JPS61267623A - Wafer transport apparatus - Google Patents

Abstract

PURPOSE:To insert and take out a wafer in and from a storing groove at a designated position by storing position information on wafer storing grooves of a wafer cassette in a memory in a wafer transport apparatus of a semiconductor manufacturing apparatus. CONSTITUTION:A wafer transporting apparatus comprises a sensor 2 for detecting the position of a wafer storing groove 3b of a wafer cassette 3, a groove position memory 22 for storing position information on the detected storing groove 3b, and means for reading the position of a desired storing groove 3b from information of the memory 22 and guiding a hand device (a wafer insert and take-out mechanism) along the storing groove 3b. The wafer transport apparatus further includes a select and change switch 25 for selecting position information and giving the information to the guide means (fork) in such a manner that instead of position information of the memory 22, detected position information is directly used for reading the position of the above desired storing groove 3b.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a wafer transport device in a semiconductor manufacturing device, more specifically, to a wafer transport device in a wafer supply/storage unit that directly moves a wafer to a wafer storage position of a wafer cassette and carries the wafer therein. -Relates to a wafer transport device equipped with a wafer insertion and removal mechanism.

[Prior Art] In semiconductor manufacturing equipment, wafers are generally housed in wafer cassettes and loaded into a wafer supply/storage section of the equipment.

Conventionally, for loading and unloading wafers into and out of wafer cassettes on the apparatus side, a belt conveyance method has often been used in which the wafer cassette is moved up and down and the wafers are placed on a conveyor belt disposed below.

However, with this method, when feeding wafers, the wafers are taken out from the bottom of the cassette, and when storing the wafers, they are lined up from the top according to the order in which they were stored, so it is not possible to take out and take out wafers from any stage in the cassette at any time. There was a drawback.

There is also a method of inserting and removing wafers by directly inserting a wafer insertion/ejection mechanism into the gap between wafer bars stored in multiple stages in a cassette, but this method does not allow accurate positioning of the wafers in the cassette. I need to know. For this reason, in the past, the wafer storage position and spacing were fixed values for feeding, and the wafer insertion/ejection mechanism was blindly fed to the predicted position based on these fixed values, but the wafer cassette In reality, there are factors that cause the correct position for inserting the wafer insertion/ejection mechanism to deviate from the above-mentioned fixed value, such as deformation of the wafer and the inclination of the cassette installation table.Therefore, in this method, it is necessary to correct the position for these factors. Shortcomings were inevitable.

Furthermore, there is also a method in which the position level of the wafer itself within the cassette is detected using a laser beam or the like.
In reality, there is a drawback that the scanning by the laser beam becomes uncertain due to the inclination or deformation of the wafer cassette, and the position of the wafer may not be accurately detected. In this case, the wafer insertion/removal position in the cassette is measured every time the wafer is inserted/taken out.

There was a difficulty in speeding up the take-out operation.

[Object of the Invention] An object of the present invention is to eliminate the various drawbacks of the prior art described above, and to accurately and quickly move the wafer insertion/ejection mechanism to the desired position of the wafer storage groove in the wafer cassette. An object of the present invention is to provide a wafer transfer device that can position the wafer.

[Configuration 1 of the Invention In other words, in the wafer transfer device of the present invention, the position level of the wafer storage grooves of the wafer cassette is detected on the front end surface of the cassette, the position of each storage groove is stored, and the wafer at the desired position is read from this stored information. By guiding the wafer insertion/ejection mechanism along the storage groove, wafers can be taken in and out of the storage groove of the cassette safely and at high speed, thereby achieving the above-mentioned problem.

In one aspect of the present invention, detection information can be directly used instead of stored position information as position information for orienting the wafer insertion/ejection mechanism to a desired wafer storage groove position. It further includes means for selecting this information.

Further, the wafer insertion/removal mechanism includes a hand device with a wafer chuck that is movably arranged on a stage that can be moved up and down and tilted, and the guide means is mounted on the stage so that it can move back and forth, and the guide means is attached to the storage groove so that it can move back and forth. The groove detection means includes a groove detection sensor such as a photodiode fixed to the stage facing in the advancing direction of the fork.

[Function] In the wafer transfer device of the present invention, the position of the wafer storage groove of the wafer cassette is directly detected and stored, so that the wafer can be inserted into the storage groove at a desired position in the stored contents.
Since the ejecting mechanism can be fed at high speed, and the guide means guides the mechanism as it enters the wafer storage groove, stable wafer loading and unloading is achieved at all times and is not affected by the inclination or deformation of the cassette. This allows the wafer insertion/removal mechanism to function in any storage groove in the cassette.

For a better understanding of the present invention, preferred embodiments of the present invention will be described below with reference to the drawings.

