KR20090058709A - Apparatus for wafer handling and method thereof - Google Patents

Abstract

A wafer transfer device and a transferring device thereof are provided to increase a transfer speed by transferring a plurality of wafers at a time by using a plurality of rotators and driving units. A wafer transfer device includes a robot arm(110), a rotation axis(120), a plurality of cylindrical rotators, a plurality of driving units, and a plurality of blades(150). A first robot arm and a second robot arm are coupled in the robot arm to be driven independently. The rotation axis is mounted in the upper part of the end of the second robot arm. The plurality of cylindrical rotators are independently rotated around the rotation axis. The plurality of driving units drive the plurality of the rotators individually. The plurality of blades are coupled in the plurality of rotators respectively.

Description

Wafer Transfer Device and Transfer Method {APPARATUS FOR WAFER HANDLING AND METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer transfer apparatus and a transfer method thereof, and more particularly, to a wafer transfer apparatus and a transfer method capable of picking up a plurality of wafers at once and exchanging them with wafers mounted on a plurality of stages.

The semiconductor industry is developing with the goal of increasing productivity along with the challenge of increasing wafer density. In particular, productivity improvement is not only an increase in production per unit time, but also an improvement in productivity per unit plant area.

To this end, a batch type of equipment configuration is a general trend, and semiconductor manufacturing apparatuses carry wafers in bulk using containers called FOUPs or containers called SMIF Pods.

1 is a plan view showing the configuration of a general semiconductor manufacturing apparatus.

As shown in FIG. 1, the loading container 20 carrying a plurality of wafers 21 is seated in a load port 11 provided in the semiconductor manufacturing apparatus 10. Thus, the wafer 21 conveyed to the semiconductor manufacturing apparatus 10 through the container 20 is conveyed to the working stage 15 provided in the semiconductor manufacturing apparatus 10 by the conveying apparatus 13, such as a robot, After the work is completed, the wafer is transferred to the unloading container 22 again.

The basic form of the existing conveying apparatus is a single arm type conveying apparatus 13 composed of one robot arm, as shown in FIG. 1, which picks up the finished wafer in the stage 15 of the manufacturing apparatus, and takes out the container. The wafer is transferred to the empty slot 22, and the wafer 21 is picked up again from the loading container 20 and seated on the stage 15.

In the case of a single arm type, there may be an advantage in that the area occupied by the equipment is small, but there is a problem that the work speed is slowed down as all the work is sequentially performed.

As an alternative, a dual arm type robot consisting of two arms is used, using one robot arm to pick up one wafer from a container, and the other robot arm to a wafer at the stage of the manufacturing apparatus. Then, the wafer is exchanged by placing the wafer picked up from the container on the stage.

In this case, while the work speed is improved while the two robot arms must be operated, the radius of action of the robot arm increases, and as a result, the area occupied by the equipment increases.

In addition, although faster than a single arm, since only one wafer is picked up at a time from the container, there is a difference in productivity and manufacturing speed of the manufacturing apparatus which is continuously speeded up. It is a bottleneck process.

Accordingly, there is a need for a wafer transfer apparatus and a transfer method capable of a faster transfer operation.

In addition, as well as the work speed, the development of a transfer device that can minimize the area occupied by the equipment is also required.

An object of the present invention is to provide a wafer transfer apparatus and a transfer method capable of performing a wafer transfer operation between a wafer container and a manufacturing apparatus at high speed even in a small space in order to solve the above problems.

In order to achieve the above object, the present invention provides a wafer transfer device for loading or unloading a wafer into a semiconductor manufacturing apparatus, comprising: a robot arm coupled to drive the first robot arm and the second robot arm independently of each other; A rotating shaft mounted to an upper end surface of the second robot arm; A plurality of cylindrical rotating bodies mounted on the rotating shaft to be independently rotatable about the rotating shaft; A plurality of drive units for rotating the rotors individually; And it provides a wafer transfer apparatus comprising a plurality of blades each coupled to the rotating body.

At this time, the rotating shaft is composed of a lower shaft fixed to the upper surface of the second robot arm and an upper shaft detachably coupled to the lower shaft, the lower shaft is equipped with two lower rotary body, the upper shaft A plurality of upper rotary bodies may be mounted, and the lower driving unit driving the lower rotating body may be installed on the second robot arm, and the upper driving unit driving the upper rotating body may be mounted on the upper shaft.

In addition, the lower drive unit is a lower drive motor; And a gear box and a belt for transmitting the rotational force of the lower driving motor to the lower rotating body, wherein the upper driving unit comprises: an upper driving motor; And a belt transmitting the rotational force of the upper driving motor to the upper rotating body.

The vacuum unit may further include a vacuum pad mounted on the upper surface of the blade so as not to shake the wafer even at a high transfer speed, and including a vacuum pad for adsorbing the wafer by vacuum and a vacuum line for supplying the vacuum generated from the vacuum pump to the vacuum pad. .

The vacuum line for supplying the vacuum to the blade is formed inside the rotating shaft, the main line for transmitting the vacuum generated by the vacuum pump, the first vacuum line is connected to the main line and the groove formed along the outer peripheral surface of the rotating shaft, the first vacuum A connection hole connected to the line is formed on the inner circumferential surface of the rotating body, and the opposite side of the connection hole includes a second vacuum line connected to the vacuum pad.

A wafer transfer method using such a wafer transfer apparatus is a wafer transfer method for exchanging wafers between a container having a plurality of slots into which a wafer is inserted and a plurality of semiconductor manufacturing apparatuses. An unloading step of simultaneously picking up a plurality of wafers mounted in the slots of the loading container; A swap step of exchanging a wafer seated on each stage of a plurality of semiconductor manufacturing apparatuses and a wafer picked up in the unloading step; And a loading step of repeating the swap step to simultaneously seat the exchanged wafers in a plurality of empty slots of the loading container or another loading container.

In this case, in the unloading step, one buffer blade to be used as a buffer remains empty, and the pickup blade of the wafer transfer device operates simultaneously, and in the swap step, the buffer blade and the wafer to be replaced are seated. Only blades are operated separately to exchange wafers one by one, and all the blades mounted on the wafer in the loading step are operated at the same time.

In the swapping step, it is also possible to exchange two wafers at the same time. For this purpose, in the unloading step, the two buffer blades used as buffers remain empty, and the pickup blade of the wafer transfer device operates simultaneously, and the swap step In the above, two buffer blades and two blades on which an exchange target wafer is mounted are simultaneously operated to exchange two wafers at the same time, and all the blades on which the wafer is mounted in the loading step may be operated simultaneously.

In the method of exchanging two wafers at the same time, it is possible to exchange two wafers at the same time in two separate stages instead of the two-stage stage. To this end, one of the two buffer blades and the two blades on which the wafer to be exchanged is mounted is divided into two groups and is operated simultaneously on two stages.

It is also possible to load wafers in two containers at the same time in the loading step. In this case, all of the blades loaded with wafers in the loading stage can be divided into two groups so that they can operate simultaneously in two containers.

When the wafer is transferred using the wafer transfer apparatus and the transfer method of the present invention, a plurality of wafers can be transferred at one time, thereby increasing the transfer speed of the wafer and ultimately improving productivity.

In addition, by using a single transfer device to perform the same performance as a number of robots to improve the productivity per hour as well as the space occupied significantly reduced compared to the existing equipment it is possible to use the space much more efficient.

In addition, as the vacuum line is configured to rotate the blade 360 degrees about the rotation axis, the movement trajectory of the blade end is reduced, thereby increasing the space utilization.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

Figure 2 is a perspective view of a wafer transfer device according to an embodiment of the present invention, Figure 3 is an exploded perspective view of the wafer transfer device.

As shown in Figures 2 and 3, the wafer transfer device 100 of the present invention is a robot arm 110 and a robot arm (110) consisting of a first robot arm 111 and a second robot arm 112 are driven independently ( Mounted at the end of 110 is characterized in that it comprises a plurality of blades 150 each rotating individually.

Looking at the structure in which the blade 150 is mounted on the robot arm 110 and rotates in detail, the rotary shaft 120 is mounted at the end of the robot arm 110, the rotary shaft 120 is a plurality of cylindrical rotors (131, 132, 135) Is also fitted to the rotary shaft 120 to rotate independently. The driving units 141 and 145 for rotating the rotating body are required by the quantity of the rotating body, and the blade 150 is mounted on each rotating body so that the blade 150 rotates while the rotating body rotates by the driving unit. .

The individually operated blades 150 operate as if driven by a single motor if necessary, for example, when a plurality of wafers mounted in a slot of a container are simultaneously picked up or mounted simultaneously. That is, by operating like a dump robot, the amount of conveyed goods per hour increases.

Robot arm 110 is also composed of the first robot arm 111 and second robot arm 112 to operate individually to perform the same type of motion as a scara robot, which is a blade in the case of a conventional wafer handling robot Unlike the two robot arms that form a link structure for linear motion, independent driving is possible, so that various motions can be operated in a narrow space, thereby improving space efficiency.

In FIG. 2 and FIG. 3, four blades 150 are mounted, but the number of blades 150 to be mounted may be variably applied depending on the characteristics of the semiconductor manufacturing apparatus to which the present transfer device is applied.

That is, the total number of blades 150 may be adjusted by adjusting the number of the rotating bodies mounted to rotate independently of the rotating shaft 120 mounted on the robot arm 110, and the mounted rotating bodies may be adjusted according to the length of the rotating shaft. It is possible to increase further.

In the case of a generally used semiconductor manufacturing apparatus, the number of the blades 150 is ideally about four. Accordingly, two of the necessary driving units are mounted on the second robot arm 112, and the remaining two driving units are Mounting on the top of the rotating shaft 120 will be reasonable in terms of the distribution of the center of gravity and power transmission structure.

In addition, by making the blade 150 detachable without forming a body with the rotating body, it is easy to replace only the blade 150 when necessary.

That is, in the case of a device in which the size of the wafer to be transferred is changed or the fixing method of the wafer is required to change from the vacuum method to the edge grip method, the blade 150 can be easily changed to operate the transfer device. There is an advantage.

However, mounting the rotating body in a row on one rotation shaft has advantages such as precisely aligning the blades 150, but has a disadvantage in that workability is poor, and is disadvantageous in terms of maintenance.

In order to solve this problem, in another embodiment of the present invention, as shown in Figure 3, the rotary shaft 120 is separated into the upper shaft 125 and the lower shaft 121, each drive unit (141, 145) 2 provides a wafer transfer device, characterized in that the robot arm 112 and the upper shaft 125 is mounted separately.

Specifically, the rotating shaft 120 is composed of a lower shaft 121 fixed to the upper surface of the second robot arm 112 and the upper shaft 125 detachably coupled to the lower shaft, the lower shaft ( Two lower rotary bodies 131 and 132 are mounted at 121, and a plurality of upper rotary bodies 135 are mounted at the upper shaft 125, and a lower driving unit 141 driving the lower rotary bodies 131 and 132 is provided. The upper driving unit 145 installed on the second robot arm 112 and driving the upper rotating body 135 is mounted on the upper shaft 125.

As such, the rotational shaft 120 is separable into two parts, so that the blade 150 may be adapted to the requirements of the equipment in terms of ease of maintenance and assembly as described above, as well as adaptability to various semiconductor manufacturing apparatuses. There is an advantage that it becomes very easy to change the quantity and function of the.

4 is a partial cross-sectional view of the wafer transfer apparatus according to the embodiment of the present invention.

3 and 4, the lower driving unit 141 includes a lower driving motor 142; And a gear box 143 and a belt (not shown) for transmitting the rotational force of the lower driving motor 142 to the lower rotating bodies 131 and 132, wherein the lower driving motor 142 is second. Lying in the longitudinal direction of the robot arm 112 is mounted.

In addition, the upper drive unit 145 is an upper drive motor 146; And a belt (not shown) for transmitting the rotational force of the upper driving motor 146 to the upper rotating body 135, and using the belt after passing the rotational force of the upper driving motor through a predetermined speed reducer. Deliver it to the rotating body.

When the wafer transfer is performed at a high speed, a problem may arise in that the wafer seated on the blade 150 leaves the blade 150 due to the inertia. In order to solve this problem, a method of mounting the vacuum pad 161 on the blade 150 and transporting the wafer while holding the wafer using a vacuum pump is mainly applied.

However, in the case of fixing the wafer using a vacuum, since the vacuum pump should be mounted on the main body of the transfer apparatus, a separate vacuum line should be provided from the vacuum pump to the end of the blade 150 provided with the vacuum pad 161.

In general, a vacuum hose is installed inside the transfer apparatus to form a vacuum. In this case, since a separate hose pipe must be formed in the operation area of the robot arm and the blade, the operation of the robot arm and the blade is limited. .

That is, the 360 rotation of the blade and the robot arm is impossible, in particular, the limitation of the operating range of the blade is a fatal weakness in the transfer device for driving a plurality of blades independently as in the present invention.

Specifically, in the case of swapping wafers, if the blade on which the wafer is mounted is restricted in a certain direction, a situation arises in which the blade must be rotated by moving the robot arm backward.

