JPH07297264A - Detecting device of wafer position - Google Patents

Abstract

PURPOSE:To obtain a device which can detect a wafer position vertically a horizontally to prevent a failure of transfer and to perform a normal transfer operation on transferring the wafer from a wafer carrier, by providing a sensor for height detection, a sensor for horizontal position detection and a drive mechanism being specific respectively. CONSTITUTION:A sensor 3 for height detection which moves vertically in relation to a wafer carrier for accommodating a plurality of wafers 8 in a horizontal state and thereby detects the position in a height direction of a prescribed wafer 8 accommodated by the wafer carrier is provided. Besides, a sensor 4 for horizontal position detection which so moves as to be inserted into a gap between the prescribed wafer 8 and the wafer positioned lower than this and thereby detects the position on the end face of the prescribed wafer 8 horizontally is provided. Moreover, a drive mechanism 2 for moving the two sensors 3 and 4 is provided. Both of the sensors 3 and 4 are made optical sensors detecting an emission light reflected from a material to be measured, for instance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer automatic transfer apparatus, and more particularly to a wafer position for detecting the three-dimensional position and orientation of a wafer in a wafer carrier (wafer storage container), which is necessary for transferring a wafer. Regarding a detection device.

[0002]

2. Description of the Related Art As a hand positioning method for automating the process of taking out and storing a wafer from a wafer carrier using a transfer hand, the position of the wafer in the wafer carrier is detected by a sensor and the information is stored. There is a method of moving the hand to a desired position.

A wafer take-out / accommodation apparatus as an example embodying this method is shown in FIGS. In FIG. 3, reference numeral 22 denotes a carrier elevator, which is a carrier table 25 on which a wafer carrier 23 is placed and a feed screw 27 which is rotated in the forward and reverse directions by a motor 29 and a carrier table 2.
It is driven up and down by a mechanism composed of a nut 26 fixed to 5. A plurality of slots 23a are formed at equal intervals in the vertical direction on both inner walls of the wafer carrier 23, and both ends of the wafer 24 are inserted into and supported by the slots 23a, respectively. An optical sensor 30 is attached to the carrier table 25, and a slit plate 31 for generating a position detection signal by turning on or off the optical sensor 30 when the table 25 moves up and down is provided.

The slit plate 31, as shown in FIG.
Two slits 31a are provided for one pitch P of the slots 23a of the wafer carrier 23.
The same slot 23 such as N-stage upper and N-stage lower
Two position detection signals are generated with respect to a.

Reference numeral 32 shown in FIG. 3 is a suction arm slidable in the direction of arrow A (horizontal direction).
Is connected to the small hole 32a at the tip of the suction arm 32.
Is set to a negative pressure to generate a suction force for the wafer 24. The suction arm 32 is inserted / removed between the adjacent slots 23a, 23a of the wafer carrier 23 to take out or store the wafer 24.

The relative position between the suction arm 32 and the wafer carrier 23 is that of the wafer 24 supported by the slot 23a at the Nth stage when the wafer carrier 23 stops upon receiving the position detection signal at the Nth stage. The bottom surface is the suction arm 3.
When the wafer carrier 23 stops at the position higher than the upper surface of No. 2 and receives the position detection signal of the Nth lower stage, the lower surface of the wafer 24 supported by the Nth slot 23a is higher than the upper surface of the suction arm 32. It is set to a low position.

The operation of the wafer take-out / accommodation device configured as described above will be described below.

That is, when the Nth stage wafer 24 is taken out from the wafer carrier 23, the carrier elevator 22 is controlled by a control circuit (not shown) to raise or lower the wafer carrier 23 so that the optical sensor 30 operates at N level.
When the position below the step is detected, the wafer carrier 23
Stop once. Subsequently, the wafer carrier 23 is raised, and is stopped again when the optical sensor 30 detects the position on the Nth stage, and the suction arm 32 is inserted below the wafer 24 on the Nth stage. Next, the wafer carrier 23 is lowered,
When the optical sensor 30 detects the position of the Nth lower stage, it is stopped so that the wafer 24 of the Nth stage is sucked by the suction arm 3.
2, the negative pressure of the suction arm 32 is turned on to suck the wafer 24, and then the suction arm 32 is pulled out of the wafer carrier 23. In this way, the taking out of the Nth stage wafer 24 is completed.

