JPH10289938A - Wafer transfer system of semiconductor manufacturing installation and wafer transfer method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clarify the verification of the fluctuation in the characteristics of the unit step in a progress by a method wherein the second cassette is mounted on the vertically operating proper number analyzer fitted to the first cassette and one side system base substance as well as on the vertically operating cassette transfer base fitted to another system base substance on an isolated point. SOLUTION: Within the transfer system of a semiconductor manufacturing installation, the first cassette 104 whereon a plurality of wafers are bonded is mounted on a fixing base 102. Besides, a vertically linear operating proper number analyzer 106 is fitted to one side system 100 base substance of the first cassette 104. On the other hand, a vertically linear operating cassette transfer base 108 is fitted to the system base substance 100 at a point isolated from this proper number analyzer at a specific interval and the second cassette 110 with the wafers unloaded therefrom is mounted on the cassette transfer base 108. Besides, a vertically linear operating wafer transfer robot 112 is fitted to the other side system base substance 100 of the first cassette 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer transfer system (System) for semiconductor manufacturing equipment and a wafer transfer method using the same, and more particularly, to a wafer transfer system using a unique number search device. Marking
And a wafer transfer system of a semiconductor manufacturing facility for automatically arranging wafers sequentially (small order / large order / odd and even order / individual selection) in accordance with the unique number. The present invention relates to a method for transferring a wafer using the method.

[0002]

2. Description of the Related Art Semiconductor manufacturing equipment has been continuously developed until the GIGA era has arrived. As the manufacturing process is more complicated and diverse, these semiconductor manufacturing facilities with various automated functions and improved control technology play a central role in determining the characteristics and manufacturing technology of semiconductor products. That is a fact of cognition. Therefore, in order to implement hundreds of process steps required in manufacturing a semiconductor device in accordance with the set process conditions, it is essential that the equipment mechanism in which the actual process is performed be stable.

[0003] Thus, the equipment mechanism (Mechanis
The reason for the requirement of the stability of m) is that when the manufacturing process of a semiconductor device is viewed as a complex and various series of processes, the unique parameters (Parameters) and processes of the unit processes are different for each stage and the wafer processing order This is because, by performing the process in a random manner, many factors that change the process conditions set while a complete product is produced through several hundred processes can be generated.

[0004] In particular, each unit process corresponding to these hundreds of processes required to produce one finished product is as follows:
Rather than having the process proceed in a completely single form,
Each process has a cross-correlation, is grafted to the environment before and after the process, passes through the process inspection (Test) stage to check whether each unit process has been performed normally, and then continuously verifies the result. When manufacturing a device having a high degree of integration of the giga-class, the stability of the equipment mechanism is required to be higher.

This will be described below with reference to a dry etching process generally used in the manufacture of a semiconductor device. Here, for the sake of explanation, two control points corresponding to an input factor and an output factor are set in a process of repeatedly performing a single process, and based on this, the mechanism of the semiconductor manufacturing equipment determines how the mechanism of the semiconductor device manufactures. A description will be given of such an influence. Using such a method as a statistical process control method, the classification of the input factor and the output factor is specifically shown in Table 1.

[0006]

[Table 1]

In Table 1, an input factor indicates a side of a semiconductor manufacturing facility (eg, a dry etching apparatus) in which dry etching is performed, and an output factor indicates a product (eg, on a wafer) generated after the dry etching process. Characteristics of a patterned film). As shown in Table 1 above, the critical dimension of the patterned film quality (Critical Dimensio
In n), the etching rate (Etch Rare) and the like are determined by the process condition of the input factor. At this time, if the stability of the manufacturing equipment mechanism is not ensured, an output factor failure occurs during the actual process.

In FIG. 9, in order to confirm this more clearly, a graph (Graph) showing a change in the growth rate of the thin film with the passage of time when forming the thin film on a plurality of wafers by the arrangement method is shown. ing. The horizontal axis represents time in the screen, the vertical axis represents the growth rate of the thin film on the wafer, N ₁ ... N _X denotes the wafer number. As shown in the graph, although the thin film is grown at a V ₁ growth rate when growing a thin film on the initial N ₁ wafer, growing a thin film on the wafer corresponding to N _X has elapsed point difference time In this case, the temperature inside the reaction path rises by a point difference due to RF (Radio Frequency) heating, and finally the growth rate in the reaction path is changed in the N ₂ state by ΔV compared to the initial N ₁ rate. A thin film is grown. At this time, if the growth rate is changed as described above, the quality of the film grown on the wafer gradually varies, and a process failure occurs.

As described above, when a process failure occurs, the thickness of the deposited thin film is not included in the range of the reference value (set value ± 0.5%) in the process inspection work performed after the completion of the unit process. The product is handled as a defective product and is discarded. When the value falls within the reference value, the next unit process is continuously performed. Therefore, although the thickness of the thin film grown on the wafer is different from the set value, if the wafer is included in the reference value range and the subsequent process is directly performed, the current wafer processing method is constant. It is not performed by a simple method (Rule), but is performed by a random method for each process. It is not possible to specifically confirm what kind of failure factor has occurred when performing the process several times in the equipment.

Here, the random method means that a wafer is variably loaded in a cassette (Cassette) according to the order in which the steps are completed irrespective of a fixed method (for example, a unique number marked on the wafer) after completion of a unit step. ) Is to be loaded.

Normally, a batch (Batc) is processed through a unit process corresponding to several hundred processes until one product is manufactured.
h) Since the process proceeds in a state where the method and the single-wafer (Single) method are mixed, the wafer processing method at the time of the progress of each unit process is very random. Here, a typical process for applying the batch method is a diffusion furnace (Diffusion Furnace).
ance), and typical processes to apply the single wafer method include a dry etching process or ion (Ion) implantation process, and a typical anti-batch process is CVD.
(Chemical Vapor Deposition) process. here,
The anti-batch method is a method in which wafers are charged into a manufacturing facility in a batch method, but the actual process is performed individually for each wafer.

[0012]

As described above, when the wafers are loaded into the cassette in a random state, only the wafers in which the process failure has occurred are caused by the process failure factors in each unit process and the semiconductor manufacturing process. Verification of the connectivity between the input factors of the equipment becomes impossible, and the above-mentioned various problems must be solved in order to accurately grasp the correlation between the input factors with a strong equipment aspect and the output factors with a strong product characteristic. There is a need to advance much research and development to solve the problem.

