimation unit 16, and the reference line passing through the notch 22 in the center position a1 of the wafer 3 and the region A on the edge. The angle θ formed by b1 and the center position a1 of the wafer 3 and a predetermined reference line b2 passing through the predetermined reference position is defined as the rotation angle θ of the wafer 3 (the notch portion 22 with respect to the predetermined reference position as a reference). (Rotation position) is calculated (step ST5).

  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, information about the center position of the wafer 3 acquired from the center position measurement unit 17 and 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.

(1-2) When using an image obtained by imaging the entire wafer In the transfer chamber 4, if it is possible to attach a large-diameter viewport that can accommodate the entire wafer 3 in the field of view of the imaging camera 2, The following measurement process may be performed.
FIG. 7 is a view for explaining another example of wafer position measurement in the transfer chamber, and describes the internal configuration of the transfer chamber 4 through the top as in FIG. FIG. 8 is a side view of the transfer chamber in FIG. 7, in which the side walls are shown through to show the internal configuration of the transfer chamber 4. 7 and 8, the same reference numerals are assigned to the components corresponding to those shown in FIG.

  As shown in FIG. 8, the view port 4 c is provided in the upper part of the transfer chamber 4, and the view port 4 d is provided in the lower part of the transfer chamber 4. The imaging camera 2 is attached to the outside of the transfer chamber 4 via the viewport 4c, and the transmitted illumination 11b is attached to the outside of the transfer chamber 4 via the viewport 4d.

  When the wafer 3 is transported to the position of the viewport 4c, the entire wafer 3 fits in the field of view b of the imaging camera 2. The transmitted illumination 11b has a larger area than the transmitted illumination 11a shown in FIG. 4, and can illuminate the entire wafer 3 located in the field of view b of the imaging camera 2 from directly below via the viewport 4d. . As a result, the imaging camera 2 can image the entire wafer 3 illuminated by the transmitted illumination 11b from directly below through the view port 4c.

  The image data acquisition unit 12 acquires image data obtained by imaging the entire wafer 3 from the imaging camera 2 and stores it in the storage unit 13. The image cutout unit 15 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, an image including the entire outer periphery of the wafer 3 is cut out from the image captured in the visual field b.

  FIG. 9 is a diagram for explaining position measurement using an image of the entire wafer. FIG. 9A shows an image of the entire wafer 3, and FIG. 9B is a diagram in FIG. The measurement process of the rotation position of the wafer 3 using the image of is shown. By using the transmitted illumination 11b, as shown in FIG. 9A, in the image in the field of view b, the portion that blocks the illumination of the transmitted illumination 11b becomes a black shadow, and the portion through which the illumination of the transmitted illumination 11b passes appears white. 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 an image 21b of the entire wafer 3 as shown in FIG. 9A from the image captured in the field of view b, and outputs the image 21b to the circle estimation unit 16. In the circle estimation unit 16, when the image 21 b is input from the image cutout unit 15, the image 21 b is scanned for each pixel column, and the edge position of the entire contour of the wafer 3 is extracted.

  Next, the circle estimation unit 16 performs an approximate calculation such as a least square method using the obtained edge position data, 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. Find the approximate circle corresponding to. 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 center position measurement unit 17 and the rotation angle measurement unit 18.

  The center position measurement unit 17 calculates the coordinates of the center position a2 of the wafer 3 from the approximate circle equation corresponding to the outer periphery of the wafer 3, as shown in FIG. The coordinate data of the center position a <b> 2 of the wafer 3 is sent from the center position measurement unit 17 to the rotation angle measurement unit 18, the communication control unit 19, and the misalignment inspection unit 20.

  On the other hand, the rotation angle measurement unit 18 compares a large number of edge position data extracted from the image 21b with the approximate circle, and obtains the position of the notch part 22 from the image 21b. For example, the edge portion of the wafer 3 included in the image 21b is scanned along the approximate circle corresponding to the outer periphery of the wafer 3 input from the circle estimation unit 16, and a portion outside the edge portion, for example, a recessed portion is notched. Extract as

  Subsequently, the rotation angle measurement unit 18 performs a predetermined line that passes through the center position a2 of the wafer 3 and the reference line c1 passing through the notch portion 22 in the region b on the edge, and the center position a2 of the wafer 3 and a predetermined reference position. The angle θ formed with the reference line c2 is calculated as the rotation angle θ of the wafer 3 (the rotation position of the wafer 3 with reference to the notch portion 22 with respect to a predetermined reference position). The rotation angle θ of the wafer 3 thus obtained is sent from the rotation angle measurement unit 18 to the communication control unit 19 and the misalignment inspection unit 20.