[Embodiment] FIGS. 1 to 3 are perspective views showing the outline of the mechanical structure of the embodiment of the present invention in mutually different operating states. A wafer storage groove 3b is formed between each edge. As shown in FIG. 1, the wafers 4 are stored in a bridging manner between the grooves 3b on the inner side wall of the mount, and these storage grooves 3b form a multistage rack for storing wafers in one cassette.

The wafer cassette 3 is removably attached to a specific location of semiconductor manufacturing equipment (not shown), and wafers are inserted and removed from the front of a hand device 14 that serves as a wafer insertion/removal mechanism. Contributes to the transportation of wafers.

The hand device 14 includes a wafer push plate 15 and a suction pad 16, and is mounted on a stage 17 so as to be movable into the cassette by a motor 10.

Also on stage 17 is a hand outfit! ! ! A pair of forks 1 as guiding means are provided on both sides of the fork 14 in the same direction by a motor 12.
has a thin blade-shaped edge portion 1a (Fig. 6) on the outside of the upper surface that is placed on the lower edge of the storage groove 3b of the cassette 3 when extended, and this edge portion 1a allows the cassette to be inserted correctly into the storage groove 3b. It is now possible to do so.

A pair of groove detection sensors 2 are fixed to the front surface of the stage 17 in the lower part of the fork 1 toward the end surface of the cassette 3, and these sensors include, for example, a light reflection type photoelectric sensor using an optical fiber or a static sensor. Non-contact sensors such as capacitive sensors are used.

Stage 17 includes fork 1, sensor 2, and hand equipment @1
4, etc., can be moved up and down by the lifting mechanism 18 as a whole, and when the fork is inserted into the cassette, the stage lifting mechanism 1 follows the direction of the insertion groove.
It is connected to the lifting mechanism 18 by a flexible connecting mechanism 19 such as a spring so that it can freely tilt in any direction with respect to the axis of 8. As shown in FIGS. 4a, 4b, and 40, this flexible coupling mechanism 19 tilts the stage 17 to follow the inclination of the cassette when the fork 1 enters the groove 3b, and when the fork 1 fully enters the groove. This ensures that the wafer storage stage and the stage 17 are in a parallel state in this state.

The configuration of the control system that performs the operations of the above-mentioned parts is as shown in FIG.

In Fig. 5, the detection output of sensor 2 is detected by comparator 5.
The signal is inputted to the threshold level generating circuit 6, compared with the signal from the threshold level generating circuit 6, and outputted as a binary signal. The threshold level generation circuit 6 provides the comparator 5 with a threshold level for error-free binarization depending on the situation, in response to a command from the CPU 7. The binary signal output from the comparator 5 indicates the presence or absence of the storage groove at that position, and this signal is
7, that is, the upper and lower positions of the hand device 14 as a wafer insertion/removal mechanism are stored in a storage device (memory) 22 together with an address signal, and the read address of this memory is given by the CPU 7.

CPU y further executes all controls for loading and unloading wafers into and out of the wafer cassette 3' based on a program. That is, based on the command from the CPU 7, the stage elevation control circuit 8 controls the drive of the motor 9 for elevation of the elevation mechanism 18, and the hand advancement/retraction control circuit 11 controls the drive of the motor 10 for advancing/retracting the hand device t14. The fork movement control circuit 13 controls the drive of the motor 12 for moving the fork 1 back and forth.

In order to generate the address signal, a precision detector 23 such as an optical scale or an encoder is provided to detect the vertical position of the stage 17, and the stage vertical position information from the detector 23 is stored in a memory by an address generation circuit 24. It is converted and output as the address of memory 22.
and the CPU 7. In addition, 25
is a selector switch for selecting whether or not to control the stage elevation control circuit 8 using stored information via the CPU 7;
By closing, real-time stage elevation control is performed based on the detection information of the sensor 2.

Figure 6 shows fork 1 and sensor 2 on the front end of the cassette.
, shows the positional relationship of the hand device 14, and stage 1
7, the tip of the fork 1, the sensor 2, and the hand device 1
The tip of the fork 4 is arranged at the same height position, and the fork 1 enters into the groove 3b at the position where the sensor 2 detects the ridge 3a of the front end surface of the cassette.

The operation of this embodiment will be described as follows.

First, the detection of grooves in the wafer cassette 3 by the sensor 2 and the writing and reading operations of the groove positions in the memory will be explained.

The CPU 7 gives a command to the stage elevation control circuit 8 to drive the stage elevation motor 9 to move the entire stage 17, on which the hand device 14, fork 1, sensor 2, etc. are mounted, up and down. The stage vertical position detector 23 detects the amount of vertical movement of the stage 17 from the initial position (
output position).

