JPH0656864B2 - Semiconductor wafer transfer positioning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a wafer processing apparatus for performing various process processes such as film formation and etching on a semiconductor wafer, and a wafer taken out from a wafer cassette by a robot operation. The present invention relates to a transfer positioning system for correcting and holding a wafer holder mounted on a robot at a correct centering position while being carried into the processing apparatus.

[Conventional technology]

First, the structure of the above-mentioned initial wafer transfer robot and the wafer transfer operation performed between the wafer cassette and the wafer processing apparatus will be described with reference to FIGS. In the figure, 1 is a cassette that accommodates a plurality of wafers 2 arranged in upper and lower stages, 3 is a load lock chamber that is connected to a process reaction chamber such as a plasma CVD apparatus, and 4 is a relay preparation chamber that is provided in front of the load lock chamber 3. Gate valves 5a and 5b partition the entrance and exit passages of the relay preparation chamber 4, and a relay tray 6 is provided inside the relay preparation chamber and receives and holds wafers carried in from outside. A wafer transfer robot for loading wafers from the relay tray 6 into the reaction chamber is provided on the load lock chamber side. Here, a robot 7 for wafer transfer is installed outside the relay preparation chamber 4 facing the entrance.

The robot 7 is a well-known mechanical pantograph type robot, and an example of its configuration is a drive unit 71 and an arm 72 that is connected to an output shaft of the drive unit and is operated vertically (Z direction) and swivel (θ direction). And an arm 73 that is linearly moved in the left-right direction on the arm 72, and a wafer holder 74 attached to the tip of the arm 73. With such a configuration, the arms 72 and 73 can be moved. By doing so, the wafer holder 74 can be moved and operated on the X, Y, Z coordinate system. Further, the robot 7 has a center 01 of the wafer holder 74.
The movement operation is performed by a numerical control according to a program command given to the control unit 8 so as to give a desired movement with the reference point.
On the other hand, the wafer holder 74 serves as a wafer suction tray, and suction holes 75 of the vacuum suction mechanism are opened on the surface of the tray.

With this configuration, the wafer 7 is taken out from the cassette 1 in a predetermined order by the operation of the robot 7 and the wafer holder 74
Of the wafer 2 is adsorbed and held on the upper surface of the wafer, and is transferred into the relay preparation chamber 4 through the gate valve 5b opened by following the transfer path of the arrow P, and the wafer 2 is transferred to the relay tray 6 there. The relay tray 6 has a two-part saucer structure in which a central portion thereof is cut out so as not to interfere with the wafer holder 74 on the robot 7 side, and a tapered guide portion inclined toward the inner peripheral side is provided on the peripheral edge thereof. I have it. When the wafer is transferred to the relay tray 6 here, the wafer holder 74 of the robot 7 is retracted to the outside of the room, the gate valve 5b is closed, and the relay preparation chamber 4 is evacuated. Then, the gate valve 5a between the load lock chamber 3 and the load lock chamber 3 is opened, and the wafer 2 received and held on the relay tray 6 is received by the transfer chamber-side transfer robot (not shown), from which the process reaction chamber (not shown) is received. Send to. When the predetermined wafer processing is completed and the wafer is carried out of the room through the carry-out path, the next wafer 2 to be processed next is taken out from the cassette 1 by the operation of the robot 7 in the relay preparation room 4 as described above. It is sent.

[Problems to be solved by the invention]

By the way, in the wafer transfer process, when the robot 7 transfers the wafer to the relay tray 6, the relay tray 6 is often used.
The transfer position of the wafer 2 with respect to the wafer is displaced, and the instability of the sliding condition of the taper guide surface of the relay tray 6 is added to the transfer position. The cause of such a deviation of the wafer transfer position is not only the tolerance of the outer diameter of the wafer but also the deviation of the accommodation position of the wafer 2 in the cassette 1, and the wafer holder 74 of the robot 7 from the cassette 1 to the wafer 2. This is because the wafer 2 is not held at the correct centering position with respect to the wafer holder 74 due to slippage when sucking and picking up the wafers. If such a centering position is deviated, the transfer accuracy of the robot 7 is reduced. The transfer position to the relay tray 6 is displaced no matter how high it is. Moreover, if such a transfer error occurs, the next wafer transfer process will be hindered and the automatic wafer transfer will be disrupted. Therefore, the operation of the apparatus must be stopped and the wafer position must be corrected by an operator each time. , The throughput of the entire device is reduced.