Therefore, the present invention uses the technology of automatically aligning wafers sequentially and grafts the history of the semiconductor manufacturing equipment itself to the point at which a process failure occurs, so that the state of each equipment during the unit process is changed. Automatically arrange wafers sequentially (small order / large order / odd number and even number order / individual selection) at each run (Run) unit using semiconductor manufacturing equipment to enable clear verification The present invention provides a wafer transfer system of a semiconductor manufacturing facility and a wafer transfer method using the same, whereby a change in a process characteristic due to continuity of a process in each unit and a process-specific characteristic during a unit process can be clearly verified. The purpose is to do.

[0014]

In order to achieve the above object, the present invention provides a system base, a cassette fixed base mounted on a predetermined portion on the system base, and a plurality of cassette bases mounted on the cassette fixed base. A first cassette loaded with wafers, a unique number search device mounted on the first cassette and one side of the system substrate and designed to be capable of vertical linear movement, and a predetermined distance from the unique number search device. A cassette moving table mounted on the system substrate at a separated point and capable of vertical linear movement; a second cassette mounted on the cassette moving table and unloaded with wafers; A wafer transfer robot of a semiconductor manufacturing facility, comprising: a wafer transfer robot mounted on the side system base and capable of vertical linear movement.

In this case, the unique number search device includes a support and a character recognition unit attached to a predetermined portion of one side of the support, and the wafer transfer robot controls a wafer on which the wafer is mounted. It comprises a transfer arm and a support vertically attached to the wafer transfer arm.
Here, the height of the unique number search device is 40 to 50 cm.
And the length of the wafer transfer arm is 33 to 37 cm.
It is preferred that Further, the character recognition unit is fixed to be inclined at an angle of 45 ° with respect to a horizontal plane on which the wafer is located, and the wafer transfer arm is designed to be able to move right and left linearly.

According to the present invention, the wafer transfer system can be designed such that a wafer transfer robot is mounted on the system substrate between the second cassette and the unique number search device, and the wafer transfer system is provided between the first and second cassettes. The wafer transfer system may be designed such that a third cassette fixing base on which the third cassette is mounted is further mounted on the system base on a line extending centrally in the vertical direction. At this time,
The third cassette is an unloading cassette in which no wafer is loaded. When a wafer transfer system is designed so that the first to third cassettes are provided on the system substrate, each cassette is placed in a central portion. Each cassette is mounted so that the cassettes are arranged at the same distance from each other. At this time, the wafer transfer arm of the wafer transfer robot is preferably manufactured to have a length of 22 to 24 cm, and the wafer transfer robot is designed to be rotatable within a range of 180 °.

As described above, when the wafers are sequentially aligned, it is not necessary to inspect all the individual wafers at the time of the process inspection work, and an engineer (Engineer) artificially weak points (Weak).
Since the process inspection work can be performed by a method of inspecting only some wafers corresponding to (Point) (for example, wafers corresponding to Nos. 22 to 24), the time loss required in the process inspection work is reduced. Further, the wafers are sequentially (small order / large order / odd and even order /
(Individual selection), it is possible to clearly verify the process characteristic change due to the continuity of the process for each step.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a structure of a wafer transfer system of a semiconductor manufacturing facility shown as a first embodiment of the present invention in which wafers are sequentially and automatically aligned. The structure of the wafer transfer system will be described below in detail with reference to the cross-sectional view.

In the transfer system for semiconductor manufacturing equipment shown in FIG. 1, a cassette fixing base 102 is mounted on a predetermined portion of a system base 100, and a plurality of (for example, 25) cassette fixing bases 102 are mounted on the cassette fixing base 102. A first cassette 104 on which wafers are loaded is mounted, and a gear (Ge) is provided on one side of the first cassette 104 on the base of the system 100.
ar) A unique number search device 106 designed to be able to perform up-down linear motion by the method is mounted. Further, a cassette moving base 108 designed to be able to move up and down linearly by a gear system is mounted on the system base 100 at a point separated from the unique number searching device 106 by a predetermined distance. A second cassette 110 on which wafers are unloaded is mounted, and a wafer transfer robot 112 designed to be able to move up and down linearly by a gear method is mounted on the other side of the system substrate 100 of the first cassette 104. It has a mounted structure. At this time,
The wafer transfer system is a computer (not shown)
mputer) and a network (Network) method.

FIG. 2 shows 25 wafers 114 per run.
FIG. 3 is a perspective view showing a state in which slots are loaded into slots (slots 1 to 25) in the first cassette 104. FIG. 3 is an enlarged view of a flat zone portion of the individual wafer shown in FIG. FIG.
FIG. 3 is a schematic diagram showing a method of searching for a wafer unique number using a unique number search device constituting the wafer transfer system of FIG. 1.

As shown in FIG.
Is marked with a wafer unique number (for example, an individual number (# 02) and a rat name (7UD875)) in a flat zone (a). In addition, the unique number search device 106 is designed to have a height of 40 to 50 cm, and is attached to a support 106b mounted on the system base 100 and a predetermined portion on one side of the support 106b. And a character recognition unit 106a.

At this time, as shown in FIG. 4, the character recognizing unit 106a uses a unique number marked on each of the 25 wafers loaded into the slots in the first cassette 104 at a constant pitch. In order that the unique number search device 106 can smoothly search for
14 is fixed to the support 106b so as to be inclined at an angle of 45 ° with respect to the horizontal plane on which it is located. The wafer transfer robot 112 includes a support table 112a mounted on the system base 100 and a wafer transfer arm 112b mounted on the upper surface of the support table 112a. It is designed to allow linear motion. Here, the wafer transfer arm 1
12b is designed to have a length of 33 to 37 cm, and the support 112a is designed to have a height of 28 to 30 cm.

At this time, the first cassette 104 and the second cassette 110 constituting the wafer transfer system are mounted on the system substrate 100 such that the cassettes 104 and 110 are arranged at positions corresponding to each other. You. When a wafer located in an arbitrary slot in the first cassette 104 is transferred to a slot corresponding to a normal position in the second cassette 110, a wafer transfer robot transfers the wafer in the first cassette 104. This is because the wafer is transferred to the horizontal position on the plane using the 112 and pushed into the second cassette 110. Therefore,
In the case of the first embodiment, the wafer transfer operation is performed in the following three stages.

1. First Step First, the number of wafers loaded per run is confirmed.
That is, as shown in FIG.
4 is loaded in the first cassette 104.
It is checked whether all five wafers 114 are loaded or not. At this time, not all of the 25 wafers are loaded, but if an empty slot is found, a wafer transfer robot is automatically loaded with a wafer loaded in the next slot in the empty slot. 112
Align the wafer using

Next, the unique numbers of the fifteen wafers 114 loaded in the first cassette 104 are sequentially searched through the character recognizing section 106a of the unique number search device 106, and the wafer transfer system is connected to the network system. The result is displayed on the computer screen 116 linked by. FIG. 5 shows a computer screen 116 on which search results are displayed. Here, the wafer 114
The reason why all the rat names marked with "7" are displayed the same in 7UD007 is that all 25 wafers indicate the wafers loaded in the first cassette 104.

At this time, the search operation using the character recognition unit 106a is performed by sequentially moving the unique number search unit 106 vertically downward from the 25th slot position of the first cassette 104 to the flat position of each wafer 114. The unique number (individual number and rat name) marked in the zone portion is scanned by reading an image (Image) on a numerical area written within a specific width at a specific position like a fax millihead. As described above, the reason why the wafer number confirmation work is performed before the wafer unique number search work is that when the transfer work is performed after the work of checking the number of wafers is performed, the time required for transferring the wafer is shorter than when the work is not performed. This is because the loss is reduced. Here, the work of checking the number of wafers can be skipped.

2. Second step Sequence selection criteria set in the computer itself (
The wafer processing method is designated in ascending order, descending order, individual selection).

3. Third Step Referring to the search results displayed on the computer screen shown in FIG. 5, the unique number search device 106 is moved vertically downward, and the search device 10 is placed in the system base 100.
6 is lowered by a predetermined depth, and the 25 wafers loaded into the first cassette 104 by the wafer processing method designated in the second step are sequentially transferred to the second wafer using the wafer transfer robot 112. It is loaded to the correct position in the cassette 110.

The normal position in the second cassette 110 is as follows.
When 25 wafers 114 are to be automatically arrayed on the second cassette 110 side by the specified wafer processing method,
The appropriate position where the individual wafer is loaded into the second cassette 110 is shown. The third stage will be described more specifically as follows. Here, a case where 25 wafers 114 are aligned in ascending order will be described as an example.

First, the fifth wafer 114 loaded in the 25th slot in the first cassette 104 is mounted on the wafer transfer arm 112b of the wafer transfer robot 112. Next, in order to load the fifth wafer 114 to the correct position (for example, the position of the fifth slot) of the second cassette 110, the cassette moving table 108 is linearly moved upward by a predetermined height. In this state, the wafer transfer arm 112b on which the fifth wafer 114 is mounted
Is moved to the fifth slot position in the second cassette 110, which is the horizontal position on the plane. As a result, the position of the second cassette 110 in the correct position (for example, the position of the fifth slot) is
The numbered wafer 114 is transferred.

When such an operation is repeatedly performed on the other 24 wafers 114 loaded in the first cassette 104 in the same manner, the first wafer may be processed by a specified wafer processing method (for example, in ascending order). Cassette 10
4 in the second cassette 110.
Can be loaded at the correct position in the inside. In the method as described above, if the wafer transfer operation is performed every time a unit process proceeds, a change in process characteristics due to the continuity of the process for each step can be clearly verified. Further, the process characteristics can be analyzed for each unit process, and the state of the semiconductor manufacturing equipment can be easily analyzed.

On the other hand, the wafer transfer system may be designed such that the wafer transfer robot is mounted not on one side of the first cassette but on the system substrate between the first cassette and the second cassette. . The details will be described below with reference to FIG. FIG. 6 shows a second embodiment of the present invention in which wafers are sequentially and automatically aligned.
FIG. 3 is a cross-sectional view illustrating a structure of a wafer transfer system of a semiconductor manufacturing facility according to an embodiment.

As shown in the figure, the wafer transfer system includes a first cassette fixing base 202 and a second cassette fixing base 208 mounted on predetermined parts of the system substrate 200 so as to be spaced apart from each other by a predetermined distance. A first cassette 204 on which a plurality of wafers 214 are loaded is mounted on the first cassette fixing base 202, and
On the cassette fixing table 208, a second cassette 210 on which wafers are unloaded is mounted. A wafer transfer robot 212 is mounted on the system substrate 200 between the first cassette 204 and the second cassette 210 so that the wafer transfer robot 212 can perform up-down linear movement and rotational movement by a gear method. And the first
On the system substrate 200 between the cassettes 204, a unique number search device 206 designed to be capable of linearly moving up and down by a gear system is mounted. At this time,
The wafer transfer system is configured to be connected to a computer (not shown) in a network manner.

Here, the wafer transfer robot 212 is composed of a support table 212a and a wafer transfer arm 212b.
Same as 2, but in addition to the vertical
The difference is that it is designed to be capable of 80 ° rotation. In this case, the wafer transfer arm 212b
Is designed to be capable of right and left linear motion, and its length is 22
Manufactured in lengths of ~ 24 cm. The reason why the length of the wafer transfer arm 212b is shorter than that in the case of the first embodiment is that the wafer transfer robot 212 is connected to the first cassette 204 and the first cassette 204 so that the wafer 214 can be transported in the shortest distance. This is because the two cassettes 210 are arranged at the center.

The unique number retrieving device 206 includes a support 206b and a character recognizing unit 206 in the same manner as in the first embodiment.
a) and has a total height of 40 to 50 cm. At this time, the character recognition unit 206a is fixed to the support 206b so as to be inclined at an angle of 45 ° with respect to the horizontal plane on which the wafer is located, as described above. In addition, the first cassette 20 constituting the wafer transfer system
The fourth cassette 210 is mounted on the system base 200 such that the cassettes 204 and 210 are arranged at mutually corresponding positions.

On the other hand, as a modification of the second embodiment, a wafer transfer robot 21 of the wafer transfer system is used.
The support table 212a can move only up and down linearly by means of a gear system, and the wafer transfer arm 212b constituting the wafer transfer system can be designed to be capable of both left-right linear movement and rotational movement. Thus, when designing a wafer transfer system, the wafer transfer arm 212b
Is designed to be able to rotate 180 °. Therefore, in the case of the second embodiment, the wafer transfer operation is performed in the following three steps.

1. First Step First, the number of wafers loaded in a run is confirmed by the same method as in the first embodiment. As a result of checking the number of loaded wafers, if not all 25 wafers are loaded, but an empty slot is found, the wafer loaded in the next slot is automatically loaded in the empty slot. Aligns the wafers using the wafer transfer robot 212. Next, the first cassette 204
The unique numbers of the 25 wafers 214 loaded in the device are sequentially searched through the character recognition unit 206a of the unique number search device 206, and the results are displayed on a computer screen 116 connected to the wafer transfer system in a network manner. indicate. FIG. 6 illustrates a computer screen 116 on which search results are displayed.

