JP2959767B2 - Semiconductor substrate, semiconductor device and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor substrate, a semiconductor device, and a method for manufacturing the same. [Summary of the Invention] The present invention relates to a Si substrate, a quartz substrate, a sapphire substrate or
By forming a semiconductor layer having a smaller lattice constant than a buffer layer on a SiC substrate via a buffer layer, a semiconductor substrate provided with a high-quality semiconductor layer can be provided. [Prior Art] A semiconductor heterojunction formed of a heterogeneous semiconductor is essential for manufacturing an element. For example, this semiconductor heterojunction is a monolithic optoelectronic integrated circuit (OEI) composed of a high-speed semiconductor device and an optical semiconductor device.
C), which is the basis of a very wide range of important applications such as monolithic integration of Si-based devices and GaAs or InP-based devices. A GaAs / Si heterojunction is a typical example of this semiconductor heterojunction. This GaAs / Si heterojunction is
It is formed by growing an aAs layer. However, while the lattice constant of GaAs is 5.6534 °, the lattice constant of Si is 5.43086 °, and the difference between them is as large as about 4%, the defect density in the GaAs layer grown on this Si substrate is high. It is difficult to grow a good quality GaAs layer. Applied Physics, Vol. 55, No. 11, (1986), pp. 1069-10
On page 73, a two-stage growth method aimed at solving such a problem is discussed. In this two-step growth method, for example, a polycrystalline or amorphous thin GaAs layer is once grown on a Si substrate, for example, and then annealed to cause solid-phase epitaxy to grow the layer once. An active layer, for example, single crystal GaAs
This is a method of growing a layer. [Problems to be Solved by the Invention] However, the quality of the compound semiconductor layer grown by the above-described two-stage growth method is not sufficient, and it has been desired to grow a higher quality compound semiconductor layer. Accordingly, an object of the present invention is to provide a semiconductor substrate in which a high-quality semiconductor layer is provided on various substrates such as a Si substrate, a quartz substrate, a sapphire substrate, and a SiC substrate, a semiconductor device using the semiconductor substrate, and a method of manufacturing the same. Is to do. [Means for Solving the Problems] According to the findings of the present inventors, another semiconductor layer having a smaller lattice constant than this semiconductor layer is grown on the semiconductor layer, for example, a Si layer on a GaAs layer. In spite of the fact that there is a difference in lattice constant between them, the upper semiconductor layer is of good quality. Therefore, on a semiconductor substrate or the like, a semiconductor layer having a larger lattice constant than a compound semiconductor layer to be finally grown is formed as a buffer layer, and when a compound semiconductor layer is grown on this buffer layer, a good quality semiconductor is obtained. can get.
Further, a substrate other than a semiconductor substrate can be used as a substrate in the sense that a high-quality compound semiconductor layer is simply grown. The present invention has been devised based on such studies. That is, a first invention of the present invention is a semiconductor substrate including a Si substrate, a buffer layer made of InAs on the Si substrate, and a GaAs layer on the buffer layer. A second invention of the present invention relates to a quartz substrate, a sapphire substrate or a SiC substrate, a buffer layer on a quartz substrate, a sapphire substrate or a SiC substrate, and a semiconductor layer formed on the buffer layer and having a smaller lattice constant than the buffer layer. A semiconductor device having: A third invention of the present invention relates to a quartz substrate, a sapphire substrate or a SiC substrate, a buffer layer on a quartz substrate, a sapphire substrate or a SiC substrate, and a compound semiconductor layer formed on the buffer layer and having a smaller lattice constant than the buffer layer. And a semiconductor device having: A fourth invention of the present invention relates to a quartz substrate, a sapphire substrate or a SiC substrate, a buffer layer on a quartz substrate, a sapphire substrate or a SiC substrate, and a compound semiconductor layer formed on the buffer layer and having a smaller lattice constant than the buffer layer. A semiconductor device having an optical semiconductor element formed on a semiconductor substrate having the following. The fifth invention of the present invention is a quartz, sapphire or SiC
In a method of manufacturing a semiconductor device, a semiconductor layer having a lattice constant different from that of a substrate is epitaxially grown on a substrate comprising: a step of forming a buffer layer on the substrate; A step of epitaxially growing a layer. [Operation] According to the above-described means, a semiconductor layer having a smaller lattice constant than the buffer layer is grown on the buffer layer.
A semiconductor substrate in which a high-quality semiconductor layer is provided over various substrates such as a substrate, a quartz substrate, a sapphire substrate, and an SiC substrate can be obtained. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment is an embodiment in which a GaAs layer which is a polar semiconductor is formed on a Si substrate which is a nonpolar semiconductor. As shown in FIG. 1, first, a lattice constant larger than that of GaAs and a polar semiconductor such as InAs (grating) is formed on a Si substrate 1 by, for example, MOCVD (metal organic chemical vapor deposition). Constant = 6.0585) The layer 2 is grown as a buffer layer. The thickness of the InAs layer 2 can be, for example, about several Å to 3 μm, and the growth can be performed, for example, at a growth temperature of 440 to 700 ° C. Next, as shown in FIG. 2, a GaAs layer 3 is grown on the InAs layer 2 as a buffer layer by, for example, MOCVD. The thickness of the GaAs layer 3 can be selected as needed, but can be, for example, about 1 μm. The growth of the GaAs layer 3 is performed, for example, at a growth temperature of 60.
It can be performed at 0 to 800 ° C. The GaAs layer 3 grown in this manner has a low density of crystal defects such as dislocations and is of good quality. As described above, according to the present embodiment, the InAs layer 2 having a lattice constant larger than that of GaAs is used as the buffer layer.
Since the GaAs layer 3 is grown on the Si substrate 1, a high-quality GaAs layer 3 can be grown on the Si substrate 1 having a significantly different lattice constant. This makes it possible to provide a semiconductor substrate provided with a high-quality GaAs layer 3. Further, when the GaAs layer 3 as a polar semiconductor is grown on the Si substrate 1 as a non-polar semiconductor, an antiphase domain (a region where phases having different directions exist) is generated and the single domain is not obtained. In the example, since the GaAs layer 3 is grown on the two InAs phases, which are polar semiconductors, there is no such problem. In addition, the thermal expansion coefficient of GaAs is about 2.5 times that of Si, which is very different from that of InAs.
1.7 times, which is an intermediate size between GaAs and Si,
Compared with the case where the GaAs layer 3 is directly grown on the substrate 1,
Stress generated in the GaAs layer 3 due to a difference in thermal expansion coefficient from the substrate 1 can be reduced. Therefore, the GaAs layer 3 can be grown to a thickness of, for example, about 4 μm or more without generating distortion, cracks, and the like. By using the high-quality GaAs layer 3 obtained in this embodiment as an active layer, a high-performance semiconductor device such as a high-speed semiconductor device can be manufactured. In addition, the monolithic integration of the high-speed semiconductor device and the optical semiconductor device enables high-performance OE
IC can be realized. As mentioned above, although one Example of this invention was described concretely, this invention is not limited to said Example,
Various modifications based on the technical idea of the present invention are possible. For example, the growth of the InAs layer 2 and the GaAs layer 3 may be performed by MBE. Further, the InAs layer 2 may be grown by the two-stage growth method described above. That is, first, for example, at a low temperature of about 400 ° C., for example, a thin amorphous In having a thickness of about 100 to 300 °
After growing an As layer and annealing it at, for example, about 500 to 550 ° C. to cause solid phase epitaxy and single crystallization, for example, 50 Å is formed on the single crystallized thin InAs layer.
A single crystal InAs layer having a required thickness at about 0 to 550 ° C. may be formed. Further, the thickness of the InAs layer 2 may be reduced to about several atomic layers. Further, instead of the InAs layer 2, for example, an InP (lattice constant = 5.8688Å) layer may be used as a buffer layer. In addition, instead of the Si substrate 1, a substrate made of various materials such as a quartz substrate, a sapphire substrate, a SiC substrate, and a glass substrate can be used. Furthermore, in the above embodiment, the case where the GaAs layer 3 is formed on the Si substrate 1 has been described. However, the present invention can be applied to the case where various compound semiconductor layers other than the GaAs layer 3 are grown. According to the present invention, a semiconductor layer having a smaller lattice constant than the buffer layer is grown on the buffer layer.
A semiconductor substrate in which a high-quality semiconductor layer is provided over various substrates such as a quartz substrate, a sapphire substrate, and an SiC substrate can be obtained, and a high-performance semiconductor device using the semiconductor substrate can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are sectional views for explaining a method of forming a semiconductor substrate according to an embodiment of the present invention in the order of steps. Description of main reference numerals in the drawings: 1: Si substrate, 2: InAs layer (buffer layer), 3: GaAs layer (compound semiconductor layer).

