JPS63158832A - Semiconductor substrate - Google Patents

Abstract

PURPOSE:To obtain a GaAs layer having desirable crystallizability, by forming a strain superlattice structure of GexSi1-x-Si on an Si substrate before forming the GaAs layer thereon. CONSTITUTION:An Si substrate 1 is introduced in an MBE apparatus. The surface of the substrate is cleaned while the temperature thereof is held at 870 deg.C. Then, while the temperature of the Si substrate is held at 600 deg.C, 300 Angstrom thick Si layers 2 and 50 A thick Ge0.6Si0.4 layers 3 are deposited in 20 cycles, for example. These layers constitute a strain superlattice layer 4. A 0.2 mum thick GaAs layer 5 is then deposited with the substrate temperature held at 600 deg.C. In this manner, GaAs having desirable crystallizability can be deposited on the Si substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor substrate in which a Ga-S semiconductor layer is formed on a Si substrate.

The integration of conventional technology 81 semiconductor and GILAi9 semiconductor allows GaAs-based semiconductor to have high electron mobility and light emitting function, while 81 semiconductor can obtain large-diameter, high-quality crystal, and device manufacturing technology is improved. Since it has been established, it is promising as a composite device that integrates highly integrated devices on a Si substrate and high-speed devices, light-emitting devices, etc. on a GaAs-based semiconductor.

As a method for growing GILAS on a Si substrate, MBE (Molecular Beam K
pitaxy) method or M OCV D ('Meta
l Organic Chemical Vapor D
GaAs is deposited using a deposition method. The method for forming a GaAg layer on an 81 substrate is to heat-treat the Si substrate at 860'C to clean the surface, then lower the substrate temperature to about 150'C, and then apply a GaAg layer on the 1000G layer. L
Form the AS buffer layer and then increase the substrate temperature to 8Q.
A method of growing a GaAs layer by increasing the O'Q has been used (S-Niji et al., growth of mono-GaAa region on 5i (100) by molecular beam epitaxy).
S, N15hi at al.

Growth of Single Domai
n GaAs on 5i(1oo)b7 Mo
1ecular Beam ICpitaxy) 17th Conference
ce 5olid 5tateand Materia
l) p, p 213). This method uses G2LA formed at low temperature! GaAl9 and Si as a buffer layer
By alleviating the distortion caused by the difference in lattice constants, high-quality G1L MUs are grown. Another method used is to deposit G6 on an 81 substrate and grow GaAs on Ga. Both methods can grow a better GaAs layer than the method of directly forming a GaAs layer on a 3i substrate, but the crystallinity is 20 to 30% higher than that of a GaAs epitaxial layer formed on a GaAs substrate. inferior in gender.

Problems to be Solved by the Invention In the conventional example, there is a problem in that the crystallinity of a GaAs layer formed on a Si substrate is inferior to that of a GaAs epitaxial layer formed on a GaAs substrate.

The present invention provides high-quality GILA on the S1 substrate! ! An object of the present invention is to provide a semiconductor substrate on which a semiconductor layer is formed.

Means for Solving the Problems The present invention provides a strained superlattice structure layer of GexSi, -8-x-Si on a 5i substrate, and epitaxially grows a GaAs layer thereon to form a GILAjI layer with good crystallinity. It's something you get.

By providing a strained superlattice structure layer of GexS and -8-x-Si on a working Si substrate, a high quality epitaxial layer can be formed by alleviating the difference in lattice constant between the Si substrate and the G&S layer. Furthermore, even if a GaAs layer is formed using a large-diameter Si substrate, warping due to the difference in thermal expansion coefficients can be reduced by providing a strained superlattice structure layer compared to the conventional method.

EXAMPLE An example of the present invention will be described in detail below. FIG. 1 shows the manufacturing process of a semiconductor substrate according to an embodiment of the present invention. Load the Si substrate 1 into the MBX device and set the substrate temperature to 870°C.
The substrate surface is cleaned by keeping it at °C (Fig. 1). While keeping the Si substrate temperature at e o o 'C, 300 layers of "0.6" and "0.4" layers 3 to 2.60 are grown for 20 cycles. This becomes the strained superlattice layer 4 (FIG. 2). NextGaAs
Layer 6 is grown to a thickness of 062 μm at a substrate temperature of 600°C. Note that Si is used as an impurity, and the carrier concentration is 1ocM.
(Figure 3).

The following table compares the present invention with a conventional low-temperature growth method using a Si buffer layer (Conventional Example M), a method in which a Ge layer is interposed between a Si substrate (and an aAs layer), and (Conventional Example B).

The half-width was determined by the X-ray two-crystal method, and the smaller the half-width, the better the crystallinity. Warpage indicates the amount of warpage when a 2-inch Si substrate is used. As is clear from the table above, the method of the present invention! GaAs with good crystallinity can be grown on a 1lSi substrate.

In the example, the GaAs semiconductor layer 5 was formed, but kl, -
xGaxAs, In, -xGaxAs, etc. or a multilayer structure of these may be formed.

We used x=o, e as GoxSi, ! =
If it was 0.3 to 0.8, a GaAs layer with good crystallinity was obtained.

MBE is used to grow GoxSi, -Si, and GaAs layers.
Although the MOCVD method was used, it goes without saying that the MOCVD method may also be used.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention provides GexSi4. -By forming a strained superlattice structure of -x-Si and forming a GaAg layer on top of it, good crystallinity of G&
The S class of people can be obtained, and its industrial value is great.

[Brief explanation of the drawing]

1 to 3 are process diagrams for explaining a semiconductor substrate according to an embodiment of the present invention. 1...81 substrate, 2...Si layer, 3...
...Goo, 6" 0.4 layer, 4 ...Geo6
Sio, -si strained superlattice layer, 6...G2LAS
layer.

Claims (1)

[Claims] A semiconductor substrate formed by providing a Ge_xSi_1_-_x-Si strained superlattice structure layer on a Si substrate, and forming a GaAs-based semiconductor layer on the Ge_xSi_1_-_x-Si strained superlattice structure layer.