JPH11220003A - Wafer holding device - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] To reliably hold and take out wafers even if their accommodation positions vary due to deformation of a cassette or hooking of each wafer caused in a wafer processing step. To SOLUTION: A movable claw support 2 is moved by a hand 1 being advanced.
0, the outer peripheral edge of the wafer W is pressed at the front end face to move the wafer W to a position where the wafer W comes into contact with the inner back face C1 of the cassette C;
In this state, the movable claw support 20 moves backward, the front leaf spring 19 does not block the optical path LF from the front light emitting section 25F to the front light receiving section 27F, and the rear leaf spring 19 is moved to the rear light emitting section. A state in which the wafer W is displaced to a position that blocks the optical path LR from the rear light receiving unit 27R to the rear light receiving unit 27R is determined as a normal position where each wafer W can be gripped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer holding device, and more particularly to a technical field related to a device suitable for holding and taking out a wafer housed in a cassette.

[0002]

2. Description of the Related Art Conventionally, as a wafer gripping device for gripping and transferring a wafer, a pair of right and left fixed claws are fixed to the distal end of a hand, as shown in Japanese Patent Application Laid-Open No. 7-201947. A movable claw is provided at the left and right central portion of the base end of the movable claw so as to be able to move back and forth, and the movable claw is gripped with a fixed claw by a relative advance of the movable claw with respect to the hand. Along with urging forward, the movable pawl is connected to the ring via a link mechanism, and the movable pawl resists the urging force of the spring via the link mechanism by the rotation of the ring due to the rotation operation around the rotation center of the hand. It is known to move the vehicle backward.

[0003] In the process of processing wafers of this type, a cassette is generally used to accommodate the wafers. Conventionally, for the purpose of detecting deformation and distortion at the time of manufacturing the cassette, for example, Japanese Unexamined Patent Publication No.
No. 725 and JP-A-2-154105 have been proposed. The former (JP-A-5-477
No. 25), a tactile plate having the same shape as the wafer accommodated in the cassette is provided on the robot hand, and this tactile plate is actually inserted into the cassette, and the cassette shape is determined based on the resistance at that time. Is determined, or a light beam is projected onto the groove for accommodating the wafer in the cassette, and the quality of the shape of the groove is determined based on the attenuation of the light beam.

On the other hand, in the case of the latter (Japanese Patent Application Laid-Open No. 2-154105), marks are provided on both the left and right sides of the cassette in accordance with the pitch of shelves for accommodating wafers, and the cassette and the left and right optical sensors are moved relative to each other. The position of the mark is detected by a sensor, and the quality of the cassette shape is determined based on the presence or absence of coincidence of the pulse signals from the optical sensors on both the left and right sides.

[0005]

However, in the above-mentioned conventional devices, since the deformation of the cassette itself is inspected, it is difficult to solve the following problems. In other words, even if a normal cassette without deformation distortion is handled by a robot in the wafer processing process and is placed or picked up at a predetermined position, the cassette is gradually deformed by repetition. May come. In addition, the cassette may be deformed even if the robot forcibly pushes or drops the cassette, and the deformation of the cassette during the wafer processing process causes a variation in the wafer accommodation position in the cassette. . Therefore, when the gripping portion of the robot is inserted into the cassette and the wafers housed therein are gripped and taken out by the hand, if there is a variation in the wafer housing position as described above, the wafers in the cassette are removed. There has been a problem that the robot cannot be reliably gripped, and the reliability of the transfer operation of the robot is reduced.

[0006] Even in a normal cassette having no deformation and distortion, if a wafer accommodated in the cassette is caught and the position of the wafer is varied, the robot surely removes the wafer as described above. It cannot be gripped.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to improve the configuration of a gripping mechanism in a wafer gripping device as described above, thereby deforming a cassette and deforming a wafer in the cassette. An object of the present invention is to ensure that a wafer can be reliably grasped and taken out even if the accommodation position of the wafer varies due to the hook.

