JP2009026938A - Edge grip type notch aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an edge grip type notch aligner that completes notch alignment in a single wafer grip and notch detection operation without performing re-holding operation of a wafer for shifting a notch part from a grip part and re-detecting operation of a notch even under the condition where the notch formed at the outer circumferential portion of the wafer is located at a wafer grip part, allowing to significantly reduce the notch alignment time when the notch is located at the wafer grip part compared with conventional methods. <P>SOLUTION: The edge grip type notch aligner for a wafer is configured in such a manner that an optical length measuring sensor is used as a notch detection sensor to detect a notch formed at the outer circumferential portion of the wafer, and the sensor is located above the wafer at a position where a distance to the outer circumferential portion of the wafer on which the notch is formed with the wafer gripped can be measured, thereby a notch position being determined by judging not ON-OFF signal of the sensor or variation in the amount of received light, but variation in a distance from the sensor to the wafer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wafer edge grip type notch aligning device that detects the position of a notch formed on the outer periphery of a wafer or the like and aligns it at a specified angle from a reference position.

  Conventionally, in a semiconductor manufacturing apparatus and various wafer inspection apparatuses, it is necessary to make the wafer direction constant when the wafer is loaded, and a certain direction in which a notch (depth of about 1 mm) formed on the outer periphery of the wafer is designated. After carrying out notch alignment to fit, it is carried into a predetermined position. As a wafer holding method at the time of this notch alignment, an edge grip method that mechanically grips the edge portion on the outer peripheral surface of the wafer as described in Patent Document 1, for example, is adopted from the conventional wafer backside vacuum suction method. There is a tendency.

  In the case of this edge grip method, a wafer stored in a cassette or the like is taken out by a wafer transfer robot, transferred to a notch alignment device, and the wafer outer peripheral side is mechanically gripped to complete alignment. At this time, the wafer gripping portion has a surface perpendicular to the wafer plane that grips the edge portion of the wafer and an inclined surface that slopes downward toward the inside of the wafer that supports the edge portion of the wafer when the gripping is released, and is perpendicular to the wafer plane. Rotate the wafer together with the wafer gripping part while holding the wafer on a smooth surface, and turn on the notch detection sensor using a transmission optical sensor or a reflection optical sensor. -The notch position is detected by a change in the OFF signal or a change in the amount of received light.

  Thereafter, the notch position is rotated from the reference position to a specified angle, the wafer gripping part is opened by the opening operation of the wafer gripping part, and the wafer placed on the inclined surface inclined downward toward the inside of the wafer. Is moved downward along with the opening operation, and the outer periphery of the wafer is placed on a plurality of support portions that are supported from below at intervals in the circumferential direction for delivery to the wafer transfer robot. finish.

JP 2003-100850 A

  In the above-described notch detection method according to the prior art, when the notch formed on the outer periphery of the wafer is located at the position of the grip when the wafer is gripped, the transmission optical sensor moves downward toward the inside of the wafer holding the edge of the grip. Since the optical axis is blocked by the inclined surface inclined in the direction, the change in the ON / OFF signal and the change in the amount of light received by the notch cannot be obtained and the notch cannot be detected.

  Similarly, in the reflection type optical sensor, there is a case where the reflection of the inclined surface inclined downward toward the inside of the wafer holding the edge portion is erroneously detected and the notch portion cannot be detected. For this reason, if notch detection is not possible when the notch is detected while the wafer is being gripped, the wafer gripping is once released by opening the wafer gripping part, and the outer periphery of the wafer is rotated around for transfer to the wafer transfer robot. The wafer is placed on a plurality of support parts that are supported from below at intervals in the direction, the grip part is rotated by the width of the grip part + α (several degrees) without gripping the wafer, and the wafer is gripped again. Since the wafer is rotated together with the gripping part and re-detection is performed by the notch detection sensor, there is a problem that the notch alignment time becomes about twice as long at this time.

  The object of the present invention is to detect the notch position by changing the distance using an optical side length sensor in the notch detection portion even when the notch formed in the outer peripheral portion of the wafer is in the wafer gripping portion. An edge grip-type notch aligner that can be used for judgment, completes notch alignment with a single wafer grip and notch detection operation, and can significantly reduce the notch alignment time when there is a notch in the wafer grip. It is to provide.

  The edge grip type notch aligning device according to the present invention includes a plurality of gripping units that mechanically lift and grip the outer peripheral portion, which is the edge of a wafer, by opening and closing operations in the radial direction of the wafer, and the plurality of gripping units at the lower part of the wafer. An opening / closing drive mechanism that opens and closes the gripper, and a rotation mechanism that rotates the gripper, the opening / closing drive mechanism, and the gripped wafer about the center of the opening / closing drive mechanism, and rotationally drives the wafer while gripping it. In addition, a notch detection unit that detects notches formed on the outer peripheral portion of the wafer.

