WO2000019502A1

WO2000019502A1 - Vertical furnace and wafer boat for vertical furnace

Info

Publication number: WO2000019502A1
Application number: PCT/JP1999/005258
Authority: WO
Inventors: Masaki Tsuruki; Takashi Machida; Toshimitsu Miyata
Original assignee: Hitachi, Ltd.; Hitachi Kokusai Electric Co., Ltd.
Priority date: 1998-09-28
Filing date: 1999-09-27
Publication date: 2000-04-06
Also published as: KR20010075412A; KR100424428B1

Abstract

In order to prevent a slip, as might otherwise occur at a heat treatment of a wafer, in a conventional wafer boat for a vertical furnace in which the wafer is supported at its circumferential edge by a facial contact of an arcuate wafer supporting member, in the face of the wafer supporting member on the wafer-supporting side groovelike notches are made at positions where notches make angles of 45 degrees at the center of the arc with respect to the wafer inserting direction in such a way that the supporting member is out of contact with the wafer.

Description

Description Vertical furnace and wafer boat for vertical furnace Technical field

The present invention relates to a wafer boat provided in a vertical furnace and a vertical heat treatment apparatus, and particularly to a vertical wafer port provided in a vertical diffusion furnace and a vertical vapor phase growth furnace. BACKGROUND ART-In the process of oxidizing and diffusing semiconductor wafers, a large number of semiconductor wafers are loaded on a wafer boat, and the wafer boat is carried into a diffusion furnace to perform a predetermined heat treatment. Vertical boats and horizontal boats are used depending on the type of diffusion furnace.

A conventional vertical boat has a structure in which a wafer boat is held at three or four points, a supporting portion for supporting a wafer protrudes in a rod shape from the boat, and a peripheral edge of the wafer and a back surface of the wafer are each a boat support. A boat is used in such a manner that it comes into surface contact with the support part (Japanese Patent Publication No. 1991-1991).

Further, a groove slightly thicker than the thickness of the wafer is formed in the boat support, and a wafer boat is used in which the peripheral edge of the wafer and the periphery of the rear surface of the wafer are supported in surface contact.

In recent years, the diameter of a wafer tends to increase. In particular, when the diameter of a wafer becomes 3 O cm (12 inches) or more, there is a problem that the wafer is bent by its own weight, and finally crystal defects such as slips are generated. In order to solve this problem, boats are used that support wafers closer to the center from the periphery of the wafer. (Japanese Unexamined Patent Publication No. H06-169010, Japanese Unexamined Patent Publication No. H09-139352).

Alternatively, a wafer port is used in which an arc-shaped or ring-shaped support member is provided on a boat support and the peripheral portion of the back surface of the wafer is brought into surface contact and supported (Japanese Patent Laid-Open No. Hei 6-260438). .

Disclosure of the invention In the conventional technology for supporting a wafer at points, even if the inside of the wafer is supported, the contact area is limited, so if the diameter of the wafer is large, the stress generated at the supporting position due to its own weight increases, and the yield increases due to an increase in the processing temperature. The stress decreases. As a result, the generated stress easily exceeds the yield stress and slip occurs.

In addition, it is necessary to provide a deep slit or a support bar in the support member to support the inside of the wafer, and there has been a problem that processing is troublesome and costly.

As described above, the conventional technique of supporting the peripheral portion of the wafer by surface contact with an arc-shaped or ring-shaped support member has been used. · However, even with this configuration, there is a problem that slip is inevitable even under conditions where the heat treatment temperature of the wafer exceeds 100 ° C.

On the upper surface of the arc-shaped or ring-shaped support member, a vertical type that comes into contact with the wafer and supports the wafer. The above object is achieved by providing a groove-shaped notch at a position on the upper surface of the support member forming an angle so that the support member does not contact the wafer.

The grounds for the above configuration will be described below. Even when the lower surface of the wafer and the circular or ring-shaped support member are supported in surface contact, the entire surface of the support member does not necessarily contact the lower surface of the wafer. Due to the deflection of the wafer and supporting member due to its own weight or temperature distribution, surface roughness, unevenness of the surface due to processing accuracy, etc., microscopically, a part of the supporting member contacts and supports the wafer, so uniform contact A larger stress is generated at the contact position than in the case of the above.