[0008]

In order to achieve the above object, the present invention utilizes a movable claw support which supports a movable claw in a robot hand so that the movable claw can move relative to each other. The wafer is pressed by the support and pressed against the rear end in the cassette, and it is determined whether or not the wafer can be gripped based on the relative displacement of the movable claw support in the pressed state. .

More specifically, according to the first aspect of the present invention, a hand connected to a robot arm and a hand provided on the hand are provided as a wafer holding device provided in a robot for holding and taking out a wafer contained in a cassette. A fixed claw fixed to the distal end of the hand, and a movable claw supported to be movable back and forth at the base end of the hand. The fixed claw and the movable claw are engaged at positions spaced apart from the outer peripheral portion of the wafer. And a holding means for holding the wafer together.

[0010] The gripping means further includes a moving body supported at a base end of the hand so as to be relatively movable in the hand moving direction, and a relatively movable body in the moving body along the hand moving direction. A movable claw support for elastically supporting the movable claw and for pressing the outer peripheral edge of the wafer by the forward movement of the hand to move the wafer to a position where the wafer abuts on the inner surface of the cassette. And

A front-rear position detecting means for detecting that the movable claw support is displaced in the hand retreating direction with the advance movement of the hand in a state where the wafer has moved to a position where it comes into contact with the inner surface of the cassette. The configuration is provided with.

According to the above configuration, when a wafer contained in the cassette is gripped and taken out by the hand, the hand is advanced and the gripping means is inserted into a side of the wafer in the cassette. At this time, as the hand advances, the movable claw support supported by the hand via the movable body presses the outer peripheral edge of the wafer, and the wafer is pushed onto the inner back surface of the cassette by the pressing of the movable claw support. Move to the contact position.
Since the movable claw support is elastically supported so as to be relatively movable along the moving direction of the hand with respect to the moving body of the hand, when the movable claw support is pressed from the wafer in contact with the inner back surface of the cassette, the movable claw support is Accordingly, the hand is displaced in the retreating direction, and this displacement is detected by the front / rear position detecting means. Therefore, when the displacement of the movable claw support is detected by the front / rear position detecting means to be within a predetermined range, the wafer in the cassette may be deformed due to the deformation of the cassette caused in the wafer processing process or the wafer in the cassette may be caught. Even if the accommodation positions of the wafers vary, the wafer is at a position where it can be gripped by the gripping means, and the wafer can be gripped reliably.

Further, since the movable claw support supports the movable claw for holding the wafer by the holding means, it is necessary to detect whether or not the wafer can be held by using an existing member called the holding means. Can be.

Thereafter, the gripping means grips the wafer, and then the hand retreats, and the wafer is taken out of the cassette and transported while being gripped by the gripping means. Therefore, the transfer operation of the robot can be performed with high reliability without interruption.

According to the second aspect of the present invention, it is assumed that right and left position detecting means for detecting the position of the outer peripheral edge in the front-rear direction of the wafer are provided at least on both sides of the center of the hand. In this way, for example, even if the upper part and the lower part of the cassette are deformed so as to be shifted left and right, the shift in the horizontal direction of the wafer based on the deformation distortion can be determined by the detection state of the left and right position detection means, and The state in which the wafer cannot be gripped can be accurately and reliably detected.

According to the third aspect of the present invention, the hand is provided with a plurality of gripping means arranged in a direction orthogonal to the hand moving direction. With this configuration, even if the storage positions of the plurality of wafers stored in the cassette are varied, the entirety of the wafers can be simultaneously pressed and moved by the movable claw support and brought into contact with the rear end surface in the cassette. . If each wafer is at a position where it cannot be gripped by the corresponding gripping means, the displacement of the movable claw support of the gripping means corresponding to each wafer falls outside the predetermined range, so that it can be determined that the wafer cannot be gripped. In particular, in the present invention, since the movable claw support individually and simultaneously presses the plurality of wafers held by the plurality of holding means, the upper portion of the cassette is deformed so as to be inclined to the opposite opening side as compared with the lower portion. However, it is possible to accurately and reliably detect a state in which the wafer cannot be gripped due to the deformation distortion.

[0017]

1 to 3 show a wafer holding device according to an embodiment of the present invention. In the drawing, reference numeral C denotes a rectangular box-shaped wafer accommodating cassette having an opening on the right side in FIG.
, A plurality of (for example, 25) disk-shaped wafers W, W,... Having the same diameter and thickness are stacked and stored in a horizontal state, and the plurality of wafers W, W,. The cassette C is supported at regular intervals (for example, 10 mm) in the vertical direction by supporting shelves (not shown) protruding from the left and right side walls in the cassette C.

Reference numeral 1 denotes a hand connected to the end of an arm of a robot (not shown) for taking out and transferring wafers W, W,... Stored in the cassette C in a clean room. It has a hand body 2. The hand main body 2 is provided with a plurality of gripping mechanisms 4, 4,... Arranged in a vertical direction which is a direction orthogonal to the advance / retreat direction of the hand 1. These gripping mechanisms 4, 4,. , 7 and the movable claw 22 are engaged with the outer peripheral edge of each wafer W at a distance from each other to grip the wafer W.

Each of the plurality of gripping mechanisms 4, 4,... Has the same configuration, and each has a base end fixed to the hand body 2 and a thin plate-shaped support having an opening 5a at the center for reducing weight. It has a plate 5. Two fixed claws 7, 7 are respectively attached to the left and right sides of the front end of each support plate 5, and each fixed claw 7 has a cross section in which the upper groove surface is shorter than the lower groove surface and is opened substantially rearward. Each of the fixing claws 7 has a V-shaped engagement groove 8, and each wafer W
The outer peripheral edges on the left and right sides on the inner side of the cassette are engaged with each other. A pair of left and right mounting plates 10 for mounting the outer peripheral edge of each wafer W on the cassette opening side is attached to the left and right sides near the base end of each support plate 5.

On the other hand, an opening 12 penetrating in the vertical direction is formed in the left and right central portions of the hand main body 2 from the hand main body 2 to the left and right central portions near the base ends of the support plates 5, 5,. In the opening 12, a rectangular frame-shaped moving body 14 having an opening at the center is arranged and supported so as to be relatively movable along the advancing / retreating direction (front-back direction) of the hand main body 2. The moving body 14 is connected and supported to a piston rod 15a of a cylinder 15 extending in the front-rear direction as an actuator attached and fixed to the hand main body 2 via a connecting plate 16 extending in the left-right direction and a connecting rod 17 extending in the front-rear direction. The moving body 14 is moved back and forth relative to the hand main body 2 by the expansion and contraction operation of the cylinder 15,
The moving body 14 is moved forward by the contraction operation of the moving body 14, while the moving body 14 is moved backward by the extending operation of the cylinder 15.

At the left vertical frame portion of the moving body 14, base ends of a pair of front and rear leaf springs 19, 19 as elastic means are attached and fixed at positions corresponding to the lower sides of the support plates 5, respectively. Have been. The two leaf springs 19 extend horizontally in parallel with each other toward the right vertical frame portion of the moving body 14, and the leading end thereof is located below each support plate 5 and at the left and right center of the opening in the moving body 14. Is fixedly mounted. That is, the movable claw support 20 is
When the hand 1 is moved forward and each gripping mechanism 4 is inserted into the space above each wafer W in the cassette C, it is elastically supported so as to be relatively movable along the moving direction of the hand 1 with respect to the moving body 14. By pressing the outer peripheral edge of the corresponding wafer W on the cassette opening side by the front end surface (front end surface) of the movable claw support 20, the whole of the plurality of wafers W, W,. When the hand 1 is moved forward in a state where the movement of each wafer W is restricted by this contact, the movable claw support 20 is displaced in the retreating direction of the hand 1 by pressing from the wafer W. It is supposed to.

