JPH11243064A - Wafer supporting plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the slip generated in a wafer, by forming the thickness of an approximately ring-shaped plate body thicker in the vicinity of a wafer inserting groove, and forming the thickness thinner as separated from a wafer groove. SOLUTION: In a wafer supporting plate 1, the side of an output/input port of a wafer supporting boat 2 is made to be a thin part 4a having the thin thickness, and the part other than the thin part 4a is made to be a thick part 4b having the thick width. Then, the water supporting plate 1 directs the thin film part 4a to the output/input port 7a and mounts the part 4a into each wafer inserting groove 7 of the wafer supporting boat 2. Furthermore, the wafer is also mounted on an upper surface 5 of the wafer supporting plate 1. The wafer supporting plate 1 is inserted into a vertical heat treating furnace, and the neat treatment of a water 8 is performed. Therefore, stress is applied on the X point of the terminal part of a supporting strut 3, wherein the water inserting groove 7 is formed, and the X' point of the end part of the thin part separated from the end part or this supporting strut 3. The shape of deflection becomes the smooth arc-shaped surface having the large radius of curvature. The water can be supported on the smooth upper surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer for heat treatment of a silicon wafer used for various semiconductor devices.
Related to a support plate.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional wafer support plate of this type. 2 (a) and 2 (b) are schematic structural views of a wafer support boat on which a conventional wafer support plate is mounted, and FIG. 2 (c) is mounted on the wafer support boat. It is a top view of the wafer support boat which shows a state.

This wafer support plate is used by being mounted on a wafer support boat accommodated in a heat treatment furnace (not shown). The wafer support boat is classified into a vertical type and a horizontal type according to the structure of the heat treatment furnace. This way
Of the support boats, the wafer on which the wafer is placed and held
A conventional wafer support plate will be described using a vertical wafer support boat having a configuration in which vertical insertion grooves are formed in multiple stages in the vertical direction.

The conventional wafer support plate shown in each of the drawings has a flat upper surface 5 for supporting the back surface of the wafer 8 by surface contact.
And a transfer machine for transporting the wafer 8 (not shown)
A flat C-shaped plate having a notch serving as a wafer carry-in port 10 through which the transfer pen passes passes and having a uniform thickness. This wafer support plate widens the space between some of the columns 3 in a wafer insertion groove 7 formed in the column 3 of the wafer support boat 2 shown in FIG. It is inserted and attached from the side of the entrance 7a formed. This conventional way
When the wafer 8 has a large diameter, the wafer support plate is mounted in the wafer insertion groove 7 of the wafer support boat 2 in order to reduce the influence of its own weight on the wafer 8. The supporting area for supporting the back surface of C8 is widened. The wafer supporting board 2 on which the wafer supporting plate 1 is mounted has a wafer 8
Is supported, the occurrence of crystal defects called slip (dislocation) in the wafer 8 can be prevented as compared with the case where the wafer 8 is directly inserted into the wafer insertion groove 7 and supported. The slip generated on the wafer 8 is
It easily occurs due to the combined stress of its own weight stress and the thermal stress generated by the temperature difference in the wafer surface during the heat treatment process, and also increases the leak current of the device and deteriorates the oxide film breakdown voltage. It is necessary to hold down. The upper surface 5 of the wafer support plate 1 is processed into a flat surface having a good flatness in order to more effectively disperse the weight of the wafer and suppress occurrence of slip.

[0005]

Since the conventional wafer support plate is constructed as described above, the front portion of the wafer support plate 1 which is on the side of the entrance 7a of the wafer support boat 2 is provided. Is not supported by the support 3, so that FIG.
As shown in (1), when the thickness of the wafer support plate 1 is uniformly thin, the front portion of the wafer support plate 1 is bent downward by its own weight. As shown in FIG. 3B, the radius of curvature of the deflection is greatest at the point X near the column 3 and the slip 14 occurs at the point X. When the thickness of the wafer support plate is set so as not to bend under its own weight as shown in FIG. 4A, the front portion of the wafer support plate 1 does not bend, but FIG. As shown in FIG. 4 (c), the wafer 8 which bends by its own weight is bent so as to enter the wafer entrance 10 of the wafer support plate 1, so that the wafer entrance 10 as shown in FIG. There is a problem that a slip 14 occurs at a nearby Y point.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a wafer support plate capable of suppressing a slip generated on a wafer, suppressing the occurrence rate of defective products, and improving the quality of the wafer. It is intended to provide.