Therefore, a larger space is required, which has the problem of halving the advantages of the conveying apparatus for operating a plurality of blades.

In order to solve this problem, the wafer transfer apparatus of the present invention is mounted on the upper surface of the blade 150 to supply the vacuum pad 161 for adsorbing the wafer by vacuum and the vacuum generated from the vacuum pump to the vacuum pad 161. It further comprises a vacuum unit comprising a vacuum line.

As described above, the vacuum line does not transmit the vacuum by a separate pipe such as a vacuum hose, but transmits the vacuum through a pipe formed on the rotating shaft and the rotating body itself. Therefore, there is an advantage that does not affect the rotation of the blade 150 separately.

5 is a perspective view showing a vacuum line.

4 and 5, the vacuum line includes a main line 164, a first vacuum line 165, and a second vacuum line 166.

As shown in FIG. 5, the main line 164 is formed inside the rotating shaft 121 and serves to transfer the vacuum generated by the vacuum pump.

The first vacuum line 165 is connected to the main line 164 and is formed as a groove along the outer circumferential surface of the rotating shaft 121, and the vacuum is transmitted to the outer circumferential surface of the rotating shaft 121 so that the vacuum is transmitted at any position of the rotating body 131. It is made up of a groove.

In the second vacuum line 166, a connection hole 167 connected to the first vacuum line 165 is formed on an inner circumferential surface of the rotating body 131, and a vacuum opposite to the connection hole 167 is connected to a vacuum pad. Line.

O-ring 170 around the connecting hole 167 and the first vacuum line 165 of the second vacuum line 166 to ensure that the vacuum transfer between the first vacuum line 165 and the second vacuum line 166 is securely performed. Airtightness is maintained by a sealing means.

In the wafer transfer method using the wafer transfer apparatus of the present invention, a wafer, which is loaded in a large quantity using a container in a semiconductor manufacturing apparatus as shown in FIG. 1, is transferred to a working stage inside the semiconductor manufacturing apparatus and, conversely, a wafer that has been completed. As a method of transporting to a container is as follows.

Referring to the drawings, FIG. 6 is a conceptual view showing a procedure of a wafer transfer method, and FIG. 7 is a plan view showing an operating range of a blade in the wafer transfer method. In the wafer transfer method of the present invention, a plurality of wafers are inserted. In the wafer transfer method for exchanging wafers between a container having a slot and a plurality of semiconductor manufacturing apparatuses, an unloading step (S10) of picking up a wafer, a swap step (S20) of exchanging wafers, and a wafer having been replaced It is characterized in that it comprises a loading step (S30) for inserting into the slot of another container.

The unloading step S10 is to simultaneously pick up a plurality of wafers 200 mounted in the slots of the loading container 310 by using a wafer transfer device having a plurality of blades 150 and a swap step S20. Is to replace the wafer 210 seated on each stage 350 of the plurality of semiconductor manufacturing apparatuses and the wafer 200 picked up in the unloading step (S10) one by one, and the loading step (S30) is a swap step ( By repeating S20, the exchanged wafers 210 are simultaneously seated in the plurality of empty slots of the loading container 310 or the other loading container 320.

In detail, when the loading container 310 containing the wafers to be processed in the semiconductor manufacturing apparatus arrives at the load port of the semiconductor manufacturing apparatus, the blade 150b of the wafer conveying apparatus simultaneously enters the loading container 310 and each of the blades. A plurality of wafers are picked up at 150b at a time. The buffer blades 150a used as a buffer among the entire blades 150 remain empty without being inserted into the loading container 310, and the required number of wafers among the remaining blades 150 except for the buffer blades 150a. 150b picks up the wafer and the blades 150b participating in the pickup move in the same direction at the same time.

In the swap step (S20), first, the buffer blade 150a picks up the wafer 210 on which the work, which is seated on the stage 350 of the semiconductor manufacturing apparatus, is completed, and the wafer mounted on the blade 150b in the empty position ( As the 200 is placed, the blade 150c having the unprocessed wafer 200 seated on the stage 350 is used as the buffer blade 150a in the next operation.

In this case, only the buffer blade 150a and the blade 150b on which the unprocessed wafer 200 to be exchanged is seated separately are operated separately, and the remaining blades are continuously moved in position and direction so that interference does not occur during the operation of the transfer device. Change it.