1] Position (center angle)

0-7. 5 7.5 to 15 15 to 22. 5 22: 5 to 30 30 to 37. 5 37. 5-45

1050 ° C 1 1 0 0 0 4

1 100 ° C 2 1 0 0 1 6

1200 "C 2 2 5 0 0 6 α Γ 5 5 5 0 1 16 Table 1 shows that using a ring-shaped support member, a wafer having a principal surface of {00 1} of about 3 O cm (12 inches) was inserted with the 1 110> direction aligned with the insertion direction. The graph shows the relationship between slip occurrence position and frequency when heat treatment is performed at 0 ° C, 110 ° C, and 1200 ° C. The slip occurrence position is represented by a central angle of 0 to 45 ° with respect to the wafer insertion direction assuming 1/8 mirror symmetry. From Table 1, it can be seen that the frequency of slip is higher near the central angle of 45 ° than at other positions regardless of the processing temperature. In other words, on a wafer whose main surface is {00 1} and whose insertion direction is the <1 1 0> direction, a position that forms an angle of 45 ° with the 方向 insertion direction, that is, 1 00>, 0 1 0 Slip tends to occur in four directions. Thus, by preventing the wafer and the support member from contacting in these four directions, it is possible to suppress the occurrence of slip.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view showing a vertical diffusion furnace (vapor phase growth furnace) according to one embodiment of the present invention.

FIG. 2 is an overall configuration diagram showing a vertical wafer boat according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line AA ′ of FIG. 1 showing a vertical wafer boat according to one embodiment of the present invention.

FIG. 4 is a plan view showing a support member of a vertical wafer boat for describing an embodiment of the present invention.

FIG. 5 is a side view showing the shape of the groove of the support member of the vertical wafer boat according to one embodiment of the present invention.

FIG. 6 is a plan view showing a support member for a vertical type hubboat according to another embodiment of the present invention.

FIG. 7 is a plan view showing a support member of a vertical wafer boat according to still another embodiment of the present invention.

FIG. 8 is a plan view showing a support member of a vertical boat boat according to still another embodiment of the present invention.

FIG. 9 shows a support member for a vertical wafer boat according to still another embodiment of the present invention. FIG.

FIG. 10 is a plan view showing a support member of a vertical wafer boat according to still another embodiment of the present invention.

FIG. 11 is a plan view showing a support member of a vertical wafer boat according to still another embodiment of the present invention.

FIG. 12 is a plan view showing a support member of a vertical wafer boat according to still another embodiment of the present invention.

FIG. 13 is a view showing the relationship between the central angle of the groove of the support member of the vertical wafer boat and the stress generated in the wafer according to still another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In FIG. 1, a reaction tube installed in a vertical resistance heating furnace 1 has a double structure composed of an outer tube 2 and an inner tube 3, and is held by a gantry 4. The reaction gas is supplied into the inner tube 3 and collected from the outer tube 2. The boat 5 is installed in the inner tube 3, and is inserted and withdrawn from a circular hole 6 provided in the center of the gantry 4. The boat 5 holds wafers 7 at arbitrary intervals in the vertical direction. The wafer 7 is taken in and out of the boat 5 from the boat 3 taken out of the in-tube 3 by the transfer device.

FIG. 2 is a view showing the entire configuration of the boat 5, and the boat 5 has a plurality of supports 8, a top plate 51, a bottom plate 52, and a cap 53.

FIG. 3 is a cross-sectional view of the boat 5, and is a cross-sectional view taken along line AA ′ in FIG. 1 viewed from a vertical direction. A boat 5 for holding a wafer 7 substantially horizontally therein has a plurality of columns 8 and a plurality of support members 9. The plurality of columns 8 are provided so as to rise substantially vertically around the periphery of the wafer 7 held inside the boat 5. Since the wafer 7 is inserted into the boat 5 in the horizontal direction, the interval between the columns 8 is increased at the insertion portion to secure the insertion space. The support member 9 has an arc shape or a ring shape, and is provided integrally with the column 8 or removably mounted in a groove provided in the column 8. The support member 9 supports the wafer 7 concentrically. That is, in the supported state, the center of the wafer 7 is substantially aligned with the center of the arc or ring of the support member 9 I do. It should be noted that the insertion direction of the arm 7 is installed so as to pass through the center of the support member 9.

