JP2002134595A - Wafer support bracket for heat treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer support bracket which suppresses slipping of a wafer by suppressing deformation of the wafer support bracket in heat treatment. SOLUTION: A wafer support bracket 11 for heat treatment comprises at least one concentric protruding flat support part 21 on its upper surface, with a recessed part 31 radially formed into which a transportation chuck 51 for placing a wafer is inserted. Otherwise, a wafer support bracket 12 for thermal process comprises at least one concentric protruding flat support 21 on its upper surface, and a notch part 32 which is cut radially, with a plate-like reinforcing structure 33 formed vertical to the plate surface at the end part of the notch part 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment technique for a semiconductor wafer, and more particularly to a silicon wafer or SIMOX.
(Separation by IMplanted
OXygen) The present invention relates to a wafer support suitable for high-temperature heat treatment at the time of wafer production or the like.

[0002]

2. Description of the Related Art With the recent increase in diameter of silicon wafers, vertical heat treatment furnaces have been used for heat treatment of silicon wafers. A vertical boat is installed inside this vertical heat treatment furnace, and a plurality of columns are provided in the vertical boat almost in parallel, and wafers are mounted in support grooves provided at equal intervals on the inner side surface of the column. Then, heat treatment is performed.

However, in a high-temperature heat treatment such as when producing a SIMOX wafer, in such a supporting method, since the load of the wafer is concentrated near the supporting portion, the stress generated near the supporting portion increases at the heat treatment temperature. If the yield stress exceeds the silicon wafer, there is a problem that a defect called slip dislocation occurs in the wafer during the heat treatment.

In order to avoid this problem, conventionally, FIG.
0, the support grooves 3 of the plurality of columns 2 of the boat 1
A method has been used in which a wafer support plate 13 is placed on a substrate, and a wafer is placed thereon to perform a heat treatment to increase the support area and suppress the occurrence of slip. Such a wafer support plate is formed of a high melting point ceramic such as SiC.

Further, the support plate has a notch 34 in a concave shape.
, It is possible to apply an automatic wafer transfer device using vacuum tweezers, and high productivity is achieved by high-speed loading and unloading of wafers.

However, even with the above technique, the suppression of the occurrence of slip is insufficient. This is because, due to the increase in the contact area, the wafer support plate made of SiC and the silicon wafer which are usually used may be welded during the heat treatment, and the shape of the support plate is set with respect to the center thereof. Because the support plate is not symmetrical and the support plate itself is not symmetrically supported by the columns, the support plate may be deformed during the heat treatment. It will happen.

[0007] In order to avoid this, conventionally, there has been proposed a support which supports three points by mounting three silicon balls on a wafer support plate having no notch (Japanese Patent Laid-Open No. 2000-91).
No. 406). However, in the heat treatment in an oxidizing atmosphere used in SIMOX annealing, the silicon spheres are not sufficiently prevented from slipping because they are welded to the silicon wafer, and there is no notch in the wafer support plate. The size of the automatic wafer transfer device has increased,
In addition, the space required for the transfer operation expands above and below the wafer support plate, so that the number of wafers processed by the heat treatment furnace per batch decreases, and the productivity decreases.

On the other hand, there has been proposed a method of preventing occurrence of slip without using a wafer support plate. For example, JP
This is a method in which four support portions are provided on a boat as described in Japanese Patent Application Laid-Open No. 1-40659. In this case, since there are four support portions, it is apparent that the stress generated by the weight of the silicon wafer at one support portion is smaller than that at the case where the support portions are supported by three support portions having similar shapes. . However,
Since the height difference of the support portion needs to be 30 μm or less,
There is a problem that it is extremely difficult and expensive to manufacture a boat having this dimensional accuracy.

As described above, heat treatment of a semiconductor wafer, particularly, a silicon wafer or SIMOX (Separatio)
Slip generation has not been sufficiently suppressed by a high-temperature heat treatment at the time of producing an n by IMplanted Oxygen wafer or the like without using productivity and using an inexpensive support tool.

[0010]

The prevention of slip generated by heat treatment is an important technical problem that must be solved from the viewpoint of improving the production yield, and in order to realize it, the following requirements must be satisfied. There is a need for a support method and a support that enables it.

That is, industrially feasible and
It is an inexpensive support, the support does not weld during the heat treatment with the silicon wafer, and even if the support is welded during the heat treatment with the silicon wafer, the support deforms little during the heat treatment and does not lead to slip. thing,
High productivity can be maintained even when the support is used,
Must be satisfied.

An object of the present invention is to provide a wafer support which has solved the above-mentioned problems.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted a heat treatment of a semiconductor wafer, particularly a silicon wafer or SIMOX.
Intensive studies have been made on wafer supports suitable for high-temperature heat treatment such as when manufacturing wafers.
And it is an inexpensive support tool, and found the structure of the support tool that can prevent the occurrence of slip while ensuring high productivity.
The present invention has been completed.