The loading step (S30) is the opposite of the unloading step (S10) described above, the blade equipped with the processed wafers 210 enters the container 320 at the same time to seat the wafer in the slot of the container 320 and return In this case, the blade 150d that finally delivers the unprocessed wafer to the semiconductor manufacturing apparatus in the swap step S20 operates separately from the other blades in the loading step S30.

In this case, the container receiving the processed wafer may be a separate carrying container 320, or may use the container used as the loading container 310 again. In addition, as in the unloading step S10, the blade 150d which does not enter the container because there is no wafer continuously changes the position and direction so that interference does not occur during the operation of the transfer apparatus.

As described above, in the swap step S20 of exchanging wafers, it is common to exchange wafers one by one, but it is also possible to exchange two wafers at the same time for faster operation.

That is, when the buffer blade 150a used as the buffer in the unloading step S10 is not one but two, the two buffer blades remain empty, and the remaining pickup blades operate simultaneously to unload the wafer. It is.

The unloaded wafer is exchanged at the same time in the swap step (S20) two wafers, for this purpose, the stage of the semiconductor manufacturing apparatus consists of two stages. That is, two buffer blades simultaneously pick up the processed wafer in a stage consisting of two stages up and down, and place the unprocessed wafer again in the empty space.

Even when the stage is composed of one stage rather than two stages, it is possible to exchange two such wafers at the same time. This feeds each wafer simultaneously to two stages of one stage, in which case the two stages must have a constant height difference from each other. In other words, there must be a height difference as much as the spacing of the blades, so that the blades enter simultaneously and exchange of wafers is possible.

8 is a plan view showing an operation of another wafer transfer method of the present invention. Referring to FIG. 8, two buffer blades and two blades 150 on which an exchange target wafer is mounted are divided into two groups and two Simultaneously work on the stage.

That is, two blades enter the corresponding stage 350 of the semiconductor manufacturing apparatus while drawing the letter "V".

Such a wafer transfer method is possible in the case of using a wafer transfer apparatus according to an embodiment of the present invention. If necessary, the wafer transfer can be performed as if two blades are one "V" shaped blade.

As such, the two blades move in a pair, and the paired blades move simultaneously. It is also possible to simultaneously operate the two blades using a single motor. The advantage is that high productivity can be achieved by increasing the number of blades in the device.

In the case of the loading step in which the exchanged wafer is loaded back into the carrying container, a method of loading a wafer into one container is common, but a method of simultaneously loading two containers is also possible.

Recently, the use of a hybrid device that can process a plurality of processes in one device is increasing trend, and may the place of processing of a particular process change from time to time according to the increase or decrease of the amount of work.

That is, when the load increases to the device that can process only process A, some of the workload should be allocated to the device that can process both A and B processes to smooth the flow of the whole process.

On the contrary, if the quantity of the A and B processes can be handled in the equipment, even if both processes can handle the process, only the A process and the B process need to be controlled in the dedicated equipment.

Therefore, there is a need to process two or more kinds of semi-finished products in one semiconductor device and send them to the next process, and the need to take out wafers from two containers occurs.

In addition, the post-processing process may be differently applied to a wafer in which the same work is completed, and in this case, loading should be performed in different containers according to the type of post-processing process.

To this end, the wafer transfer method according to another embodiment of the present invention is characterized in that all the blades loaded with the wafer in the loading step are divided into two groups and operate simultaneously in two containers.

9 is a plan view showing the operation of the wafer transfer method of the present invention. Referring to Fig. 9, the processed wafers are classified into two types according to their characteristics, the degree of processing or the type of the next process, and the separated two types of wafer groups are separated into two containers 310. Referring to FIG. To load it.

To this end, the blades 150 on which the wafer is mounted are divided into two so as to be able to enter the container, and the blades simultaneously load the wafer into the container 310 as shown in FIG.

What has been described above is just one embodiment for carrying out the wafer transfer apparatus and the transfer method according to the present invention, the present invention is not limited to the above embodiment, as claimed in the following claims Without departing from the gist of the present invention, those skilled in the art to which the present invention pertains to the technical spirit of the present invention to the extent that various changes can be made.

       1 is a plan view showing the configuration of a general semiconductor manufacturing apparatus;

2 is a perspective view of a wafer transfer apparatus according to an embodiment of the present invention;

3 is an exploded perspective view of a wafer transfer apparatus according to an embodiment of the present invention;

4 is a cross-sectional view of a wafer transfer apparatus according to an embodiment of the present invention;

5 is a perspective view showing a vacuum line of the wafer transfer apparatus according to the embodiment of the present invention;

6 is a conceptual diagram showing a procedure of a wafer transfer method according to another embodiment of the present invention;

7 is a plan view showing the operation of the wafer transfer method of the present invention;

8 is a plan view showing the operation of another wafer transfer method of the present invention;

9 is a plan view showing the operation of the wafer transfer method of the present invention.

<Short description of the symbols in the drawings>

10: semiconductor manufacturing apparatus 20, 22: container

100: wafer transfer device 110: robot arm

111: first robot arm 112: second robot arm

120: rotation axis 121: lower axis

125: upper shaft 130: rotating body

131,132: lower rotor 135,136: upper rotor

141: lower drive unit 142: upper drive unit

150: blade 160: vacuum unit

161: vacuum pad 163: vacuum line

164: main line 165: first vacuum line

166: second vacuum line

Claims (10)

In the wafer transfer device for loading or unloading the wafer into the semiconductor manufacturing apparatus, A robot arm coupled to the first robot arm and the second robot arm to be driven independently of each other; A rotating shaft mounted to an upper end surface of the second robot arm; A plurality of cylindrical rotating bodies mounted on the rotating shaft to be independently rotatable about the rotating shaft; A plurality of drive units for rotating the rotors individually; And Wafer transfer apparatus comprising a plurality of blades each coupled to the rotating body. The method of claim 1, The rotating shaft is composed of a lower shaft fixed to the upper surface of the second robot arm and an upper shaft detachably coupled to the lower shaft, Two lower rotary bodies are mounted on the lower shaft, and a plurality of upper rotary bodies are mounted on the upper shaft. A lower driving unit for driving the lower rotating body is installed on the second robot arm, and an upper driving unit for driving the upper rotating body is mounted on the upper shaft. According to claim 2, wherein the lower drive unit Lower drive motor; And Wafer transfer apparatus comprising a gear box and a belt for transmitting the rotational force of the lower drive motor to the lower rotating body. According to claim 2, wherein the upper drive unit Upper drive motor; And And a belt for transmitting the rotational force of the upper drive motor to the upper rotating body. The method according to any one of claims 1 to 4, And a vacuum unit mounted on the upper surface of the blade, the vacuum unit including a vacuum pad for adsorbing a wafer by vacuum and a vacuum line for supplying a vacuum generated from the vacuum pump to the vacuum pad, The vacuum line is A main line formed inside the rotating shaft and transferring a vacuum generated by the vacuum pump; A first vacuum line connected to the main line and formed as a groove along an outer circumferential surface of the rotation shaft; A connecting hole connected to the first vacuum line is formed on an inner circumferential surface of the rotating body, and the opposite side of the connecting hole includes a second vacuum line connected to the vacuum pad. A wafer transfer method for exchanging a wafer between a container having a plurality of slots into which a wafer is inserted and a plurality of semiconductor manufacturing apparatuses, An unloading step of simultaneously picking up a plurality of wafers mounted in a slot of an loading container by using a wafer transfer device having a plurality of blades; A swap step of exchanging a wafer seated on each stage of a plurality of semiconductor manufacturing apparatuses and a wafer picked up in the unloading step; And And a loading step of repeating the swap step to simultaneously seat the exchanged wafers in a plurality of empty slots of the loading container or another loading container. The method of claim 6, In the unloading step, one buffer blade used as a buffer is kept empty, and the pickup blade of the wafer transfer device operates simultaneously, In the swap step, only the blades on which the buffer blade and the wafer to be exchanged are seated are operated separately to exchange wafers one by one. The wafer transfer method, characterized in that all the blades mounted in the loading step operates simultaneously. The method of claim 6, In the unloading step, the two buffer blades used as buffers remain empty, and the pickup blades of the wafer transfer device operate simultaneously. In the swap step, the two blades on which the two buffer blades and the wafer to be exchanged are simultaneously operated are simultaneously exchanged for two wafers, The wafer transfer method, characterized in that all the blades mounted in the loading step operates simultaneously. The method of claim 6, In the unloading step, the two buffer blades used as buffers remain empty, and the pickup blades of the wafer transfer device operate simultaneously. In the swap step, the two blades on which the two buffer blades and the wafer to be exchanged are separated are divided into two groups and simultaneously operate in two stages. The wafer transfer method, characterized in that all the blades mounted in the loading step operates simultaneously. The method according to any one of claims 6 to 9, All the blades mounted on the wafer in the loading step is separated into two groups, characterized in that for operating in two containers at the same time.

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