JPH05114645A - Wafer holding device - Google Patents

Abstract

PURPOSE:To protect a silicon wafer from plastic deformation at high temperature and prevent the generation of a non-conforming article by a method wherein a structure is provided to mount a silicon wafer on a silicon support board attached to support columns to be inserted in an electric furnace. CONSTITUTION:Four support columns 3, which are laid out vertically almost in parallel, are installed between a top board 1 and a bottom board 2, which are horizontally opposed to each other almost in parallel. A wafer support board 4 is mounted on the support columns 3 respectively on its peripheral edge. A recessed cut portion 5 is installed in the central part of the wafer support board 4 where a silicon wafer is loaded. The silicon wafer 6 is loaded on the surface of the wafer support board 4. A whole wafer holding device is inserted in an electric furnace under the condition described above. Therefore, load is concentrated only on the peripheral edge of the silicon wafer 6 so that no further action may be exerted. Even when the wafer is heat-treated at a temperature which exceeds 1300 deg.C, this construction makes it possible protect the silicon wafer 6 from deformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer holding device for holding a silicon wafer in a heat treatment process of the silicon wafer.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a wafer holding device is used for holding a plurality of silicon wafers and inserting the silicon wafers into the electric furnace in order to heat-treat the silicon wafers in the electric furnace. A conventional wafer holding device will be described below with reference to FIGS. 4 and 5.

A conventional wafer holding device is shown in FIG.
As shown in (b), four pillars 3 made of a SiC sintered body and arranged substantially parallel to each other are arranged in parallel and face each other. It is fixed to the lower plate 2. Each of the columns 3 is provided with a plurality of groove portions 7, and as shown in FIG. 4A, the silicon wafer 6 is formed in the groove portion 7 of each column 3 formed at the same height in the peripheral portion thereof. By fitting, one silicon wafer is held. In this manner, the number of silicon wafers 6 corresponding to the number of the groove portions 7 provided in each of the columns 3 is held, and in that state, the silicon wafers 6 are inserted into the vertical furnace for heat treatment, and the heat treatment of the silicon wafers is performed. ..

In such a wafer holding device, in a semiconductor manufacturing process, impurities such as boron, phosphorus, and arsenic are injected into a semiconductor, and then a heat treatment process for electrically activating the impurity or a silicon oxide film. It is used in a heat treatment step for baking the film after depositing the above.

In such a heat treatment process, after fixing a plurality of silicon wafers 6 in the groove portions 7 formed in the columns 3 at substantially equal intervals, the entire wafer holding device is placed in an electric furnace provided with a cartal heater or the like. And a heat treatment is performed at about 800 ° C. to 1200 ° C. according to each manufacturing process of the semiconductor device.

[0006]

However, according to the conventional wafer holding apparatus having the above-mentioned structure,
When a heat treatment at a high temperature of 00 ° C. or higher is attempted, the contact portion between the silicon wafer 6 and the wafer holding device is limited to the groove portion 7, and therefore, the peripheral portion of the silicon wafer 6 fitted in the groove portion 7 is very small. The region supports the load of the silicon wafer 6 itself. Therefore, the load is concentrated on a small area, so that the silicon wafer 6 is plastically deformed there, and the silicon wafer 6 remains deformed even after the heat treatment process is completed.

In order to solve the above conventional problems, it is an object of the present invention to provide a wafer holding device capable of preventing the plastic deformation of a silicon wafer even in a high temperature heat treatment step of 1300 ° C. or higher. And

[0008]

In order to solve the above problems, a wafer holding device of the present invention comprises a plurality of pillars arranged substantially in parallel, and a wafer holding support attached to the pillars for holding a wafer. And a board.

Further, in a preferred embodiment of the wafer holding apparatus of the present invention, the wafer holding support plate has a recessed recess.

[0010]

According to the wafer holding apparatus of the present invention, by placing the wafer on the wafer holding support plate attached to the support and inserting it into the electric furnace, the load is concentrated on a partial area of the wafer. Therefore, plastic deformation of the wafer during heat treatment is prevented.

Further, by providing the support plate for holding the wafer with a concave recess, it is possible to reduce the weight of the support plate for holding the wafer without impairing the effect of preventing plastic deformation of the wafer. It is possible to reduce the weight of the wafer holding device as a whole.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
A description will be given based on (b). The wafer holding apparatus of the present embodiment refers to 11 (a) and (b), and vertically extends substantially parallel to each other between an upper plate 1 and a lower plate 2 which are horizontally arranged so as to face each other in substantially parallel to each other. Are provided with four columns 3.
A plurality of wafer support plates 4 are horizontally arranged on the support column 3 with a space therebetween. The wafer support plate 4 is attached to each of the four columns 3 at the peripheral portion thereof. The wafer support plate 4 and the support column 3 are fixed to each other by fitting the outer periphery of the support column 3 at a position corresponding to the support column 3 on the outer periphery of the wafer support plate 4 at a notch 4a formed along the outer peripheral surface of the support column 3. It is fixed by joining. The support 3 of the wafer support plate 4
The attachment to is not limited to such a method, and for example, as shown in FIG.
The wafer support plate 4 may be fitted into the support column 3 by means similar to the conventional method of fitting the silicon wafer 6 and the support column 3 as described with reference to FIG.

At the center of the position where the silicon wafer 6 is placed on the wafer support plate 4, there is provided a concave portion 5 which is cut out in a concave shape.

In the wafer holding device having such a structure, the silicon wafer 6 is placed on the surface of the wafer supporting plate 4, and in that state, the entire wafer holding device is inserted into the electric furnace. Therefore, as in the case of the conventional example,
The load is not concentrated and acts only on the peripheral portion of the silicon wafer 6, and the contact area between the silicon wafer 6 and the wafer holding device is increased. Therefore, even when the heat treatment is performed at a high temperature of 1300 ° C. or higher, the conventional problem that the silicon wafer 6 is deformed by the plastic deformation is solved.

Further, the recess 5 provided in the wafer support plate 4
Is formed to the extent that the effect of preventing plastic deformation of the silicon wafer 6 is not impaired.
Thus, the weight of the wafer support plate 4 can be reduced. Therefore, the weight of the entire wafer holding device can be reduced.

Further, since the concave portion 5 is provided, it becomes easier to take out the silicon wafer 6 at this portion with tweezers or place the silicon wafer 6 on the wafer support plate 4 by sandwiching it with the tweezers. is there.

When the silicon wafer is heat-treated at 1300 ° C. or higher, which can effectively use the wafer holding apparatus of this embodiment, for example, oxygen ions are 2 × 10 ¹⁸ / cm 3.
Was injected at ² or so, and to form a buried oxide film in the semiconductor substrate by performing heat treatment SIMOX (S epar
ationby IM planted OX ygen)
There is a law.

In the SIMOX method, after injecting oxygen, the oxygen is diffused and rearranged to form a steep silicon / oxide film interface.
The heat treatment at 0 ° C. is performed for 1 to 8 hours.

The shape of the recess 5 of the wafer support plate 4 is
The shape is not limited to that shown in the present embodiment, and may have any shape as long as the silicon wafer 6 can be placed at high temperature without causing plastic deformation. Specifically, for example, as shown in FIG. 2, the concave portion 5 is formed so that the central portion of the wafer supporting plate 4 is opened in a donut shape and the mounted silicon wafer 6 is easily grasped by tweezers or the like. Slit 8
It is also possible to use b or the like. Further, as shown in FIG. 3, it is conceivable that the wafer supporting plate 4 is divided into two by providing a slit 8c in addition to the shape shown in FIG. Such a recess 5 of the wafer support plate 4 is provided in order to reduce the weight of the wafer support plate 4 and to easily grip the silicon wafer 6 with tweezers or the like. It goes without saying that the use of 4 also has the effect of preventing plastic deformation of the silicon wafer 6 due to high temperature.

The wafer holding device used in the heat treatment process of the silicon wafer usually uses a high melting point ceramic such as a SiC sintered body as its material. Such a high melting point ceramic tends to cause thermal stress due to the temperature distribution when it is inserted into an electric furnace and cause cracks. Therefore, by forming the recess 5 in the wafer holding plate 4 as described above, the wafer supporting plate 4 is easily elastically deformed, so that the thermal stress is absorbed and the stress is dispersed in one place without being concentrated. There is also the effect of doing.

In the above embodiment, the vertical wafer holding device for heat-treating the silicon wafer 6 in the so-called vertical electric furnace is described. With the structure for holding the wafer 6, it is possible to use it in a horizontal electric furnace with the same operation and effect.

[0022]

As described above, according to the present invention, since the silicon wafer 6 is placed on the wafer supporting plate attached to the supporting column and inserted into the electric furnace, the silicon wafer at high temperature can be obtained. 6 plastic deformation is prevented.
As a result, this apparatus can be used for heat treatment at 1300 ° C. or higher, and defective products due to plastic deformation of the silicon wafer 6 at high temperatures can be prevented.

Further, by forming the concave portion 5 cut into the wafer supporting plate 4 in a concave shape, the weight of the entire apparatus can be reduced, and the silicon wafer 6 can be easily inserted and taken out by sandwiching it with tweezers or the like. And workability is improved. Further, since the wafer support plate 4 itself is easily elastically deformed by having the recess 5, the wafer support plate 4
It is also possible to prevent plastic deformation of itself at high temperatures.

[Brief description of drawings]

FIG. 1A is a perspective view of a wafer holding device according to an embodiment of the present invention as viewed from the front upper side, and FIG. 1B is a sectional view taken along the line CC of FIG.

FIG. 2 is a sectional view showing the other embodiment of the present invention at the same position as in FIG. 1 (b).

FIG. 3 shows another embodiment of the present invention, FIG. 1 (b).
It is sectional drawing of the same position as.

FIG. 4A is a perspective view showing an example of a conventional wafer holding apparatus as seen from diagonally above the front, and FIG. 4B is a sectional view taken along the line AA of FIG.

5A is a partial cross-sectional view showing, in an enlarged manner, a fitting portion between a silicon wafer 6 and a column 3 in the conventional wafer holding device shown in FIG. 4, and FIG. 5B is a BB cross-section arrow thereof. It is a perspective view.

[Explanation of symbols]

 1 Upper Plate 2 Lower Plate 3 Supports 4 Wafer Pointing Plate 5 Recesses 6 Silicon Wafer

Claims (2)

[Claims] 1. A wafer holding device comprising a plurality of pillars arranged substantially parallel to each other, and a wafer holding support plate attached to the pillars for holding a silicon wafer. 2. The wafer holding apparatus according to claim 1, wherein the wafer holding support plate has a recessed recess.