At this time, the search operation using the character recognition unit 206a is performed by sequentially moving the unique number search device 206 vertically downward from the 25th slot position of the first cassette 204 while flattening each wafer 214. The method is implemented by reading and scanning an image of a numerical image in which a unique number marked in a zone portion is written within a specific width at a specific position like a fax millimeter head. Also in this case, the work of checking the number of wafers can be skipped.

2. Second step A wafer processing method is designated by an array selection criterion (small order, large order, individual selection) set in the computer (not shown).

3. Third Step Referring to the search results displayed on the computer screen shown in FIG. 5, the unique number search device 206 is moved vertically downward to place the search device 2 in the system base 200.
06 is lowered by a predetermined depth, and the 25 wafers loaded into the first cassette 204 by the wafer processing method designated in the second step are sequentially transferred to the second wafer using the wafer transfer robot 212. It is loaded to the correct position in the cassette 210. The third stage will be described more specifically as follows. Here, as an example,
A case in which 25 wafers 214 are aligned in ascending order will be described.

First, the No. 5 wafer 214 loaded in the No. 25 slot in the first cassette 204 is mounted on the wafer transfer arm 212b of the wafer transfer robot 212, and then the No. 5 wafer 214 is designated by a designated wafer processing method. Is moved to the normal position of the second cassette 210 (for example, the position of the fifth slot).

Next, the wafer transfer robot 212 is
Rotate at an angle of 80 °. In this state, the fifth wafer 2
The wafer transfer arm 212b on which the wafer 14 is mounted is moved to the fifth slot position in the second cassette 210, which is a horizontal position on a plane. As a result, the second cassette 21
The fifth wafer 214 is transferred to a zero normal position (for example, the position of the fifth slot).

When such an operation is repeatedly performed on the other 24 wafers 214 loaded in the first cassette 204 in the same manner, the first wafer may be processed according to a designated wafer processing method (for example, in ascending order). Cassette 20
4 are all 25 wafers 214 in the second cassette 210
Can be loaded at the correct position within

On the other hand, as in the modification of the second embodiment, the support table 212a of the wafer transfer robot 212 can only move up and down linearly, and the wafer transfer arm 212b constituting it can rotate. When a wafer transfer system is designed, the wafer is
It is transferred into the cassette 210. At this time, the first and second
Since the steps proceed in the same manner as in the second embodiment, a description thereof will be omitted, and the description will focus on the third step after the wafer unique number search operation and the wafer processing method designation are completed. Also in this case, a case will be described in which 25 wafers 214 are aligned in ascending order.

First, the unique number search device 206 is moved vertically downward, and the search device 206 is loaded into the 25th slot in the first cassette 204 while being lowered into the system base 200 by a predetermined depth. The fifth wafer 214 is mounted on the wafer transfer arm 212b of the wafer transfer robot 212, and the fifth wafer 214 is designated according to a specified wafer processing method (for example, in ascending order).
Is moved to the normal position of the second cassette 210 (for example, the position of the fifth slot).

Next, the support table 212a of the wafer transfer robot 212 is not rotated, and only the wafer transfer arm constituting the support table 212a is rotated at an angle of 180 °.
The wafer transfer arm 2 on which the fifth wafer 214 is mounted
12b is moved to the fifth slot position in the second cassette 210, which is the horizontal position on the plane. As a result, the second
The fifth wafer 214 is transferred to the normal position of the cassette 210 (for example, the position of the fifth slot).

The above-mentioned operation is repeated for the other 24 wafers 214 loaded in the first cassette 204 in the same manner, thereby completing the wafer transfer operation. Further, the wafer transfer system mounts the wafer transfer robot not on one side of the first cassette but on the system substrate between the first cassette and the second cassette, and separates another third cassette into the first and the second cassettes. The wafer transfer system may be designed such that the wafer transfer system is further mounted on the system substrate at a point separated from the two cassettes by a predetermined distance.

The operation will be described in detail with reference to FIG. FIG. 7 is a plan view showing a structure of a wafer transfer system of a semiconductor manufacturing facility according to a third embodiment of the present invention in which wafers are automatically aligned sequentially. The reason why the plan view is illustrated in the above embodiment is to enhance the understanding of the structure of the system.

As shown in the figure, the wafer transfer system includes first to third cassette fixing bases 30 so that predetermined portions on the system substrate 300 are spaced apart from each other by a predetermined distance.
2, 308 and 315 are mounted, and a plurality of (for example, 25) wafers 31 are placed on the first cassette fixing base 302.
4 is loaded on the first cassette 304, and the second cassette 31 on which wafers are unloaded is mounted on the second and third cassette fixing tables 308 and 315.
0 and the third cassette 316 are mounted. Also, the wafer transfer robot 31 designed to be capable of vertical linear motion and rotational motion by a gear system is provided on the system substrate 300 between the first cassette 304 and the second cassette 310.
2 is mounted on the system base 300 between the wafer transfer robot 312 and the first cassette 304 to have a structure in which a unique number search device 306 designed to be capable of vertical linear motion by a gear system is mounted. Have been.
At this time, the wafer transfer system is a computer 115
And a network connection.

Here, the first and second cassettes 30
4, 310 are disposed at mutually corresponding positions on the system substrate 300, and the third cassette 316 is
And the second cassettes 304 and 310 are mounted so as to be arranged on a line extending vertically from the center. At this time,
The first to third cassettes 304, 310, and 316 need to be arranged so as to be equidistant from the center of the first and second cassettes 304, 310.

As described above, the first to third cassettes 30
The reason for disposing the 4,310,316 at equal intervals from the center is that the wafer transfer robot 312 of the wafer transfer system is designed to perform vertical and linear motion and rotational motion within a certain range. This is because it is difficult to transfer wafers accurately when the cassette is placed outside the range.

As described above, when two cassettes in which wafers are unloaded are mounted on the system substrate 300, a technician may selectively separate and align individual wafers or remove individual wafers. The wafer can be easily aligned when it is desired to sort by odd and even numbers. The wafer transfer robot 312 includes a support table 312.
a and the wafer transfer arm 312b are the first
This is the same as the wafer transfer robots 112 and 212 of the second embodiment and the second embodiment, but the support table 312a
However, there is a difference in that a 90 ° or 180 ° rotational movement is designed in addition to the vertical linear movement. in this case,
The wafer transfer arm 312b is designed to be able to move linearly to the left and right, and has a length of 22 to 24 cm. Also,
The support 312a is manufactured to have a height of 28 to 30 cm.

