JP2002100581A - Supporter for heat-treated substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a crystal transition based on centralized stress by reducing stress at supported portions, and to suppress the crystal transition based on a flaw caused by a slip by minimally decreasing the slip between a processed substrate and upper end of the supported member for supporting the processing substrate. SOLUTION: The substrate supporter for heat treatment has a supporting plate 23 and plural supporting members 24 erected on the supporting plate 23, and is configured to horizontally support a preprocessing substrate 22 by placing the lower surface of the substrate 22 to be treated on the upper terminal edges of the plural supporting members 24. Each of supporting members 24 is composed of a coil spring 24a fixing the lower end thereof on the supporting plate 23 and a cap 24b covering the upper end of the coil spring 24a, and the upper terminal edge of the cap 24b is formed into plane capable of surface contact with the substrate 22 to be treated. Each of the coil spring 24a and the cap 24b is formed from quartz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-treating substrate support used for heat-treating a substrate such as a silicon wafer.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a horizontal portion 6a formed on the inner peripheral edge of a ring-shaped support 6 has been used as a heat-treating substrate support for supporting a silicon wafer when heat-treating the silicon wafer. Is known that supports the wafer 7 horizontally. However, since this substrate support mainly supports the lower surface of the peripheral region of the wafer 7, the central region of the wafer 7 is easily bent downward by its own weight, and the stress due to this bending is dislocated to the wafer 7 particularly during high-temperature heat treatment. This is liable to occur, and the yield has to be reduced. It has been pointed out that such a problem becomes more serious as the diameter (diameter) of the wafer 7 increases, for example, to 12 inches. In order to solve this problem, as shown in FIG. 5, a pin-shaped support member 2 having an upper end tapered on the upper surface side of a disk-shaped support plate 1
There is known a substrate support which is erected, and has a wafer 3 mounted on the upper edge of the plurality of support members 2 and horizontally supports the wafer 3. In this substrate support, the wafer 3 is supported on the inner side from the outer peripheral edge, thereby suppressing the bending in the central region of the wafer 3 and reducing the stress caused by the bending to suppress the generation of dislocation.

[0003]

However, when the wafer 3 is horizontally supported by the three pin-shaped support members 2 and the heat treatment is performed, stress concentrates on the portions of the wafer 3 supported by the support members 2. However, there is a problem that dislocations occur due to the concentrated stress. In order to solve this problem, it is conceivable to increase the number of the support members 2 and reduce the stress in the portion of the wafer 3 supported by the support members 2. An uneven load occurs due to uniform undulation and warpage, and there is a problem that dislocation occurs due to stress concentration due to the uneven load. In addition, when the wafer 3 is horizontally supported by the three pin-shaped support members 2 and the heat treatment is performed, a slip between the support member 2 and the wafer 3 occurs due to a difference in the thermal expansion coefficient between the support plate 1 and the wafer 3. Occurs,
There was also a problem in that the surface of the contact portion of the wafer 3 caused by the slip was damaged, and crystal dislocation due to the scratch was generated in the portion supported by the support member 2. An object of the present invention is to provide a heat-treating substrate support capable of reducing stress in a supported portion and suppressing crystal dislocation caused by concentrated stress. Another object of the present invention is to provide a heat treatment substrate support capable of minimizing the slip between the upper end of a support member that supports a substrate to be processed and the substrate to be processed, and suppressing crystal dislocation due to scratches caused by the slip. To provide.

[0004]

The invention according to claim 1 is
As shown in FIG. 1, the pre-processing substrate includes a support plate 23 and a plurality of support members 24 erected on the support plate 23, and the lower surface of the substrate to be processed 22 is placed on the upper edges of the plurality of support members 24. 22
This is an improvement of the substrate support for heat treatment configured to horizontally support the substrate. The characteristic configuration is that the support member 24 includes a coil spring 24a having a lower end fixed to the support plate 23 and a cap 2 covered on the upper end of the coil spring 24a.
4b, and the upper end edge of the cap 24b is formed on a plane that can make surface contact with the substrate 22 to be processed. In the heat treatment substrate support according to the first aspect, when the lower surface of the substrate to be processed 22 is placed on the upper edges of the plurality of support members 24, the position of the cap 24b on which the substrate to be processed 22 is mounted is elastically deformed by the coil spring 24a. The substrate moves freely up and down to a support point position corresponding to the deformation of the substrate 22 to be processed. Therefore, even if more than three support members 24 are provided,
The stress at each support point on the support member 24 of the substrate 22 to be processed becomes uniform, thereby avoiding the occurrence of uneven load as in the prior art, and providing more than three support members 24 allows the substrate 22 to be processed. The stress at the portion in contact with the upper surface of the cap 24b is reduced, and the occurrence of dislocation due to the stress is prevented.

