Wafer detection system

Abstract

To stably detect the storage state of a wafer in a wafer storage container without requiring a special operation by a transfer robot or the like.SOLUTION: A wafer detection system (10) that detects the storage state of the wafer stored in the wafer storage container (20) with the lid (21) closed when the lid (21) is moved in a predetermined direction by the opening / closing mechanism (30) includes a first lighting unit attached to a predetermined member (31) that moves in a predetermined direction together with a lid when the lid is moved in a predetermined direction by an opening / closing mechanism, and illuminates a first position on the side surface of the wafer, a second lighting unit that is attached to the predetermined member and illuminates a second position different from the first position on the side surface of the wafer where the first position is illuminated, a photographing unit (40) attached to the predetermined member and acquiring a photographed image of a range including the first position and the second position on the wafer, and a detection unit (60) that detects the housing state of the wafer on the basis of the photographed image acquired by the photographing unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wafer detection system for detecting the accommodation state of wafers accommodated in a wafer accommodation container.

Background Art

[0002] Conventionally, there has been a wafer detection system including a wafer accommodation container that accommodates a plurality of wafers stacked in the vertical direction, an illumination device that irradiates light onto the wafers in the wafer accommodation container, and a photographing device onto which reflected light from the wafers is incident (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the system described in Patent Document 1, the illumination device is attached to the left and right sides of the load port of the wafer processing device via attachment members, respectively. On the other hand, the photographing device is attached to the hand of a transfer robot that grasps the wafer and moves it back and forth and up and down. Then, while the transfer robot lowers the photographing device, the photographing device photographs the wafer.

[0005] Therefore, in the system described in Patent Document 1, in order to detect the accommodation state of the wafer, a special operation is required to lower the imaging device by the transfer robot. Furthermore, the relationship between the angle and range at which the illumination device irradiates light on the wafer and the angle and range at which the imaging device captures the wafer changes when the imaging device descends. Therefore, depending on the position of the wafer in the wafer accommodation container, there is a variation in the intensity of the reflected light incident from the wafer to the imaging device, and there is a possibility that the accommodation state of the wafer cannot be stably detected. In addition, when the entire side surface of the wafer is irradiated by one illumination device, there is a variation in the intensity of the reflected light incident on the imaging device depending on the position within the wafer, and there is a possibility that the accommodation state of the wafer cannot be stably detected.

[0006] The present invention has been made to solve the above problems, and its main object is to provide a wafer detection system that does not require a special operation by a transfer robot or the like and can stably detect the accommodation state of the wafers in the wafer accommodation container.

Means for Solving the Problems

[0007] The first means for solving the above problems is a wafer detection system for detecting the accommodation state of wafers accommodated in a wafer accommodation container in which a plurality of wafers are accommodated at a predetermined interval in a predetermined direction and a lid is closed, when the lid is moved in the predetermined direction by an opening / closing mechanism, comprising a first illumination unit attached to a predetermined member that moves in the predetermined direction together with the lid when the lid is moved in the predetermined direction by the opening / closing mechanism, and illuminates a first position on the side surface of the wafer; a second illumination unit attached to the predetermined member and illuminating a second position on the side surface of the wafer that is different from the first position where the first position is illuminated; a photographing unit attached to the predetermined member and acquiring a photographed image of a range including the first position and the second position on the wafer where the first position and the second position are illuminated; A detection unit that detects the accommodation state of the wafer based on the captured image acquired by the imaging unit; is provided.

[0008] According to the above configuration, the wafer detection system detects the accommodation state of the wafers accommodated in a wafer accommodation container in which a plurality of wafers are accommodated at a predetermined interval in a predetermined direction and the lid is closed, when the lid is moved in the predetermined direction by an opening / closing mechanism.

[0009] Here, the first illumination unit is attached to a predetermined member that moves in the predetermined direction together with the lid when the lid is moved in the predetermined direction by the opening / closing mechanism, and illuminates a first position on the side surface of the wafer. For this reason, the first illumination unit can illuminate the first position on the side surface of the wafer while moving in the predetermined direction together with the lid and the predetermined member when the lid is moved in the predetermined direction by the opening / closing mechanism. Further, the second illumination unit is attached to the predetermined member and illuminates a second position different from the first position on the side surface of the wafer where the first position is illuminated. For this reason, the second illumination unit can illuminate a second position different from the first position on the side surface of the wafer while moving in the predetermined direction together with the lid, the predetermined member, and the first illumination unit when the lid is moved in the predetermined direction by the opening / closing mechanism. That is, the first illumination unit and the second illumination unit can be moved in the predetermined direction while illuminating the first position on the side surface of one wafer with the first illumination unit and illuminating the second position with the second illumination unit. Note that the predetermined member includes a case where it is one member and a case where it is a plurality of integrated members.