Here, the reason why the length of the wafer transfer arm 312b is made shorter in the first embodiment is that the wafer transfer robot 312 is moved from the first to the first in order to transport the wafer 31 within the shortest distance. 3 cassettes 304, 31
This is because it is arranged at the center of 0,316. As shown in FIG. 4, the unique number search device 306 includes a support base and a character recognition unit, and has a total height of 40 to 50 cm.
Produced in Further, the character recognition unit is fixed to the support base so as to be inclined at an angle of 45 ° with respect to the horizontal plane on which the wafer is located as described above.

On the other hand, as a modification of the third embodiment,
The support table 312a of the wafer transfer robot 312 of the wafer transfer system can be moved only up and down linearly by a gear system, and the wafer transfer arm 312b constituting the wafer transfer system is designed to be able to perform both left and right linear movement and rotational movement. You can also. Thus, when designing a wafer transfer system, the wafer transfer arm 312
b is designed to be rotatable by 90 ° or 180 °. Here, when the wafer transfer arm 312b is rotated by 90 °, the wafer transfer arm 312b is disposed on the third cassette 316 side, and when rotated by 180 °, the wafer transfer arm 312b is connected to the second cassette 310. Placed on the side.

Therefore, in the case of the third embodiment, the wafer transfer operation is performed through the following three steps. In the first and second steps, the wafer transfer operation proceeds in the same manner as in the first and second embodiments, so that the description will be simplified, and the third step will be mainly described here.

1. First Step First, the number of wafers loaded per run is confirmed.
As a result of checking the number of loaded wafers, if an empty slot is found instead of all 25 wafers being loaded, the wafer loaded in the next slot is automatically loaded into the empty slot. Aligns the wafers using the wafer transfer robot 312. Thereafter, the unique numbers of the 25 wafers loaded in the first cassette 304 are searched by the scanning method through the character recognition unit of the unique number search device 306, and the results are displayed on the computer screen 116. At this time, the work of checking the number of wafer loadings can be skipped.

2. Second step A wafer processing method is designated according to an array selection criterion (odd and even order, individual selection) set in the computer 115 itself.

3. Third step Referring to the search result displayed on the computer screen 116, the unique number search device 306 is moved vertically downward, and the search device 306 is lowered into the system base 300 by a predetermined depth. The 25 wafers loaded into the first cassette 304 according to the wafer processing method designated in the second step are sequentially positioned in the second cassette 310 or the third cassette 316 using the wafer transfer robot 312. To be loaded.

The third step will be described more specifically as follows. Here, as an example, a case will be described in which the unique numbers of the wafers are sorted in the order of odd numbers and even numbers so that 25 wafers 314 are aligned. First, the first cassette 30
The fifth wafer 314 loaded in the 25th slot in No. 4 is mounted on the wafer transfer arm 312b of the wafer transfer robot 312, and the wafer transfer robot 312 on which the fifth wafer 314 is mounted according to a specified wafer processing method. The second cassette 310 is moved to the correct position (for example, the position of the third slot).

Next, the wafer transfer robot 312 is
Rotate at an angle of 80 °. In this state, the fifth wafer 31
When the wafer transfer arm 312b on which the wafer No. 4 is mounted is moved to the third slot position in the second cassette 310, which is a horizontal position on a plane, the second cassette 310 becomes the correct position (for example, the position of the third slot). Is transferred to the fifth wafer 314. At this time, if the wafer loaded in the 25th slot of the first cassette 304 is the 6th wafer instead of the 5th wafer, the wafer transfer robot is rotated by about 90 ° and the wafer 314 is moved to the third cassette 316. The wafer is transferred by a method of loading the wafer.

As described above, when the same operation is repeatedly performed on the other 24 wafers 314 loaded in the first cassette 304, the operation is performed in the first cassette 304 according to the designated wafer processing method. 25 wafers 314 of the second cassette 310 and the third cassette 31
6 can be loaded at the correct position.
On the other hand, as in the modification of the third embodiment, the support table 312a of the wafer transfer robot 312 can only move up and down linearly.
If the wafer transfer system is designed so that the wafer 2b can be rotated, the wafer 314 is transferred into the second and third cassettes 310 and 316 by the following method. At this time,
Since the first and third steps proceed in the same manner as in the second embodiment, a description thereof will be omitted. Here, the third step after completion of the wafer unique number search operation and the designation of the wafer processing method will be mainly described. It will be described as. Also in this case, the unique numbers of the wafers 314 are divided in the order of odd and even numbers, and 25 wafers 31
4 will be described.

First, the unique number search device 306 is moved vertically downward to lower the search device 306 into the system base 300 by a predetermined depth, and then loaded into the 25th slot in the first cassette 304. The fifth wafer is mounted on the wafer transfer arm 312b of the wafer transfer robot 312, and the wafer transfer robot 312 on which the fifth wafer 314 is mounted according to the specified wafer processing method is moved to the correct position of the second cassette 310 (for example, (3rd slot position).

Next, the support 312a of the wafer transfer robot 312 is not rotated, and only the wafer transfer arm 312b constituting the support is rotated at an angle of 180 °. In this state, the wafer transfer arm 312b on which the fifth wafer 314 is mounted is moved to the second cassette 31 at a horizontal position on a plane.
Move to the third slot position in 0. As a result, the fifth wafer 314 is transferred to the normal position of the second cassette 310 (for example, the position of the third slot).

The wafer transfer operation is completed by repeatedly performing the above operation on the other 24 wafers 314 loaded in the first cassette 304 in the same manner. If the wafer transfer system is designed as in the second and third embodiments, there is an advantage that the wafer can be transferred in the shortest distance. FIG. 8 shows a wafer processing method (small order / large order / odd and even order / individual selection) selected when wafers are transferred by applying the wafer transfer systems presented in the first to third embodiments. A table showing an example of wafer alignment is shown.

As shown in FIG. 8, when the wafers are automatically aligned in ascending order, the first wafer is loaded into the first slot of the second cassette and the second wafer is loaded into the second slot. When 25 wafers are loaded according to the following equation and the wafers are automatically aligned in descending order, 25 slots are set in the first slot of the second cassette.
The 25th wafer is loaded in such a manner that the 2nd wafer is loaded and the 2nd slot is loaded with the 24th wafer.

