JPS61168934A - Wafer handling method - Google Patents

Abstract

PURPOSE:To perform supply and recovery of wafers by the same cassette, by transferring all the wafers stored in the cassette to a stocker so as to empty the cassette, conveying the wafers from the stocker for treatment, and recovering the treated wafers into the original cassette. CONSTITUTION:A cassette 22A, in which wafers 2 that are not injected are accommodated, is mounted on the uppermost position. The wafer 2 is taken out of the lower stage side of the cassette 22A one by one and inputted into the lower side immediately beneath a dummy wafer 2d in a stocker 26A in sequence. All the wafer 2 in the cassette 22A are transferred to the stocker 26A. Then, the wafers 2 are sequentially supplied to a disk 4 from the lowest stage of the stocker 26A. After ion implantation, the wafer 2 is taken out of a position P1 of the disk 4 and recovered to the uppermost stage (i.e., original position) of the original cassette 22A through a space part S in the stocker 26A. The next wafer 2 in the stocker 26A is mounted on the position P1 of the disk 4, and the second ion implantation is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wafer handling method when processing a wafer, for example when implanting ions into the wafer in an ion implantation apparatus.

[Conventional technology]

FIG. 7 is a schematic plan view of an end station for explaining an example of a conventional wafer handling method.

In this example, wafer handling is performed in the atmosphere. That is, a plurality of unimplanted wafers 2 are stored in advance in the cassette 7 of the loader 6 installed in the atmosphere, and after ion implantation, the wafers 2 are transferred (pulled out) from the vacuum to the atmosphere. The loaded wafer 2 that has been implanted is stored in a cassette 9 of an unloader 8 provided in the atmosphere, and the unimplanted wafer 2 is supplied from the cassette 7 to the disk 4 and loaded.

FIG. 8 is a schematic plan view of another end station for explaining another example of the conventional wafer handling method. In this example, the disk 4 is always in a vacuum, the cassette 7.9 is in the atmosphere, and the wafers 2 are supplied and retrieved via the air chamber 16. That is, the disk 4 is
A high vacuum (e.g. 10-6
~10-? The directional control chamber 14 is housed in a vacuum container 12 with a temperature of about 100 yen (T o r r), and the direction control chamber 14 directly communicates with the vacuum container 12 without using a gate valve or the like. Direction control room 14
and atmosphere via a gate valve 18.20 to a low vacuum (e.g. 10-"IQ-"T).

An airlock chamber 16 of approximately 100 mm (approx.

A plurality of uninjected wafers 2 are stored in advance in the cassette 7 of the loader 6 installed in the atmosphere, and the injected wafers 2 mounted on the disk 4 are transferred to the direction control chamber 14.
The unloaded wafers 2 are stored in the cassette 9 of the unloader 8 installed in the atmosphere via the aerodynamic chamber 1G, and the uninjected wafers 2 are transferred from the cassette 7 of the loader 6 to the aerodynamic chamber 16 and the direction control chamber 14. It is supplied to the disk 4 via the disk 4 and mounted thereon.

[Problem that the invention seeks to solve]

The wafer handling method explained in FIG. 7 has the following problems.

(2) Since the cassette 7 of the loader 6 and the cassette 9 of the unloader 8 are separate, the wafer 2 after implantation is collected in a different cassette 9 from the one when not implanted. However, depending on the operating conditions of the ion implanter, it may be more convenient to collect the wafer 2 after implantation into the cassette 7 in which it was originally placed, and in such a case, the wafer 2 may be exchanged between cassettes. Additional steps are required, which is very time-consuming and reduces processing capacity (number of wafers processed per unit time).

■ Since there is both a supply cassette 7 and a recovery cassette 9, there is a possibility that the cassette 7 will run out of wafers during handling (or if the cassette 9 becomes full of wafers). In such a case, the cassette 7 or 9 must be replaced, which requires a lot of effort, and the handling operation is halted for the time required for these replacements, which reduces the processing capacity accordingly.