When the wafer 24 is to be stored in the N-th slot 23a in the wafer carrier 23, the wafer carrier 23 is raised or lowered in the same manner as above.
The wafer carrier 23 is once stopped at the position above the stage, and then the wafer carrier 23 is lowered and stopped again at the position below the N stage, and the suction arm 32 that sucks the wafer 24 is held.
Is inserted into the upper side of the slot 23a of the Nth stage, and the negative pressure of the suction arm 32 is turned off. Next, the wafer carrier 23 is lifted and stopped at a position above the Nth stage, so that the wafer 24 is placed in the slot 23a at the Nth stage, and then the suction arm 32 is pulled out of the wafer carrier 23. In this way, the storage of the wafer 24 in the N-th slot 23a is completed.

[0010]

SUMMARY OF THE INVENTION In the above conventional method,
Accurately, it is possible to determine the positional relationship between the suction arm 32 and the wafer carrier 23 by using the position detection sensor. What position the wafer 24 supported by the slot 23 a of the wafer carrier 23 in the wafer carrier 23 can be determined. ， It is not possible to detect whether it is in the posture.

Therefore, the wafer 24 is transferred when the wafer is transferred.
The positioning of the suction arm 32 with respect to the wafer carrier 23 is performed with respect to the wafer carrier 23, and the positional deviation and inclination of the wafer in the wafer carrier are not taken into consideration.
For this reason, when the wafer is unloaded and loaded, there are cases where the wafer cannot be accurately transferred due to the displacement of the wafer due to friction with the support slot of the carrier.

Further, in the above-mentioned wafer take-out / accommodation device, a special drive device (carrier elevator 22) for position detection corresponding to the wafer carrier 23 is also required, which causes a problem in terms of cost and versatility of the device. is there.

Therefore, according to the present invention, in order to prevent a transfer failure at the time of transferring a wafer from the wafer carrier and to perform a normal transfer operation, the position of the wafer stored in the wafer carrier in the height direction and the horizontal direction. An object of the present invention is to provide a wafer position detecting device that can detect the position in each direction.

[0014]

SUMMARY OF THE INVENTION A wafer position detecting device of the present invention is a predetermined wafer stored in a wafer carrier by vertically moving a wafer carrier for storing a plurality of wafers in a horizontal state. A sensor for height detection that detects the position in the height direction of the wafer, and the horizontal position on the end face of the predetermined wafer by moving so as to be inserted into the gap between the predetermined wafer and the lower wafer. It is characterized by comprising a horizontal position detecting sensor for detecting and a drive mechanism for moving these two sensors.

Further, the wafer position detecting device of the present invention is characterized in that the horizontal position detecting sensor detects the positions of three points on the end face of a predetermined wafer.

Further, the wafer position detecting device of the present invention is characterized in that both the height detecting sensor and the horizontal position detecting sensor are optical sensors for detecting the reflected light of the emitted light from the object to be measured. To do.

Further, in the wafer position detecting apparatus of the present invention, the height detecting sensor is oriented horizontally in the detecting direction, and the horizontal position detecting sensor is oriented vertically in the detecting direction and is incorporated in one pedestal. , A sensor module is configured.

Further, the wafer position detecting apparatus of the present invention is characterized in that the sensor module is moved vertically and horizontally by a robot arm.

[0019]

In the wafer position detecting apparatus of the present invention, the height detecting sensor is moved vertically with respect to the wafer carrier by the driving mechanism. By using an optical sensor as the height detection sensor, the sensor determines the presence or absence of the wafer at that position by detecting the reflected light from the wafer. Thus, the position of the specific wafer in the height direction is detected.

Next, the horizontal position detecting sensor is moved horizontally with respect to the wafer by the driving mechanism, and this sensor is moved so as to be inserted into the gap between the specific wafer and the lower wafer. At this time, by using an optical sensor as the horizontal position detection sensor, when the vertically upward emitted light from this optical sensor crosses the end face of the wafer, the sensor detects the reflected light from the end face. ,
The horizontal position of this particular wafer can be detected.

The above detection operation is performed for a total of 3 on a specific wafer.
By executing on the points, three sets of three-dimensional position data can be obtained. In general, the position of the plane is uniquely determined by giving the positions of three points on this plane, and thus the data obtained by this method can be used to know the horizontal position and tilt of the wafer supported by the wafer carrier. be able to.