The present invention has been conceived in view of the above points, and an object thereof is to carry out a wafer taken out from a cassette by a robot operation before being carried into a process processing apparatus, and to utilize a control function of the robot itself. It is an object of the present invention to provide a wafer transfer positioning system that corrects and holds a wafer holder at a correct centering position.

[Means for solving problems]

According to the present invention, in order to solve the above-mentioned problems, a wafer in which a plurality of optical line sensors are dispersedly arranged on the circumference of a wafer holder movement trajectory by a robot arm operation in correspondence with the outer dimensions of the wafer. Equipped with a peripheral position detection device,
The wafer taken out from the cassette by the robot operation is transferred to the detection device before being carried into the wafer processing device,
In addition, after aligning the wafer holder with the center of the detector, the wafer is once released from the wafer holder and handed over to and carried by the detector. At this position, the video signal of the wafer outer peripheral position detected by the optical line sensor is used as a base. Then, the deviation of the center position with respect to the wafer is obtained with the center of the detection device as the virtual center, and this positional deviation amount is used as a correction amount to perform centering correction of the wafer holder with respect to the wafer by the fine movement operation of the robot arm. The wafer holder is used for holding.

[Action]

With the above configuration, the wafer outer peripheral position detection device disperses a plurality of optical line sensors on the horizontal base in the radial direction of the wafer, and the device temporarily receives the wafer received from the wafer holder of the robot. Further, it is provided with a vacuum suction mechanism for holding it at the outer circumference detection position.

Here, the wafer taken out from the cassette is transported to the wafer outer peripheral position detection device before being loaded into the wafer processing device,
Here, with the wafer holder aligned with the center of the detection device, the wafer is landed on the detection device side from the wafer holder, the wafer holder is once released and suction-held on the detection device side, and then the optical line sensor is used. The outer peripheral position of the wafer is detected. In this case, if the wafer is not held at the correct centering position with respect to the wafer holder in the state where it is taken out from the cassette, it is between the virtual center centered on the center of the detection device and the center of the wafer held here. The positional shift remains, and the direction and amount of this positional shift can be obtained by processing the output video signal of the optical line sensor. Here, the position shift amount is used as a correction amount, and the robot is finely operated to perform a correction movement by finely operating the robot so that the wafer holder is located at the correct centering position with respect to the wafer held on the detection device side by a command from the control unit. At this position, the wafer is again received from the detector side and sucked and held by the wafer holder.

As a result, the positional deviation caused when the wafer is taken out of the cassette is corrected, and the wafer in the middle of being conveyed is correctly held at the centering position with respect to the wafer holder. Therefore, by operating the robot from here to load the wafer holder into the process processing apparatus, the wafer can be transferred to the relay tray on the wafer processing apparatus side at the correct position without error. Moreover, this correction operation can be performed by the control function of the robot itself without requiring a separate power source, and can be flexibly dealt with even when the wafer size is changed or the wafer outer diameter tolerance is varied.

〔Example〕

1 to 4 show an embodiment of the present invention,
FIGS. 1 and 2 show the entire apparatus, and FIGS. 3 and 4 show a detailed structure diagram of a wafer outer peripheral position detection device and a wafer holder showing a state in which a wafer centering correction operation is performed. The same members corresponding to FIGS. 5 and 6 are designated by the same reference numerals.

