JPH0239549A - Semiconductor-water supporting method - Google Patents

Abstract

PURPOSE:To prevent bending and distortion of a wafer or occurrence of crystal defect and cracking by suspending and supporting the wafers so that the surfaces of the semiconductor wafers are kept at the vertical state. CONSTITUTION:A hole 3 is formed in each silicon single crystal wafer 1. A supporting rod 2 made of quartz is inserted in the hole 3. The silicon single crystal wafers 1 are suspended and supported with the supporting rod 2. In this way, a plurality of the silicon single crystal wafers 1 are suspended from the supporting rod 2 at a constant interval. Both ends of the supporting rod 2 are supported with supporting jigs 6. Then, the wafers are inserted in a silica tube 4. The inside of the silica tube 4 is filled with suitable gas atmosphere and heated. The silicon single crystal wafers 1 undergo heat treatment. The diameter of the hole 3 is formed so that it is slightly larger than the supporting rod 2. Even if the supporting rod 2 is slightly inclined, the surface of each silicon single crystal wafer 1 is always kept in the vertical state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of supporting a semiconductor wafer during, for example, heat treatment.

[Problems to be solved by conventional technology and inventions] Silicon! 11-Semiconductor wafers such as crystal wafers are subjected to oxidation, impurity introduction, thin film deposition, annealing, etc.
It may be heat treated by heating in an appropriate atmosphere. Fifth
FIG. A is a side sectional view showing an example of a conventional method of supporting a semiconductor wafer during such heat treatment. Also,
FIG. 5B is a sectional view taken along the line VB-VB in FIG. 5A. Silicon single crystal wafer 6 to be subjected to heat treatment
1 are arranged with their lower parts fitted into grooves 63 formed in a support base 62 made of quartz. Next, as shown in FIGS. 5A and 5B, this support base 62 is inserted into the quartz tube 64, and the inside of the quartz tube 64 is heated to create a suitable gas atmosphere to heat-treat the silicon single crystal wafer 61. are doing. The reason why the silicon single crystal wafers 61 are lined up one by one in the groove 63 formed in the support stand 62 is to minimize the mechanical stress applied to each silicon single crystal wafer. This is also to enable each silicon single crystal wafer to come into contact with the atmosphere under the same conditions so that the silicon single crystal wafers can be heated uniformly. Heating is generally done at a high temperature of around 1000°C.

FIG. 6 is an enlarged side view showing how a semiconductor wafer is supported in the conventional semiconductor wafer supporting method shown in FIGS. 5A and 5B. As shown in FIG.
Since the groove 63 is larger than the thickness of the silicon single crystal wafer 61, the silicon single crystal wafer 61 is not supported in a completely vertical state but is supported in a slightly inclined state. In this state, the silicon single crystal wafer 61 is completely
The silicon single crystal wafer 61 is supported by a fulcrum 65 at the upper end of the silicon single crystal wafer 61, and mechanical stress acts on the silicon single crystal wafer 61 to bend the silicon single crystal wafer 61 into the shape shown by the imaginary line in FIG. . If such mechanical stress is applied to a silicon single crystal wafer during heat treatment, it may cause the wafer to bend or distort, or cause crystal defects or cracks in the wafer.

FIG. 7A is a side view showing another example of the conventional method for supporting a semiconductor wafer. As shown in FIG. 7A, the support plate 76
If the silicon single crystal wafer 71 is placed horizontally on top of the silicon wafer 71 and subjected to heat treatment, it is possible to prevent warping of a large silicon single crystal wafer as in the conventional method described above. However, in this case as well, as shown in the enlarged side view in FIG. 7B,
Since the contact surfaces of the silicon single crystal wafer 71 and the support plate 76 are not completely flat, for example, the fulcrum 7
It is in a state where it is supported by a plurality of fulcrums such as 5a and fulcrum 75b. Therefore, even with such a method, the silicon single crystal wafer is still bent in minute portions, which causes crystal defects and the like. Furthermore, in this conventional method, there are parts that are in contact with the support plate 76 and parts that are not in contact with it, and the heat conduction in each part is different, resulting in uneven temperature distribution and the occurrence of mechanical stress. Cause.

An object of the present invention has been made to eliminate such conventional drawbacks, and to provide a method for supporting a semiconductor wafer that can minimize the mechanical stress applied to the semiconductor wafer when supporting the semiconductor wafer. There is one thing we can do together.

[Means for Solving the Problems] The supporting method of the present invention is characterized in that the semiconductor wafer is suspended and supported so that the surface of the semiconductor wafer is maintained in a vertical state.

[Operation] In the supporting method of the present invention, since the semiconductor wafer is suspended and supported, the semiconductor wafer's center of gravity is always perpendicular to the center point of the support point supporting the semiconductor wafer due to its own weight. It is kept in position in the direction. Therefore, the surface of the semiconductor wafer is always kept vertical, and no mechanical stress is applied to the semiconductor wafer that would cause it to curve.

[Embodiment] Fig. 1A is a side sectional view showing an apparatus for explaining a first embodiment of the present invention, and Fig. 1B is a sectional view taken along line IB-IB in Fig. 1A. be. Also, 2nd B
The figure is a front view showing a semiconductor wafer in the first embodiment. As shown in FIG. 2B, a silicon single crystal wafer 1
A hole 3 is formed in the hole 3, a support rod 2 made of quartz is inserted into the hole 3, and the silicon single crystal wafer 1 is suspended and supported by the support rod 2. In this way, a plurality of silicon single crystal wafers 1 are suspended from the support rod 2 at regular intervals, and both ends of the support rod 2 are supported by the support jig 6 as shown in FIGS. 1A and 1B.

Next, the silicon single crystal wafer 1 is inserted into a quartz tube 4 and heated by creating a suitable gas atmosphere inside the quartz tube 4 to heat-treat the silicon single crystal wafer 1 .

In this embodiment, holes 3 are formed in silicon single crystal wafer 1, but if holes 3 are formed directly in silicon single crystal wafer 1, problems such as cracking of silicon single crystal wafer 1 may occur. Therefore, a recommended method is to form penetrating holes by poling in the ingot state before slicing, and then slice into wafers to obtain silicon single crystal wafers with holes at predetermined positions.

FIG. 2A is a sectional view taken along line IIA-IIA in FIG. 2B. As shown in FIG. 2A, the diameter of the hole 3 formed in the silicon single crystal wafer 1 is slightly larger than that of the support rod 2. As shown in FIG. Therefore, the silicon single crystal wafer 1 can freely rotate around the support rod 2.

Therefore, as shown in FIG. 2A, even if the support rod 2 is not completely horizontal and is slightly inclined, the center of gravity of the silicon single crystal wafer 1 will always be on the support rod 2 due to its own weight. The surface of the silicon single crystal wafer 1 is always maintained in a vertical state. Therefore, no mechanical bending stress is applied to the silicon single crystal wafer 1 to cause it to curve, and even if it is heated to a high temperature of around 1000°C, crystal defects, bending or distortion of the wafer, etc. will not occur. This does not occur, and the wafer does not crack. In particular, as the area of a semiconductor wafer becomes larger, mechanical stress during support becomes a problem, so the present invention is particularly effective when supporting a semiconductor wafer having a large wafer area.

Furthermore, the support t+2 used in this embodiment has a smaller body diameter than the quartz support used in the Congo and Song Dynasties, and therefore has a small heat capacity. In addition, since the silicon single crystal wafer is maintained in a vertical position, uniform heating is possible, and silicon! Thermal stress applied to the J1 crystal wafer can be minimized.

In the above embodiment, one circular hole was formed in the silicon LLI crystal wafer, but the shape and number of holes can be appropriately selected depending on the purpose of support and other conditions. Further, the shape of the support portion formed on the semiconductor wafer is not limited to a hole, and may be, for example, a notch or a protrusion.

Examples of these are shown in FIGS. 3A-3F. In the example shown in FIG. 3A, two holes 13 are formed above the silicon single crystal wafer 11, and the silicon single crystal wafer 11 is supported at two locations. In the example shown in FIG. 3B, a long hole 23 is formed above the silicon single crystal wafer 21. In the example shown in FIG. A plurality of support rods or the like can be passed through this hole 23 for support. In the example shown in FIG. 3C, cutouts 33 are formed above the silicon single crystal wafer 31, extending inward from both sides. A support rod or the like can be passed through this notch 33 for support. In the example shown in Figure 3D,
Protrusions 43 are formed above the silicon single crystal wafer 41, extending from the inside to the outside toward both sides. A support rod can be engaged with and supported by such a protrusion 43.

FIG. 3E shows an example in which a groove 53 extending along the surface direction is formed above the silicon single crystal wafer 51. As shown in FIG. Moreover, FIG. 3F is a side view of the silicon single crystal wafer 51 shown in FIG. 3E. In such an embodiment, the silicon single crystal wafer 51 can be supported by hooking a support rod along the direction in which the groove 53 extends.

FIG. 4A is a side view showing a support rod in a seventh embodiment of the invention. Moreover, 'yjS4B is a sectional view taken along the TVB-TVB line in FIG. 4A. 4th A
As in the embodiment shown in FIGS. and 4B, a plurality of protrusions 12a may be provided on the upper part of the support rod 12, and the position of the semiconductor wafer may be determined between the protrusions 12a. Also,
The support rod may be formed with four parts for positioning.

In the embodiments, a silicon single crystal wafer has been described as an example, but the present invention is also applicable to supporting other semiconductor wafers. In addition, in the embodiment, quartz was used as an example of the material for supporting the semiconductor wafer, but other materials such as polysilicon, BN, alumina, and graphite, which are strong enough to withstand high temperatures of 1000° C. If so, it can be used as a support means during heat treatment.

In the above description, the supporting method of the present invention has been explained as a supporting method during heat treatment, but the supporting method of the present invention is not limited to supporting during heat treatment, but can be applied to other steps, such as It can also be applied as a support method during a general semiconductor wafer transportation process. Even when the present invention is applied to such a transportation process, since no bending stress or the like is applied to the semiconductor wafer, it is possible to prevent cracking of the wafer, which has conventionally been one of the causes of a decrease in yield. Naturally, if such high temperatures are not applied, the material for the means for suspending and supporting the semiconductor wafer does not need to be heat resistant, so polystyrene or similar plastics can be used.

[Effects of the Invention] According to the semiconductor wafer supporting method of the present invention, the semiconductor wafer is suspended and supported so that the surface of the semiconductor wafer is maintained in a vertical state, so that the mechanical stress applied to the semiconductor wafer is reduced. can be minimized. Therefore, it is possible to prevent bending and distortion of the wafer, occurrence of crystal defects, and cracking of the wafer, which have been problems in the past.

[Brief explanation of the drawing]

FIG. 1A is a side sectional view showing an apparatus for explaining a first embodiment of the invention. FIG. 1B is a sectional view taken along line IB-IB in FIG. 1A. Figure 2A shows
FIG. 2 is an enlarged cross-sectional view showing a state in which a semiconductor wafer is supported in a first embodiment of the present invention. FIG. 2B is a front view showing a semiconductor wafer in the first embodiment of the invention. FIG. 3A is a front view showing a semiconductor wafer in a second embodiment of the invention. FIG. 3B shows the third embodiment of the present invention.
It is a front view showing the semiconductor ueno\ in the example. FIG. 3C is a front view showing a semiconductor wafer in a fourth embodiment of the invention. Figure 3D shows the fifth embodiment of this invention.
It is a front view showing a semiconductor wafer in an example. FIG. 3E is a front view showing the semiconductor urchin/% in the sixth embodiment of the present invention. FIG. 3F shows the sixth embodiment of this invention.
FIG. 2 is a side view showing a semiconductor wafer in Example. FIG. 4A is a side view showing a support rod in a seventh embodiment of the invention. Figure 4B is the IVB in Figure 4A.
It is a sectional view along the -IVB line. FIG. 5A is a side sectional view showing an example of a conventional method for supporting a semiconductor wafer. FIG. 5B is a sectional view taken along the line VB-VB in FIG. 5A. FIG. 6 is an enlarged side view showing a state in which a semiconductor wafer is supported in the conventional semiconductor wafer supporting method shown in FIG. 5A. FIG. 7A is a side view showing another example of the conventional method for supporting a semiconductor wafer. Figure 7B shows the seventh
FIG. 2 is an enlarged side view showing a state in which a semiconductor wafer is supported by the conventional semiconductor wafer support method shown in FIG. In the figure, 1. il, 21. ．． 31, 41.51 are silicon single crystal wafers, 2, 12 are support rods, 3.13.2
3 is a hole, 33 is a notch, 43 is a protrusion, 53 is a groove, 4 is a quartz tube, 5 is a fulcrum, 6 is a support jig, and 12a is a convex portion. Figure S7A Figure 2A Figure 2B Figure 1B Figure gBA Figure 38 Warm Figure 3C Figure 3D Figure 3E Figure 3F Figure 5A Figure 5B

Claims (1)

[Claims] (1) In order to keep the surface of the semiconductor wafer vertical,
A method for supporting a semiconductor wafer, comprising suspending and supporting the semiconductor wafer.