[0007]

SUMMARY OF THE INVENTION A wafer support plate according to the present invention is formed of a substantially ring-shaped plate, and has a column formed with a wafer insertion groove for holding a wafer at a predetermined interval. A wafer support plate mounted in a wafer insertion groove of a wafer support boat having the wafer mounted thereon; and a wafer mounted on a substantially ring-shaped plate mounted in the wafer insertion groove. In the above, the thickness of the substantially ring-shaped plate body is formed thicker in the vicinity of the wafer insertion groove, and thinner as the distance from the wafer insertion groove increases. As described above, in the present invention, the thickness is reduced as the distance from the wafer insertion groove is reduced. Therefore, when the portion of the wafer support plate separated from the wafer insertion groove is bent by its own weight, the bent portion is formed. The curved shape of the upper surface becomes a smooth arc-shaped curved shape having a large curved surface radius, the wafer can be supported by the smooth curved surface, and the slip generated near the wafer insertion groove can be prevented. Also, since the wafer support plate that is separated from the wafer insertion groove bends, the wafer is supported by being curved in a smooth arc on the upper surface of the wafer support plate.
A tension acts on the central portion of the wafer, and the tension prevents the central portion of the wafer from entering the central opening of the wafer support plate.
The slip can be prevented from occurring at the peripheral edge of the central opening of the support plate. For this reason, the occurrence of slip can be suppressed by preventing stress concentration from being applied to a special portion of the wafer, and the occurrence rate of defective wafers can be reduced and the quality can be improved.

The wafer support plate according to the present invention may be a substantially C-shaped plate formed by cutting out a part of the substantially ring-shaped plate if necessary. -Formed as a carry-in entrance, formed thick at the wafer insertion side,
The wafer is formed thin at the wafer loading port. As described above, in the present invention, the wafer is separated from the wafer insertion groove by mounting the wafer support plate on the column so that the wafer carry-in port is located at a position away from the wafer insertion groove. The portion of the wafer support plate on the carry-in side bends into a smooth arcuate curved state having a large radius of curvature in the same manner as described above, so that the wafer can be supported on a smooth curved surface, and slip generated near the column is prevented. can do. In addition, since the wafer is supported in a gently curved shape in the same manner as described above, tension is also applied to the wafer portion on the wafer entrance side, and the wafer portion does not enter the wafer entrance. In addition, it is possible to prevent the slip occurring at the periphery of the wafer loading port.

The wafer support plate according to the present invention is made of a material selected from the group consisting of SiO ₂ , SiC, and Si, or a mixture containing at least one of these materials, an impregnating material, or a laminated material as required. As described above, in the present invention, since the wafer support plate is made of a material having a small deformation even at a high temperature, the thin portion of the wafer support plate is curved with a gentle radius of curvature. Has a smooth curved surface, thereby preventing the wafer from slipping.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment of the Present Invention) Hereinafter, a wafer support plate according to a first embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b). Description will be made with reference to (a) and (b). FIG. 1A is a right side view of the wafer support plate of the present embodiment, and FIG. 1B is a diagram showing a bent state when a heat treatment is performed on the wafer.

As shown in FIG. 1 (a), the wafer support plate according to the present embodiment has a thin portion having a small thickness at the inlet / outlet 7a side of the wafer support boat 2, as shown in FIG. 4a
And a portion other than the thin portion 4a is a thick portion 4b having a large thickness. Next, an operation state in which the wafer support plate according to the present embodiment based on the above configuration supports the wafer 8 will be described. First, the wafer support plate 1 is mounted in each wafer insertion groove 7 of the wafer support boat 2 in the same manner as in the prior art, with the thin portion 4a facing the entrance 7a (FIG. 2 (b)). reference). The wafer 8 is also placed on the upper surface 5 of the wafer support plate 1 as in the prior art. After that,
C. Insert the support plate 1 into a vertical heat treatment furnace (not shown) set at 700 ⁰ C, raise the temperature in the furnace to 1200 ⁰ C, hold this state for 1 hour, then lower the temperature to 700 ⁰ C Then, the heat treatment of the wafer 8 was performed.

As a result, the thin portion 4a of the wafer support plate 1 which is not supported by the column 3 on the side of the entrance 7a is bent downward by its own weight. As shown in FIG. 1B, the bending is at the X point located at the end of the column 3 where the wafer insertion groove 7 is formed and at the end of the thin portion 3 separated from the end of the column 3. The stress is applied to the point X ′, which causes the deflection. Since the stress is dispersed at the two points X and X 'in this manner, the shape of the bending is a smooth arc-shaped curved surface having an extremely large radius of curvature, and the wafer can be supported by the smooth upper surface.