Further, in the wafer position detecting device of the present invention, the height detecting sensor and the horizontal position detecting sensor are incorporated in one mount to constitute a sensor module, so that one drive mechanism is provided. It enables cost reduction.

Further, in the wafer position detecting apparatus of the present invention, the height detecting sensor and the horizontal position detecting sensor are formed in a sensor module, and the sensor module is moved vertically and horizontally by the robot arm. As a result, the coupling between the sensor module and the drive mechanism is simplified, and the reliability is improved.

[0024]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

A wafer position detector according to an embodiment of the present invention is shown in FIGS. 1 (a) and 1 (b). As shown in FIG.
A wafer position detecting device according to an embodiment of the present invention includes a sensor module 1 for detecting the position / orientation of a wafer as three-dimensional data, and a robot arm 2 for moving the sensor module 1 to a measurement position. .

As shown in FIG. 1B, the sensor module 1 is an optical height detecting sensor 3 for detecting the position in the height direction of the wafer 8 horizontally supported in the wafer carrier. And an optical horizontal position detection sensor 4 for detecting the horizontal position of the end face of the wafer 8 are incorporated in one pedestal 5, and this pedestal 5 is an upper surface near one end of a rectangular plate 6. It is configured to be attached to.

The optical height detecting sensor 3 has a structure in which a light receiving element detects the reflected light of the emitted light from the light source from the object to be measured, and the detection direction is directed horizontally to the gantry 5. It is installed.

Further, the optical horizontal position detecting sensor 4 is rod-shaped and has a light emitting port for emitting light from the light source and a light receiving port for guiding reflected light from the object to be measured to the light receiving element on the upper surface of the tip end thereof. Is arranged so that the detection direction is directed vertically upward and is separated from the detection directivity line of the height detection sensor 3 by a required dimension downward, so that the rod-shaped sensor main body is kept horizontal. It is attached to the bottom of 5.

The robot arm 2 has its operating rod 2a.
Is coupled to the upper surface of the plate 6 of the sensor module 1 near one end and holds the sensor module 1, and performs movement and rotation in the X and Y directions in the horizontal plane of the sensor module 1 and movement in the height direction. Can be made.

Next, the operation of the wafer position detecting apparatus according to the embodiment of the present invention constructed as described above will be described below.

First, the robot arm 2 moves the sensor module 1 vertically with respect to the wafer carrier 7 shown in FIG. At this time, the height detecting sensor 3
Detects the light reflected by the wafer 8 in the wafer carrier 7 to determine the presence / absence of a wafer at that position. Thus, the desired position of the specific wafer 8 in the height direction is detected.

Next, the robot arm 2 is moved horizontally with respect to the specific wafer 8 and, as shown in FIG.
The horizontal position detecting sensor 4 is moved so as to be inserted into the gap between the specific wafer 8 and the lower wafer.
During this movement, when the vertically upward emitted light from the horizontal position detecting sensor 4 crosses the end face of the wafer 8, the sensor 4 detects the reflected light from the end face, and the horizontal direction of this specific wafer 8 is detected. The position of can be detected.

By performing the above-described detection operation on a plurality of points on the specific wafer 8, for example, a total of three points, three sets of three-dimensional position data can be obtained. In general, the position of the plane is uniquely determined by giving the positions of three points on this plane. Therefore, using the data obtained by this method, the horizontal position of the specific wafer 8 supported by the wafer carrier 7 is used. Then, it is possible to know the non-uniformity of the position in the height direction, that is, the inclination of the wafer 8.

According to the wafer position detecting apparatus of one embodiment of the present invention, the position and orientation of the wafer 8 are measured based on the three-dimensional position data of the predetermined wafer 8 to be transferred, Hand for transfer (suction arm 32 in FIG. 3)
Since the positioning is performed, it is possible to cope with the positional deviation and the inclination of the wafer, which enables accurate transfer.

Further, if this wafer position detecting device is used, no special mechanism (the carrier elevator 22 in FIG. 3 or the like) is required on the wafer carrier 7 side, so that it can be applied to any wafer carrier. ,
This is an advantage that the prior art does not have. The present invention is not limited to the above-described embodiments, but can be modified and implemented as follows.

(1) The moving mechanism of the sensor module 1 is not limited to the robot arm 2, but the sensor module 1
Other mechanisms capable of changing the position and direction of the may be used.