Continuation of front page       (56) References JP-A-61-210675 (JP, A)                 JP-A-62-11221 (JP, A)                 JP-A-62-229821 (JP, A)                 JP-A-62-291909 (JP, A)

Claims (1)

(57) [Claims] A semiconductor substrate comprising: a Si substrate; a buffer layer made of InAs on the Si substrate; and a GaAs layer on the buffer layer. 2. A quartz substrate, a sapphire substrate or a SiC substrate; a buffer layer on the quartz substrate, the sapphire substrate or the SiC substrate; and a semiconductor layer formed on the buffer layer and having a smaller lattice constant than the buffer layer. Semiconductor device. 3. A quartz substrate, a sapphire substrate, or a SiC substrate; a buffer layer on the quartz substrate, the sapphire substrate, or the SiC substrate; and a compound semiconductor layer formed on the buffer layer and having a smaller lattice constant than the buffer layer. Semiconductor device. 4. On a semiconductor substrate having a quartz substrate, a sapphire substrate or a SiC substrate, a buffer layer on the quartz substrate, a sapphire substrate or a SiC substrate, and a compound semiconductor layer formed on the buffer layer and having a smaller lattice constant than the buffer layer A semiconductor device, wherein an optical semiconductor element is formed on the semiconductor device. 5. In a method for manufacturing a semiconductor device wherein a semiconductor layer having a lattice constant different from that of a substrate made of quartz, sapphire or SiC is epitaxially grown, a step of forming a buffer layer on the substrate; Epitaxially growing a semiconductor layer having a lattice constant smaller than that of the buffer layer.