-Tactically speaking, wafer 2 to cassette 7 or 9
Since the number of wafers 2 loaded onto the disk 4 is smaller than the number of wafers 2 stored in the disk 4 (for example, the former is 25 and the latter is 14), one cassette's worth of wafers 2 are processed at one time. It is not possible. For this reason, 1 cent of power is processed in several steps, or 10 points is processed in several steps, but in that case, in the last process, the number of wafers 2 inevitably falls short of the number of disks 4 installed. There are cases.

In such a case, if ion implantation is performed while there is a part where the wafer 2 is not attached, a problem will occur in the disk 4.For example, in the part of the disk 4 where the wafer 2 is attached,
Silicone rubber is laid to improve heat conduction between the wafer 2 and the disk 4, and if ions are implanted there without the wafer 2 attached, the silicone rubber will be damaged. In order to prevent this from occurring, if there is a shortage of wafers 2 to be supplied to the disk 4, ions must be implanted after, for example, mounting a dummy wafer.In such a case, the wafer handling method explained in FIG. In this case, the worker uses the loader 6
A cassette containing dummy wafers must be attached to the wafer, which is very time-consuming. Furthermore, sorting the dummy wafers collected by the unloader 8 must be done manually, which is troublesome.

On the other hand, in the end station shown in FIG. 8, a dummy station 10 is provided, and the supply and recovery of the dummy wafers 2d from the cassette 1-1 there is performed automatically, which solves the problem (2) mentioned above. has been resolved. However, since the cassette 7 of the loader 6 and the cassette 9 of the unloader 8 are separate as in the case of FIG. 7, the above-mentioned problems 1 and 2 still exist.

Accordingly, a primary object of the present invention is to provide a wafer handling method that allows wafers to be supplied and retrieved using the same cassette.

[Means for solving problems]

The wafer handling method of the first invention uses a cassette in which a plurality of unprocessed wafers are stored in advance and a stocker capable of storing wafers in excess of the number of wafers stored in the cassette. All the wafers are transferred to the stocker to empty the cassette, the wafers are then carried out from the stocker for processing, and the processed wafers are returned to the original cassette.

The wafer handling method of the second invention includes a cassette in which a plurality of unprocessed wafers are stored in advance, a plurality of dummy wafers in advance, and further wafers in excess of the number of wafers stored in the cassette. First, all the wafers stored in the cassette are transferred to the stocker to empty the cassette, and then the wafers are taken out from the stocker and supplied to the disk. At that time, if there are insufficient wafers to be supplied to the disk In such a case, the insufficient number of dummy wafers are supplied to the disk, and the processed wafers are collected into the original cassette, and the dummy wafers are collected into the original stocker.

A wafer handling method according to a third aspect of the invention includes a plurality of cassettes in which a plurality of unprocessed wafers are each stored in advance, and a pair of cassettes in which a plurality of dummy wafers are stored in advance. Moreover, using a plurality of stockers capable of storing more wafers than the number of wafers stored in the pair of cassettes, first, all the wafers stored in each cassette are transferred to the pair of stockers and each cassette is emptied. Next, wafers are taken out from one stocker and supplied to the disk, and if there is a shortage of wafers to be supplied to the disk, either dummy wafers are supplied to the disk by the insufficient number from the stocker, or dummy wafers are supplied from another stocker by the insufficient number. Either the wafers are supplied to the disk, the processed wafers are collected into the original cassette, and the dummy wafers are collected into the original stocker.

[Effect]

In the wafer handling method of the first invention, the processed wafer is collected into the original cassette.

In the wafer handling method of the second invention, dummy wafers are supplied to the disk by the number of wafers lacking,
Moreover, the wafers after processing are collected into the original cassette, and the dummy wafers are collected into the original stocker.

In the wafer handling method of the third invention, when there is a shortage of wafers on the disk, dummy wafers are supplied for that amount or wafers are supplied from another stocker, and the wafers after processing are collected into the original cassette. ,
The dummy wafers are returned to the original stocker.

〔Example〕

FIG. 1 is a schematic plan view of an end station for explaining an example of the wafer handling method according to the present invention, and FIG. 2 is a schematic cross-sectional view taken along line nn in FIG. 1. This example shows a case where wafers are handled in the atmosphere. That is, the pair of cassette 22A and stocker 26A (this is called stage A), the pair of cassette 22B and stocker 26B (this is called stage B), etc. are provided in the atmosphere, and the disk 4 is also used for taking out the wafer 2. And when mounting, it is transferred (pulled out) from the vacuum to the atmosphere.