  The communication control unit 19 uses the information about the center position of the wafer 3 acquired from the center position measurement unit 17 and the information about the rotation position of the wafer 3 acquired from the rotation angle measurement unit 18 as measurement results by the measurement unit 14 to the control device 8. Send.

  For example, an appropriate wafer position is registered in the control device 8 in advance, and the appropriate wafer position is compared with the measurement result of the measurement unit 14 to determine whether the wafer 3 is misaligned. 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 measurement using the image obtained by imaging the entire wafer, the center position and the rotational position of the wafer 3 are measured at the same position of the transfer chamber 4 before being transferred into the process chamber 5 and after being transferred out of the process chamber 5. It may be. 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.

  In the above (1), the notch portion 22 is obtained as a reference for obtaining the rotational position. However, the rotational position of the wafer 3 may be obtained by detecting the orientation flat portion.

(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. 10 is a diagram for explaining the wafer position measurement at the transfer position of the process chamber. As in FIG. 1, the transfer chamber 4 is seen through from above and its internal configuration is described. In FIG. 10, the same reference numerals are given to the components corresponding to the components shown in FIG. In the example shown in FIG. 10, 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 2a 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 at the lower opening of the cylindrical structure part to which the bottom plate-like flange is attached. Deploy. Since the opening of the cylindrical structure portion of the process chamber 5 has a larger diameter than that of the viewport, a visual field c that can accommodate the entire wafer 3 can be given to the imaging camera 2a.

  As shown in FIG. 10, the robot arm 9 is used to transfer the wafer 3 to the process chamber 5 before assembly described above. At this transfer position, the entire wafer 3 fits in the field of view c of the imaging camera 2a. Thereafter, position measurement is performed using an image obtained by imaging the entire wafer 3 in the same procedure as the processing described in (1-2) above. 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, an image including at least the contour line (edge portion) of the wafer 3 is disposed outside the transfer chamber 4 and the view port 4a provided in the transfer chamber 4. A relational expression indicating the outline of the wafer 3 is obtained using one imaging camera 2 to be imaged and wafer edge position data extracted from the image captured by the imaging camera 2, and the position of the wafer 3 is determined based on this relational expression. Therefore, it is possible to accurately measure the center position and rotation position (rotation angle) of the wafer 3 and confirm the positional deviation.

  Further, according to the first embodiment, the imaging camera 2 a that captures an image including at least the contour line (edge portion) of the wafer 3 transferred to the position of the process chamber 5 is provided, and the measurement unit 14 includes the imaging camera 2 a. Using the edge position data extracted from the image of the wafer 3 transported to the position of the process chamber 5 imaged in step 3, a relational expression indicating the outline of the wafer 3 is obtained, and the position of the wafer 3 is measured based on this relational expression. Therefore, it is possible to confirm whether or not a positional deviation occurs before the wafer 3 is transferred from the transfer chamber 4 to the process chamber 5.

  Further, according to the first embodiment, the position measurement results of the wafer 3 measured by the measurement unit 14 at the same position in the transfer chamber 4 before being carried into the process chamber 5 and after being carried out from the process chamber 5 are compared. Thus, since the misalignment inspection unit 20 for inspecting misalignment is provided, it is possible to confirm whether or not misalignment has occurred before loading into the process chamber 5 and after unloading from the process chamber 5.

  Further, according to the first embodiment, the misalignment inspection unit 20 compares the positional information of the wafer 3 aligned by the wafer aligner 7 with the position measurement result of the wafer 3 by the measurement unit 14 and performs misalignment. Since the inspection is performed, it is possible to correct the deviation from the position of the wafer 3 which has been previously aligned by the wafer aligner 7.