That is, according to the present invention, a wafer outer peripheral position detection device (hereinafter, simply referred to as a detection device) indicated by reference numeral 9 on the movement locus of the wafer holder 74 attached to the robot arm is supported by the robot body on the side of the robot 7. It is installed and deployed through. This detection device 9 includes a horizontal base 91 and a horizontal base 91.
A plurality of (four in the illustrated example) optical line sensors 92 dispersedly arranged around the center 02 of the base on the upper surface side of the base 91, and a projector 93 facing above each optical line sensor 92. , And a vacuum suction mechanism 94 arranged on the inner peripheral side of the optical line sensor 92.
The optical line sensor 92 is a one-dimensional image sensor that is often used in a normal optical measurement system, and each optical line sensor 92 detects the outer peripheral position of the wafer 2 according to the size of the wafer in the radial direction. It is installed in.
Further, as the optical line sensor 92, a line sensor having a long detection range is prepared in advance in consideration of the size of the wafer and the change of the position of the orientation flat 2a.

On the other hand, as described in detail in FIGS. 3 and 4, the wafer holder 74 on the robot side has a central portion in order to avoid interference with the optical line sensor 92 of the detection device 9, the vacuum suction mechanism 92, and the like. An escape groove 76 is provided in the. In the figure, 77 is a vacuum suction hole 75.
A vacuum pump of the vacuum suction mechanism leading to the vacuum suction mechanism and a vacuum pump 95 leading to the suction hole of the vacuum suction mechanism 94 provided on the detection device 9 side.

Next, the wafer transfer and positioning operation with the above configuration will be described. First, one wafer 2 is taken out from the cassette 1 by the operation of the robot 7, is transferred to the detection device 9 before being carried into the process processing device during its transportation, and is subjected to the centering correction operation to be described later, and then processed. It is transferred to the device side and delivered to the relay tray 6. That is, when the wafer 2 taken out from the cassette 1 is transferred to the position of the detection device 9 while being sucked and held on the upper surface of the wafer holder 74 by the robot operation, the center 01 of the wafer holder 74 is detected by the predetermined program control. Stop at a position that coincides with the center 02 of the base of the device 9,
From this point, the robot arm is lowered to land the wafer 2 on the vacuum suction mechanism 94 on the detection device side, and after the wafer suction of the wafer holder 74 is once released, the wafer 2 is suction-held on the detection device side. . Since the escape groove 76 is opened in the wafer holder 74 when the robot arm descends, it does not interfere with the detection device side.

When the wafer 2 is received and held on the detection device 9, the optical line sensors 92 arranged on the circumference at that position detect the outer peripheral position of the wafer 2, and the control unit 8 causes the optical line sensors 92 to be detected.
Is processed to calculate the positional deviation between the virtual center centered on the center 02 of the base of the detection device 9 and the center of the wafer 2 held therein. Subsequently, a correction command is given from the control unit 8 to the robot 7 by using the center position shift amount obtained as described above as a correction amount, and based on this, the robot 7 finely operates the robot arm in the X and θ directions to perform the wafer holder 74.
The center 01 is centered on the wafer 2. Next, the wafer suction on the detection device 9 side is released, and at the same time, the robot arm is moved up in the Z-axis direction to move the wafer 2
Are again transferred to the wafer holder 74 to be suction-held. This completes the wafer centering correction work, and the wafer 2 is held at the correct centering position centered on the center 01 of the wafer holder 74. That is, the misalignment that occurs when the wafer 1 is initially taken out from the cassette 1 is corrected by this centering correction work.

On the other hand, after the centering correction work is completed, the robot 7 restarts from the correction position and transfers the wafer holder 74 to the designated transfer position for the relay tray 6 on the process processing apparatus side according to a command from the control unit 8. Here, the vacuum suction of the wafer holder 74 is released and the wafer 2 is held in the wafer holder.
Deliver from 74 onto the relay tray 6. Moreover, in the process of this transfer, the deviation of the holding position that occurs when the wafer 1 is first taken out from the cassette 1 is corrected by the above-described centering correction operation, so that the transfer error of the wafer 2 as in the conventional case occurs. Without it, the relay tray 6 can be accurately and smoothly transferred to its central position.