Since the wafer cassette 3 is fixed and does not move vertically, the detected vertical movement amount of the stage becomes the vertical position on the wafer cassette of the wafer insertion/ejection mechanism mounted on the stage. The stage vertical position address generation circuit 24 converts the stage vertical position output from the detector 23 into an address of the groove position memory 22 and outputs the address. Note that this output is always stored in the memory 2 as the stage 17 moves up and down.
2 address line and CPLJ 7.

Further, groove detection information by the sensor 2 is output as an analog signal, and a threshold level generation circuit 6 outputs the threshold level written by the CPLJ 7.
It is compared with the output of 5 by a comparator 5, and is outputted to the CPU pass line as a binary detection signal. As the stage moves up and down, this detection information is sequentially written into the memory 22 using the stage up and down position addresses as memory addresses. Information is read from the memory 22 by the CPU 7 generating a memory address according to a given program and reading the memory contents as appropriate.The read groove position information in the h set 3 is sent to the stage elevation control circuit 8. Enter.

When the CPU y controls the elevation drive of the stage based on the groove position information read from the memory 2 and inputted to the I11 control circuit 8 in this way, the CPU 7 first instructs the stage elevation control circuit 8 to move the stage up and down. C.P.L.J.
7 constantly checks the stage vertical position address from the stage vertical position detector 23 via the address generation circuit 24, and stops the motor 9 of the stage lifting mechanism 18 when the address corresponding to the previously input groove position is detected. By doing so, the stage 11 is accurately stopped at the position of the previously detected groove, resulting in the state shown in FIG. In this state, the fork 1 can be inserted into the cassette. Here, if the switch 25 is open, the stage's vertical movement is controlled by the method described above, but if the switch 25 is closed, the stage's vertical movement is stopped by the detection of the wafer storage groove 3b by the sensor 2. This is done in real time without using the CPU 7. The stage vertical motor control circuit 8 forms a servo loop including the sensor 2, and its servo function causes the stage 11 to stop at a predetermined groove-corresponding position as shown in FIG.

Next, the operation of taking out the wafer 4 from the wafer cassette 3 will be explained.

The entire stage 17 is moved up and down by the stage lifting mechanism 18, and during this time the CPU 7 operates the address generation circuit 24.
Position information of multiple grooves is sequentially read out from the memory 22 by address signals output from the memory 22. Then, according to a preset program, the sixth storage slot is placed at the address position corresponding to the desired storage groove given by the CPU 7 through setting input.
As shown in the figure, the vertical movement of the stage 17 is stopped.

At this position, the insertion position of the fork is determined.

Next, the fork 1 is moved forward along the groove 3b of the cassette 3 by the fork front and rear motor 1G and inserted as shown in FIG. At this time, the sensor 2 does not move because it is fixed to the stage 11. The insertion amount of the fork is controlled to such an extent that the tip of the fork 1 does not touch the end surface of the wafer 4, and the advance of the fork is stopped when the notch 1b of the fork 1 hits the front surface of the cassette.

In this fork insertion operation, if the bottom of the wafer insertion/ejection mechanism (hand device) and the groove 3b of the wafer cassette are not parallel due to distortion of the cassette 3, etc.
As shown in Fig. 40, the stage 1T is tilted as the fork is inserted so that the fork 1 is inserted straight into the groove 3b by the coupling mechanism 19 following the force of the friction between the fork 1 and the groove 3b of the cassette. , the groove 3b of the cassette and the stage 17 become completely parallel.

Thereafter, the hand device 14 moves forward as shown in FIG. 2 and is correctly inserted into the lower surface of the wafer 4. Roughly, the wafer 4 is suctioned and fixed by the suction pad 16 on the hand device [14, and
As shown in the figure, first the hand device [14 is moved back together with the wafer,
The wafer 4 passes over the upper surface of the fork and is pulled out, and the hand device 14 stops moving back at a predetermined position. After confirming that the wafer 4 has been pulled out, the fork 1 is moved back and pulled out, and then stopped at a predetermined position.

Next, the wafer insertion operation will be explained.

First, the state shown in FIG. 3 is an initial state, and the stage 17 is brought to the desired full position 3b of the wafer cassette 3 read by the CPU 7 and stopped as shown in FIG.

Next, the fork 1 is inserted along the detected groove 3b as shown in Fig. 2.
is inserted. At this time, as mentioned earlier, the connecting mechanism 19
Due to this function, the stage 17 becomes completely parallel to the groove 3b.

Thereafter, the hand device 14 moves forward, and the wafer 4 is inserted along the groove 3b by being attracted to the suction pad 16 of the hand device 14 and being pushed by the wafer pressing plate 15. When the wafer 4 is inserted into the groove 3b to a predetermined position, the wafer 4 is removed by the pad 16 of the hand device @14.
The adsorption of is released. Thereafter, the hand device 14 is retreated and pulled out from the groove 3b, leaving the wafer 4 at a predetermined position in the storage groove of the cassette 3.