FIG. 4 shows an example of the support member 9 of this embodiment. The support member 9 has a ring shape, and four grooves 10 are provided on the upper surface of the indicating member 9 in a direction at an angle of 45 ° to the wafer insertion direction at the center of the ring of the support member 9. As a result, the lower surface of the {0 0 1} wafer 7 does not come into contact with the supporting portion 9 in the directions <100>, <110>, <100> and <110>. .

The groove 10 is a groove having a short sectional shape.

The groove 10 may be of any shape as long as it has a depth force S that can prevent the lower surface of the wedge 7 from contacting the upper surface of the support member 9 and may be a concave depression or a hole. FIG. 5 is a side view showing an example of the groove 10. In addition, Fig. 5 (a) (with a curvature of the groove having a short cross-sectional shape having a curvature), Fig. 5 (b) (with a chamfer of the corner of a groove with a short cross-section), and Figs. Fig. 5 (c) (groove with a cross-sectional shape of a wedge), Fig. 5 (d) (groove with a trapezoidal cross-section), Fig. 5 (e) (curvature at the corner of a groove with a wedge-shaped or trapezoidal cross-section) The same effect can be obtained.

At the end of the groove or notch, the wafer 7 and the support member 9 make point or line contact or a surface contact close to it, so that there is a groove, the wedge is at the end of the notch, and a large stress is generated at the contact of 7 May be. Therefore, it is desirable to provide a curvature at the end or the ridge of the groove or the notch because it has an effect of increasing the contact area with the wafer at the end of the groove or the notch and reducing the stress.

Grooves or cuts have the effect of suppressing the occurrence of slip as a result of the support member coming into contact with the swell, resulting in improper stress. Of course, in the region of the groove or cut, the support member It cannot support the wafer. For this reason, the wafer is bent by its own weight in the area, and stress is generated. The larger the circumferential width of the groove or the notch, the greater the generated stress. Therefore, the circumferential width of the groove or the notch must be appropriately large.

Figure 13 shows a ring-shaped support member with a groove at a position at 45 ° to the insertion direction of a wafer whose main surface is {001} of 30 cm (12 inches) size by FEM analysis. The center with the groove width when supported by (The groove width when viewed as an arc The results of analyzing the circumferential stress generated at the center of the groove of the wafer with the center angle of the groove as a parameter are shown. The stress was expressed as a ratio of the central angle of the groove to 0 °, that is, the stress with no groove.

Thus, the central angle of the groove or cut should preferably be less than 12 ° which does not exceed 110 ° of the stress generated when the amount of generated stress does not have a groove ^: If possible, the increase in stress will be 1 1 6 ° or less, which can be suppressed to 00 or less, is particularly desirable. In this example, the central angle was set to about 4 °.

FIG. 6 shows another example of the support member 9. The support member 9 of the present embodiment has an arc shape with an open front part in the wafer insertion direction so that the transfer device for the wafer 7 can be inserted. Non-uniform wafer support and stress, but with the right width, will not cause any slip.

FIG. 7 shows still another example of the support member 9 in which a notch 11 is provided in place of the groove 10. With this structure, the thickness of the support member can be made smaller than that provided with the groove 10, and as a result, a wafer boat that can load many wafers at the same boat height can be realized. In this structure, high stress is generated in the narrow part of the notch, but reliability can be secured by appropriate structural design and material selection.

FIG. 8 shows still another example of the support member 9.ゥ To provide a space on the back side in the c-insertion direction so that the c-transfer device can be inserted to the back of the c-cha, it is convex on the outer periphery. Alternatively, the curvature may be increased.

Also, as shown in Fig. 9, even if grooves 10 are not provided in all four directions, the provision of some grooves reduces the probability of occurrence of slip, and reduces the number of slips generated on one wafer. Is also effective in improving device yield.