A plurality of (for example, 25) unprocessed (uninjected) wafers 2 are stored in each of the cassettes I-22A and 22B in advance. In each of the stockers 26A and 26B provided between the cassettes 22A and 22B and the disk 4, a plurality of dummy wafers 2d are preliminarily placed on the upper stage, for example, the number of wafers 2 attached to the disk 4 (for example, nine).
is stored, and a pair of cassettes 2 are stored in the bottom row.
It is possible to store more wafers 2 (for example, 25 wafers) than the number of wafers 2 that can be stored in 2A and 22B.

The wafers 2 are taken out from the cassette 22A and the wafers 2 are collected therein by raising or lowering the cassette 22A step by step using a lifting mechanism 32A consisting of a motor, etc., and by rotating the transport bell 24A forward or backward. It will be done. Storing the wafers 2 in the stocker 26A and taking out the wafers 2 and dummy wafers 2d from the stocker 26A is carried out by raising or lowering the stocker 26A step by step using an elevating mechanism 34A consisting of a motor, etc., and rotating the transport bell 24A in the normal or reverse direction. carried out by. Wafer 2 or dummy wafer 2d to disk 4
The loading and unloading is performed by raising the conveyor belt 30 using an elevating mechanism 38 consisting of an actuator or the like, rotating the conveyor belt 30 forward or reversely, and rotating the disk 4 in stages. The cassette 22B1 stocker 26B is also the same as described above, but when transporting the wafer 2 or dummy wafer 2d from these, the elevating mechanism 36 consisting of an actuator etc.
to raise the conveyor belt 28.

Next, a wafer handling method at the end station will be explained. First, wafer 2 containing unimplanted wafer 2
When two cassettes 22A and 22B are installed, cassette 2
The wafers 2 are taken out one by one from the lower stage of the cassette 22A, and the wafers 2 are sequentially enlarged from just below the dummy wafer 2d of the stocker 26A, and all the wafers 2 of the cassette 22A are transferred to the stocker
Transfer to 6A. Similarly, all the wafers 2 in the cassette 22B are transferred to the stocker 26B, and the wafers 2 in the cassette 22A are
, 22B is emptied once.

Next, the wafers 2 are sequentially taken out from the bottom of the stocker 26A and supplied to the disk 4, and the wafers 2 are placed at a position on the disk 4.
The wafers 2 are sequentially mounted from position P to position P, and then the disk 4 is placed in a high vacuum implantation chamber (not shown) to perform ion implantation.

After ion implantation, the disk 4 is returned to the atmosphere, and the implanted wafer 2 is taken out from position P on the disk 4.
The original cassette 22A passes through the space of the stocker 26A.
The next wafer 2 in the stocker 26A is
is mounted on the disk 4 at position P. After performing the same process from position P2 to the open position of the disk 4, the second ion implantation is performed. In this case, the wafer 2 after implantation is placed in the same cassette as when it was supplied, and in the same location within it (
that is, in the same order in which they were previously stored).

When the wafer 2 in the stocker 26A runs out, it is detected by, for example, a photo sensor, and the wafer 2 in the stocker 26A is removed.
The unimplanted wafer 2 is supplied to the disk 4 from 6B.

When the cassette 22A is full of implanted wafers 2,
For example, it is detected by a photo sensor, etc., and the disc 4
The implanted wafer 2 is automatically collected into the cassette 22B, and a signal for replacing the cassette 22A is issued.

When the operator who receives this removes the cassette 22A in which the injected wafers 2 have been collected and attaches the cassette 22A in which the uninjected wafers 2 are stored, the wafers 2 are placed in the stocker 26A as described above. The transfer is performed automatically and the device enters a standby state. Meanwhile, in parallel, supply of wafer 2 from stocker 26B, ion implantation, and cassette 2
Wafer 2 is being collected to 2B.