On the upper surface of the tip (front end) of each movable claw support 20, one movable claw 22 composed of a concave roller located above the support plate 5 is supported by a support shaft 21 extending vertically. It is rotatably supported. That is,
The movable claw 22 is supported by the leaf springs 19, 19 so as to be relatively movable with respect to the moving body 14 in the advancing and retreating direction of the hand main body 2. In addition, the entire outer peripheral surface of the movable claw 22 composed of the concave roller is located at the same height position as the engagement groove 8 of the fixed claw 7 and the upper groove surface is shorter than the lower groove surface in a V-shaped cross section. The movable claw 22 engages the outer peripheral edge of each wafer W on the cassette opening side with the concave groove 23 on the outer peripheral surface.

A front light-emitting portion 25F that emits light downward is mounted on the lower surface of the upper horizontal frame portion of the moving body 14, and a similar rear light-emitting portion 25R is mounted and fixed on the rear surface thereof via a bracket 26. On the other hand, on the upper surface of the lower horizontal frame portion of the moving body 14, the front light emitting unit 2
A front light receiving portion 27F on which light from 5F is incident, and a rear light receiving portion 27R on which light from the rear light emitting portion 25R is incident on a rear surface of the horizontal frame portion just below the rear light emitting portion 25R.
Are mounted and fixed via a bracket 28, respectively, and an optical path LF from the front side light emitting portion 25F to the front side light receiving portion 27F is located just above the front side leaf spring 19 in the uncurved state, and the rear side light emitting portion. From the part 25R to the rear light receiving part 27
The optical path LR reaching R is set so as to pass through a position directly behind the rear leaf spring 19 in the same state (note that the optical path LR is the same).
The respective light emitting units 25F and 25R may be reversed below the moving body 14 and the respective light receiving units 27F and 27R may be reversed above the moving body 14).

The light emitting units 25F and 25R and the light receiving unit 27
F and 27R together constitute front / rear position detecting means. As described above, with each wafer W moved to a position where it comes into contact with the inner back surface C1 of the cassette C, the hand 1 is further moved forward. When the movable claw support 20 is displaced in the hand retreating direction, this is detected by the light emitting units 25F and 25R and the light receiving units 27F and 27R, and the proper displacement of the movable claw support 20 causes the front light emitting unit 25F to move forward. Light receiving unit 27
The front leaf spring 19 is displaced from the position of the optical path LF reaching F, the light from the front light emitting section 25F is received by the front light receiving section 27F, and the light path LR from the rear light emitting section 25R to the light receiving section 27R is moved to the rear side. When the leaf spring 19 is cut off and the light from the rear light emitting unit 25R is not received by the rear light receiving unit 27R, the state is detected as a normal state. On the other hand, the movable platen support 20 is not displaced, and the rear leaf spring 1 is moved from the position of the optical path LR from the rear light emitting portion 25R to the rear light receiving portion 27R.
9 comes off, and the light from the rear light emitting unit 25R is transmitted to the rear light receiving unit 2R.
7R, and the front leaf spring 19 cuts off the optical path LF from the front light emitting unit 25F to the front light receiving unit 27F, and the front light receiving unit 27F does not receive the light from the front light emitting unit 25F, or Due to the excessive displacement of the movable claw support 20, the front leaf spring 19 moves from the position of the optical path LF extending from the front light emitting section 25F to the front light receiving section 27F, and the optical path extends from the rear light emitting section 25R to the rear light receiving section 27R. When the rear leaf springs 19 are disengaged from the LR position, respectively, and the light from the front and rear light-emitting portions 25F and 25R is received by the front and rear light-receiving portions 27F and 27R, respectively, both states are changed. It is detected as an abnormal state, and based on this detection signal, the transfer operation of the robot is stopped, or a warning of a poor grip of the wafer W is issued.