[0010] The imaging unit is attached to the predetermined member and acquires a captured image by capturing a range including the first position and the second position on the wafer illuminated at the first position and the second position. For this reason, when the opening / closing mechanism moves the lid in a predetermined direction, the imaging unit can acquire a captured image by capturing a range including the first position and the second position on the wafer while moving in the predetermined direction together with the lid, the predetermined member, the first illumination unit, and the second illumination unit. Therefore, without requiring a special operation by a transfer robot or the like, by using the operation of moving the lid in the predetermined direction by the opening / closing mechanism, captured images of a plurality of wafers accommodated at predetermined intervals in the predetermined direction can be sequentially acquired. Note that the imaging unit includes a case where only one wafer is captured at a time and a case where a plurality of wafers are captured at a time.

[0011] Furthermore, since the first illumination unit, the second illumination unit, and the imaging unit all move in the predetermined direction together with the lid and the predetermined member, the relationship between the angle and range at which the first illumination unit and the second illumination unit irradiate light on the wafer and the angle and range at which the imaging unit captures the wafer does not change when the imaging unit moves in the predetermined direction. Moreover, compared with the variation in the intensity of the reflected light incident on the imaging unit depending on the position within the wafer when the entire side surface of the wafer is irradiated by one illumination device, the variation in the intensity of the reflected light incident on the imaging unit at the first position and the second position can be reduced. Then, the detection unit detects the accommodation state of the wafer based on the captured image acquired by the imaging unit. Therefore, the accommodation state of the wafers in the wafer accommodation container can be stably detected. Also, the imaging unit acquires a captured image by capturing a range including the first position and the second position on the wafer. For this reason, the cost of the wafer detection system can be reduced compared with the case where an imaging unit for capturing the first position and an imaging unit for capturing the second position are provided respectively.

[0012] In the second means, when viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the imaging unit is deviated from the center of the wafer. Therefore, when compared with the case where the optical axis of the imaging unit passes through the center of the wafer when viewed from a direction perpendicular to the largest surface of the wafer, a wider range of the side surface of the wafer can be included in the field of view of the imaging unit under the condition that the distance from the wafer to the imaging unit is the same. Accordingly, even for an imaging unit with a narrow field of view, it becomes easier to image the range including the first position and the second position.

[0013] When the optical axis of the imaging unit is deviated from the center of the wafer when viewed from a direction perpendicular to the largest surface of the wafer, if an attempt is made to widen the interval between the first position and the second position by disposing the imaging unit between the first illumination unit and the second illumination unit, the following problem occurs. That is, under the condition that the distance from the imaging unit to the first illumination unit and the distance to the second illumination unit are the same, it becomes difficult for the reflected light that is irradiated in the optical axis direction of one illumination unit and reflected by the wafer to enter the imaging unit.

[0014] In the third means, when viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the imaging unit is deviated from the center of the wafer in a first direction, the first illumination unit is disposed in the first direction with respect to the optical axis of the imaging unit, and the second illumination unit is disposed in a second direction opposite to the first direction with respect to the optical axis of the imaging unit. In this case, if an attempt is made to widen the interval between the first position and the second position, under the condition that the distance from the imaging unit to the first illumination unit and the distance to the second illumination unit are the same, it becomes difficult for the reflected light that is irradiated in the optical axis direction of the first illumination unit and reflected by the wafer to enter the imaging unit. In this regard, the distance from the imaging unit to the first illumination unit is longer than the distance from the imaging unit to the second illumination unit. Therefore, while widening the interval between the first position and the second position, it becomes easier for the reflected light that is irradiated in the optical axis direction of the first illumination unit and reflected by the wafer to enter the imaging unit. Accordingly, it is possible to suppress a decrease in the intensity of the reflected light incident on the imaging unit from the first position, and it is possible to stably detect the accommodation state of the wafer in the wafer accommodation container.

[0015] In a wafer storage container, the opposing portion facing the largest surface of the lid is often formed of a transparent member in order to facilitate visual recognition of the inside of the storage container. For this reason, when viewed from a direction perpendicular to the largest surface of the wafer, if the optical axis of the imaging unit is parallel to a straight line perpendicular to the largest surface of the lid, stray light incident from the opposing portion into the storage container easily directly enters the field of view of the imaging unit.

[0016] In this regard, in the fourth means, when viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the imaging unit intersects a straight line perpendicular to the largest surface of the lid. Therefore, it is possible to suppress stray light incident from the opposing portion into the storage container from directly entering the field of view of the imaging unit, and it is possible to stably detect the storage state of the wafers in the wafer storage container.

[0017] In the fifth means, the imaging unit images a predetermined range including a plurality of the first positions and a plurality of the second positions in the predetermined direction, the first illumination unit illuminates the plurality of the first positions included in the predetermined range, and the second illumination unit illuminates the plurality of the second positions included in the predetermined range.

[0018] According to the above configuration, the imaging unit images a predetermined range including a plurality of the first positions and a plurality of the second positions in the predetermined direction. For this reason, the imaging unit can acquire a captured image obtained by imaging a plurality of wafers at once. Then, the detection unit can detect the storage states of a plurality of the wafers at once based on the captured image acquired by the imaging unit.

[0019] Here, the first lighting unit illuminates the plurality of the first positions included in the predetermined range, and the second lighting unit illuminates the plurality of the second positions included in the predetermined range. Therefore, when the imaging unit captures an image of the predetermined range, the states of the plurality of the first positions and the plurality of the second positions included in the predetermined range can be clearly captured. Further, since the first lighting unit, the second lighting unit, and the imaging unit all move in a predetermined direction together with the lid and the predetermined member, the relationship between the angles and ranges at which the first lighting unit and the second lighting unit irradiate light onto a plurality of wafers and the angles and ranges at which the imaging unit captures images of the plurality of wafers does not change when the imaging unit moves in the predetermined direction. Accordingly, the accommodation states of the plurality of wafers in the wafer accommodation container can be stably detected.

[0020] In the sixth means, the detection unit detects the accommodation state of the wafer based on an image of a first region including the first position of the wafer when the accommodation state of the wafer is normal and an image of a second region including the second position of the wafer when the accommodation state of the wafer is normal in the captured image obtained by the imaging unit. According to such a configuration, since the accommodation state of the wafer is detected based on the image of the first region and the image of the second region instead of the entire captured image, the influence of ambient light can be suppressed. Accordingly, the accommodation state of the wafer in the wafer accommodation container can be stably detected.

Brief Description of the Drawings

[0021]

Figure 1

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Figure 7

Best Mode for Carrying Out the Invention

[0022] An embodiment embodied in a wafer detection system for detecting the accommodation state of wafers accommodated in a wafer accommodation container when introducing a wafer into a semiconductor processing apparatus will be described below with reference to the drawings.

[0023] As shown in FIG. 1, in a semiconductor processing apparatus (processing apparatus), the left side (one side) of the partition wall 11 is a pre-chamber, and the right side (the other side) of the partition wall 11 is a processing chamber. The cleanliness of the processing chamber is higher than that of the pre-chamber. On the pre-chamber side with respect to the partition wall 11, a mounting table 12 is provided. A FOUP (Front Opening Unified Pod) 20 is placed on the mounting table 12.

[0024] The FOUP 20 (wafer accommodation container) is a well-known multi-stage wafer accommodation container that accommodates a plurality of wafers W at equal intervals (predetermined intervals) in the downward direction (predetermined direction). The cleanliness inside the FOUP 20 is higher than that of the pre-chamber. The plurality of wafers W are arranged in the FOUP 20 such that the main surfaces Wm, which are the surfaces with the largest area of the wafers W, are parallel to each other, and the centers of the plurality of wafers W are arranged on the same straight line (concentrically). The FOUP 20 is formed in a rectangular parallelepiped shape and is provided with a lid 21 on the front surface. In the FOUP 20, the opposing portion 20a that faces the main surface 21a, which is the largest surface of the lid 21, is formed of a transparent (light-transmissive) member in order to facilitate visual recognition of the inside of the FOUP 20. Note that the side walls of the FOUP 20 other than the opposing portion 20a are formed of opaque members or include opaque portions.

[0025] An opening 11a is formed in the partition wall 11 at a position facing the lid 21 of the FOUP 20. The opening 11a is closed by a lid holding portion 31 of the opening / closing mechanism 30. That is, the pre-chamber and the processing chamber are blocked by the lid holding portion 31. Note that a load port is configured by the partition wall 11, the mounting table 12, the opening / closing mechanism 30, and the like.