(2) In the embodiment of FIG. 1, both the height detecting sensor 3 and the horizontal position detecting sensor 4 are attached to the sensor module 2 and moved by the same driving device, but two sensors are used. May be independent of each other and may be driven by different driving mechanisms.

(3) In the embodiment shown in FIG. 1, after the height detecting sensor 3 detects the height of the wafer 8, the horizontal position detecting sensor 4 detects the horizontal position. It need not be this procedure. When the height of the wafer 8 is roughly known, it is possible to operate the sensor 4 and the sensor 3 in this order.

(4) If there is no gap in the lower part of the wafer for which the position and orientation are to be detected, the horizontal position detecting sensor 4 can be mounted on the upper part of the sensor module.

(5) In addition to the transfer device, the wafer position detecting device of the present invention can be adapted with a similar structure when there is a gap into which a sensor can be inserted between wafers stored in a hierarchical manner. .

[0041]

As described above in detail, according to the wafer position detecting apparatus of the present invention, the height detecting sensor detects the position of the wafer in the height direction, and the horizontal position detecting sensor detects the horizontal position of the wafer. By performing the detection operation for detecting the position in the direction for three points on the wafer, the position and orientation of the wafer are measured based on the three-dimensional position data of the wafer to be transferred, and Since the transfer hand (suction arm) is positioned on the basis of this, it is possible to cope with the positional deviation and inclination of the wafer, and compared with the conventional technique in which the hand is positioned with respect to the wafer carrier.
Enables accurate transfer.

Further, if the wafer position detecting apparatus of the present invention is used, no special mechanism (carrier elevator or the like) is required on the wafer carrier side, so that it can be applied to any wafer carrier. This is an advantage that does not exist.

In the wafer position detecting device of the present invention, the height detecting sensor and the horizontal position detecting sensor are incorporated in one mount to form a sensor module, so that only one drive mechanism is required. Enables cost reduction.

Further, in the wafer position detecting device of the present invention, the height detecting sensor and the horizontal position detecting sensor are formed in the sensor module, and the sensor module is moved in both the vertical and horizontal directions by the robot arm. The connection between the sensor module and the drive mechanism is simplified, which leads to cost reduction and improved reliability.

[Brief description of drawings]

FIG. 1 shows a wafer position detecting device according to an embodiment of the present invention, and FIG. 1 (a) is a perspective view showing the whole.
FIG. 1B is a perspective view showing an enlarged part A of FIG.

2A and 2B are views for explaining a detection operation in the wafer position detection apparatus of FIG. 1, FIG. 2A is a perspective view showing a height detection operation, and FIG. 2B is a horizontal position. It is a perspective view which shows a detection operation.

FIG. 3 is a perspective view showing a main part of a conventional wafer unloading and storing apparatus.

FIG. 4 is a side view of a main part of a slit plate in the wafer takeout / accommodation device of FIG.

[Explanation of symbols]

 1 ... Sensor module 2 ... Robot arm 3 ... Height detection sensor 4 ... Horizontal position detection sensor 5 ... Stand 6 ... Plate 7 ... Wafer carrier 8 ... Wafer 22 ... Carrier elevator 23 ... Wafer carrier 24 ... Wafer 25 ... Carrier Table 30 ... Optical sensor 31 ... Slit plate 32 ... Suction arm

Claims (5)

[Claims] 1. Height detection for detecting a position in a height direction of a predetermined wafer stored in the wafer carrier by moving the wafer carrier in a vertical direction with respect to a wafer carrier for horizontally storing the plurality of wafers. And a horizontal position detecting sensor for detecting a horizontal position on the end face of the predetermined wafer by moving the same so as to be inserted into a gap between the predetermined wafer and the lower wafer.
A wafer position detecting device comprising a driving mechanism for moving two sensors. 2. The wafer position detecting device according to claim 1, wherein the horizontal position detecting sensor detects the positions of three points on the end face of the predetermined wafer. 3. The height detecting sensor and the horizontal position detecting sensor are both optical sensors for detecting the reflected light of the emitted light from the object to be measured. The wafer position detection device according to item 1. 4. The height detecting sensor is oriented horizontally in the detection direction, and the horizontal position detecting sensor is oriented vertically in the detection direction and is incorporated in one mount to constitute a sensor module. The wafer position detecting device according to claim 1, wherein: 5. The wafer position detecting device according to claim 4, wherein the sensor module is moved vertically and horizontally by a robot arm.