After detecting and confirming that the hand device 14 has been pulled back to a predetermined position on the stage, the fork 1 similarly retreats to the predetermined position and is pulled back, thereby completing the insertion operation of the wafer 4.

In the embodiment described above, the fork 1 and the hand device 14 have separate drive systems and are driven independently, but the wafer storage groove 3b stage 17 of the wafer cassette
If the parallelism between the two is already good as a structural condition of the device, it is also possible to drive these at the same time by one drive system. In that case, to take out the wafer from the groove, insert the hand device 14 at the same time as the insertion of the fork 1 in FIG. By pulling them out at the same time, the state shown in FIG. 3 is achieved and the extraction operation is completed.

Further, in the case of a wafer insertion operation, the procedure is the reverse of this ejection operation.

In the above embodiment, the wafer ejection/insertion mechanism is moved up and down by moving the stage 17 up and down, and the wafer cassette is fixed. However, there is also a method in which the wafer cassette is moved up and down by the up and down movement mechanism and the stage is fixed. It is possible.

Furthermore, in the above embodiment, the position of the wafer storage groove of the wafer cassette is detected by a sensor as accurate wafer position information, and a fork is inserted along the detected groove.
Wafers were inserted and removed using a hand device using this fork as a guide. However, another method for detecting multiple wafer storage grooves in one cassette is to check the shape of the storage grooves and the bits on the front of the wafer cassette in advance. Prepare matched mold parts, use the top surface of the cassette as a reference position, attach this mold part to the front of the cassette, use the mold parts as a reference to determine the vertical position of the hand device, and insert and remove wafers. You can also do it.

Figure 7 shows an example of this, where 20 is the groove 3b on the front of the cassette.
The mold part has an L-shaped part on the upper part, and is positioned and mounted by bringing it into contact with the upper surface of the cassette 3 from above. Further, 21 is a contact rod that comes into contact with the groove of the mold part 20 to detect the position, and this functions as a sensor.

The hand device 14 is moved in and out of the storage groove based on the position of this rod.

[Effects of the Invention] As explained above, according to the present invention, the position of the wafer storage groove of the wafer cassette is detected as accurate wafer position information, and a fork is inserted into the groove, and the wafer is inserted using the fork as a guide. By taking out the wafer, it is possible to accurately detect the position of the wafer in the cassette, and it is also possible to avoid collisions between the wafer and the hand device due to inaccurate insertion of the hand device. This allows insertion and removal operations.

In addition, since the position information of the wafer storage grooves of the cassette can be stored in the memory, the groove positions of all the storage grooves of the cassette can be detected in advance, and all groove positions can be stored from the detection results. The position of the wafer storage groove can be immediately and freely selected for take-out operations, etc., and the insertion/take-out mechanism can be moved to the desired groove position without having to detect the position each time, enabling high-speed operation. It is.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the mechanical structure of an embodiment of the invention, FIGS. 2 and 3 are similar perspective views in different operating states, and FIGS. 4a to 40 illustrate the conceptual structure and operation of the coupling mechanism. Figure 5 is a block diagram of the electric circuit that controls this device, Figure 6 is an enlarged sectional view showing the relative positional relationship between the wafer storage groove of the cassette, the sensor, the fork, and the hand device, and Figure 7 is the other diagram. FIG. 2 is a schematic perspective view showing an embodiment of the invention. Code explanation 1 is a fork (guiding means), 2 is a sensor (detection means),
3 is a sea urchin eight cassette, 3b is a wafer storage groove, 9 is a stage vertical drive motor, 10 is a hand front and back drive motor, 12
14 is a fork front and back drive motor, 14 is a hand device (wafer insertion/retrieval mechanism), 17 is a stage, 18 is a stage elevating mechanism, 19 is a coupling mechanism, 22 is a memory (storage means),
23 is a stage vertical position detector, 24 is a stage vertical position address generation circuit, and 25 is a switch (selection means).

Claims (1)

[Scope of Claims] 1. In a wafer transfer device equipped with a mechanism for inserting and ejecting wafers into and out of a wafer cassette, means for detecting the position of a wafer storage groove of the wafer cassette and storing information on the detected position of the storage groove. A wafer transport device comprising means for reading the position of a desired storage groove from the position information stored in the storage means and for guiding the wafer insertion/removal mechanism along the storage groove. 2. Selection means for selecting and providing the detected position information to the guide means so that the detected position information can be directly used instead of the position information in the storage means for reading the position of the desired storage groove. A wafer transport device according to claim 1, having the following.