[0026] The opening / closing mechanism 30 is a well-known mechanism for opening and closing the lid 21 of the FOUP 20 in a semiconductor processing apparatus. The lid 21 is held by the lid holding portion 31, and the lid holding portion 31 is moved in the front-rear direction and the up-down direction. The opening / closing mechanism 30 moves the lid holding portion 31 forward (rightward in FIG. 1) in a state where the lid 21 is held by the lid holding portion 31, and then moves it downward. Thereby, the lid 21 is removed from the FOUP 20, and the inside of the FOUP 20 is opened to the processing chamber. That is, the lid holding portion 31 (predetermined member) moves downward together with the lid 21 when the opening / closing mechanism 30 moves the lid 21 downward. Then, the wafer W in the FOUP 20 can be taken out to the processing chamber by a transfer robot or the like disposed in the processing chamber. When closing the lid 21 of the FOUP 20, the opening / closing mechanism 30 executes the reverse operation to the above.

[0027] A camera 40 and lights 51 and 52 (see FIG. 2) are attached to the upper end portion (the end portion in the direction opposite to the predetermined direction) of the lid holding portion 31. FIG. 2 is a plan view showing the arrangement of the wafer W, the camera 40, and the lights 51 and 52.

[0028] The camera 40 (imaging unit) is a two-dimensional image sensor such as a CCD image sensor or a CMOS image sensor. When viewed from a direction (up-down direction) perpendicular to the main surface Wm of the wafer W, the optical axis C1 of the camera 40 is deviated from the center O of the wafer W. Specifically, when viewed from a direction perpendicular to the main surface Wm of the wafer W, the optical axis C1 of the camera 40 is deviated in the first direction A1 with respect to the center O of the wafer W.

[0029] Note that if the optical axis C1 of the camera 40 is parallel to the straight line C2 perpendicular to the main surface 21a of the lid 21 when viewed from a direction perpendicular to the main surface Wm of the wafer W, external light incident from the opposing portion 20a (see FIG. 1) into the FOUP 20 easily enters directly into the field of view of the camera 40.

[0030] In this regard, when viewed from a direction perpendicular to the main surface Wm of the wafer W, the optical axis C1 of the camera 40 intersects a straight line C2 perpendicular to the main surface 21a of the lid 21. Therefore, it is possible to suppress the disturbance light incident from the opposing portion 20a into the FOUP 20 from directly entering the field of view of the camera 40.

[0031] The lights 51 and 52 are lighting devices such as LED lights, for example. The light 51 (first lighting unit) illuminates the first position P1 on the side surface of the wafer W. The light 52 (second lighting unit) illuminates the second position P2 different from the first position P1 on the side surface of the wafer W. Then, the camera 40 acquires a captured image obtained by capturing a range including the first position P1 and the second position P2 on the wafer W where the first position P1 and the second position P2 are illuminated.

[0032] Here, when viewed from a direction perpendicular to the main surface Wm of the wafer W, the optical axis C1 of the camera 40 is deviated from the center O of the wafer W, the light 51 is arranged in the first direction A1 with respect to the optical axis C1 of the camera 40, and the light 52 is arranged in the second direction A2 opposite to the first direction A1 with respect to the optical axis C1 of the camera 40. In this case, if an attempt is made to arrange the camera 40 between the light 51 and the light 52 to widen the distance between the first position P1 and the second position P2, the following problem occurs. That is, under the condition that the distance from the camera 40 to the light 51 and the distance to the light 52 are the same, it becomes difficult for the reflected light irradiated in the direction of the optical axis C3 of the light 51 and reflected by the wafer W to enter the camera 40. Specifically, the reflected light irradiated in the direction of the optical axis C3 of the light 51 and reflected by the wafer W is more likely to go in the left direction (A1 direction) than the camera 40.

[0033] In this regard, the distance from the camera 40 to the light 51 is set to be longer than the distance from the camera 40 to the light 52. Therefore, while widening the distance between the first position P1 and the second position P2, it becomes easier for the reflected light irradiated in the direction of the optical axis C3 of the light 51 and reflected by the wafer W to enter the camera 40. Note that the light from the light 51 is irradiated to the peripheral range centered on the optical axis C3, but the intensity of the light irradiated in the direction of the optical axis C3 is the largest. The same applies to the optical axis C4 and the intensity of the light of the light 52.

[0034] The wafer detection system 10 having the above configuration detects the accommodation state of the wafer W accommodated in the FOUP 20 with the lid 21 closed when the lid 21 of the FOUP 20 is opened by the opening / closing mechanism 30 and the lid 21 is moved downward.

[0035] Specifically, when the opening / closing mechanism 30 moves the lid 21 downward, the light 51 illuminates the first position P1 on the side surface of the wafer W while moving downward together with the lid 21 and the lid holding portion 31. Further, the light 52 illuminates a second position P2 different from the first position P1 on the side surface of the wafer W where the first position P1 is illuminated. Then, when the opening / closing mechanism 30 moves the lid 21 downward, the camera 40 acquires a captured image that captures a range including the first position P1 and the second position P2 on the wafer W while moving downward together with the lid 21, the lid holding portion 31, the light 51, and the light 52. That is, by using the operation of moving the lid 21 downward by the opening / closing mechanism 30, captured images of a plurality of wafers W accommodated at predetermined intervals downward are sequentially acquired.