When dummy wafers are used due to a shortage of wafers to be supplied to the disk 4, the dummy wafers 2d in the upper row of the stockers 26A and 26B are supplied to the disk 4, and after ion implantation, the dummy wafers 2d are returned to their original state (i.e., the same as when they were supplied). (same) stockers 26A and 26B. For this purpose, for example, the source of supply of the dummy wafers 2d, the number of supplied wafers, etc. are stored in the control means.

In this case, if there are two or more stages each consisting of a pair of cassette and stocker (FIGS. 1 and 2 show an example of two stages), the problem occurs when there is a shortage of wafers 2 to be supplied to the disk 4. Although various methods can be considered for supplying the dummy wafer 2d from the stage or supplying the wafer 2 from another stage, a typical example is shown in FIG. When the number of wafers loaded on the disk 4 is M (for example, 9) and the number of wafers stored in each stage is N (for example, 25), FIG. A case is shown in which the insufficient number of dummy wafers are supplied from the stage each time. For example, during ion implantation l and H, nine wafers 2 are supplied to the disk 4 from the stocker 26A of stage A, and during ion implantation - seven wafers 2 and 2 are supplied from the stocker 26A.
Next, wafers 2 or dummy wafers 2d are supplied from stage B in the same manner.

On the other hand, FIG. 3(b) shows that when there is a shortage of wafers 2 supplied from one stage, the insufficient number of wafers 2 are supplied from other stages, and then dummy wafers 2d are supplied in bulk after ion implantation. Indicates when to do so.

Which of the above methods is used depends on the injection conditions and the like.

For example, when changing the injection conditions for each cassette, the third
If the method shown in FIG. 3(a) is used to continuously implant ions into a large number of wafers under the same conditions, the method shown in FIG. 3(b) may be used.

The wafer handling method described above provides the following effects.

(2) The wafer 2 after implantation is collected into the same cassette as when it was supplied. Therefore, the conventional step of exchanging wafers between cassettes is not necessary, the associated effort can be saved, and processing capacity can be improved. Moreover, as in the above example, the wafers 2 after implantation are not only collected in the same cassette in which they were supplied, but also in the same order in the same cassette. can. The main advantage of doing so is that if different types of wafers 2 are stored in one cassette, there is no need to replace the wafers if the wafers 2 after implantation are recovered in the same order as the original. This means that post-processing becomes much easier.

■ As before, the cassette and unloader on the Rogue side
The side cassette is not separate, and the wafer 2 after implantation is collected into the original cassette, so the number of cassettes can be half of the conventional one, and therefore the frequency and effort of replacing cassettes is half that of the conventional one. The processing capacity can also be improved by

■ If the dummy wafers 2d are stored in the stockers 26A and 26B in advance as in the above example, when there is a shortage of wafers 2 to be supplied to the disk 4, the dummy wafers 2d can be automatically supplied and collected without requiring any human intervention. You can also.

■ Furthermore, as in the above example, if two pairs of cassettes and paired stockers are used (in other words, two stages), wafers can be transferred from the other stage to the disk 4 while the cassette in one stage is being replaced. 2 can be supplied. Therefore, it is possible to eliminate the interruption of ion implantation due to wafer breakage during handling, thereby further improving the throughput. Of course, three or more stages may be used.

Note that some end stations carry the wafers 2 one by one into the implantation chamber, implant ions, and take them out without using the disk 4 as described above; The wafer handling method of the invention can be used. In that case, there is only one stage, and there is no need to store the dummy wafer 2d in the stocker.Even in such a case, the effects of (1) and (2) above can be obtained.

Next, a case in which wafers are handled in a vacuum will be described. FIG. 4 is a schematic plan view of another end station for explaining another example of the wafer handling method according to the present invention, and FIG. 5 is a schematic cross-sectional view taken along line V-V in FIG. 4. . Components equivalent to those in FIGS. 1 and 2 are given the same reference numerals, and their explanations will be omitted.

The disk 4 is housed in a high-vacuum container 12 that communicates with an implantation chamber (not shown), and is rotated in stages as shown by the solid line in FIG. 5 during wafer handling, and during ion implantation. It is rotated and translated in the state indicated by the broken line (reference numeral 4') in FIG.