[0005] Even if the substrate 22 placed on the supporting member 24 undergoes uneven undulation or warpage during the heat treatment, the position of the cap 24b can be freely moved up and down according to the undulation or warpage due to the elastic deformation of the coil spring 24a. Moving. As a result, the processing target substrate 22 uniformly contacts the upper surface of the cap 24b, almost no internal stress is generated in the processing target substrate 22, and dislocation based on the stress during the heat treatment is generated in the processing target substrate 22. Can be suppressed. Also, cap 2
4 is formed on a plane that can make surface contact with the substrate 22 to be processed.
The stress at the portion in contact with the upper surface is significantly reduced as compared with the conventional case using the pin-shaped support member, and almost no internal stress is generated in the substrate to be processed 22, and the generation of dislocation due to the stress can be suppressed as compared with the conventional case. Further, when the substrate to be processed 22 is heated, it expands, and the portion in contact with the cap 24b slightly moves. At this time, the coil spring 24a moves slightly to move the cap 24b in contact with the substrate 22 in accordance with the expansion of the substrate 22 while keeping the cap 24b in contact with the substrate 22. As a result,
Slippage between a portion of the substrate 22 to be contacted with the cap 24b and the cap 24b is minimized, and crystal dislocations due to scratches caused by the slippage are suppressed as compared with the related art.

The invention according to claim 2 is the invention according to claim 1, wherein the coil spring 24a and the cap 24
b is a heat treatment substrate support made of quartz. In the heat treatment substrate support according to claim 2,
The support member 24 having sufficient heat resistance can be obtained.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. 1 to 3 show a vertical heat treatment furnace 10 provided with a heat treatment substrate support 13 of the present invention. The vertical heat treatment furnace 10 includes a reaction tube 11 made of SiC extending in a vertical direction, and a plurality of rod-like supports 12 erected in the reaction tube 11 at predetermined intervals and formed of SiC.
And a plurality of holder grooves 14 which are respectively formed on the plurality of supports 12 at predetermined intervals in the longitudinal direction and which allow the outer peripheral edge of the substrate support 13 for heat treatment to be loosely inserted. An outer peripheral surface of the reaction tube 11 is provided with a cylindrical heater 17 through a heat equalizing tube 16.
(FIG. 3). The support 12 is erected on a boat cap 21 via a base 18 and a heat retaining tube 19.
In this embodiment, the number of the wafer supports 12 is four, and they are provided at equal intervals on the same semicircle (FIG. 2). The support 12 is formed of SiC in order to prevent deformation of the support 12 itself due to high heat during heat treatment and to prevent particles and the like from being generated and contaminating the inside of the reaction tube 11.

The heat treatment substrate support 13 has a support plate 23 formed in a disk shape without a notch, and four support members 24 erected on the support plate 23. The support plate 23 is made of SiC
Formed by As an example, SiC is deposited by a CVD method on a carbon base material formed in the same shape as the support plate 23, and when the SiC reaches a predetermined thickness, the carbon base material is burned off. The support plate 23 is formed in a predetermined shape. The support plate 23 constituting the heat-treating substrate support 13 rests on the lower horizontal plane of the four holding groove 14 located in the same horizontal plane of the four supports 12, and the support constituting the heat-treating substrate support 13. An 8-inch silicon wafer 22, which is a substrate to be processed, is mounted on the upper end surface of the member 24 (FIGS. 1 and 2).

The support member 24 includes a coil spring 24a having a lower end fixed to the support plate 23, and a cap 24b over the upper end of the coil spring 24a. The coil spring 24a and the cap 24b are each made of quartz glass, and the upper edge of the cap 24b is formed in a plane that can make surface contact with the silicon wafer 22. In this support member 24, each coil spring 24
a, the wafer 22 is placed on a cap 24b placed on the upper end of the coil spring 24a.
It is constituted so that it may be elastically supported. In this embodiment, four support members 24 are provided, and the support points of the four support members 24 are four.
As long as 3 can be supported at three or more points, three support members 24
Five, six, seven, eight, nine, or ten or more may be provided.

The support plate 23 is sufficiently thicker than the wafer 22 and does not deform even when the coil spring 24a and the wafer 22 are placed on the support plate 23, even when the peripheral edge of the support plate 23 is locked in the holder groove 14. It preferably has a degree of rigidity. In this embodiment, the edge 2 is provided on the outer peripheral side of the support plate 23.
3a is provided to prevent backlash in the holder groove 14. Further, the position where the coil spring 24a is provided on the support plate 23 can be arbitrarily selected, but it is preferable to select a portion where the amount of deformation of the wafer 22 is large.

When an 8-inch silicon wafer 22 to be subjected to heat treatment is placed on the heat treatment substrate support 13 having the above-described structure, and the wafer 22 is deformed, the cap 24b on which the wafer 22 of the substrate support 13 rests is placed. The position is freely moved up and down by the elastic deformation of the coil spring 24a, and becomes a support point position corresponding to the deformation of the wafer 22. Therefore, even if the four support members 24 are provided, the stress at each of the support points of the support member 24 of the wafer 22 becomes uniform, so that the occurrence of the uneven load as in the prior art is avoided, and the occurrence of dislocation is prevented. Is prevented.

After the silicon wafer 22 as a substrate to be processed is placed on the substrate support 13 for heat treatment, the substrate support 13 for heat treatment is placed on the heat treatment furnace 1 together with the silicon wafer 22.
0, and the outer peripheral edge of the support plate 23 constituting the heat treatment substrate support 13 is inserted into the four retainer grooves 14 in the same horizontal plane of the support 12, and these retainer grooves 14 are formed. Place on the lower horizontal surface. With this, the work of accommodating the wafer 22 placed on the substrate support 13 for heat treatment in the heat treatment furnace 10 is completed. Thereafter, when the heat treatment furnace 10 is operated, the temperature in the heat treatment furnace 10 is raised to 1000 ° C. or more by the heater 17.
At this time, since the support plate 23 has a disk shape without a notch,
Even if the support plate 23 is heated as described above, the support plate 2
No warpage occurs in 3. Further, even if uneven undulation or warpage occurs in the wafer 22 during the heat treatment, the position of the cap 24b moves freely up and down according to the undulation or warpage due to the elastic deformation of the coil spring 24a.
As a result, the wafer 22 uniformly contacts the upper surface of the cap 24b, and the upper edge of the cap 24 is
2, the stress in the portion of the wafer 22 that contacts the upper surface of the cap 24b is significantly reduced as compared with the conventional case, and almost no internal stress occurs in the wafer 22, Generation of dislocations can be suppressed.

On the other hand, when the silicon wafer 22 is heated, the silicon wafer 22 expands due to the heat and its diameter slightly increases, and the portions in contact with the cap 24b slightly move outward from each other. At this time, the coil spring 24a moves slightly around and the cap 24b is brought into contact with the silicon wafer 22 while the silicon wafer 2 is in contact.
Move according to the expansion of 2. As a result, slip between the portion of the silicon wafer 22 that contacts the cap 24b and the cap 24b is minimized, and crystal dislocation due to scratches caused by the slip is suppressed as compared with the related art.

When the heat treatment of the wafer 22 in the heat treatment furnace 10 is completed, the substrate support 13 for heat treatment is
At the same time, the silicon wafer 13 subjected to the heat treatment is transferred from the heat treatment substrate support 13 to the next processing step by the robot arm (not shown) from the heat treatment substrate support 13.
In the above embodiment, a silicon wafer is described as a substrate to be processed, but a substrate to be processed is a GaP wafer,
A GaAs wafer or the like may be used, and the outer diameter of the wafer is not limited to 8 inches, and may have another outer diameter.

[0015]

As described above, according to the present invention, the supporting member is constituted by the coil spring whose lower end is fixed to the supporting plate and the cap which is put on the upper end of the coil spring. When the substrate is deformed, the cap in contact with the substrate is easily moved up and down by the elastic deformation of the coil spring, so that the stress in each supporting portion of the substrate is uniform, and the occurrence of an uneven load is prevented. . In addition, since the upper edge of the cap is formed in a plane that can make surface contact with the substrate to be processed, the stress of the portion of the substrate to be processed that contacts the upper surface of the cap is significantly reduced as compared with the conventional case using a pin-shaped support member, Almost no internal stress is generated in the substrate to be processed. As a result, the stress in the supported portion is reduced, and the crystal dislocation caused by the concentrated stress can be effectively suppressed. Further, during the heat treatment of the substrate to be processed, the coil spring moves slightly and moves in accordance with the expansion of the substrate to be processed in a state where the cap is in contact with the substrate to be processed. Slippage between the portion and the cap is minimized, and crystal dislocation due to scratches caused by the slippage can be suppressed more than before.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along the line AA of FIG. 2 including a heat-treated substrate support according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG. 3;

FIG. 3 is a sectional configuration diagram of a heat treatment furnace including the heat treatment substrate support.

FIG. 4A is a plan view of a conventional substrate support that supports a substrate to be processed in a horizontal portion. (b) A longitudinal sectional view of the conventional substrate support.

FIG. 5A is a plan view of a conventional substrate support that supports a substrate to be processed with a plurality of support pins. (b) A sectional view taken along line CC of (a) showing the conventional substrate support.

[Explanation of symbols]

 13 heat treatment substrate support 22 substrate to be processed 23 support plate 24 support member 24a coil spring 24b cap

Continued on the front page F term (reference) 5F031 CA02 HA62 HA65 MA28 MA30 5F045 AA20 AD14 AD15 AD16 AD17 AD18 AF03 AF04 BB12 BB13 DP19 DQ05 EM08

Claims (2)

[Claims] A support member provided on the support plate, wherein a lower surface of the substrate to be processed is placed on the support member; ), The heat treatment substrate support configured to horizontally support the substrate to be processed (22) mounted on the upper edge thereof, wherein the lower end of the support member (24) is fixed to the support plate (23). It is constituted by a coil spring (24a) and a cap (24b) covered on the upper end of the coil spring (24a), and the upper edge of the cap (24b) is in a plane that can make surface contact with the substrate (22). A support for a heat-treated substrate, wherein the support is formed. 2. A coil spring (24a) and a cap (24)
2. The support for a heat-treated substrate according to claim 1, wherein b) is formed of quartz.