[0036] In the present embodiment, the lights 51 and 52 illuminate a predetermined number (a plurality of) of wafers W arranged downward simultaneously (collectively), and the camera 40 captures the first position P1 and the second position P2 of a predetermined number of wafers W arranged downward simultaneously (collectively). Thereafter, the same process is executed each time a predetermined number (a plurality of) of wafers W that have not been captured enter the imaging range of the camera 40.

[0037] FIG. 3 is a schematic diagram showing the imaging range S by the camera 40 and the illumination ranges L1 and L2 by the lights 51 and 52, and FIG. 4 is a schematic diagram showing an enlarged view of the imaging range S in FIG. 3. Note that FIG. 3 shows the imaging range S when the lid holding portion 31, the camera 40, and the lights 51 and 52 are moving downward.

[0038] The camera 40 captures an imaging range S (predetermined range) that includes a plurality of first positions P11, P12, P13 and a plurality of second positions P21, P22, P23 in the downward direction. The center of the imaging range S is shifted to the right from the center of the wafer W in the horizontal direction (left - right direction).

[0039] The lights 51, 52 illuminate illumination ranges L1, L2 respectively, where the vertical width (length) is wider than the horizontal width (width). The vertical widths of the illumination ranges L1, L2 are wider than the vertical width of the imaging range S. That is, the light 51 illuminates the plurality of first positions P11, P12, P13 included in the imaging range S. The light 52 illuminates the plurality of second positions P21, P22, P23 included in the imaging range S.

[0040] The image processing unit 60 (see FIG. 1) is a well - known image processing device composed of a CPU, ROM, RAM, input / output interface, etc. The image processing unit 60 (detection unit) detects the accommodation state of the wafer W based on the captured image acquired by the camera 40.

[0041] Specifically, the image processing unit 60 sets detection regions R11, R12, R13 (first regions) that respectively include the first positions P11, P12, P13 of the wafer W when the accommodation state of the wafer W is normal, for the captured image acquired from the camera 40. The detection regions R11, R12, R13 are set to include the first positions P11, P12, P13 and their peripheries respectively. The detection regions R11, R12, R13 are set to such a size that even when two wafers W are accommodated overlapping, or the left and right ends of the wafer W are supported at different levels and the wafer W is tilted, or the wafer W protrudes slightly forward, the first positions P11, P12, P13 illuminated by the light 51 are respectively included in the detection regions R11, R12, R13. Similarly, the image processing unit 60 sets detection regions R21, R22, R23 (second regions) that respectively include the second positions P21, P22, P23 of the wafer W when the accommodation state of the wafer W is normal, for the captured image acquired from the camera 40.

[0042] Then, the image processing unit 60 detects the accommodation state of the wafer W based on the images of the detection regions R11, R12, R13 and the detection regions R21, R22, R23 in the captured image acquired from the camera 40.

[0043] FIG. 5 is a schematic diagram showing the accommodation states of wafers W1 to W4 in the imaging range. This figure shows an example in which the wafer W1 is normally accommodated, the wafers W1 and W2 are accommodated overlapping each other, and the wafer W4 is accommodated in an inclined state.

[0044] FIG. 6 is a schematic diagram showing a captured image acquired by the camera 40. On the side surfaces of the wafers W1 to W4, the brightness of the first positions P11, P12, P13 illuminated by the light 51 is high. Similarly, on the side surfaces of the wafers W1 to W4, the brightness of the second positions P21, P22, P23 illuminated by the light 52 is high. The first positions P11, P12, P13 are respectively included in the detection regions R11 to R13. The second positions P21, P22, P23 are respectively included in the detection regions R21 to R23.

[0045] FIG. 7 is a schematic diagram showing a binarized image. The image processing unit 60 performs binarization processing on the detection regions R11 to R13 and the detection regions R21 to R23 in the captured image, setting the value of the portion where the brightness is higher than the threshold to 1 and the value of the portion where the brightness is equal to or lower than the threshold to 0. Also, the image processing unit 60 sets the value to 0 for the portions other than the detection regions R11 to R13 and the detection regions R21 to R23 in the captured image. That is, the image processing unit 60 detects the accommodation state of the wafer W based on the images of the detection regions R11, R12, R13 including the first positions P11, P12, P13 of the wafer W when the accommodation state of the wafer W is normal, and the images of the detection regions R21, R22, R23 including the second positions P21, P22, P23 of the wafer W when the accommodation state of the wafer W is normal, in the captured image acquired by the camera 40.

[0046] Then, the image processing unit 60 detects the accommodation state of the wafer W based on the position, vertical width, inclination, etc. of the portion with a value of 1. For example, in the upper part of the imaging range S, since the position and vertical width of the portion with a value of 1 are within the range of normal values, it is detected that the accommodation state of the wafer W1 is normal. In the middle part of the imaging range S, since the vertical width y of the portion with a value of 1 exceeds the range of normal values, it is detected that the wafers W2 and W3 are accommodated overlapping each other. In the lower part of the imaging range S, since the inclination of the portion with a value of 1 or the inclination of the straight line S1 connecting the portions with a value of 1 exceeds the range of normal values, it is detected that the wafer W4 is accommodated inclined.

[0047] The present embodiment described in detail above has the following advantages.

[0048] · The light 51 is attached to the lid holding part 31 that moves downward together with the lid 21 when the lid 21 is moved downward by the opening / closing mechanism 30, and illuminates the first position P1 on the side surface of the wafer W. Therefore, when the lid 21 is moved downward by the opening / closing mechanism 30, the light 51 can illuminate the first position P1 on the side surface of the wafer W while moving downward together with the lid 21 and the lid holding part 31. Also, the light 52 is attached to the lid holding part 31 and illuminates the second position P2 that is different from the first position P1 on the side surface of the wafer W where the first position P1 is illuminated. Therefore, when the lid 21 is moved downward by the opening / closing mechanism 30, the light 52 can illuminate the second position P2 that is different from the first position P1 on the side surface of the wafer W while moving downward together with the lid 21, the lid holding part 31, and the light 51. That is, while illuminating the first position P1 on the side surface of one wafer W with the light 51 and illuminating the second position P2 with the light 52, the lights 51 and 52 can be moved downward.

[0049] · The camera 40 is attached to the lid holding portion 31 and acquires a captured image by photographing a range including the first position P1 and the second position P2 on the wafer W where the first position P1 and the second position P2 are illuminated. For this reason, when the opening / closing mechanism 30 moves the lid 21 downward, the camera 40 can acquire a captured image by photographing a range including the first position P1 and the second position P2 on the wafer W while moving downward together with the lid 21, the lid holding portion 31, the light 51, and the light 52. Therefore, without requiring a special operation by a transfer robot or the like, by using the operation of moving the lid 21 downward by the opening / closing mechanism 30, captured images of a plurality of wafers W accommodated at a predetermined interval downward can be sequentially acquired.

[0050] · Since the light 51, the light 52, and the camera 40 all move downward together with the lid 21 and the lid holding portion 31, the relationship between the angle and range at which the light 51 and the light 52 irradiate the wafer W with light and the angle and range at which the camera 40 photographs the wafer W does not change when the camera 40 moves downward. Moreover, compared with the variation in the intensity of the reflected light incident on the camera 40 caused by the position within the wafer W when irradiating the entire side surface of the wafer W with one lighting device, the variation in the intensity of the reflected light incident on the camera 40 at the first position P1 and the second position P2 can be reduced. Then, the image processing unit 60 detects the accommodation state of the wafer W based on the captured image acquired by the camera 40. Therefore, the accommodation state of the wafer W within the FOUP 20 can be stably detected.

[0051] · The camera 40 acquires a captured image by photographing a range including the first position P1 and the second position P2 on the wafer W. For this reason, the cost of the wafer W detection system can be reduced as compared with the case where a camera for photographing the first position P1 and a camera for photographing the second position P2 are respectively provided.

[0052] · When viewed from a direction perpendicular to the main surface Wm of the wafer W, the optical axis C1 of the camera 40 is deviated from the center O of the wafer W. Therefore, when compared with the case where the optical axis C1 of the camera 40 passes through the center O of the wafer W when viewed from a direction perpendicular to the main surface Wm of the wafer W, a wider range of the side surface of the wafer W can be included in the field of view of the camera 40 under the condition that the distance from the wafer W to the camera 40 is the same. Therefore, even for the camera 40 with a narrow field of view, it becomes easier to photograph the range including the first position P1 and the second position P2.

[0053] · The distance from the camera 40 to the light 51 is longer than the distance from the camera 40 to the light 52. Therefore, while widening the interval between the first position P1 and the second position P2, it becomes easier for the reflected light irradiated in the direction of the optical axis C3 of the light 51 and reflected by the wafer W to enter the camera 40. Therefore, it is possible to suppress a decrease in the intensity of the reflected light incident on the camera 40 from the first position P1, and the accommodation state of the wafer W in the FOUP20 can be stably detected.