  In addition to the above, there are a plurality of support portions for supporting the outer peripheral portion of the wafer from below at intervals in the circumferential direction in order to perform delivery with the wafer transfer robot. In this edge grip type notch alignment device, an optical side length sensor is installed above the wafer in the notch detection unit, and the distance to the wafer is continuously measured during wafer rotation, and the notch portion formed on the outer periphery of the wafer. Is detected not by a change in the ON / OFF signal of a conventional optical sensor or a change in the amount of light received by the notch, but by a change in distance.

When determining the notch at this time, if the notch is positioned on an inclined surface that slopes downward toward the inside of the wafer that supports the edge of the grip, the distance from the optical side sensor to the notch is rotating. In this measurement, the thickness of the wafer abruptly (755 to 795 μm in the case of a φ300 mm wafer) becomes longer than the wafer surface other than the notch portion, and even when the wafer is positioned on the gripping portion, it can be determined as the notch portion. When the notch portion is not located in the grip portion, the change in distance becomes abnormally large at the notch portion or the distance measurement becomes impossible, and this portion can be determined as the notch portion and can be detected.
Thus, in the edge grip type notch aligning device according to the present invention, it is possible to determine the notch portion even when the notch portion formed on the outer peripheral portion of the wafer is located on the wafer gripping portion. It is possible to end the notch alignment by the detection operation.

  According to the present invention, even when the notch formed on the outer periphery of the wafer is in the wafer gripping part, the notch position is determined by detecting the notch part by the change in distance using the optical side length sensor in the notch detection part. Even when the notch is positioned at the wafer gripping portion, the notch alignment can be completed by one wafer gripping and notch detection operation without changing the wafer and performing the notch redetection operation. Therefore, the notch alignment time when the notch is positioned at the wafer gripping portion can be shortened by half compared to the conventional case, and the throughput of the apparatus can be improved.

  FIG. 1 is a schematic configuration diagram of an edge grip type notch aligning device according to an embodiment of the present invention, and FIG. 2 is a plan view of FIG. FIG. 3 shows a partial view of notch detection, FIG. 4 and FIG. 5 show examples of detected waveforms when the notch at the time of detection according to FIG. 3 is in the gripping part, and FIG. 6 and FIG. An example of a detection waveform when the notch at the time is not in the gripping portion is shown.

  A notch is provided in the outer peripheral portion of the wafer 26. As shown in FIG. 1, the edge grip type notch aligning apparatus is provided with a plurality of gripping tools 1 for gripping the outer peripheral portion of the wafer 26. This gripping tool 1 is connected to a connecting housing 5 by a shaft 2. The shaft 2 is guided by a guide bearing 4 incorporated in the housing 5.

  Furthermore, the shaft 2 is connected to a driven pulley 6 by a connecting plate 3. Thereby, the plurality of gripping tools 1 can be operated in conjunction with the rotation and vertical movement of the driven pulley. On the lower inner side of the driven pulley 6, there is provided a vertical slide bearing 8 that can rotate in accordance with the rotation of the driven pulley 6 and moves the housing 5 up and down. A guide shaft 16 having one end supported on the base 24 is provided. A plate 18 is supported via a guide bearing 15 provided on the guide shaft 16.

  The plate 18 is configured to move up and down by the operation of the vertical drive source 14 and the spring 17. The plate 18 is provided with a slide shaft 8a through a bearing 9. The slide shaft 8a moves up and down in conjunction with the vertical movement of the plate 18, and the driven pulley 6 also moves up and down. Is transmitted to the shaft 2 via the connecting plate 3.

  As the slide shaft 8 a of the upper and lower slide bearings 8 rises, the plurality of gripping tools 1 are closed in conjunction with the radial direction via the connecting plate 3, and the gripping operation of the wafer 26 is performed. Similarly, when the slide shaft 8a is lowered, the plurality of gripping tools 1 are opened in an interlocking manner in the radial direction via the connecting plate 3, and the gripping of the wafer 26 can be released.

  The driven pulley 6 and the slide shaft 8a are configured to be rotatable by the bearing 7 incorporated in the base 24 and the bearing 9 supporting the lower end of the slide shaft 8a. The shaft 2 and the plurality of gripping tools 1 connected to the driven pulley 6 via the connection plate 3 can rotate.

  Here, the driven pulley 6 is rotated by the motor 11 and the driving pulley 10 via the belt 13. The rotation angle of the driven pulley 6 can be detected by the encoder 12 provided at the shaft end of the motor 11 and the origin sensor 23. Further, the support pins 19 and 20 which are the locations where the wafer is transferred to and from the transfer robot are arranged so as to sandwich the gripping tool 1 as shown in FIG.