When the wafers are sorted in an odd-numbered and even-numbered order and are automatically aligned, the first wafer is loaded in the first slot of the second cassette, and the third wafer is loaded in the second slot.
The third wafer is loaded, the third wafer is loaded with the fifth wafer in the third slot, the odd-numbered wafer is loaded, the second wafer is loaded in the first slot of the third cassette, and the second wafer is loaded in the second slot. The even-numbered wafer is loaded in such a manner that the fourth wafer is loaded and the sixth slot is loaded into the third slot.

When the technician performs automatic alignment by individually selecting wafers, the fourth wafer is loaded into the first slot of the second cassette and the seventh wafer is loaded into the second slot. In the third slot, 25 wafers are loaded in such a manner that the 24th wafer is loaded. In this way, when the wafers are sequentially and automatically aligned, it is not necessary to inspect all the individual wafers at the time of the process inspection work performed every time the unit process is performed, and the technician artificially falls into the weak point. Since the process inspection work can be performed by a method of inspecting only the process, the time loss required in the process inspection work can be reduced.

[0068]

As described above, according to the present invention, a sequential (small order / large order / odd number and even number order / individual selection) is performed by a designated wafer processing method each time a unit process is performed during semiconductor device manufacturing. The arrangement described in (1) enables not only the necessity of individually managing large-diameter wafers but also computerization of individual wafers. In addition, it is possible to analyze the process characteristics of each unit process, which facilitates the investigation and analysis of the state of semiconductor manufacturing equipment, and automatically arranges wafers by a sequential reference alignment method even in a repeated process. Therefore, a change in process characteristics due to the continuity of the process for each step can be clearly verified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a wafer transfer system structure of a semiconductor manufacturing facility shown as a first embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which 25 wafers are loaded in units of a run into a first cassette constituting the wafer transfer system of FIG. 1;

FIG. 3 is an enlarged view of a main part of a flat zone portion of the individual wafer shown in FIG.

FIG. 4 is a schematic diagram showing a method of searching for a wafer unique number using a unique number search device included in the wafer transfer system of FIG. 1;

FIG. 5 is a view showing a result of searching for a unique number of an individual wafer on a computer screen by using a unique number searching device included in the wafer transfer system of FIG. 1;

FIG. 6 is a sectional view showing a structure of a wafer transfer system of a semiconductor manufacturing facility shown as a second embodiment of the present invention.

FIG. 7 is a plan view showing a structure of a wafer transfer system of a semiconductor manufacturing facility shown as a third embodiment of the present invention.

FIG. 8 shows a selection of a wafer processing method (small order / large order / odd and even number / individual selection) when a wafer is transferred by applying the wafer transfer system presented in the first to third embodiments. FIG. 4 is a diagram showing an example of wafer alignment by the above method.

FIG. 9 is a graph showing a change in a growth rate of a thin film according to a time flow when a thin film is formed on a plurality of wafers by a conventional arrangement method.

[Explanation of symbols]

 100, 200, 300: system base 102: cassette fixing base 104, 204, 304: first cassette 106, 206, 306: unique number search device 106a, 206a: character recognition unit 106b, 206b: support base 110, 210, 310 : Second cassette 112, 212, 312: wafer transfer robot 112a, 212a, 312a: support base 112b, 212b, 312b: wafer transfer system 114, 214, 314: wafer 202, 302: first cassette fixing base 208, 308: Second cassette fixing base 315: Third cassette fixing base 316: Third cassette

Claims (75)