[0054] · When viewed from a direction perpendicular to the main surface Wm of the wafer W, the optical axis C1 of the camera 40 intersects a straight line C2 perpendicular to the main surface 21a of the lid 21. Therefore, it is possible to suppress the disturbance light incident from the opposing portion 20a into the FOUP20 from directly entering the field of view of the camera 40, and the accommodation state of the wafer W in the FOUP20 can be stably detected.

[0055] · The camera 40 photographs a photographing range S including a plurality of first positions P11, P12, P13 and a plurality of second positions P21, P22, P23 in the downward direction. For this reason, the camera 40 can acquire a photographed image obtained by photographing a plurality of wafers W1 to W4 at once. Then, the image processing unit 60 can detect the accommodation states of a plurality of wafers W1 to W4 at once based on the photographed image acquired by the camera 40.

[0056] · The light 51 illuminates a plurality of first positions P11, P12, P13 included in the imaging range S, and the light 52 illuminates a plurality of second positions P21, P22, P23 included in the imaging range S. Therefore, when the imaging range S is imaged by the camera 40, the states of the plurality of first positions P11, P12, P13 and second positions P21, P22, P23 included in the imaging range S can be clearly imaged. Further, since the light 51, the light 52, and the camera 40 all move downward together with the lid 21 and the lid holding portion 31, the relationship between the angle and range at which the light 51 and the light 52 irradiate light on the plurality of wafers W and the angle and range at which the camera 40 images the plurality of wafers W does not change when the camera 40 moves downward. Therefore, the accommodation state of the plurality of wafers W in the FOUP 20 can be stably detected.

[0057] · The image processing unit 60 detects the accommodation state of the wafer W based on the images of the detection regions R11, R12, R13 including the first positions P11, P12, P13 of the wafer W and the images of the detection regions R21, R22, R23 including the second positions P21, P22, P23 of the wafer W in the captured image obtained by the camera 40 when the accommodation state of the wafer W is normal. According to such a configuration, since the accommodation state of the wafer W is detected based on the images of the detection regions R11, R12, R13 and the images of the detection regions R21, R22, R23 instead of the entire captured image, the influence of ambient light can be suppressed. Therefore, the accommodation state of the wafer W in the FOUP 20 can be stably detected.

[0058] Note that the above embodiment can also be implemented with the following modifications. For parts identical to the above embodiment, the description will be omitted by assigning the same reference numerals.

[0059] · Instead of setting the detection regions R11, R12, R13, R21, R22, R23 for the captured image, the entire captured image can be binarized, and the accommodation state of the wafer W can be detected based on the binarized image.

[0060] · Set the imaging range S of the camera 40 to a range including the first position P1 and the second position P2 of one wafer W, and it is also possible to detect the accommodation state of the wafer W one by one in the multi-stage FOUP 20. In this case, the lights 51 and 52 may illuminate the first position P1 and the second position P2 on the side surface of one wafer W, respectively.

[0061] · It is also possible to set the optical axis C1 of the camera 40 to be parallel to a straight line C2 perpendicular to the main surface 21a of the lid 21. In that case, it is desirable that the opposing portion 20a of the FOUP 20 is formed of an opaque (light-impermeable) member.

[0062] · When viewed from a direction perpendicular to the main surface Wm of the wafer W, it is also possible to set the optical axis C1 of the camera 40 to pass through the center O of the wafer W.

[0063] · It is also possible to set the distance from the camera 40 to the light 51 and the distance from the camera 40 to the light 52 to be the same.

[0064] · When viewed from a direction perpendicular to the main surface Wm of the wafer W, both the light 51 and the light 52 can be arranged on the left side or the right side of the optical axis C1 of the camera 40.

[0065] · The predetermined members to which the lights 51 and 52 and the camera 40 are attached are not limited to the lid holding portion 31, and may be other members integrated with the lid holding portion 31, such as an attachment member attached to the lid holding portion 31 or a link connected to the lid holding portion 31. Also, the lid holding portion 31 and other members integrated with the lid holding portion 31 can be collectively interpreted as a predetermined member. In short, the predetermined member may be a member that moves downward (in a predetermined direction) together with the lid 21 when the lid 21 is moved downward (in a predetermined direction) by the opening / closing mechanism 30. Note that the wafer detection system 10 can also detect the accommodation state of the wafer W accommodated in the FOUP 20 at a predetermined interval in the upward (predetermined direction) when the lid 21 is moved upward (in a predetermined direction) to close the lid 21 of the FOUP 20 by the opening / closing mechanism 30.