〔The invention's effect〕

As described above, according to the present invention, a wafer outer peripheral position detecting device in which a plurality of optical line sensors are dispersedly arranged on the circumference of the movement trajectory of the wafer holder by the robot arm operation corresponding to the outer dimension of the wafer. The wafer is removed from the cassette by a robot operation, transferred to the detection device before being loaded into the wafer processing device, and the wafer holder is aligned with the center of the detection device and then the wafer is once released from the wafer holder. Then, it is transferred to and carried by the detection device side, and based on the video signal of the outer peripheral position of the wafer detected by the optical line sensor at this position, the center position of the detection device is calculated as the virtual center and the deviation of the center position from the wafer is obtained. Using the amount as a correction amount, the robot arm is finely operated to correct the centering of the wafer holder with respect to the wafer, and then the wafer is robotized. Since the wafer is held by the wafer holder on the side, the deviation of the wafer holding position with respect to the wafer holder caused during the process of taking out the wafer from the cassette by the robot operation corrects the centering by the centering correction work performed during the wafer transfer. It is possible to correct the position and carry it to the next process, so that when the wafer is carried into the wafer processing apparatus side, it can be delivered to the relay tray with good position accuracy and smoothly without any delivery error. Moreover, the positioning correction operation of the centering can be performed by utilizing the control function of the robot itself without requiring a separate power source, and can flexibly and satisfactorily deal with the change of the wafer size and the variation of the wafer outer diameter tolerance. The effect such as is also obtained.

[Brief description of drawings]

FIGS. 1 and 2 are plan layout views showing the overall configuration of an embodiment of the present invention, and side views thereof, and FIGS. 3 and 4 are wafer outer peripheral position detections showing a state in which centering positioning operation is performed, respectively. A plan view showing the detailed structure of the apparatus and the wafer holder, and side views thereof, and FIGS. 5 and 6 are wafer transfer system diagrams between a conventional cassette and process processing apparatus. In each figure, 1: cassette, 2: wafer, 3: load lock chamber, 4:
Relay preparation room, 6: Relay tray, 7: Robot, 72, 73:
Robot arm, 74: Wafer holder, 8: Controller, 9:
Wafer peripheral position detection device, 91: horizontal base, 92: optical line sensor, 93: light projector, 94: vacuum suction mechanism, 01: center of wafer holder, 02: center of base of detection device.

Claims (2)

[Claims] 1. A wafer arm picked up from a cassette by the operation of a robot arm having a wafer holder at its tip is corrected to a correct centering position with respect to the wafer holder during transfer to be loaded into a wafer processing apparatus. A semiconductor wafer transfer / positioning method, in which a plurality of optical line sensors are dispersedly arranged on the circumference of a wafer holding tool movement locus by a robot arm operation according to the outer dimensions of the wafer. The wafer is taken out from the cassette by the robot operation, transferred to the detection device before being carried into the wafer processing device, and the wafer holder is aligned with the center of the detection device and then the wafer is once released from the wafer holder. The video signal of the wafer outer peripheral position detected by the optical line sensor at this position is transferred to and carried by the detector side. Then, the deviation of the center position with respect to the wafer is obtained with the center of the detection device as the virtual center, and this positional deviation amount is used as a correction amount to perform centering correction of the wafer holder with respect to the wafer by the fine movement operation of the robot arm. The semiconductor wafer transfer and positioning method is characterized in that the wafer is held by the wafer holder. 2. The transfer positioning system according to claim 1, wherein the wafer outer peripheral position detecting device is a device in which a plurality of optical line sensors are dispersed on a horizontal base and are arranged in the wafer radial direction. In addition, the apparatus is provided with a vacuum suction mechanism for temporarily holding the wafer received from the wafer holder of the robot at the outer peripheral detection position thereof.