[Claims] 1. A system base, a cassette fixing table mounted on a predetermined portion on the system base, a first cassette mounted on the cassette fixing table and loaded with a plurality of wafers, A unique number search device mounted on one side of the system base and designed to be capable of vertical linear movement, and mounted at a predetermined distance from the unique number search device on the system base and capable of vertical linear movement A cassette moving table designed on the above, a second cassette mounted on the cassette moving table and unloaded with a wafer, and mounted on the system base on the other side of the first cassette and designed to be capable of vertical linear movement. A wafer transfer robot for a semiconductor manufacturing facility, comprising: 2. The apparatus according to claim 2, wherein the unique number search device is 40 to 50c.
2. The wafer transfer system according to claim 1, wherein the wafer transfer system has a height of m. 3. The apparatus according to claim 1, wherein the unique number search device includes a support mounted on the system base and a character recognition unit attached to a predetermined portion of one side of the support. 2. A wafer transfer system for a semiconductor manufacturing facility according to claim 1. 4. The wafer transfer system according to claim 3, wherein the character recognition unit is fixed so as to be inclined at an angle of 45 ° with respect to a horizontal plane on which the wafer is located. 5. The wafer transfer robot according to claim 1, wherein the wafer transfer robot comprises a support mounted on the system base and a wafer transfer arm disposed on the support and on which a wafer is mounted. A wafer transfer system for a semiconductor manufacturing facility as described in the above. 6. The wafer transfer system according to claim 5, wherein the wafer transfer arm is designed to be able to move right and left linearly. 7. The wafer transfer arm according to claim 7, wherein:
6. The wafer transfer system according to claim 5, wherein said wafer transfer system has a length of m. 8. The wafer transfer system according to claim 5, wherein the support has a height of 28 to 30 cm. 9. The wafer transfer system according to claim 1, wherein the wafer transfer system of the semiconductor manufacturing equipment is connected to a computer in a network manner. 10. The wafer transfer system according to claim 1, wherein the first cassette and the second cassette are arranged at mutually corresponding positions on the system substrate. 11. A system base, a first cassette fixed base and a second cassette fixed base mounted on the base of the system so as to be separated from each other by a predetermined distance, and mounted on the first cassette fixed base. A first cassette on which a plurality of wafers are loaded, a second cassette mounted on the second cassette fixing table and unloaded with wafers, and the system substrate between the first cassette and the second cassette. A wafer transfer robot mounted and capable of vertical linear movement and rotational movement; and a unique number mounted on the system substrate between the wafer transfer robot and the first cassette and designed to be capable of vertical linear movement. A wafer transfer system for semiconductor manufacturing equipment, comprising a search device. 12. The wafer transfer system according to claim 11, wherein the wafer transfer robot is designed to rotate by 180 °. 13. The device for retrieving a unique number, comprising:
12. The wafer transfer system for a semiconductor manufacturing facility according to claim 11, wherein the wafer transfer system has a height of 10 cm. 14. The apparatus according to claim 1, wherein the unique number search device includes a support mounted on the system base and a character recognition unit attached to a predetermined portion of one side of the support. 12. A wafer transfer system for a semiconductor manufacturing facility according to claim 11. 15. The wafer transfer system according to claim 14, wherein the character recognition unit is fixed to be inclined at an angle of 45 ° with respect to a horizontal plane on which the wafer is located. 16. The wafer transfer robot according to claim 11, wherein the wafer transfer robot comprises a support mounted on the system base, and a wafer transfer arm disposed on the support and on which a wafer is mounted. A wafer transfer system for a semiconductor manufacturing facility as described in the above. 17. The wafer transfer system according to claim 16, wherein the wafer transfer arm is designed to be able to move right and left linearly. 18. The wafer transfer arm according to claim 18, wherein
17. The wafer transfer system of a semiconductor manufacturing facility according to claim 16, having a length of about 1 cm. 19. The wafer transfer system according to claim 16, wherein the support has a height of 28 to 30 cm. 20. The wafer transfer system according to claim 11, wherein the first cassette and the second cassette are arranged at positions corresponding to each other on the system substrate. 21. The wafer transfer system of a semiconductor manufacturing facility according to claim 11, wherein the wafer transfer system of the semiconductor manufacturing facility is connected to a computer by a network. 22. A system base, a first cassette fixing base and a second cassette fixing base mounted on the system base so as to be separated from each other by a predetermined distance, and mounted on the first cassette fixing base. A first cassette loaded with a plurality of wafers, a second cassette mounted on the second cassette fixing base and unloaded with wafers, and the system substrate between the first cassette and the second cassette A wafer transfer robot designed to be capable of up-down linear movement mounted on the system; and a unique number designed to be mounted on the system base between the wafer transfer robot and the first cassette and capable of up-down linear movement. A wafer transfer system for semiconductor manufacturing equipment, comprising a search device. 23. The wafer transfer robot according to claim 22, wherein the wafer transfer robot includes a support table mounted on the system base and a wafer transfer arm disposed on the support table and on which a wafer is mounted. A wafer transfer system for a semiconductor manufacturing facility as described in the above. 24. The wafer transfer system according to claim 23, wherein the wafer transfer arm is designed to be capable of a right-left linear motion and a rotary motion. 25. The wafer transfer system according to claim 24, wherein the wafer transfer arm is designed to be rotatable by 180 °. 26. The wafer transfer arm according to claim 22, wherein
25. The wafer transfer system of a semiconductor manufacturing facility according to claim 24, wherein the wafer transfer system has a length of cm. 27. The wafer transfer system according to claim 23, wherein the support has a height of 28 to 30 cm. 28. The unique number search device, wherein:
23. The wafer transfer system of a semiconductor manufacturing facility according to claim 22, having a height of cm. 29. The apparatus according to claim 29, wherein the unique number search device includes a support mounted on the system base and a character recognition unit attached to a predetermined portion of one side of the support. 23. A wafer transfer system for a semiconductor manufacturing facility according to claim 22. 30. The wafer transfer system according to claim 29, wherein the character recognition unit is fixed to be inclined at an angle of 45 ° with respect to a horizontal plane on which the wafer is located. 31. The wafer transfer system according to claim 22, wherein the first cassette and the second cassette are arranged at positions corresponding to each other on the system substrate. 32. The wafer transfer system of a semiconductor manufacturing facility according to claim 22, wherein the wafer transfer system of the semiconductor manufacturing facility is connected to a computer in a network manner. 33. A system base, first to third cassette fixing bases mounted on the system base so as to be spaced apart from each other by a predetermined distance, and a plurality of wafers mounted on the first cassette fixing base. A first cassette loaded with, a second and a third cassette mounted on the second and third cassette fixing bases and unloaded with wafers, and the system substrate between the first cassette and the second cassette A wafer transfer robot mounted on the top and capable of vertical linear movement and rotational movement, and mounted on the system substrate between the wafer transfer robot and the first cassette so as to be capable of vertical linear movement A wafer transfer system for a semiconductor manufacturing facility, comprising: 34. The first cassette and the second cassette are arranged at positions corresponding to each other, and the third cassette is arranged on a line extending vertically from the center of the first and second cassettes. 34. The method according to claim 33, wherein
A wafer transfer system for a semiconductor manufacturing facility as described in the above. 35. The first to third cassettes, wherein:
35. The wafer transfer system of a semiconductor manufacturing facility according to claim 34, wherein the wafers are arranged so as to be equally spaced apart from the center of the second cassette. 36. The wafer transfer system according to claim 33, wherein the wafer transfer robot is rotated at any one of 90 ° and 180 °. 37. The apparatus for retrieving a unique number, comprising:
34. The wafer transfer system of a semiconductor manufacturing facility according to claim 33, wherein the wafer transfer system has a height of cm. 38. The unique number search device, comprising: a support mounted on the system base; and a character recognition unit attached to a predetermined portion of one side of the support. 34. The wafer transfer system for a semiconductor manufacturing facility according to claim 33. 39. The wafer transfer system according to claim 38, wherein the character recognition unit is fixed to be inclined at an angle of 45 ° with respect to a horizontal plane on which the wafer is located. 40. The wafer transfer robot according to claim 33, wherein the wafer transfer robot comprises a support mounted on the system base and a wafer transfer arm disposed on the support and on which a wafer is mounted. A wafer transfer system for a semiconductor manufacturing facility as described in the above. 41. The wafer transfer system of a semiconductor manufacturing facility according to claim 40, wherein the wafer transfer arm is designed to be able to move right and left linearly. 42. The wafer transfer arm according to claim 22, wherein