[0066] ·The lights 51 and 52 may be lighting devices that adjust the light irradiation range of not only LED lights but also fluorescent lights, halogen lamps, incandescent bulbs, etc. with reflectors and slits.

[0067] ·The shape of the wafer W is not limited to a disc shape, and may be a rectangular plate shape, a polygonal plate shape, etc.

[0068] ·The wafer W may be before the process is executed or after the process is executed. Also, the wafer W may be before the circuit or the like is formed or after the circuit or the like is formed.

[0069] ·By a detection system similar to the wafer detection system 10, instead of the wafer W, it is also possible to detect the accommodation state of a plurality of plate-shaped workpieces accommodated in an accommodation container at a predetermined interval in a predetermined direction.

[0070] It should be noted that each of the above modification examples can also be implemented in combination.

Explanation of Reference Numerals

[0071] 10…Wafer detection system, 20…FOUP (wafer accommodation container), 21…Lid, 30…Opening / closing mechanism, 31…Lid holding part (predetermined member), 40…Camera (imaging part), 51…Light (first lighting part), 52…Light (second lighting part), 60…Image processing part (detection part).

Claims

1. A wafer detection system for detecting the accommodation state of wafers accommodated in a wafer accommodation container in which a plurality of wafers are accommodated at a predetermined interval in a predetermined direction and a lid is closed, the system detecting when the lid is moved in the predetermined direction by an opening / closing mechanism, a first illumination unit attached to a predetermined member that moves in the predetermined direction together with the lid when the lid is moved in the predetermined direction by the opening / closing mechanism, the first illumination unit illuminating a first position on a side surface of the wafer; a second illumination unit attached to the predetermined member, the second illumination unit illuminating a second position different from the first position on the side surface of the wafer where the first position is illuminated; a photographing unit attached to the predetermined member, the photographing unit acquiring a photographed image of a range including the first position and the second position on the wafer where the first position and the second position are illuminated; a detection unit for detecting the accommodation state of the wafer based on the photographed image acquired by the photographing unit; The wafer detection system is provided with: When viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the photographing unit is deviated in a first direction with respect to the center of the wafer, the first illumination unit is arranged in the first direction with respect to the optical axis of the photographing unit, and the second illumination unit is arranged in a second direction opposite to the first direction with respect to the optical axis of the photographing unit, A wafer detection system, wherein the distance from the photographing unit to the first illumination unit is longer than the distance from the photographing unit to the second illumination unit.

2. A wafer detection system for detecting the accommodation state of wafers accommodated in a wafer accommodation container in which a plurality of wafers are accommodated at a predetermined interval in a predetermined direction and a lid is closed, the system detecting when the lid is moved in the predetermined direction by an opening / closing mechanism, a first illumination unit attached to a predetermined member that moves in the predetermined direction together with the lid when the lid is moved in the predetermined direction by the opening / closing mechanism, the first illumination unit illuminating a first position on a side surface of the wafer; a second illumination unit attached to the predetermined member, the second illumination unit illuminating a second position different from the first position on the side surface of the wafer where the first position is illuminated; a photographing unit attached to the predetermined member, the photographing unit acquiring a photographed image of a range including the first position and the second position on the wafer where the first position and the second position are illuminated; a detection unit for detecting the accommodation state of the wafer based on the photographed image acquired by the photographing unit; The wafer detection system is provided with: the photographing unit photographs a predetermined range including a plurality of the first positions and a plurality of the second positions in the predetermined direction. The first illumination unit illuminates the plurality of the first positions included in the predetermined range. The second illumination unit illuminates the plurality of the second positions included in the predetermined range, and is a wafer detection system.

3. The wafer detection system according to claim 2, wherein, when viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the imaging unit is deviated from the center of the wafer.

4. When viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the imaging unit is deviated in a first direction with respect to the center of the wafer, the first illumination unit is arranged in the first direction with respect to the optical axis of the imaging unit, and the second illumination unit is arranged in a second direction opposite to the first direction with respect to the optical axis of the imaging unit. The wafer detection system according to claim 2 or 3, wherein the distance from the imaging unit to the first illumination unit is longer than the distance from the imaging unit to the second illumination unit.

5. The wafer detection system according to any one of claims 1 to 4, wherein, when viewed from a direction perpendicular to the largest surface of the wafer, the optical axis of the imaging unit intersects a straight line perpendicular to the largest surface of the lid.

6. The detection unit detects the accommodation state of the wafer based on an image of a first region including the first position of the wafer and an image of a second region including the second position of the wafer when the accommodation state of the wafer is normal in the captured image acquired by the imaging unit. The wafer detection system according to any one of claims 1 to 5.

Images