FIG. 10 also shows still another example of the support member 9. If the plate thickness is too thin, the rigidity is lost, the wafer cannot be supported, the stress due to contact increases, and slip occurs. However, as the plate thickness increases, the pitch between the grooves for attaching and detaching the support members provided on the columns increases, and the number of wafers that can be loaded on the boat 5 at one time decreases. In addition, the increase in plate thickness increases the weight, which increases the load on the boat support and increases the overall size of the equipment, leading to an increase in cost. In the embodiment of FIG. 10, the support member 9 has an L-shaped cross section. Inserted into the groove for attaching and detaching the support member W

7

By making the thickness of the part thinner and increasing the thickness of the other parts, the pitch of the groove for attaching and detaching the support member is not increased, the weight is also suppressed, and the rigidity of the support member 9 is secured. it can. As a method of reducing the weight without reducing the rigidity of the support member 9, it is also effective to provide reinforcing ribs in the circumferential direction and the radial direction on the back surface of the support member instead of increasing the plate thickness.

FIG. 11 shows still another example of the support member 9. The support member 9 has an arc shape in front of the wafer insertion direction and an angle between the wafer insertion direction and the center of the arc opening at least in the range of 45 ° to + 45 °, and has the lowest yield stress of the wafer. The position can be prevented from contacting the support member, and the wafer transfer device can be inserted.

FIG. 12 shows still another example, in which a support member 9 is formed integrally with a support column 8.

ADVANTAGE OF THE INVENTION According to this invention, the diameter of a wafer is increased and the stress generation by contact with a supporting member when the processing temperature rises can be suppressed, and the contact part of a wafer and a boat at the time of the heat treatment in a vertical diffusion furnace and a vertical vapor phase growth furnace. Can prevent the occurrence of slippage. As a result, the influence of the slip on the device characteristics is eliminated, and a remarkable effect on the device yield can be obtained.

Claims

The scope of the claims

1. a heating furnace,

A reaction tube disposed in a heating furnace;-means for supplying a reaction gas into the reaction tube;

Arrangement means for arranging a wafer in the reaction tube,

A vertical furnace for heating the wafer in a state where the wafer is {001} as a main surface and has a crystal orientation of 100>, <010>, <100> and <0-10> without being in contact with the placement means.

2. The vertical furnace according to claim 1, wherein the reaction tube has a double structure including an outer tube and an inner tube, and the heater is disposed in the inner tube.

3. Heat treatment of wafers in which the crystal orientation of the wafer with {001} as the main surface is not supported by <100>, <010>, <100> and <0-10> Method.

4. A wafer whose main surface is {001} and whose desired crystallographic orientation is other than <100>, <010>, <100>, and <0-10>, and then heat-treated the wafer. Heat treatment method.

5. A plurality of columns arranged in the vertical direction, and a wafer supporting member arranged at a predetermined interval in the vertical direction of the columns, and supporting the wafer by surface contact with the peripheral portion of the wafer. In the vertical furnace wafer boat provided with a supporting member, the surface of the supporting member on the side supporting the wafer has an angle of 45 ° between the wafer insertion direction and the arc or the center of the ring. A vertical furnace wafer boat, wherein a groove-shaped notch is provided at a position so that the support member does not contact the wafer.

6. The wafer boat for a vertical furnace according to claim 5, wherein the support member is not provided in a region in a range of + 45 ° to -45 ° with respect to a wafer insertion direction.

7. The vertical furnace wafer boat according to claim 5, wherein an end of the groove-shaped notch is bent. A wafer boat for a vertical furnace characterized by providing a rate.

8. A plurality of columns arranged in a vertical direction, and a wafer support member arranged at predetermined intervals in the vertical direction of the columns, and supporting the wafer by surface contact with a peripheral portion of the wafer. In a vertical furnace wafer boat provided with a supporting member configured as described above, the wafer having {001} as a main surface has a crystal orientation, <100>, <—100>, <010>, < A wafer boat for a vertical furnace, wherein a groove-shaped notch is provided in the support member so as not to contact the support member in the direction of 0-10>.