  Further, according to the first embodiment, the position measurement result of the object to be processed by the measuring unit 14 is used as the operation correction data for the robot arms 9 and 10 with respect to the control device 8 that controls the operations of the robot arms 9 and 10. Alternatively, since the communication control unit 19 that transmits the result of the misalignment inspection by the misalignment inspection unit 20 is provided, the misalignment in the process of transporting the wafer 3 can be corrected.

  Furthermore, according to the first embodiment, the measurement unit 14 uses the contour position data of the wafer 3 extracted from the image captured by the imaging camera 2 to estimate a circle indicating the relational expression indicating the contour circle of the wafer 3. Based on the relational expression obtained by the part 16 and the circle estimation part 16, the center position measuring part 17 for calculating the center position of the wafer 3, the center position obtained by the center position measuring part 17 and the first part passing through the notch part 22. And a rotation angle measuring unit 18 that calculates an angle formed by the reference line and the second reference line passing through the center position and a predetermined reference position as the rotation position of the wafer 3. The rotational position (rotation angle) and the like can be accurately measured.

  Furthermore, according to the first embodiment, the measurement unit 14 uses the edge (contour) position data extracted from the image including a part of the contour line of the wafer 3, and the relational expression that approximates the entire contour of the wafer 3. Since the position of the wafer 3 is measured based on this relational expression, an approximate circle is obtained using all the edge positions constituting the edge portion (contour line), and the circle corresponding to the outer periphery of the wafer 3 is trusted. A highly efficient circle can be estimated.

  Further, according to the first embodiment, the measurement unit 14 obtains a relational expression indicating the outline of the wafer 3 using the edge position data extracted from the image including the entire wafer 3, and based on the relational expression. Since the position of the processing object is measured, a highly reliable circle can be estimated as a circle corresponding to the outer periphery of the wafer 3.

  Furthermore, according to the first embodiment, the wafer is provided with the transmission illumination 11 that gives illumination from the back surface side (or front surface side) of the wafer 3, and the measurement unit 14 is illuminated by the imaging camera 2 from the transmission illumination 11. 3, the position of the wafer 3 is measured using an image picked up from the front surface side (or the back surface side), so that the edge portion becomes unclear due to the influence of the material of the wafer 3 and the circuit pattern formed on the wafer 3. In this way, stable position measurement can be performed.

  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.

  Further, in the first embodiment, the case where the present invention is applied to a single-wafer transport semiconductor manufacturing apparatus is shown. However, the present invention can be applied to any single-wafer transport vacuum processing apparatus. The shape is not limited to a semiconductor wafer.

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 for demonstrating the position measurement using the one part image of a wafer outer periphery. 3 is a flowchart illustrating a flow of wafer position measurement processing by the image processing apparatus according to the first embodiment. It is a figure for demonstrating the other example of the wafer position measurement in a transfer chamber. FIG. 8 is a side view of the transfer chamber in FIG. 7. It is a figure for demonstrating the position measurement using the image of the whole wafer. It is a figure for demonstrating the wafer position measurement in the conveyance position of a process chamber.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image processing apparatus, 2, 2a Imaging camera, 3 Wafer (object to be processed), 4 Transfer chamber (vacuum chamber for conveyance), 4a, 4b, 4c, 4d Viewport, 5 Process chamber (processing chamber), 6 Load / Unload device, 7 Wafer aligner (aligner device), 8 Control device, 9, 10 Robot arm (transfer mechanism), 11, 11a, 11b Transmitted illumination (transmitted illumination means), 12 Image data acquisition unit, 13 Storage unit, 14 Measurement unit (measurement unit), 15 image cutout unit, 16 circle estimation unit (circle estimation unit), 17 center position measurement unit (center position measurement unit), 18 rotation angle measurement unit (rotation angle measurement unit), 19 communication control unit (Communication control means), 20 position deviation inspection part (position deviation inspection means), 21a, 21b image, 22 notch part (reference part).

