JP2000269223A - Support device of semiconductor crystal substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a crystal substrate support device, which is used in a thermal treatment process of a semiconductor crystal substrate and possessed of support pins high in flexibility degree of material and shape and where crystal defects hardly occur in the crystal substrate. SOLUTION: Eight crystal axes are present on the primary surface 20 of a crystal substrate 10, whose primary surface 20 is a (100) crystal face. The crystal substrate 10 is supported by support positions 34, 36, and 38 located on the crystal axes near its peripheral edge. The peripheral part on the crystal axes of the substrate 10 is a place, where crystal defects determined by the intrinsic crystal structure hardly occur. The crystal substrate 10 is supported by the support positions, with which crystal defects caused by a support device can be prevented. At this point, no special restrictions are imposed on the material and shape of support pins, so that the support pin can be enhanced in flexibility degree of material and shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a support device for supporting a semiconductor crystal substrate, and more particularly to a support device for a semiconductor crystal substrate provided in a heat treatment device for heating the semiconductor crystal substrate.

[0002]

2. Description of the Related Art When manufacturing a semiconductor device such as an IC from a semiconductor crystal substrate such as gallium-arsenic or silicon, a heat treatment step for heating the semiconductor crystal substrate such as a thermal oxidation step or an annealing step is an essential step. It is.

FIG. 5A is a cross-sectional view of a portion supporting a semiconductor crystal substrate in a lamp annealing apparatus used in an annealing step in a heat treatment step.
In the lamp annealing apparatus, the gallium-arsenic crystal substrate 10 is supported on support pins 14, 16, 18 of a quartz tray 12.
The crystal substrate 10 is heated in this state. FIG. 5B shows the crystal substrate 10 supported in FIG.
FIG. 6 shows the support positions 24, 26, 28 of 6, 18; Conventionally, when the center O of the crystal substrate 10 is set as the origin,
The supporting positions 24, 26, and 28 were arranged on the outer peripheral portion of the crystal substrate so as to have an angle of 120 degrees with each other. However, the support pins 1 at the support positions 24, 26, 28
Due to the difference between the thermal conductivity of the crystal substrate 10 and the thermal conductivity of the crystal substrate 10, the temperature distribution at the outer peripheral portion of the crystal substrate 10 becomes non-uniform,
It is widely known that a slip 30 caused by a crystal defect shown in FIG.

[0004] Further, crystal defects caused by heating a crystal substrate are caused by dislocations in a <110> slip system of {111} crystal planes. Sawada et al., 1996 IEEE GaAs IC Sy
mpsium's “Slip Defect”
Generation on GaAs Wafer
s During High Temperature
Process: Athermoelastic S
study from a Crystallog
Hic Viewpoint "(hereinafter simply referred to as literature). In this document, the position of a slip generated on a gallium-arsenic crystal substrate having a (001) crystal plane is analyzed. FIG. 6 shows an analysis result of the slip position in this document. FIG. 6 shows only a half portion of the circular crystal substrate 10, and shows a slip where a plurality of solid lines (for example, solid lines 30 and 31) extending from the outer periphery of the crystal substrate to the inside of the crystal substrate 10 occur. ing. When the center point O of the crystal substrate 10 is set as the origin, the crystal axes extending from the origin O exist on the surface of the crystal substrate 10. Here, [010] from the [110] crystal axis
It is shown that when the direction toward the crystal axis is defined as θ, slip is likely to occur at the following angle θ.

[0005]

## EQU1 ## θ = π / 8 + n × π / 4 (n = 0, 1, 2,
3) In the crystal substrate supporting device provided in the conventional heat treatment apparatus, the material and shape of the support pin are devised to reduce the difference in thermal conductivity between the support pin and the crystal substrate in order to prevent the crystal defects described above. By improving the uniformity of the temperature distribution of the substrate, crystal defects have been reduced.

[0006]

However, reducing the crystal defects by devising the material and shape of the support pin imposes certain restrictions on the material and shape of the support pin, and the material and shape of the support pin are reduced. The degree of freedom in selecting a shape is reduced, and the degree of freedom in device design in manufacturing a support device is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a high degree of freedom in selecting a material and a shape of a support pin, and has a crystal substrate supporting apparatus in which crystal defects of the crystal substrate are less likely to occur. The purpose is to provide.

[0008]

SUMMARY OF THE INVENTION The present invention is an apparatus for supporting a semiconductor crystal substrate which supports one main surface of a semiconductor crystal substrate at a plurality of support points, wherein the center of the main surface of the semiconductor crystal substrate is defined as an origin. The support point is arranged near the outer periphery of the substrate on a crystal axis extending from the origin toward the outer periphery of the substrate.

The apparatus for supporting a semiconductor crystal substrate according to the present invention supports the semiconductor crystal substrate at a position near the outer periphery of the substrate on a crystal axis where crystal defects of the semiconductor crystal substrate are unlikely to occur. Therefore, it is possible to reduce crystal defects caused by the supporting device.

[0010] Further, the position where the crystal defect of the semiconductor crystal substrate hardly occurs is determined by the crystal structure unique to the semiconductor crystal substrate. Therefore, the position where the crystal defect is unlikely to occur is not related to the material or shape of the supporting device. Therefore, the degree of freedom in selecting the material and shape of the support device is increased,
It is possible to increase the degree of freedom in designing the support device.

[0011]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. In the drawings, the number of the crystal axis and the direction of the crystal in which each numeral is overlined is denoted by adding "-" before the numeral in the description of the embodiment described below. For example, a [010] (1 is overlined) crystal axis in the drawings is referred to as a [0-10] crystal axis in the description of the embodiment.

FIG. 1A shows a crystal substrate supporting apparatus 100 according to this embodiment. Crystal substrate support device 100
Are used to connect the main surface 20 of the crystal substrate 10 to the support pins 14, 16, 1
8 support. The material of the support pins 14, 16, 18 is quartz, SiC, AlN, graphite or the like.
Note that the shape of the support pins 14, 16, 18 is
Any shape can be used as long as it can locally support.

FIG. 1B shows a supported crystal substrate 1.
0 is a plan view when viewed from the direction of the main surface 20, and a support position 3 where the support pins 14, 16, 18 support the crystal substrate 10;
4, 36, 38 are shown.

The main surface 20 of the crystal substrate 10 is (10
0) A gallium-arsenic crystal substrate having a crystal plane.
The straight portion 40 on the outer peripheral portion of the crystal substrate 10 is called an orientation flat, and indicates the orientation of the [011] crystal axis in the present embodiment. Assuming that the center O of the crystal substrate 10 is the origin, there is a crystal axis extending from this origin toward the outer periphery of the substrate. In FIG. 1B, each arrow represents a crystal axis. For example, an arrow extending from the center O toward the orientation flat 40 and perpendicular to the orientation flat represents the [011] crystal axis. Similarly, other crystal axes are also indicated by arrows in FIG. 1B, and the main surface 20 of the crystal substrate 10 has eight crystal axes shown in FIG. 1B.

It is disclosed in the above-mentioned document that crystal defects occur in a specific direction due to the crystal structure of the gallium-arsenic crystal substrate 10 having a (100) crystal plane. FIG. 2 shows eight disassembled shear stresses predominant in the occurrence of slip in a gallium-arsenic crystal substrate cut out on a (100) crystal plane. FIG.
In FIG. 1 (b), from [011] crystal axis to [001]
1] The direction toward the crystal axis is defined as θ. In FIG. 2, the radial stress σr = 0.01 [MPa] and the circumferential stress σθ = 7 [MPa]. And the critical stress σc
It is assumed that r = 3 [MPa]. The critical stress σcr is a limit stress at which a slip occurs when each decomposed shear stress σi (i = 1, 2, 3,..., 8) exceeds σcr.

FIG. 3 is a graph showing the distribution of the angle θ of the difference (σi−σcr) between each decomposed shear stress σi and the critical stress σcr. The σi-σcr value is a value proportional to the dislocation density in the crystal. As the σi-σcr value is larger,
The density of dislocations generated in the crystal increases, and slip is likely to occur. Conversely, as the σi-σcr value is smaller, slipping is less likely to occur. Therefore, in the crystal substrate 10, slip does not easily occur at the following angle θ in the main surface 20.

[0017]

## EQU2 ## θ = n × π / 4 (n = 0, 1, 2,..., 7) The above-mentioned angle is such that the position on each crystal axis of the crystal substrate 10 described above is a position where slip is unlikely to occur. It indicates that there is.

In the crystal substrate supporting apparatus of the present embodiment,
As shown in FIG. 1B, the supporting positions 34, 36, and 38 correspond to a [010] crystal axis, a [0-11] crystal axis, and a [0-11] crystal axis.
[01] It is arranged on the crystal axis and near the outer peripheral portion of the crystal substrate 10. Since the supporting positions 34, 36, and 38 are located on the crystal axis, when the crystal substrate 10 is supported at this position, slip is unlikely to occur, and crystal defects caused by the crystal substrate supporting device can be prevented.

The positions of the support positions 34, 36 and 38 are as follows:
The present invention is not limited only to the [010] crystal axis, the [0-11] crystal axis, and the [001] crystal axis. It is sufficient that three of the eight crystal axes on the crystal substrate 10 are arbitrarily selected, and the position may be any position on the selected crystal axis around the periphery of the substrate.

The reason why the three supporting positions are set is that the three positions are most efficient for supporting the crystal substrate 10. Therefore, the support positions are not limited to three, and the support positions 42, 44, 46, and 48 may be arranged at four positions on the crystal axis as shown in FIG. Note that the support positions may be arranged at four or more positions as long as they are on the crystal axis.

The crystal substrate is not limited to a crystal substrate having a (100) crystal plane. The crystal substrate supporting apparatus of the present embodiment is applicable to a crystal substrate having, as a main surface, a plane crystallographically equivalent to a (100) plane generally referred to as a {111} crystal plane. Are arranged on a crystal axis appropriately selected.

The supporting position is determined by a unique crystal structure of the crystal substrate. Therefore, if the crystal substrate of indium-phosphorus having the same zinc-blende structure as gallium-arsenic is supported at the same supporting position as in the present embodiment, it is possible to reduce crystal defects. . Also,
Although the crystal structure is a diamond structure different from gallium-arsenic, a silicon crystal substrate having the same atomic arrangement is also supported at the same support position as in the present embodiment,
Crystal defects can be reduced. in this way,
If the crystal structure has the same atomic arrangement as the gallium-arsenic crystal substrate, if it is supported at the support position of the present embodiment,
Crystal defects can be reduced.

The supporting device of the present embodiment is preferably provided in a heat treatment device for heating a semiconductor crystal substrate.

[0024]

As described above, the apparatus for supporting a semiconductor crystal substrate according to the present invention supports the semiconductor crystal substrate at a position near the outer periphery of the substrate on the crystal axis where crystal defects of the semiconductor crystal substrate hardly occur. Therefore, it is possible to reduce crystal defects caused by the supporting device.

Further, the position where the crystal defect of the semiconductor crystal substrate hardly occurs is determined by the crystal structure unique to the semiconductor crystal substrate. Therefore, the position where this crystal defect hardly occurs is
It is not related to the material or shape of the support device. Therefore, the degree of freedom in selecting the material and the shape of the support device is increased, and the degree of freedom in designing the support device can be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a support device of the present embodiment and a plan view showing a position where the support device supports a crystal substrate.

FIG. 2: Gallium cut out from a (100) crystal plane
In the arsenic crystal substrate, 8
3 is a table showing the disassembled shear stresses.

FIG. 3 is a graph showing a distribution of an angle θ of a difference (σi−σcr) between each decomposed shear stress σi and a critical stress σcr.

FIG. 4 is a plan view showing a position where a supporting device of another embodiment supports a crystal substrate.

FIG. 5 is a cross-sectional view of a portion supporting a semiconductor crystal substrate in a lamp annealing apparatus used in an annealing step, and a plan view showing a supporting position of a conventional crystal substrate.

FIG. 6 is a plan view showing a slip position of a crystal substrate disclosed in the cited document.

[Explanation of symbols]

10 crystal substrate, 14, 16, 18 support pins, 20
Main surface, 24, 26, 28, 34, 36, 38, 42, 4
4, 46, 48 Support position, 100 Crystal substrate support device.

Claims (1)

[Claims] 1. A semiconductor crystal substrate support device for supporting one main surface of a semiconductor crystal substrate at a plurality of support points, wherein the center of the main surface of the semiconductor crystal substrate is defined as an origin, and from the origin, an outer periphery of the substrate is provided. A supporting device for a semiconductor crystal substrate, wherein the supporting point is arranged near a peripheral portion of the substrate on a crystal axis extending toward the substrate.