Further, a rear end of a plate-shaped bracket 31 extending forward is mounted and fixed on the upper surface of the upper horizontal frame portion of the moving body 14, and four lower light-emitting portions are provided on the lower surface of the front end of the plate-shaped bracket 31. .. (Only two are shown in FIG. 2) correspond to the position of the outer peripheral edge of the rear end side of the wafer W at an appropriate position with respect to the support plate 5 of each gripping mechanism 4. The hand 1 is attached symmetrically to the left and right centers and in an arc shape. Further, a rear end of a plate-like bracket 33 extending similarly to the front side is attached and fixed to the lower surface of the lower horizontal frame portion of the movable body 14, and the light-emitting portions 32, 32, The light-emitting portions 32, 3 are located at positions corresponding to the top and bottom (circular positions corresponding to the positions of the outer peripheral edge portions on the rear end side of the wafer W at appropriate positions on the support plate 5).
Light receiving sections 34, 3 on which light from 2, 2,.
The light path L extending from each light emitting section 32 to each corresponding light receiving section 34 corresponds to the position of the rear end side outer peripheral edge of the wafer W at an appropriate position on each support plate 5. It is set so as to pass (in this case, each light emitting unit 32 may be reversed below the moving body 14 and each light receiving unit 34 may be reversed above the moving body 14).

The light emitting units 32, 32,...
, 34,... Together constitute left and right position detecting means.
As described above, the wafers W, W,
When the hand 1 is retracted after detecting the displacement of the movable claw support 20 in the hand retreating direction by pressing from the... And determining the position of the wafers W, W,.
.. From the light receiving portions 34, 34,... Are blocked by any of the wafers W, W,. The timing of the state where the light enters the light receiving unit 34 is detected. If the detection timing does not deviate from the preset reference value by a predetermined amount or more, the state is detected as a normal state. When the value deviates from the value by a predetermined amount or more, the state is detected as an abnormal state, and the detection signal is used to stop the transfer operation of the robot or to warn of a gripping failure of the wafer W.

Incidentally, for the wafer W which is in contact with the inner back surface C1 of the cassette C in advance, the movable claw support 2
0 does not move. Further, even in a state where the outer peripheral edge of the wafer W is in contact with the inner deep portion of the cassette C, spaces are provided on both left and right sides of the cassette C so that the fixing claws 7 can be accommodated.

Next, the operation of the first embodiment will be described. The plurality of wafers W stored in the cassette C,
When gripping and transporting W,... By the transfer hand of the robot, first, the cylinder 15 of the hand body 2 is extended to move the moving body 14 relatively to the hand body 2, and Each movable claw 22 elastically supported by the leaf springs 19 and 19 and the movable claw support 20 also retracts. In this state, the movable claw 2 in each gripping mechanism 4
2 is separated from the fixed claws 7, 7 at the tip of the support plate 5, and the fixed claws 7, 7 and the movable claws 22 are in an open state in which the respective wafers W can be inserted and arranged therebetween.

Thereafter, as shown in FIGS. 1 and 2, the hand 1 advances, and the support plate 5 of each gripping mechanism 4 is inserted into the upper space of each wafer W in the cassette C corresponding thereto. . With the advance of the hand 1, first, the movable claw support 20 supported by the hand body 2 moves the corresponding outer peripheral edge of the corresponding wafer W on the cassette opening side at the front end surface (front end surface). The wafer C is pressed at one position in the center, and each wafer W is moved to a position where it comes into contact with the inner back surface C1 of the cassette C by the pressing of the movable claw support 20. Thus, even if the initial accommodation positions of the wafers W, W,... In the cassette C vary, all of the wafers W, W,. It will be located at a predetermined allowable accommodation position with respect to the inner back surface C1.