Claims (11)

The vacuum processing apparatus includes a processing chamber that performs processing on a processing target, and a transfer vacuum chamber that has a transport mechanism for the processing target and loads the processing target into and out of the processing chamber. In the image processing apparatus used for measuring the position of the processing object of the vacuum processing apparatus,
One imaging camera that is installed outside the transfer vacuum chamber and picks up an image including at least an outline of the object to be processed via a viewport provided in the transfer vacuum chamber;
A plurality of contour position data indicating points on the contour line of the processing object extracted from the image captured by the imaging camera are acquired , and the contour of the processing object is determined using three points of the contour position data. After obtaining the relational expression shown, the deviation between each contour position data and the relational expression showing the outline is obtained, and when the maximum value of the deviation amount is larger than a predetermined value, A relational expression indicating a new contour is obtained by changing the combination, and when the maximum value of the deviation amount is equal to or less than a predetermined value, a measuring unit that measures the position of the processing object based on the relational expression is provided. An image processing apparatus comprising the image processing apparatus. The vacuum processing apparatus includes a processing chamber that performs processing on a processing target, and a transfer vacuum chamber that has a transport mechanism for the processing target and loads the processing target into and out of the processing chamber. In the image processing apparatus used for measuring the position of the processing object of the vacuum processing apparatus,
  One imaging camera that is installed outside the transfer vacuum chamber and picks up an image including at least an outline of the object to be processed via a viewport provided in the transfer vacuum chamber;
  A plurality of contour position data indicating points on the contour line of the processing object extracted from the image captured by the imaging camera are acquired, and the processing object is used by using three points having different combinations among the contour position data. Each of the relational expressions indicating the contours of each of the contour position data and the relational expressions indicating the respective contours is obtained, and the relational expression having the smallest deviation amount is obtained. An image processing apparatus comprising: a measuring unit that measures a position of the processing object based on the measurement unit. An imaging camera that captures an image including at least a contour line of the processing object conveyed to the position of the processing chamber;
The measuring means obtains a relational expression indicating the contour of the processing object using the contour position data of the processing object extracted from the image of the processing object conveyed to the position of the processing chamber imaged by the imaging camera. the image processing apparatus according to claim 1 or claim 2 wherein measuring the position of the processing object on the basis of this relationship. Misalignment inspecting means for inspecting misalignment by comparing each position measurement result of the processing object measured by the measuring means at the same position in the transfer vacuum chamber before carrying into the processing chamber and after unloading from the processing chamber. The image processing apparatus according to any one of claims 1 to 3, further comprising: The positional deviation inspection means compares the positional information of the processing object aligned by the aligner device provided in the vacuum processing apparatus and the positional measurement result of the processing object by the measuring means to inspect the positional deviation. The image processing apparatus according to claim 4, wherein: Transmits the position measurement result of the object to be processed by the measuring means or the position deviation inspection result by the position deviation inspection means as operation correction data for the conveyance mechanism to the control device that controls the operation of the conveyance mechanism provided in the vacuum processing apparatus. the image processing apparatus according to any one of claims 5, further comprising: a communication control means of claims 1, characterized in that. The object to be treated has a disk shape with a reference portion formed on the outer periphery,
Measuring means
Circle estimation means for obtaining a relational expression indicating the contour circle of the processing object using the contour position data of the processing object extracted from the image captured by the imaging camera;
Center position measuring means for calculating the center position of the processing object based on the relational expression obtained by the circle estimating means;
The angle formed by the center position obtained by the center position measuring means and the first reference line passing through the reference portion and the second reference line passing through the center position and a predetermined reference position is the rotation of the processing object. the image processing apparatus according to any one of claims 1 to 6, characterized in that a rotation angle measuring means for calculating a position. The measurement means obtains a relational expression that approximates the entire contour of the processing target using contour position data extracted from an image including a part of the contour line of the processing target, and based on the relational expression, calculates the processing target. the image processing apparatus according to any one of claims 1 to 7, wherein, characterized in that for measuring the position of the object. The measurement means obtains a relational expression indicating the outline of the processing target using contour position data extracted from an image including the entire contour of the processing target, and measures the position of the processing target based on the relational expression. the image processing apparatus according to any one of claims 1 to 7, wherein, characterized by. Comprising a transmission illumination means for providing illumination from the back side of the object to be treated;
The measuring means measures the position of the processing object using an image taken from the surface side of the processing object illuminated by the transmission illumination means by an imaging camera. The image processing apparatus according to claim 9 . A transmission illumination means for providing illumination from the surface side of the processing object;
The measuring unit measures the position of the processing object using an image captured from the back side of the processing object illuminated by the transmission illumination unit by an imaging camera. The image processing apparatus according to claim 9 .

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