A transfer chamber 42 directly communicates with the vacuum container 12 without using a gate valve or the like. Between the transfer chamber 42 and the atmosphere,
Low vacuum cassette chambers 40A and 40B are provided,
On both sides thereof, cassette doors 44A, 44B and gate valves 46A, 46B are provided, respectively. The aforementioned cassettes 22A and 22B are housed in cassette chambers 40A and 40B, respectively, and both stockers 26A and 26B are housed in transfer chamber 42. Furthermore, the aforementioned conveyor belts 24A and 24B are divided into conveyor belts 23A and 27A and conveyor belts 23B and 27B, respectively, in this example.

Next, a wafer handling method at the end station will be explained with reference to FIG.

In step 1, the cassette doors 44A and 44B are opened, and the cassette 22 containing uninjected wafers 2 is opened.
Attach A and 22B to the end station. In step 2, the cassette doors 44A and 44B are closed, and in step 3, the cassette chambers 4OA and 40B are vacuumed (roughly evacuated).

In step 4, the gate valves 46A and 46B are opened, and in step 5, the wafer 2 is transferred to the cassettes 22A and 22.
Transfer everything from B to stockers 26A and 26B. In step 6, nine wafers 2 are removed from the stocker 26A.
is supplied to and mounted on the disk 4, and in step 7, ions are implanted into the wafers 2 sequentially.In step 8, the implanted wafers 2 are collected into the cassette 22A, and only 9 unimplanted wafers 2 are transferred to the cassette 22A. )7 is supplied to the disk 4 from the car 26A, and ions are implanted in step 9. In step 10, the implanted wafers 2 are collected into the cassette 22A, and seven unimplanted wafers 2 are supplied to the disk 4 from the stocker 26A. In this example, the number of wafers 2 stored in the cassettes 22A and 22B are both Since the number of wafers is 25, only 7 unimplanted wafers 2 remain in one stage at the third loading time), and the missing two wafers are transferred to the stocker 2 of the other stage.
Supplied from 6B. After ion implantation in step 11, in step 12, the seven implanted wafers 2 are
is collected into the original cassette 22A, the two wafers 2 are collected into the original cassette throat 22B, and the uninjected wafers 2
9 sheets are supplied from the stocker 26B to the disk 4. In step 13, ions are implanted and the gate valve 46A is closed. In step 14, the wafer 2 is loaded and unloaded in the same manner as described above, and
By injecting nitrogen gas etc. into the cassette chamber 40A, the cassette chamber 4
Bring the OA to atmospheric pressure (vent). In step 15, ions are implanted and the cassette door 44A is opened, and in step 16, the cassette 22A is replaced.

That is, the cassette 22A in which the implanted wafers 2 were collected
22A containing uninjected wafers 2 is attached. After that, the same operation as above is repeated. Then, in step 27, the stocker 26
The remaining three wafers 2 are supplied from A to the disk 4, and six dummy wafers 2d are supplied from the stocker 26A to cover the shortage. The wafer 2 and dummy wafer 2d at this time are
In step 29, the original cassette 22A and the original stocker 26A are recovered. That is, in this example, the third
The method of supplying dummy wafers shown in Figure (b) is adopted.

As mentioned above, in this wafer handling method,
Since the handling is performed in a vacuum, the processing capacity is further improved compared to the handling method explained in FIGS. 1 and 2, in which the disk 4 is moved in and out between the vacuum and the atmosphere. Of course, it goes without saying that the effects (1) to (4) described in FIGS. 1 and 2 can also be obtained. Further, although there is a conventional handling method using an end station in which the loader cassette and the unloader cassette are housed separately in two cassette chambers, the wafer handling method of the present invention differs from that conventional example. In comparison, the number of cassette chambers can be halved, and therefore the vacuuming of the cassette chambers can also be halved, and the throughput can be improved accordingly.