Thereafter, the hand 1 further moves forward. Since the movement of each wafer W is restricted by contacting the inner back surface C1 of the cassette C, the movable claw is reversed with the advance of the hand 1. The support 20 is pushed from the wafer W and the leaf spring 1
The hand 9 is relatively displaced in the retreating direction while bending the hands 9 and 19. Then, due to the displacement of each movable claw support 20, the front leaf spring 19 is displaced from the position of the optical path LF extending from the front light emitting section 25F to the front light receiving section 27F, and the light from the front light emitting section 25F is transmitted to the front light receiving section 27F. Received by
Further, an optical path LR from the rear light emitting unit 25R to the rear light receiving unit 27R is blocked by the rear leaf spring 19, and the rear light emitting unit 25R is closed.
When the light from R is not received by the rear light receiving unit 27R,
The state is determined to be a normal state. That is, when the front side light receiving portion 27F is in the light receiving state and the rear side light receiving portion 27R is in the light blocking state, the deformation distortion of the cassette C generated in the wafer processing step and the pulling of the wafers W, W,. Even if the accommodation positions of the wafers W, W,... In the cassette C vary due to the hanging or the like, it is detected that the wafers W, W,. .

On the other hand, if the movable claw support 20 is not displaced or is displaced excessively, the rear light emitting section 2
The rear leaf spring 19 is disengaged from the position of the optical path LR from 5R to the rear light receiving section 27R, and the light from the rear light emitting section 25R is received by the rear light receiving section 27R and the front light emitting section 25F.
The optical path LF from the front to the front light receiving portion 27F is the front leaf spring 1.
9, or from the position of the optical path LF from the front light-emitting portion 25F to the front light-receiving portion 27F to the front leaf spring 1
9, the rear leaf springs 19 are displaced from the position of the optical path LR from the rear light-emitting portion 25R to the rear light-receiving portion 27R, and light from the front and rear light-emitting portions 25F and 25R is respectively transmitted to the front and rear. The light is received by the side light receiving units 27F and 27R. At this time, it is determined that the robot is in an abnormal state and the transfer operation of the robot is stopped or the wafer W
Is warned.

When it is detected that the front and rear positions of the wafers W, W,... In the cassette C are at grippable positions, the hand 1 continues to retreat and is once extracted from the cassette C.

When the hand 1 retreats in this manner, the four light-emitting portions 32, 32,... Of the upper plate-shaped bracket 31 correspond to the four light-receiving portions 34, 3 until then.
The light paths L, L,... Of the light incident on the light-receiving portions 34 are blocked by the wafers W, respectively. Is started. The incident timing of the light of these four light receiving units 34, 34,... Is detected and compared with a preset reference value. Is detected as On the other hand, when the detection timing deviates from the set reference value by a predetermined amount or more, the state is detected as an abnormal state, and the robot operation is stopped by this detection signal, or a warning of a defective gripping of the wafer W is issued. For example, when any of the wafers W is shifted to the left, the light receiving timing of the right light receiving units 34, 34 is relatively earlier than that of the left light receiving units 34, 34. To the left.

Specifically, four light receiving sections 34, 34,.
Three light receiving units 34, 34,...
The outer diameters and center positions of the four types of circles with respect to the wafer W are obtained from the light receiving timing, and the outer diameter and the center position of the worst information having the largest deviation among them are respectively compared with a reference value, and the difference is calculated. Is within the allowable range.

When the grippable state of the wafers W, W,... Is determined in this way, the hand 1 moves slightly downward and then advances again, and the support plate 5 of each gripping mechanism 4 moves to the corresponding position. The wafer W is reinserted into the lower space. In this hand 1, as shown in FIG. 3, the right and left fixing claws 7, 7 at the tip of the support plate 5 in each gripping mechanism 4 are slightly deeper inside the cassette C than the outer peripheral edge of the wafer W inside the cassette. And the wafer W is positioned between the fixed claws 7 and the movable claws 22 in the open state of the respective gripping mechanisms 4.

Thereafter, the hand 1 is slightly raised, and each wafer W is lifted from each support shelf (not shown) of the cassette C. In this state, the engagement grooves 8,
8, the left and right outer peripheral portions on the inner side of the cassette on the lower groove surface of each wafer W, and the cassettes of the wafers W on the mounting plates 10, 10 attached to the left and right sides near the base end side of each support plate 5. The left and right outer peripheral edges on the opening side are respectively placed.

Next, after the hand 1 has retreated slightly from the cassette C, the cylinder 15 contracts to move
Moves forward relative to the hand main body 2 and the moving body 14
The movable claws 22 elastically supported by the movable member 22 move forward. As a result, the movable claw 22 is fixed to the fixed claw 7, 7 at the tip of the support plate 5.
And the gap between the fixed claws 7, 7 and the movable claw 22 is closed, and each wafer W has its outer peripheral edge between the claws 7, 7, 22 in the engagement groove 8 of the fixed claw 7 and the concave groove of the movable claw 22. 23 are held in a state of being engaged with the bottom of each groove. In this gripping state, the leaf springs 19, 19, which elastically support the movable claws 22, are bent rearward, and the movable claws 22 are urged forward by the spring force. Is pressed against the fixed claws 7, 7 and gripped.

In this case, since the movable claw 22 is a rotatable concave roller, the movable claw 22 rolls even if the wafer W moves to the right or left during gripping. Is in a rolling friction state. For this reason, similarly to the above, dust generation can be reduced as compared with the case where the movable claw 22 and the wafer W are in a sliding friction state, and dust generation during the manufacturing process of the wafer W can be suppressed. it can.

After the plurality of wafers W are gripped by the corresponding gripping mechanisms 4, 4,..., The hand body 2 moves backward, and the plurality of wafers W, W,. Are taken out of the cassette C while being gripped by the..., And then transported to another predetermined process.

Therefore, in this embodiment, as described above, before the plurality of wafers W, W,... In the cassette C are gripped by the gripping mechanisms 4, 4,. , W,... Are always positioned at positions in contact with the inner back surface C1 of the cassette C. Moreover, even if the accommodation positions of the wafers W, W,... In the cassette C vary due to the deformation distortion of the cassette C generated in the wafer processing process or the hooking of the wafers W in the cassette C, the light receiving units 27F, 27R , 25 to 34, 34, 34
F, 25R, 32, 32, as long as the light reception or the light reception cutoff state is properly detected, the wafer W, W,.
Are at positions where they can be gripped by the gripping mechanisms 4, 4,.... For this reason, the robot uses the gripping mechanisms 4, 4,.
.. Can always be gripped by gripping the wafers W, W,... On the basis of the position of the wafer W, W,. ... can be securely grasped and taken out,
The transfer operation of the robot can be performed reliably without interruption.

The movable claw support 20 supports the movable claw 22 for gripping the wafer W in each of the gripping mechanisms 4. It is possible to detect whether or not it is possible to hold.

In particular, in the case of this embodiment, the plurality of wafers W,
,... Are individually and simultaneously pressed by the movable claw support members 20, 20,..., Respectively. It is possible to accurately and reliably detect the non-holding state of the wafers W, W,...

In the above-described embodiment, four pairs of the light emitting section 32 and the light receiving section 34 are provided on each of the left and right sides of the hand 1 as the left and right position detecting means. At least one pair (34 in total) may be provided on the left and right sides of the hand 1.

In the above embodiment, the case where a plurality of wafers W, W,... Accommodated in the cassette C are taken out at once is explained.
, Or a case where a cassette accommodates one wafer W and the single wafer W is taken out. Can be.

Further, the gripping mechanism 4 is limited to a structure having two fixed claws 7 on the right and left ends of the support plate 5 and one movable claw 22 elastically supported by the moving body 14 as in the above embodiment. Instead, the number of the fixed claws 7, 7 and the number of the movable claws 22 can be increased or decreased. In short, it is only necessary to have a fixed claw and a movable claw, and hold the wafer W by engaging the fixed claw and the movable claw with the outer peripheral edge of the wafer W.

[0046]

As described above, according to the first aspect of the present invention, when the wafer held in the cassette is gripped and taken out by the hand of the robot, the fixed claw fixed to the tip end of the hand is provided with: A movable claw supported on the base end side of the hand so as to be able to move back and forth; a movable body supported on the base end of the hand so as to be relatively movable along the movement direction of the hand; And a movable claw support for supporting the movable claw and for pushing the outer peripheral edge of the wafer by the forward movement of the hand to move the wafer to a position where the wafer abuts on the inner surface of the cassette. With the gripping means having a position, the front and rear positions are detected when the movable claw support is displaced in the hand retreating direction as the hand moves forward with the wafer moved to a position where it comes into contact with the inner back surface of the cassette. By detecting by step, even if the wafer storage position varies due to the deformation distortion of the cassette generated in the wafer processing process or the hooking of the wafer in the cassette, the wafer can be securely gripped by the gripping means. Can be taken out, and the reliability of the transfer operation of the robot can be improved.

According to the second aspect of the present invention, the left and right position detecting means for detecting the position of the outer peripheral edge in the front-rear direction of the wafer are provided at least on both sides of the center of the hand. Even if the wafer is displaced so as to be shifted to the left and right, it is possible to accurately and reliably detect a state in which the wafer cannot be gripped due to the distortion.

According to the third aspect of the present invention, a plurality of gripping means are provided on the hand in a direction perpendicular to the hand advancing and retreating direction, so that the accommodation positions of the plurality of wafers accommodated in the cassette vary. Also, the wafers are simultaneously pressed and moved by the movable claw support to abut against the rear end face in the cassette, and when even one of the plurality of wafers is in a position where it cannot be gripped by the gripping means, The non-grasping state can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a plan sectional view showing a state in which a movable claw support in a hand gripping mechanism presses a wafer in a cassette in an embodiment of the present invention.

FIG. 2 is a side sectional view showing a state in which a movable claw support of a gripping mechanism presses a wafer.

FIG. 3 is a plan sectional view showing a state in which a gripping mechanism grips a wafer.

[Explanation of symbols]

 C cassette C1 Inner inner surface W Wafer 1 Wafer transfer hand 2 Hand body 4 Gripping mechanism (gripping means) 5 Support plate 7 Fixed claw 8 Engagement groove 14 Moving body 19 Leaf spring 20 Movable claw support 22 Movable claw 23 Groove 25F, 25R Light emitting unit (front / back position detecting means) 27F, 27R Light receiving unit (front / back position detecting means) 32 Light emitting unit (left / right position detecting means) 34 Light receiving unit (left / right position detecting means) LF, LR, L Optical path

Claims (3)

[Claims] 1. A wafer holding device provided in a robot for holding and taking out a wafer contained in a cassette, comprising: a hand connected to a robot arm; and a hand provided to the hand and fixed to a tip end side of the hand. Fixed claw, and a movable claw supported movably back and forth on the base end side of the hand, and grips the wafer by engaging the fixed claw and the movable claw at positions spaced apart from the outer peripheral portion of the wafer. A gripper, wherein the gripper is supported at a base end of the hand so as to be relatively movable in the direction of movement of the hand, and the gripper is capable of relative movement in the direction of movement of the hand. A movable claw support for elastically supporting the movable claw, pressing the outer peripheral edge of the wafer by moving the hand forward, and moving the wafer to a position where it abuts against the inner surface of the cassette; You And a front / rear position detecting means for detecting that the movable claw support is displaced in the hand retreating direction as the hand moves forward in a state where the wafer has moved to a position where the wafer comes into contact with the inner back surface of the cassette. A wafer holding device characterized by the above-mentioned. 2. The wafer holding device according to claim 1, further comprising left and right position detecting means for detecting a position of an outer peripheral edge in a front-rear direction of the wafer, at least on both left and right center sides of the hand. apparatus. 3. The wafer gripping device according to claim 1, wherein a plurality of gripping means are provided on the hand in a direction orthogonal to the direction in which the hand advances and retreats.