As a result, the wafer 8 is supported in a gently curved shape without stress concentrated at one point near the wafer insertion groove 7 and is generated at one point near the wafer insertion groove 7. The slip 14 can be prevented. Further, tension acts on the central portion of the wafer 8 which is supported in a gently curved shape, and the central portion of the wafer 8 does not enter the central opening of the wafer support plate 1 due to this tension. The slip 14 generated at the periphery of the central opening of the wafer support plate can also be prevented. For this reason, stress concentration is prevented from being applied to a special portion of the wafer 8, and the occurrence of the slip 14 can be reduced.
And the quality of defective products can be reduced.

The diameter of the wafer support plate 1 depends on the wafer to be supported.
It depends on the size of c8. Also, the wafer support plate 1
Are formed in a plane C shape having a wafer entrance 10 as shown in the present embodiment, and a wafer entrance 1
Either one formed in a plane O shape without zero is used. Further, the inner peripheral edge of the upper surface 5 of the wafer support plate 1 is configured to have an edge as shown in the present embodiment or to be configured to bevel in an arc shape.

An example of specifying specific numerical values in the embodiment will be described below. The thickness of the wafer support plate 1 is preferably 2.5 mm to 4.0 mm,
The thickness of the thin portion 4a is preferably in the range of 1/3 to 4/5 of the thick portion 4b. The reason for this range is that the lower limit of the thick portion 4b is that if it is thinner than this, bending occurs and the strength for supporting the wafer 8 cannot be sufficiently obtained. The reason for this is that the strength of the change does not change much. On the other hand, if the lower limit of the thin portion 4a is further reduced, the wafer support plate 1 is largely bent at the boundary between the thick portion 4b and the thin portion 4a, causing stress concentration on the wafer 8, and the upper limit is set to this value. This is because if the thickness is larger than the above, it will not bend, and stress concentration will occur on the wafer at the periphery of the central opening of the wafer support plate 1 as in the case of the conventional thick and uniform wall thickness.

(Second Embodiment of the Present Invention) Hereinafter, a wafer support plate according to a second embodiment of the present invention will be described with reference to FIG.
A description will be given based on (c) and (d) with reference to FIGS. FIG. 1 (c) is a right side view of the wafer support plate of the present embodiment, and FIG. 1 (d) is a view showing a warped state when the wafer is subjected to a heat treatment.

As shown in FIG. 1 (c), the wafer support plate according to the present embodiment in each of the above-described drawings is arranged so that the wafer support plate extends from the vicinity of the column 3 where the wafer insertion groove 7 is formed. To 2
The thin portion 4a gradually becomes thinner as it moves away from the inlet / outlet 7a side, and a thick portion 4b other than the thin portion 4a becomes a thick portion 4b.

Next, a description will be given of an operation state in which the wafer support plate according to the present embodiment having the above-described configuration supports the wafer 8. First, the wafer support plate 1 has a thin portion 4a.
Is mounted in the wafer insertion groove 7 of the wafer support boat 2 in the same manner as in the prior art toward the access port 7a (FIG. 2 (b)).
reference). The wafer 8 is also placed on the upper surface 5 of the wafer support plate 1 as in the prior art. Thereafter, the heat treatment of the wafer 8 is performed in the same manner as in the first embodiment.

As a result, the thin portion 4a of the wafer support plate on the side of the slot 7a which is not supported by the column 3 bends downward by its own weight, but the thickness of the thin portion 4a is reduced by the wafer insertion groove 7.
The thickness of the thin portion 4a gradually decreases as the distance from the wafer insertion groove 7 to the inlet / outlet 7a side decreases, and the bending of the thin portion 4a is shown in FIG. As shown, stress is applied to the point X located at the end of the column 3 where the wafer insertion groove 7 is formed and the point X 'located at the end of the thin portion 3 separated from the end of the column 3 and flexed. Will occur. Since the stress is dispersed at the two points X and X 'in this manner, the shape of the bending is a smooth arc-shaped curved surface having a very large radius of curvature including the point X, and the wafer 8 is made smooth. It can be supported on the upper surface 5. As a result, the wafer 8 is supported in a gently curved shape in which stress is further prevented from concentrating at one point near the wafer insertion groove 7, as in the first embodiment. The slip 14 generated at one point near the wafer insertion groove 7 can be further prevented. Further, a tension acts on a central portion of the wafer 8 which is supported in a gently curved shape as in the first embodiment, and the wafer 8 is supported by the tension.
Of the wafer support plate 1 does not enter the central opening of the wafer support plate 1, and the slip 14 generated at the periphery of the central opening of the wafer support plate 1 can also be prevented. Therefore, similarly to the first embodiment, it is possible to prevent stress from being concentrated on a special portion of the wafer 8 and to reduce the occurrence of the slip 14.
And the quality of defective products can be reduced.

In the first and second embodiments, the material of the wafer support plate 1 is silicon (Si), but instead of silicon, silicon carbide (SiC) is used.
As described above, the occurrence of the slip 14 could be prevented even when using the. Also, as described above, a wafer support plate made of silicon carbide impregnated with silicon or a wafer support plate made of silicon carbide and coated with quartz (SiO ₂ ) on the upper surface, as described above. 14
Can be prevented.

[0021]

As described above, according to the present invention, the way
Since the thickness is formed thinner as the wafer is separated from the insertion groove, when the portion of the wafer support plate separated from the wafer insertion groove is bent by its own weight, the curved shape of the upper surface of the bent portion becomes:
It has a smooth arcuate curve shape with a large curved surface radius, so that the wafer can be supported by a smooth curved surface, and there is an effect that slip generated near the wafer insertion groove can be prevented. Also, since the wafer support plate that is separated from the wafer insertion groove bends, the wafer is supported by being curved in a smooth arc on the upper surface of the wafer support plate. A tension is applied to the center of c, and this tension
The central portion of the wafer does not enter the central opening of the wafer support plate, and the slip can be prevented from occurring at the periphery of the central opening of the wafer support plate. For this reason,
It is possible to prevent stress from being applied to a special portion of the wafer to suppress the occurrence of slip, and to reduce the occurrence rate of defective wafers and improve the quality. Further, in the present invention, the wafer is separated from the wafer insertion groove by mounting the wafer support plate on the support so that the wafer carry-in port is located at a position away from the wafer insertion groove. The portion of the wafer support plate on the carry-in side bends into a smooth arcuate curved state having a large radius of curvature in the same manner as described above, so that the wafer can be supported on a smooth curved surface, and slip generated near the column is prevented. It has the effect that it can be done. In addition, since the wafer is supported in a gently curved shape in the same manner as described above, tension is also applied to the wafer portion on the wafer entrance side, and the wafer portion does not enter the wafer entrance. ,
This has the effect of preventing slippage occurring at the periphery of the wafer loading port. In the present invention, the way
Since the support plate is made of a material that is small in deformation even at high temperatures,
The thin portion of the wafer support plate is curved with a gentle radius of curvature, and the upper surface of the wafer support plate has a smooth curved surface, which has the effect of preventing the occurrence of wafer slip. .

[Brief description of the drawings]

FIG. 1A is a right side view of a wafer support plate according to a first embodiment of the present invention. (B) is the way of (a).
It is a figure which shows the bending state at the time of performing the heat processing of the wafer in a c support plate. (C) is a right side view of the wafer support plate according to the second embodiment of the present invention. (D) is a view showing a warped state of the wafer support plate of (c) when the wafer is subjected to a heat treatment.

FIG. 2A is a schematic configuration diagram of a wafer support boat to which a conventional wafer support plate is mounted. (B) is a way
It is a figure which shows the state which attached the conventional wafer support plate to the wafer support boat. (C) is a plan view of the wafer support boat showing a state of being mounted on the wafer support boat.

FIG. 3 (a) shows a wafer in a conventional wafer support plate.
It is a c support plate and is a figure which shows the bending state at the time of performing the heat processing of a wafer. (B) is a diagram showing the position of a slip generated on a wafer that has been heat-treated with the wafer support plate of (a).

FIG. 4 (a) shows a wafer in a conventional wafer support plate.
It is a c support plate and is a figure which shows the bending state at the time of performing the heat processing of a wafer. (B) is a front view showing a position of a slip generated on a wafer which has been heat-treated with the wafer support plate of (a). (C) is a plan view of (b) showing a slip position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer support plate 2 Wafer support boat 3 Support 4a Thin part 4b Thick part 5 Top surface 7 Wafer insertion groove 7a Slot 8 Wafer 10 Wafer carrying entrance 10a Notch

Claims (3)

[Claims] 1. A wafer support groove having a support formed of a substantially ring-shaped plate body and having a wafer insertion groove for holding the wafer at a predetermined interval. A wafer support plate on which a wafer is mounted on a substantially ring-shaped plate to be mounted in the wafer insertion groove, wherein the thickness of the substantially ring-shaped plate is the wafer; A wafer support plate formed to be thicker in the vicinity of the wafer insertion groove and to be thinner as the distance from the wafer insertion groove increases. 2. The wafer supporting plate according to claim 1, wherein the substantially ring-shaped plate is formed by cutting a part of the substantially ring-shaped plate.
A cut-out portion is formed as a wafer carry-in port, the wafer is formed to be thick at the wafer insertion side and thin at the wafer carry-in port. C support plate 3. The wafer support plate according to claim 1, wherein the material is any one of SiO ₂ , SiC, and Si, or a mixture containing at least one of the materials, an impregnating material, or a laminated material. Wafer support plate