JP2000003952A - Wafer holder for vertical cvd device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer holder suitable for an automatic transfer of a wafer. SOLUTION: A wafer holder 6 which holds a wafer when a CVD film is formed on the surface of the wafer 2 is equipped with a wafer holder main body 6a provided with a flat surface and pawls 7 provided along the periphery of the wafer 2 on the flat surface of the wafer holder main body 6a. The wafer 2 held by stepped parts 7a provided in the pawls 7 is levitated up from the flat surface of the wafer holder main body 6a so as to provide a gap between the wafer 2 and the flat surface of the wafer holder main body 6a for inserting a wafer transfer arm 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical CVD apparatus used for performing a wafer process such as forming a CVD film such as a low-temperature oxide film (LTO film) or a phosphorus-doped low-temperature oxide film on a wafer surface using a vertical CVD apparatus. The present invention relates to a wafer holder for a CVD apparatus.

[0002]

2. Description of the Related Art Conventionally, when a CVD film such as a polysilicon film or a nitride film is formed on the surface of a wafer,
This is carried out by loading the wafer 2 on a quartz wafer boat 5 and using an LTO film (forming temperature 3) using SiH ₄ and O _2.
00 to 400 ° C.), PSG film (LTO film doped with phosphorus), high-temperature oxide film using SiH ₄ and N ₂ O (HTO film, generation temperature 700 to 850 ° C.), phosphorus-doped polysilicon film, etc. In the production, a quartz wafer holder held by a boat is used.
As shown in the figure, the wafer 2 is placed on the wafer holder 16.
Are placed in close contact with each other to form a film.

[0003]

However, in the conventional wafer holder 16, since the back surface of the wafer 2 is in close contact with the wafer holder 16, the wafer 2
There is a problem that it is difficult to carry out automatic transfer when attaching or detaching the wafer holder 16 to or from the wafer holder 16. Also,
Since the wafer 2 can freely move on the wafer holder 16, there is a problem that the wafer may drop off when the wafer holder 16 moves.

The present invention has been made in view of the above problems, and has as its object to provide a wafer holder suitable for automatic transfer.

[0005]

In order to achieve the above object, a wafer holder of the present invention is provided on a flat surface of a wafer holder main body having a flat surface and along the outer periphery of a wafer to be held. And a plurality of claws capable of abutting the peripheral surface of the placed wafer, on which the wafer is placed, and the plurality of claws allow the held wafer to float from the flat surface of the wafer holder body. A gap is formed between the wafer and the flat surface of the wafer holder body so that the wafer transfer arm can be inserted.

[0006] Each of the claws is provided with a step, and the step has a substantially flat flat surface that comes into contact with the back surface of the wafer.
A movement restriction surface for restricting the lateral movement of the wafer, and the step portion can be directed to the center side of the wafer on which the wafer is mounted.

[0007]

The wafer transport arm for transporting an unprocessed wafer is lowered from above the wafer holder, and then brought into contact with the nail, and then further lowered to form a gap between the wafer and the flat surface of the wafer holder body. The wafer can be placed on the claws without the wafer transfer arm coming into contact with the wafer holder. In addition, for the processed wafer held on the wafer holder, the wafer transfer arm is inserted into the gap between the wafer and the flat surface of the wafer holder body and rises, so that the wafer transfer arm moves to the wafer holder. The wafer can be taken out of the wafer holder and transferred without contact.

Further, by restricting the movement of the wafer by the movement restricting surface, it is possible to prevent the held wafer from tilting or falling off when the wafer holder moves, and to stably hold the wafer.

[0009]

FIG. 1 is a perspective view showing one embodiment of the wafer holder of the present invention. In this embodiment, the wafer holder 6
Comprises a plurality of (four in this example) pawls 7 on the wafer holder main body 6a having a flat surface along the outer periphery of the wafer 2 to be held.
Is provided. Each claw 7 is formed with a stepped portion 7a above the wafer holder main body 6a and on which the wafer 2 is placed. The step portion 7a has a substantially flat flat surface 7b in contact with the back surface of the wafer 2, and a movement limiting surface 7c orthogonal to the flat surface 7b and capable of contacting the peripheral surface of the wafer 2. The step portion 7a composed of 7b and the movement limiting surface 7c faces the center of the wafer 2 to be placed. By lifting the wafer 2 from the flat surface of the wafer holder main body 6a by, for example, about 4 mm by the step portion 7a,
When attaching or detaching the wafer 2 to or from the wafer holder 6, the vacuum suction unit 4 of the wafer transfer arm 4 of the wafer transfer machine 3 is provided between the wafer 2 and the wafer holder body 6 a.
By inserting a, the wafer 2 can be moved by sucking the back surface of the wafer 2. Further, since the plurality of movement limiting surfaces 7c are arranged at intervals around the peripheral surface of the wafer 2, the movement of the wafer 2 on the wafer holder 6 in the lateral direction is limited by these movement limiting surfaces 7c. I have.

FIG. 2 is a perspective view showing an example of a wafer transfer mechanism of a vertical CVD apparatus. The wafer holder 6 is held on the vertical quartz wafer boat 5 at an angle of about 1.1 degrees, and the plurality of claws 7 support the wafer 2 from below, thereby preventing the wafer 2 from falling off. Also,
The wafer 2 can be prevented from moving when the wafer boat 5 is rotated or moved up and down.

A cassette 1 containing unprocessed wafers 2 is placed on a cassette elevator 8 and has a vacuum suction part 4a (FIG. 3) of a wafer transfer arm 4 having a telescopic unit of a wafer refilling machine 3 and a vertical mechanism. 2), the wafer 2 is sucked out of the cassette 1 and taken out. Next, the wafer transfer arm 4 of the wafer changer 3 rotates the taken-out wafer 2 by 90 degrees and transfers it to the wafer holder 6 held on the boat 5. When the wafer 2 comes above the wafer holder 6, the wafer transfer arm 4 descends to bring the wafer 2 into close contact with the step 7 a of the pawl 7 of the wafer holder 6. At the same time, the suction by the vacuum suction unit 4a is released, and the wafer 2 is placed on the step 7a.
The wafer transfer arm 4 is further lowered and then contracted, escapes from the gap between the wafer 2 and the wafer holder main body 6a, and prepares for transfer of the next wafer 2.

Since the thickness of the wafer transfer arm 4 is about 2 mm, if the gap between the wafer 2 and the wafer holder body 6a is about 4 mm as described above, the wafer 2
The wafer transfer arm 4 can sufficiently move up and down in the gap when the wafer is mounted on or detached from the wafer holder 6. When the boat 5 is moved up and down by the elevating mechanism 10 and a predetermined number of wafers 2 are transferred to the boat 5, the boat 5 on which the film-formed wafers are mounted and the unprocessed wafers are mounted by the boat transfer mechanism 9. The boat 5 on which the unprocessed wafers are placed is moved to the lifting mechanism 11.
Thus, a reaction gas is supplied from the gas inlet 13 into the reaction tube 12 from below, and a CVD film is formed on the wafer surface in the reaction tube 12.

When the film forming process is completed, the wafer 2 is transferred to the cassette 1 in the reverse procedure. The automatic transfer of the wafer 2 can be performed according to the above procedure.
Since the pawl 7 is provided on the wafer holder main body 6a, when an LTO film is generated using the wafer holder 6 under the generation conditions of Table 1 below, N
As shown in o.2, the film thickness at the peripheral portion of the wafer becomes thick, and the uniformity of the film thickness at the 5 mm peripheral portion exceeds ± 10%, and the uniformity of the entire film thickness becomes ± 4 to 8%. Table 2 below
As shown in No. 1, although the overall film thickness uniformity when using the conventional wafer holder 16 is worse than ± 2 to 3%, the wafer 2 is automatically transferred. Therefore, manufacturing costs can be reduced.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

As described above, according to the present invention,
On the flat surface of the wafer holder main body, a plurality of claws are provided along the outer periphery of the wafer to be held, and the claws lift the wafer from the flat surface of the wafer holder main body, and a wafer transfer arm is provided between the wafer and the wafer holder main body. Since a gap that can be inserted is formed, the wafer transfer arm can place the wafer on the nail without touching the wafer holder, and as a reverse operation,
Since the wafer mounted on the claw can be taken out and transferred without the wafer transfer arm entering the gap and the wafer transfer arm coming into contact with the wafer holder, automatic transfer of the wafer becomes possible.

Further, by restricting the lateral movement of the wafer by the movement restricting surface, it is possible to prevent the held wafer from tilting or falling off when the wafer holder moves, and to stably hold the wafer. Can be.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a perspective view and a sectional view taken along line IV-IV, respectively, showing an embodiment of a wafer holder of the present invention.

FIG. 2 is a perspective view showing an example of a wafer transfer mechanism of a vertical CVD apparatus.

FIG. 3 is a perspective view of a wafer transfer arm used in FIG. 2;

FIG. 4 is a side view showing a conventional wafer holder.

[Explanation of symbols]

 2 Wafer 4 Wafer transfer arm 6 Wafer holder 6a Wafer holder body 7 Second 7a Step 7b Flat surface 7c Movement restriction surface

Claims (2)

[Claims] 1. A wafer holder for a vertical CVD apparatus for holding a wafer when performing wafer processing, the wafer holder body having a flat surface, and the wafer holder body along the outer periphery of the wafer to be held. And a plurality of claws (7) provided on the flat surface of 6a), on which the wafer (2) is placed and which can contact the peripheral surface of the placed wafer (2). Nail (7)
Thereby, the held wafer (2) can be lifted from the flat surface of the wafer holder body (6a), and the wafer transfer arm (4) can be inserted between the wafer (2) and the flat surface of the wafer holder body (6a). A vertical wafer holder for a vertical CVD apparatus, wherein a vertical gap is formed. 2. A step (7a) is provided on each of the claws (7). The step (7a) has a substantially flat flat surface (7b) in contact with the back surface of the wafer (2) and a wafer (2). 2) a movement restricting surface (7c) for restricting the lateral movement of (2), wherein the step (7a) faces the center of the wafer (2) on which the step is placed. 3. The wafer holder for a vertical CVD apparatus according to claim 1, wherein