As a result of investigating the relationship between the structure of the wafer support and the slip generated during the heat treatment, the welding of the wafer support and the wafer during the heat treatment occurs at a larger number of contact portions as the contact area between the two increases. Even in the case of welding, it has been found that the less the deformation of the support during the heat treatment, the less the occurrence of slip, and the occurrence of slip can be prevented by suppressing the deformation of the support during the heat treatment.

The present invention has been made based on these findings, and is configured as follows.

(1) A plate-like support for supporting a wafer, comprising: a convex support portion having a flat upper surface concentrically on the upper surface of the support; and a transport chuck for mounting the wafer. A concave portion formed in a radial direction so as to be able to move up and down.

(2) A plate-like support for supporting a wafer, a convex support having a flat upper surface concentrically on the upper surface of the support, and a notch cut out in a radial direction of the support. And a reinforcing structure provided in the notch in a direction perpendicular to the wafer mounting surface.

(3) The support is further characterized by further having concentric reinforcing ribs.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wafer support for heat treatment according to the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment> In a first embodiment, as shown in FIG. 1 and FIG.
1, a concentrically provided convex support portion 21 having a flat upper surface, and a concave portion having a size (depth) in which the automatic transport chuck can move up and down in the radial direction of the support member 11. 31. The support 11 is provided with a reinforcing rib 22 for suppressing deformation during heat treatment. In this embodiment, two reinforcing ribs 22 are provided concentrically.

Although the number of the convex support portions 21 is one in the present embodiment, two or three convex support portions may be provided concentrically.

The transfer of the wafer to the support 11 is performed as follows.

First, as shown in FIG. 3, the wafer 41 is fixed to the chuck 51 for automatic transfer by a method such as vacuum suction, and is moved directly above the support 11. At this time, FIG.
As shown in (a), the wafer 41 and the automatic transfer chuck 51 have a gap required for transfer with respect to the support 11.

Next, the chuck 51 for automatic transfer, which has attracted the wafer 41, descends, and as shown in FIG.
Touch the top surface.

Next, the automatic transfer chuck 51 releases the suction of the wafer 41, and as shown in FIG. 4C, further lowers, thereby mounting the wafer 41 on the support 11.

Next, as shown in FIG. 5, the automatic transfer chuck 51 is pulled out of the support 11, and the operation proceeds to the next transfer operation.

Such an automatic transfer operation is a method which is also employed in direct support of a wafer by a boat which is a conventional technique. According to this method, the distance between the supports can be made smaller than in the method described in Japanese Patent Application Laid-Open No. 2000-91406, in which the conveyance is performed by a combination of a lifting pin and an automatic conveyance chuck. Therefore, the transport mechanism is simple, and the transport device can be downsized.

FIGS. 8 and 9 show a conventional support plate 13 and a conventional support member 14. FIG. Comparing the conventional support plate 13 and the support tool 14 with the support tool 11 according to the present invention, the support tool 11 replaces the notch 34 or 35 provided in the conventional support plate 13 and support tool 14. In addition, it has a structure in which it is connected by the recess 31 capable of automatic conveyance as described above.

The conventional support plate 13 and support 14 are provided with notches 34 or 35, however, the presence of these notches 34 or 35 causes a large amount of deformation during the heat treatment, and the wafer and the support As a result, the stress applied to the wafer increases.

On the other hand, in the case of the support 11 according to the present invention,
A recess 3 having a structure in which a portion corresponding to the notch 34 or 35 is connected by a recess capable of being automatically transported;
1, the amount of deformation of the support 11 during the heat treatment is small, and even if welding occurs between the support 11 and the wafer, the generated stress can be suppressed to be small, and therefore, the occurrence of slip can be prevented. can do.

The above-mentioned deformation amount can be suppressed by a combination of a ring-shaped support and a method of carrying by a combination of an elevating pin and an automatic carrying chuck. However, a combination of an elevating pin and an automatic carrying chuck is also possible. This is the next best method as long as the upper and lower gaps required for the transport method are large.

<Second Embodiment> In the support according to the second embodiment, as shown in FIGS. 6 and 7, a substantially circular support 12 is provided concentrically with a flat upper surface. It has a convex support portion 21, a notch portion 32 in which the chuck for automatic conveyance can move up and down, and a plate-like reinforcing structure 33 for suppressing deformation during heat treatment. The reinforcing structure 33 is a plate-shaped member formed in a direction perpendicular to the wafer mounting surface.

In the present embodiment, the number of the convex support portions 21 is one, but a plurality of, such as two or three, may be provided concentrically.

The support 12 is further provided with a reinforcing rib 22 for suppressing deformation during heat treatment.
Also in the present embodiment, two reinforcing ribs 22 are provided concentrically.

In the case of the support 12 in the present embodiment,
Since the deformation during the heat treatment is suppressed by the plate-like reinforcing structure 33, the occurrence of slip can be prevented as in the first embodiment described above. Even if the amount of deformation of the support 11 during the heat treatment is small and welding occurs between the support 11 and the wafer, the generated stress can be suppressed to a small value.
The occurrence of slip can be prevented.

The semiconductor wafer to be mounted on the wafer support according to the present invention is not limited to a particular type, but in recent years a silicon wafer having a large diameter and a remarkable increase in its own weight or a SIMOX which requires high-temperature heat treatment after oxygen ion implantation is essential. It can be particularly suitably used as a wafer support for heat treatment of a wafer or the like.

[0037]

The present invention will be specifically described below with reference to examples.

Using the supports 11 and 12 according to the above-described first and second embodiments and the conventional support plates 13 and 14, an experiment was conducted to confirm the effects of the present invention.

The supports 11 and 12 and the support plates 13 and 14 all have an outer diameter of 9 inches (225.4 m).
m), made of SiC having a thickness of 1 mm.

The width of the concave portion 31 of the support 11 in which the automatic transfer chuck can move up and down, and the width of the notch 32 of the support 12 were 50 mm. The support plate 1
The width of the following portions of the support 3 and the support 34 was also 50 mm.

The convex support portions 21 of the supports 11 and 12 have a radius of 70 to 70 mm of an 8-inch (200 mm) wafer.
75%, the inner reinforcing ribs 22 have the same radius of 50 to 53
%, The outer reinforcing ribs 22 have the same radius of 99 to 101%.
, Respectively. The convex support portion 21 has a width of 5 mm and a height of 4 mm, and the upper portion has a flat convex shape.
mm and a depth of 3 mm.

In the experiment, the above-mentioned support members 11 and 12 and support plate 1 were used.
3, and an 8-inch (200 mm) silicon wafer were placed on the support 14 and heat-treated at 1350 ° C. and 100% oxygen for 24 hours. Table 1 shows the results of investigating the occurrence of slip using an X-ray topograph.

[0043]

[Table 1]

As shown in Table 1, as a result of the experiment, no slip was observed in the supports 11 and 12 according to the present invention, whereas the slip was observed in the support plates 13 and 14 of the conventional structure. Occurred. From these results, it is understood that the support of the present invention can prevent the occurrence of the slip of the wafer in the high-temperature heat treatment.

[0045]

As described above, according to the present invention,
Heat treatment of semiconductor wafers, especially silicon wafers and SI
A wafer support suitable for high-temperature heat treatment such as when manufacturing MOX wafers. It is an industrially feasible and inexpensive support that can prevent slippage while maintaining high productivity. Can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a wafer support according to a first embodiment of the present invention.

FIG. 2 is a plan view and a cross-sectional view taken along line AA ′ of the wafer support according to the first embodiment.

FIG. 3 is a process chart showing a procedure for placing a wafer on a wafer support in the first embodiment.

FIG. 4 is a process chart showing a procedure for placing a wafer on a wafer support in the first embodiment.

FIG. 5 is a process chart showing a procedure for placing a wafer on a wafer support in the first embodiment.

FIG. 6 is a perspective view of a wafer support according to a second embodiment of the present invention.

FIG. 7 is a plan view and a cross-sectional view taken along line AA ′ of a wafer support according to a second embodiment of the present invention.

FIG. 8 is a perspective view of a conventional wafer support plate.

FIG. 9 is a perspective view of a conventional wafer support.

FIG. 10 is a perspective view of a vertical boat on which a wafer support is mounted.

DESCRIPTION OF SYMBOLS 1 boat 2 boat support 3 support groove 11, 12, 14 wafer support 13 wafer support plate 21 convex support portion 22 reinforcing rib 31 concave portion 32, 34 for vertical movement of automatic transfer chuck 35 Notch for vertical movement of automatic transfer chuck 33 Plate-shaped reinforcing structure 41 Silicon wafer 51 Automatic transfer chuck

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Keisuke Kawamura 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Atsuki Matsumura 20-1 Shintomi, Futtsu-shi, Chiba New Japan F-term (Reference) 5F031 CA02 HA64 MA28 5F045 BB13 EM08 EM09 EN04

Claims (3)

[Claims] 1. A plate-like support for supporting a wafer, comprising: a convex support portion having a flat upper surface concentrically on an upper surface of the support; And a recess formed in a radial direction so as to be movable. 2. A plate-like supporter for supporting a wafer, comprising: a convex support portion having a flat upper surface concentrically formed on an upper surface of the supporter; and a notch portion cutout in a radial direction of the supporter. And a reinforcing structure provided in the notch in a direction perpendicular to the wafer mounting surface. 3. The wafer support according to claim 1, wherein the support further includes concentric reinforcing ribs.