JPH08298246A - Wafer boat - Google Patents

Abstract

PURPOSE: To obtain a wafer boat which is simpler in structure, lower in manufacturing cost, and used in a vertical thermal treatment furnace, wherein wafers can be stably supported without causing stress to them. CONSTITUTION: A wafer 8 is inserted into a wafer boat through an outlet/inlet 6 and placed on a seat 5a, wherein a U-shaped support member 5 provided with the seats 5a which are mounted on a support pole 4 as tilted downwards from the outlet/inlet 6 by an angle of θ with a horizontal plane is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer boat used in a vertical heat treatment furnace, and more particularly to a vertical wafer boat for storing a plurality of wafers in a vertical direction.

[0002]

2. Description of the Related Art Conventionally, a wafer boat of this type has a support rod vertically arranged so as to surround a wafer to be inserted with a rectangular groove slightly wider than the thickness of the wafer.
At this groove, the edge of the wafer and the periphery of the back surface of the wafer were in surface contact with each other to support the wafer.

However, the coefficient of thermal expansion of a silicon wafer is larger than that of a quartz support rod, and the edges of the wafer are locally subjected to thermal stress due to the grooves of a plurality of support rods for supporting the wafer, causing crystal defects such as slips. It has the drawback of occurring.

A wafer boat that solves this problem is disclosed in Japanese Patent Laid-Open No. 1022523/1992. This wafer boat holds the wafer by partially or circularly making line contact with the backside of the wafer, reducing the contact with the wafer, reducing the thermal stress on the wafer surface, and suppressing the occurrence of slippage. I was trying.

[0005]

In the conventional wafer boat described above, although the thermal stress applied to the wafer by the line contact can be reduced, the wafer support is unstable and the wafer boat is rotated. The problem often occurred that the wafer slipped from the wafer entrance / exit of the boat. Further, the wafer supporting portions protruding from the supporting rods are independently derived from the respective supporting rods, and can be deformed by the thermal cycle received in the furnace to maintain the line contact portion of the wafer supporting portion in the same plane. It becomes difficult and the problem of the wafer slipping down occurs more and more.

Further, independently deriving the wafer supporting portion from each supporting rod complicates the structure and requires a large number of man-hours even if it is manufactured, which is very expensive. .

Therefore, an object of the present invention is to provide a wafer boat which can stably support a wafer without giving stress to the wafer and which has a simpler structure and is inexpensive.

[0008]

A feature of the present invention is that a plurality of supports that surround the outer peripheral portion of a wafer, which is a semiconductor substrate, other than the entrance / exit portion of the wafer, are vertically arranged side by side. There is a bar member and a seat surface that extends from the inside of these support bar members toward the center of the wafer by a predetermined length and mounts the peripheral portion of the wafer, and this seat surface extends from the entrance to the back. It is a wafer boat provided with the support member which inclines so that it may descend.

[0009]

Next, the present invention will be described with reference to the drawings.

1 (a) to 1 (c) are views (a) showing a state of being housed in a heat treatment furnace showing an embodiment of a wafer boat of the present invention, an enlarged view of part A (b), and from above. It is the figure seen (c). As shown in FIGS. 1B and 1C, the wafer board 1 housed in the heat treatment furnace 9 of FIG. 1A has an outer periphery of the wafer 8 other than a portion of the entrance / exit 6 into which the wafer 8 is inserted or withdrawn. A plurality of support rods 4 surrounding the portions and arranged vertically side by side, and a seat surface on which the peripheral portion of the wafer 8 is mounted, which extends from the inside of these support rods 4 toward the center of the wafer by a predetermined length L. And a horseshoe-shaped support member 5 having a seat surface 5a that is inclined by θ degrees from the entrance / exit 6 side toward the back.

Here, the inclination θ of the seat surface 5a supporting the wafer 8 is preferably in the range of 3 degrees to 5 degrees. The horseshoe-shaped support member 5 is made of quartz, which is the same material as the support rod 4, and the seating surface has a smooth surface so that the surface is heated to high heat to be in a reflow state, and the surface is the same as the free surface. It is desirable to finish it.

If the seating surface is made a smooth surface and the accuracy of the flatness is improved in this way, the contact area with the back surface of the wafer 8 becomes large, the load due to its own weight is dispersed, and the stress applied to the wafer 8 becomes small, so Also smoothed, wafer 8
The wafer 8 is not scratched at the time of loading and unloading.

Further, since the wafer 8 is not placed in a groove-like structure that fits around the wafer 8 as in the prior art, but is simply put on the wafer 8, thermal stress is not applied to the wafer 8 due to thermal history. Furthermore, this seat surface 5a
Is inclined downward from the entrance / exit 6 of the wafer 8 so that the wafer boat 1 is rotated to rotate the wafer 8
The wafer 8 does not slide down from the entrance / exit 6 even when processing the above.

On the other hand, in manufacturing the horseshoe-shaped support member, since it is an integral simple plate member, the seating surface 5a of the horseshoe-shaped support member 5 is manufactured with a high degree of flatness, and then the support rod 4 is manufactured. You can attach it to. The horseshoe-shaped support member 5 is thick and can be attached without disturbing the flatness of the seat surface 5a. On the other hand, as in the conventional case, it is possible to easily attach the line contact portions of the individual wafer support portions at the same predetermined position of each support rod in the same plane with high precision.

Further, the horseshoe-shaped support member 5 has a large plate thickness and is not deformed even if it is subjected to many heat cycles.

[0016]

As described above, according to the present invention, there is provided an integrated thick horseshoe-shaped support member for mounting a seat surface on which a wafer is inserted and placed so as to incline so as to descend from the entrance of the wafer toward the back. By providing it, it is supported in a wide area, the load due to its own weight is dispersed, the stress is reduced, and the stress that causes scratches and slips on the wafer is not given.

Further, since the horseshoe-shaped support member is an integrated plate material having a plate thickness, the structure is simple, and it can be easily attached to the support rod without losing the flatness of the seating surface, and it is inexpensive and deformable. It has the effect that it will not occur.

[Brief description of drawings]

FIG. 1 is a diagram (a) showing a state of being housed in a heat treatment furnace showing an embodiment of a wafer boat of the present invention, a diagram (b) in which an A part is enlarged, and a diagram (c) seen from above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer boat 4 Support rod 5 Horseshoe-shaped support member 5a Seating surface 6 Inlet / outlet 8 Wafer 9 Heat treatment furnace

Claims (1)

[Claims] 1. A plurality of support rod members which are vertically arranged side by side around the outer peripheral portion of the wafer other than the entrance / exit portion into which the wafer, which is a semiconductor substrate, is inserted or pulled out, and the inside of these support rod members. A support member having a seating surface that extends toward the center of the wafer by a predetermined length and mounts the peripheral portion of the wafer, and the seating surface is inclined downward from the entrance to the back. A wafer boat comprising: