JP3157866B2 - Substrate holder for molecular beam crystal growth and molecular beam crystal growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molecular beam crystal growth method for growing an epitaxial layer on a substrate of a semiconductor, particularly a compound semiconductor, and a substrate holder used for the method.

[0002]

2. Description of the Related Art In growing a molecular beam crystal, a substrate is held by a substrate holder in a high-vacuum apparatus. FIG. 3 shows a conventional substrate holder. Substrate holder 30
Has a hollow disk shape, and the hollow portion is
As 1, the substrate 33 is disposed here. An annular support 32 is formed on the substrate holding unit 31. Substrate 3
3 is supported on the entire periphery by the support 32.

[0003]

The substrate is heated by radiation while being held by the substrate holder. The substrate holder is made of a material (for example, tantalum and molybdenum) that hardly volatilizes elements even at a temperature of several hundred degrees centigrade in a high vacuum, while the material for forming the substrate (for example, a compound semiconductor such as GaAs) emits radiation. Easy to transmit light. Therefore, when the substrate held by the holder is heated, the temperature of the holder rises more rapidly than the substrate, so that a thermal gradient is formed between the peripheral portion and the center of the substrate where the holder contacts. You. For this reason, thermal distortion occurs in the substrate, and in particular, there is a problem that a large number of slips occur on the (110) plane and its vicinity at the peripheral edge of the substrate.

An object of the present invention is to suppress occurrence of slip when heating a substrate in molecular beam crystal growth.

[0005]

A substrate holder for growing a molecular beam crystal according to the first invention holds a substrate by supporting a peripheral portion of the substrate in order to expose the substrate to a molecular beam in a molecular beam crystal growing apparatus. The holder includes a plurality of support pieces that hold the substrate in contact with a plurality of locations on the peripheral portion of the substrate. Further, the plurality of support pieces are provided on a peripheral portion of the substrate.
It is provided at a predetermined interval so as to be able to contact a part distant from the (110) plane part .

[0006] Molecular beam epitaxy method according to the second aspect of the present invention is the method of irradiating with an incident molecular beams to the heated substrate to grow an epitaxial layer on a substrate, the substrate peripheral portion (11
0) The substrate is heated by holding a portion away from the surface portion by a substrate holder.

[0007]

When the substrate is placed on the substrate holder according to the first aspect of the invention, the support pieces of the substrate holder come into contact with a plurality of positions on the peripheral portion of the substrate, and the substrate is supported. Thus, the substrate is held by the substrate holder in the molecular beam crystal growth apparatus.
A plurality of support pieces for supporting the substrate are provided at predetermined intervals, and can be in contact with a portion of the peripheral edge of the substrate holder away from the portion where <110> growth appears. For example, in the case of a GaAs substrate, as shown by an arrow in FIG.
Although <110> growth appears in several places, if a plurality of supporting pieces are provided so that the supporting pieces come into contact between these portions, (11)
0) The substrate can be supported while avoiding the plane portion . The spacing, number, size, etc. of the support pieces may be set to be optimal according to the size and weight of the substrate.

[0008] Thus, by preventing the contact of the holder to the (110) plane portion and the vicinity thereof, (110)
A large temperature gradient is prevented from being applied in the vicinity of the surface portion , thereby preventing the occurrence of slip.

Further, according to a second aspect of the present invention, at the peripheral portion of the substrate,
If the substrate is heated while holding the part away from the (110) plane part by the substrate holder, the generation of thermal strain in the (110) plane part where heating is likely to occur and the vicinity thereof is suppressed.

[0010]

EXAMPLE A substrate holder shown in FIG. 1 was manufactured according to the present invention. In FIG. 1, (a) is a plan view of a substrate holder,
(B) shows an AA 'sectional view.

The substrate holder 10 has a hollow disk shape, and the hollow portion serves as a substrate holding portion 11. The substrate holding part 11 has a shape along the substrate, and the portion where the orientation flat is located is made flat, while the other portions are made cylindrical. The substrate holding portion 11 has an appropriate size so that the substrate does not shift during molecular beam crystal growth.