  When there is an instruction to turn the detected notch position to either of the support pins 19 or 20 when the notch is positioned in the gripping tool 1 or when the gripping tool 1 has no notch, the notch position after detection When the gripping tool 1 and the support pin 19 or 20 come into contact with each other when the gripping tool 1 is directed to the designated position, the support pin 20 on the side on which the gripping tool 1 contacts is driven by driving the support pin vertical drive source 21 or 22. Alternatively, 21 can be lowered.

  Further, a notch is formed on the outer periphery of the wafer 26 held by the holding tool 1. In order to detect this notch, a notch detection sensor 25 comprising an optical length measuring sensor is provided above the end of the wafer 26. As shown in FIG. 3, the notch detection sensor 25 is installed at a position where the distance L1 from the notch detection sensor 25 to the wafer 26 and the distance L1 + t to the upper surface of the gripping portion inclined surface located below the notch portion can be measured. is there. The distance from the notch detection sensor 25 to the base 24 is L2.

  Here, specific detection examples of notches are shown in FIGS. First, as shown in FIG. 4, when the notch is positioned on the gripping tool 1, the distance from the notch detection sensor 25 to the upper surface of the wafer 26 is measured by a distance L1, and the thickness t of the wafer 26 is added to the notch portion and L1 + t Measured in

  Before and after the range of L1 + t becomes discontinuous and the thickness t of the wafer 26 changes abruptly with respect to L1, so this range from the origin can be determined as a notch. Here, even if the wafer thickness t cannot be accurately measured due to the influence of the inclined surface of the gripping portion, it can be determined from the front and rear discontinuous points.

Furthermore, even if the wafer thickness t cannot be measured due to the influence of the gripping portion inclined surface, it can be determined that the range in which measurement data cannot be obtained is a notch portion as shown in FIG. Next, as shown in FIG. 6, when the notch is not positioned in the gripping tool 1, the notch portion is measured at a distance L <b> 2 to the base 24. Since it becomes discontinuous before and after the range of L2, and the distance L2 to the base 24 changes rapidly with respect to L1, this range from the origin can be determined as a notch.
Further, even if the distance L2 to the base 24 exceeds the measurement range of the optical length sensor and measurement is impossible, the range in which measurement data cannot be obtained as shown in FIG. 7 can be determined as the notch portion.
As explained above, unlike the conventional method of detecting the notch position based on the ON / OFF signal of the optical sensor and the change in the amount of received light, the change in the distance and data can be obtained by using the optical length measuring sensor. Because it is possible to determine the notch range as the notch position, there is no need to move to the support pin when there is a notch in the gripping part as in the conventional case, and the notch re-detection operation after the changeover. It is possible to reduce the notch alignment time in the case of positioning to half that of the prior art.

1 is a schematic configuration diagram of an edge grip type notch aligning device according to an embodiment of the present invention. The top view of FIG. FIG. 7 is a partial view of notch detection. Explanatory drawing of a detection waveform when the notch at the time of the detection by FIG. 3 exists in a holding part. FIG. 4 is an explanatory diagram of a detection waveform when the notch at the time of detection according to FIG. 3 is present in the gripping portion and the slope of the gripping portion cannot be measured. Explanatory drawing of the detection waveform when the notch at the time of the detection by FIG. 3 does not exist in a holding part. FIG. 4 is an explanatory diagram of a detection waveform in which the notch at the time of detection according to FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Holding tool, 2 ... Shaft, 3 ... Connection plate, 4 ... Guide bearing, 5 ... Housing, 6 ... Driven pud shaft, 9 ... Bearing, 10 ... Driving pulley, 11 ... Motor, 12 ... Encoder, 13 ... Belt 14, vertical drive source 22, support pin vertical drive source 23, origin sensor 24, base 25, notch detection sensor 26 wafer

Claims (1)

A plurality of gripping parts for mechanically lifting and lowering the edge of a disk-shaped wafer having a notch on the outer peripheral part of the wafer by opening and closing operations in the radial direction of the wafer, and the gripping parts are connected at the lower part of the wafer to open and close the gripping part An opening / closing drive mechanism for operating, a rotating mechanism for rotating the gripped wafer and the opening / closing drive mechanism with the wafer held by the center of the opening / closing drive mechanism, and the rotating mechanism in a state where the edge of the wafer is gripped by the gripper And a notch detection sensor for detecting a notch on the outer periphery of the wafer, and adjusting the position of the notch of the wafer detected by the notch detection sensor to a specified angle from a reference position. Wafer notch aligning device comprising a plurality of support portions for supporting the outer peripheral portion of the wafer from below at intervals in the circumferential direction for delivery Oite,
An edge grip type notch alignment apparatus for a wafer, wherein the notch detection sensor is installed above the wafer and detects the notch portion by a change in distance using an optical side length sensor.

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