Finally, in the examples shown in FIGS. 1 and 2 and the examples shown in FIGS. 4 to 6, the end station has a disk 4, has two stages, and uses a dummy wafer 2d. However, the present invention is not limited thereto, and the above-mentioned effects (1) and (2) can be obtained by the handling method (first invention) using a cassette and a stocker, and further, by using the disk 4 and the dummy wafer 2d. The handling method (second invention) provides the effects (1) to (2) described above, and the handling method (third invention) having multiple stages also provides the effects (1) to (4) described above.

〔Effect of the invention〕

As described above, in the first invention, a cassette and a stocker are used, and the wafers after processing are collected into the original cassette. Therefore, there is no need for the conventional process of exchanging wafers between cassettes, and the associated effort can be saved, and processing capacity can be improved. In addition, there is no need to replace both the rogue side cassette and the unloader side cassette as in the past, but only one cassette needs to be replaced, so the frequency and effort of replacing cassettes is halved compared to conventional methods. It is possible to improve processing capacity.

In the second invention, in addition to the first invention, since dummy wafers can be automatically supplied to the disk, in addition to the effect of the first invention, when there is a shortage of wafers to be supplied to the disk, manual labor is required. Another advantage is that dummy wafers can be quickly supplied without any problems.

In the third invention, in addition to the second invention, a plurality of pairs of cassettes and stockers are used, and it is possible to eliminate interruptions in ion implantation due to wafer breakage during handling. In addition to this effect, there is also the effect that the processing capacity can be further improved.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of an end station for explaining an example of the wafer handling method according to the present invention. FIG. 2 is a schematic cross-sectional view taken along the line ■--■ in FIG. 1. FIG. 3 is a diagram for explaining how to supply a wafer or dummy wafer to a disk. Figure 4 shows
FIG. 7 is a schematic plan view of another end station for explaining another example of the wafer handling method according to the present invention. FIG. 5 is a schematic cross-sectional view taken along line V-V in FIG. 4. FIG. 6 is a diagram for explaining the wafer handling operation at the end station shown in FIGS. 4 and 5. FIG. FIG. 7 is a schematic plan view of an end station for explaining an example of a conventional wafer handling method. FIG. 8 is a schematic plan view of another end station for explaining another example of the conventional wafer handling method.

Claims (4)

[Claims] (1) A wafer handling method when processing wafers, using a cassette in which a plurality of unprocessed wafers are stored in advance, and a stocker capable of storing more wafers than the number of wafers stored in the cassette, A wafer characterized in that all the wafers stored in the cassette are first transferred to a stocker to empty the cassette, then the wafers are carried out from the stocker for processing, and the processed wafers are returned to the original cassette. Handling method. (2) When collecting wafers after processing into the original cassette,
The wafer handling method according to claim 1, wherein the wafers are collected in the same order as the wafers were stored in advance. (3) A wafer handling method in which a plurality of wafers are mounted on a disk and sequentially processed, the cassette containing a plurality of unprocessed wafers in advance;
Using a stocker in which a plurality of dummy wafers are stored in advance and can further store wafers greater than the number of wafers stored in the cassette, first, all the wafers stored in the cassette are transferred to the stocker and the cassette is emptied. ,
Next, the wafers are taken out from the stocker and supplied to the disk, and if there is a shortage of wafers to be supplied to the disk, dummy wafers are supplied to the disk by the insufficient number of wafers, and the processed wafers are returned to the original cassette, and the dummy wafers are is a wafer handling method characterized by collecting the wafers in the original stocker. (4) A wafer handling method for loading a plurality of wafers onto a disk and sequentially processing them, comprising: a plurality of cassettes each containing a plurality of unprocessed wafers; Using a plurality of stockers that form a pair, store a plurality of dummy wafers in advance, and can store more wafers than can be stored in the pair of cassettes, the wafers are first stored in each cassette. All the wafers are transferred to the pair of stockers to empty each cassette, and then the wafers are taken out from one stocker and supplied to the disk. At this time, if there are insufficient wafers to be supplied to the disk, the wafers are depleted from the stocker. Either dummy wafers are supplied to the disk by the number of wafers, or wafers are supplied from another stocker to the disk by the insufficient number, and the processed wafers are collected into the original cassette, and the dummy wafers are collected into the original stocker. A wafer handling method characterized by: