JPH11204448A - Manufacturing apparatus of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To circumvent constraints of sequential control of a wafer transfer machine over a boat by setting a cover on each wafer on the boat. SOLUTION: A boat 9 horizontally holds a plurality of wafers 3 at established longitudinal intervals. Shielding plates 23 which shields particles from dropping on the wafers 3 by covering the upside of each wafer 3 are placed between the wafers 3. The shielding plates 23 may be fixed or removably attached to the boat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly, to a semiconductor manufacturing apparatus in which a plurality of wafers are loaded on a boat, loaded into a reaction tube, and heat-treated in the reaction tube in a batch system.

[0002]

2. Description of the Related Art A conventional semiconductor manufacturing apparatus, for example, a vertical diffusion / CVD apparatus will be described with reference to FIG. The wafers 3 placed in a plurality of stages from the cassette 2 in the cassette storage shelf 1 are held by the tweezers 4 of the wafer transfer machine 5 that moves up and down by an elevator (not shown) and transferred to the quartz boat 9. A boat 9 lifted by a boat elevator (not shown) is carried into a quartz reaction tube 10, the wafer 3 is heated by a heater 11, a reaction gas or an inert gas is introduced from a gas inlet 12, and gas is exhausted. Exhaust from the mouth 13.

When the heat treatment of the wafer 3, for example, the impurity diffusion treatment, the annealing treatment, the thermal oxidation treatment, the chemical vapor deposition reaction, etc., is completed, the inside of the reaction tube 10 is replaced with an inert gas atmosphere, and the boat 9 is lowered by the boat elevator. Reaction tube 10
When the temperature of the wafers 3 placed on the boat 9 becomes lower than a predetermined temperature, the wafers 3 placed on a plurality of stages are transferred from the boat 9 to the cassettes in the cassette storage shelf 1 by the wafer transfer machine 5. Transfer to 2.

FIGS. 2A and 2B show a boat 9 carried in and out of the reaction tube, wherein FIG. 2A is a side view, FIG. 2B is a side view when a wafer is transferred, and FIG. 2C is a partially enlarged view of FIG. FIG. Quartz boat 9
Has a plurality of columns 14 standing between the upper plate 21 and the lower plate 22.
A number of slits 15 for inserting the wafer 3 are cut. A large number of wafers 3 are transferred to these slits 15 and can be batch-transferred into a reaction tube (not shown). As a material of the boat 9, quartz or the like is used as a material having no problem in film formation in the reaction tube.

[0005] A predetermined number of side dummy wafers are transferred to the upper and lower ends of the boat 9 in order to secure a uniform heat length, or monitor wafers are sandwiched one by one at required portions of process wafers. Is being done.

In the boat configuration described above, since there is no cover for protecting each wafer 3, when the wafer 3 is transferred to the boat 9, contact between the boat 9 or the slit 15 and the wafer 3 to be transferred is made. As a result, dust or particles (hereinafter simply referred to as particles) may fall onto the lower wafer 3. When the particles fall on the wafer 3, a film formation failure occurs, and the yield of the product is reduced accordingly.

Therefore, as a measure for preventing particles from falling, the wafer 3 is loaded from above the boat 9 at the time of loading.
At the time of taking out, the wafer 3 is taken out from under the boat 9. If the wafers 3 are sequentially loaded from above to below at the time of loading, the wafers 3 have not yet been transferred below the loaded wafers 3, so that there is no problem if the particles fall. On the other hand, boat 9
When the wafers are sequentially taken out from below, there is no wafer below the wafer 3 to be taken out, so that there is no problem even if particles fall. This prevents the particles from falling onto the lower wafer both when the wafer 3 is loaded and unloaded.

[0008]

However, in the above-mentioned prior art, a sequence control in which a wafer is loaded from above when a boat is loaded and removed from a bottom when a boat is loaded must be incorporated in the wafer transfer machine. This has been a constraint on the sequence control of the wafer transfer machine.

If the wafer transfer machine lifted by the elevator falls while the wafers 3 are being loaded into the boat 9 due to a power failure or the like, the tweezers of the wafer transfer machine move to the position. There was a possibility of damaging the wafer. In particular, unless a method of loading the boat from the top to the bottom at the time of loading is adopted, all the wafers below the position will be damaged.

An object of the present invention is to solve the above-mentioned problems of the prior art by covering each wafer on a boat, to eliminate the restriction on the sequence control of the wafer transfer machine, and to transfer the wafer. An object of the present invention is to provide a semiconductor manufacturing apparatus capable of avoiding breakage of a wafer even when a machine falls.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a semiconductor manufacturing apparatus provided with a boat for holding a plurality of wafers horizontally at predetermined intervals in a vertical direction, wherein each wafer is held between the wafers to be held by the boat. A shielding plate is provided to cover the upper part of the wafer and block particles falling from above.

Even if the particles fall from above when transferring the wafer to the boat, the particles are blocked by the shielding plate provided between the wafers, so that the particles do not drop onto the wafer.

Further, since a shielding plate is provided between the wafers,
Even if the wafer transfer machine lifted by the elevator falls while the wafers are being loaded into the boat and falls due to a power outage, etc., only the tweezers of the wafer transfer machine will be damaged or the shielding plate will be damaged. Therefore, the wafer below the position is not damaged.

[0014]

Embodiments of the present invention will be described below. FIG. 1 shows vertical diffusion / CVD as a semiconductor manufacturing apparatus
1 shows a quartz boat 9 provided in the apparatus. (a) is a plan view, (b) is a bottom view, (c) is a side view, and (d) is a partially enlarged view of (c).

The quartz boat 9 includes a circular lower plate 22 and four pillars 14 vertically set at, for example, 60 ° intervals along a half circumference of the wafer to be held horizontally on the lower plate 22. And a circular upper plate 21 mounted in parallel with the lower plate 22 on these columns 14.

On the opposite side of each column 14, the processing wafer 3 to be held in parallel with the upper plate 21 and the lower plate 22 is provided.
A large number of slits 15 for inserting the shielding plate 23 are cut at equal pitches along the length direction of the pillar 14 and at a depth reaching the center line of the pillar 14. The pitch may be the same as the wafer holding pitch of the wafer cassette, but may be different depending on the type of film or film formation conditions.

In the slit 15 of the boat 9, FIG.
As shown in (d), every other shielding plate 23 in the shape of a wafer is inserted. The shielding plate 23 is inserted into the slits 15 between the slits 15 in which the process wafers 3 are inserted every other in order to cover the upper part of each wafer 3 and block particles falling from above. Note that there is no difference in shape between the slit 15 into which the processing wafer 3 is inserted and the slit 15 into which the shielding plate 23 is inserted.

The shielding plate 23 is made of, for example, quartz made of the same material as the boat 9. The shielding plate 23 may be configured to be welded to the column 14, or may be configured to be detachable. The welding is performed by, for example, laser welding. The attachment / detachment may be performed by a wafer transfer machine similarly to the transfer of the process wafer 3, or may be performed manually.

Now, a case where a thin film of, for example, polysilicon is formed by using the boat 9 provided with the above-mentioned shield plate 23 so as to be welded or detachable will be described. The process wafer 3 and the monitor wafer are transferred between the shield plates 23 of the boat 9. If the shield plates 23 are detachable, every other shield plate 23 is transferred to the slit 15 of the boat 9 in advance.

One or a plurality of wafers are taken out from a cassette storage shelf (not shown) by a wafer transfer machine (not shown) and transferred to the slit 15 of the boat 9 between the shielding plates 23. At this time, the boat 9 may be thrown in from above, may be thrown in from below, or may be thrown in from the middle. The reason is that even if heavy particles fall from above, the particles are blocked by the shielding plate 23 provided between the wafers, so that the particles do not fall on the wafer.

In this way, the boat 9 is carried into a quartz reaction tube (not shown), heated and a reaction gas is introduced. A process wafer and a monitor wafer are heated, and a polysilicon film is formed thereon. At this time, a film is similarly formed on the shielding plate 23. Since the shielding plate 23 has substantially the same shape as the wafer and is set every other, the same heat retaining effect and gas rectifying effect as those of the side dummy wafer can be obtained during the film formation. When the wafer heating process is completed, the boat 9 is unloaded from the reaction tube, and the processing wafer is transferred from the boat 9 to a cassette in a cassette storage shelf by a wafer transfer machine. At this time, the boat 9 may be taken out from above, below, or from the middle, and may be taken out from any position on the boat. The reason is that even if the particles fall from above, the particles are blocked by the shielding plate 23 provided between the wafers, so that the particles do not fall on the wafer. This polysilicon thin film formation was repeated for several batches.

In the case of a side dummy wafer made of silicon, when a thin film is repeatedly formed in several batches, it is necessary to replace the polysilicon film deposited on the side dummy wafer with a new side dummy wafer when the polysilicon film reaches a specified value or more. . However, in the present embodiment, a quartz shielding plate 23 in the shape of a wafer is used, and cleaning can be performed in the same manner as the quartz reaction tube and boat 9, so that there is no need to insert or replace the shielding plate 23.

That is, in the same manner as when cleaning the polysilicon film deposited on the inner wall of the quartz reaction tube, the boat surface and the shielding plate 2 are kept while the shielding plate 23 is provided on the boat 9.
The polysilicon film deposited on 3 may be cleaned. At this time, since the shielding plate 23 is made of quartz instead of silicon, damage due to gas cleaning can be minimized. By removing the reaction products attached to the shield plate 23 by cleaning, the shield plate 23 is removed.
Can be reused without having to insert and replace them.

As described above, the shield plate 23 may be welded to the boat 9 or may be detachable. In the case of welding, the shielding plate 23 can be handled integrally with the boat 9, so that the handling is convenient. However, this is inconvenient when the shield plate 23 needs to be replaced. For example, a process wafer is placed in each slit 15 of the boat 9 for processing convenience.
It may be transferred more than every other. If such a request is required, it is preferable that the shielding plate 23 is not welded but is detachable from the boat 9 so that different transfer sheets / transfer positions can be set. Thus, the wafer pitch on the boat 9 and the pitch of the shield plate 23 can be set freely while maintaining the shielding effect, and it is possible to cope with film types that are restricted by the pitch.

As described above, according to the present embodiment, the shielding plate is provided between the wafers so that the particles generated at the time of transferring the wafer are prevented from dropping on the lower wafer, so that the film formation failure caused by the particles is drastically reduced. be able to.
In addition, since the particles are prevented from dropping onto the wafer, there is no restriction on sequence control during wafer transfer, such as loading from the top when loading and removing from the bottom when removing, so the control program has a high degree of freedom and Uniformity is obtained and its creation becomes easy.

In the above embodiment, a quartz plate is used as a shielding plate so that there is no problem in film formation, but the present invention is not limited to this. Other than the quartz plate, a wafer covered with a silicon oxide film (SiO ₂ ), or AlN, Si
A C plate or the like may be used.

Further, when the wafer transfer device falls, the shield plate receives the tweezers instead of the wafer, so that the expensive wafer can be protected. When the material and the thickness of the shield plate and the tweezer are made the same, the stress generated in the tweezer is calculated to be about 13 times larger, so that the tweezer is more damaged. Even if the material is different, for example, even if the shielding plate is made of quartz and the tweezer is made of alumina having a strength about 10 times that of quartz, the tweezers are stressed 13 times larger, so the tweezers are more damaged. . Therefore,
Damage to the wafer, as well as damage to the shielding plate, cannot occur.
If the safety aspect is further taken into consideration, the shielding plate may be made thicker than the tweezers. That is, it is possible to reliably protect the wafer by giving strength to the shielding plate.

Further, in the above embodiment, the case where the film attached in the reaction tube is applied to the polysilicon film has been described, but the present invention is not limited to this. The present invention can be applied to an amorphous silicon film, a silicon nitride film, a tungsten film, a tungsten silicide film, and the like.

[0029]

According to the present invention, when a wafer is transferred to a boat, it is possible to prevent particles from dropping onto the wafer by providing a shielding plate. As a result, the product yield is improved. Since the wafer is protected by the shielding plate, it is possible to effectively prevent the wafer from being damaged by a failure of the wafer transfer device or the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wafer boat provided with a shielding plate according to an embodiment.

FIG. 2 is a configuration diagram of a wafer boat according to a conventional example.

FIG. 3 is a configuration diagram of a vertical diffusion / CVD apparatus.

[Explanation of symbols]

 3 Wafer 9 Boat 23 Shield plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukinori Yutani 3-14-20 Higashinakano, Nakano-ku, Tokyo Kokusai Electric Co., Ltd. (72) Inventor Satoshi Taniyama 3-14-20 Higashinakano, Nakano-ku, Tokyo Kokusai Electric (72) Inventor Kazuhiro Nakagome 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Co., Ltd.

Claims (1)

[Claims] 1. A semiconductor manufacturing apparatus provided with a boat for holding a plurality of wafers horizontally at predetermined intervals in a vertical direction, wherein said boat covers an upper part of each wafer and blocks particles falling from above. A semiconductor manufacturing apparatus comprising a shielding plate.