On the other hand, substrate support pieces 12a, 12b, 12c and 12d are formed at four places on the substrate holding portion 11. Since the orientation flat 14 (hereinafter abbreviated as OF) of the GaAs substrate 13 to be held has a (110) plane, a portion 15 facing the OF on the outer peripheral surface of the substrate 13, an IF 16 rotated by 90 degrees from the OF, And IF
<110> growth appears in the portion 17 opposing the. Therefore, for example, the substrate support piece 12a
The support piece 12c is formed at a position facing 12a, and the support pieces 12b and 12d are formed at positions rotated by 90 degrees from the 12a to the left and right in the figure. As shown in the figure, the substrate 13 is held in the substrate holder 10 by supporting the peripheral portion of the substrate 13 with four support pieces.

In a molecular crystal growth apparatus, a GaAs substrate having a diameter of 4 inches was held by the substrate holder described above, and an undoped GaAs layer was grown. The growth conditions were as follows.

Heating temperature: 20 ° C./min, growth temperature: 6
50 ° C., growth time: 1 hour, cooling temperature: 20 ° C./min,
As pressure: 1 × 10 ⁻⁵ Torr, growth rate: 1 μm / h
r.

On the other hand, molecular beam crystal growth was carried out under the same conditions using the conventional substrate holder shown in FIG.

As a result of comparing and observing the surfaces of the substrates epitaxially grown under these conditions, the length and the number of the slips can be suppressed to less than half when the holder of the present invention is used and when the conventional holder is used. Was. Therefore, it has been clarified that the occurrence of slip is suppressed according to the present invention.

In the above embodiment, the substrate support pieces are provided at four positions. However, the number, interval, size, shape, etc. of the substrate support pieces are not limited to the above embodiment, and various changes are possible. It is. For example, as shown in FIG. 2, supporting pieces can be provided at eight positions of the substrate holding portion according to the present invention.

[0018]

As described above, according to the present invention, the occurrence of slip is suppressed in molecular beam crystal growth. Therefore, the area that can be used as a device such as a high-speed element or a light-emitting element on the substrate is increased as compared with the related art, and the present invention contributes to improvement in the yield of device manufacturing.

[Brief description of the drawings]

FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along the line AA ′, showing an example of a substrate holder according to the present invention.

FIG. 2 is a plan view showing another example of the substrate holder according to the present invention.

FIG. 3A is a plan view and FIG. 3B is a cross-sectional view showing a conventional substrate holder.

FIG. 4 is a plan view for explaining a growth direction of a substrate.

[Explanation of symbols]

 11, 31 substrate holding parts 12a, 12b, 12c, 12d substrate support pieces

Continuing from the front page (72) Inventor Hiroshi Okada 1-1-1, Konokita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Junro Sakai 5-81, Yotsuya, Fuchu-shi, Tokyo (72) Inventor ▲ Taka ▼ Shigenori Kishi 1-1-1, Kunyokita, Itami-shi, Hyogo Prefecture Itami Works, Sumitomo Electric Industries, Ltd. (56) References JP-A-61-201420 (JP, A) Fully open 1988-157925 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/68 C30B 25/12 H01L 21/203

Claims (3)

(57) [Claims] 1. A molecular beam crystal growth substrate holder for holding a substrate by supporting a peripheral portion of the substrate in order to expose the substrate to a molecular beam in a molecular beam crystal growing apparatus. And a plurality of support pieces for supporting the substrate in contact with the above-mentioned portions, wherein the plurality of support pieces are a (110) surface portion of the peripheral portion of the substrate.
Provided at a predetermined interval so that it can contact the portion apart from the distribution, molecular beam crystal growth substrate holder. 2. In a molecular beam crystal growth method for growing an epitaxial layer on a substrate by applying a molecular beam to a heated substrate, a portion of the peripheral portion of the substrate that is separated from a (110) plane is held by a substrate holder. And heating the substrate. 3. comprising four or eight said support pieces;
The substrate holder for growing a molecular beam crystal according to claim 1.