41. The wafer transfer system of a semiconductor manufacturing facility according to claim 40, wherein the wafer transfer system has a length of cm. 43. The wafer transfer system according to claim 40, wherein the support has a height of 28 to 30 cm. 44. The wafer transfer system according to claim 33, wherein the wafer transfer system of the semiconductor manufacturing equipment is connected to a computer in a network manner. 45. A system base, first to third cassette fixing bases mounted on the system base so as to be separated from each other by a predetermined distance, and a plurality of wafers mounted on the first cassette fixing base. Is loaded on the first cassette, the second cassette and the third cassette mounted on the second and third cassette fixing tables and the wafers are unloaded, and the first cassette and the second cassette are A wafer transfer robot mounted on the system base and designed to be capable of vertical linear movement; and a wafer transfer robot mounted on the system base between the wafer transfer robot and the first cassette, designed to be capable of vertical linear movement. And a unique number search device. 46. The wafer transfer robot according to claim 45, wherein the wafer transfer robot includes a support table mounted on the system base and a wafer transfer arm disposed on the support table and on which a wafer is mounted. A wafer transfer system for a semiconductor manufacturing facility as described in the above. 47. The wafer transfer system of a semiconductor manufacturing facility according to claim 46, wherein the wafer transfer arm is designed to be able to perform right and left linear movement and rotational movement. 48. The wafer transfer arm has a 90 ° angle and a 1 ° angle.
17. The wafer transfer system of a semiconductor manufacturing facility according to claim 16, wherein the wafer is rotated at any one angle selected from 80 [deg.]. 49. The wafer transfer arm according to claim 24, wherein
The wafer transfer system of a semiconductor manufacturing facility according to claim 46, wherein the wafer transfer system has a length of cm. 50. The wafer transfer system according to claim 46, wherein the support has a height of 28 to 30 cm. 51. The apparatus for retrieving a unique number, comprising:
46. The wafer transfer system of a semiconductor manufacturing facility according to claim 45, wherein the wafer transfer system has a height of cm. 52. The unique number search device, comprising: a support mounted on the system base; and a character recognition unit attached to a predetermined portion of one side of the support. 45. The wafer transfer system of a semiconductor manufacturing facility according to 45. 53. The wafer transfer system according to claim 52, wherein the character recognition unit is fixed to be inclined at an angle of 45 ° with respect to a horizontal plane on which the wafer is located. 54. The first cassette and the second cassette are arranged at positions corresponding to each other, and the third cassette is arranged on a line extending vertically from the center of the first and second cassettes. 46. The method according to claim 45, wherein
A wafer transfer system for a semiconductor manufacturing facility as described in the above. 55. The first to third cassettes include the first cassette.
55. The wafer transfer system of a semiconductor manufacturing facility according to claim 54, wherein the wafer transfer system is disposed so as to be equidistant from the center of the second cassette. 56. The wafer transfer system of a semiconductor manufacturing facility according to claim 45, wherein the wafer transfer system of the semiconductor manufacturing facility is connected to a computer in a network manner. 57. A first method of searching for a unique number of a plurality of wafers loaded in a first cassette using a unique number search device, and displaying the result on a computer screen.
A second step of specifying a wafer processing method according to an array selection criterion set in the computer; and a plurality of wafers in the first cassette using a wafer transfer robot according to the wafer processing method specified in the second step. A step of sequentially loading the wafers at the correct position in the second cassette where the wafers are unloaded. 58. The wafer transfer method of a wafer transfer system according to claim 57, wherein the wafer processing method is set so as to be sorted in ascending order, descending order, and individual selection. 59. The third step, wherein an arbitrary wafer in the first cassette is mounted on a wafer transfer arm of a wafer transfer robot, and the cassette in which the second cassette is mounted by a specified wafer processing method. The method according to claim 1, further comprising: moving the moving table up and down linearly by a predetermined height; and loading a wafer mounted on the wafer transfer arm into a second cassette mounted on the cassette moving table. 58. The wafer transfer method of the wafer transfer system according to Item 57. 60. The wafer transfer system according to claim 57, wherein in the first step, the unique number searching device searches a unique number of the wafer by a scanning method through a character recognition unit of the unique number searching device. Wafer transfer method. 61. The wafer transfer system according to claim 57, wherein the wafer transfer method of the wafer transfer system further includes an operation of confirming the number of wafers loaded in the first cassette before the first step. Wafer transfer method. 62. The third step, wherein an arbitrary wafer in the first cassette is mounted on a wafer transfer arm of a transfer robot, and the wafer is positioned at a correct position on the second cassette according to a specified wafer processing method. Moving the transfer robot, rotating the wafer transfer robot at a predetermined angle, and loading the wafer mounted on the wafer transfer arm into the second cassette. 58. A wafer transfer method for the wafer transfer system according to claim 57. 63. The method of claim 62, wherein the wafer transfer robot rotates 180 degrees. 64. The third step, wherein an arbitrary wafer in the first cassette is mounted on a wafer transfer arm of a wafer transfer robot, and the wafer is moved to a normal position of the second cassette by a specified wafer processing method. Moving the wafer transfer robot at a predetermined angle; and loading the wafer mounted on the wafer transfer arm into the second cassette. 58. The wafer transfer method of the wafer transfer system according to claim 57. 65. The method according to claim 64, wherein the wafer transfer arm rotates 180 degrees. 66. A first step of retrieving a plurality of wafer unique numbers loaded in a first cassette using a unique number search device and displaying the results on a screen, and an arrangement set in the computer A second step of specifying a wafer processing method according to a selection criterion; and a plurality of wafers in the first cassette are sequentially transferred to the second cassette and the third cassette using a wafer transfer robot according to the wafer processing method specified in the second step. A wafer transfer method for a wafer transfer system, the method being performed in a third step of loading the wafer at a correct position in the cassette. 67. The wafer transfer method according to claim 66, wherein the wafer processing method is set so as to be divided into odd / even order and individual selection. 68. The third step, wherein an arbitrary wafer in the first cassette is mounted on a wafer transfer arm of a wafer transfer robot, and the second cassette and the third cassette are moved according to a designated wafer processing method. Moving the wafer transfer robot to the correct position of any one of the cassettes selected; rotating the wafer transfer robot at a predetermined angle toward the selected cassette; and mounting the wafer transfer robot on the wafer transfer arm. 67. The method of claim 66, further comprising the step of loading the wafer into a selected cassette. 69. The wafer transfer method according to claim 68, wherein the wafer transfer robot rotates 180 ° when the second cassette is selected. 70. The wafer transfer method according to claim 68, wherein the wafer transfer robot rotates by 90 ° when the third cassette is selected. 71. The third step comprises: mounting an arbitrary wafer in the first cassette on a wafer transfer arm of a wafer transfer robot; and Moving the wafer transfer robot to the correct position of any one of the cassettes selected in the step of: rotating the wafer transfer arm at a predetermined angle to the selected cassette side; and mounting the wafer transfer arm on the wafer transfer arm. 67. The method of claim 66, further comprising loading the wafer into a selected cassette. 72. The method of claim 71, wherein the wafer transfer robot rotates 180 ° when the second cassette is selected. 73. The wafer transfer method according to claim 71, wherein the wafer transfer robot rotates 90 ° when the third cassette is selected. 74. The wafer transfer system according to claim 66, wherein in the first step, the unique number search device searches for the unique number of the wafer through a character recognition unit of the unique number search device in a scanning manner. Wafer transfer method. 75. The wafer transfer system according to claim 66, wherein the wafer transfer method of the wafer transfer system further includes an operation of confirming the number of wafers loaded in the first cassette before the first step. Wafer transfer method.