JPH02177320A - Manufacture of hetero epitaxial thin film - Google Patents

Abstract

PURPOSE:To obtain a hetero epitaxial film of low transition density by a simple method by growing a buffer layer, to which n-type or amphoteric impurity high concentration is added, on a substrate, and then growing a desired epitaxial layer on the buffer layer. CONSTITUTION:First, the surface of an Si substrate 1 is cleaned. Next, a buffer layer, to which n-type or amphoteric impurity in concentration of 10<18>cm<-3> or more is added, for example, GaAs buffer layer 2, to which In is added by 2X10<19>cm<-3>, is grown on this substrate 1. Next, a desired epitaxial layer, for example, a GaAs layer 3 is grown on the layer 2. Hereby, a hetero epitaxial film of low transition density can be made without adding distorted superlattice or applying heat treatment.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a heterogeneous taxial thin film.
More specifically, the present invention relates to a method for manufacturing a heteroepitaxial thin film having a low lattice defect density and having a lattice constant significantly different from that of a substrate.

[Prior Art] Until now, the growth of a GaAs thin film on an epitaxial film with a lattice constant significantly different from that of the substrate, for example, a 81-substrate, has been
, : MOCV D method, MBE method etc. ff1(,N,
This is done using a method called the two-step growth method. In this method, a thin buffer layer is first grown at a low growth temperature. Misfit dislocations are generated at the interface between the buffer layer and the substrate, the stress due to the difference in lattice constant between the epitaxial layer and the substrate is relaxed, and the lattice of the buffer layer 7 returns to its original lattice. Therefore, an epitaxial layer can be easily grown on this buffer layer at a normal high temperature growth temperature.

[Problems to be Solved by the Invention] However, the epitaxial thin film grown in this manner has a very large number (109 to 108.-2) of dislocations. In order to reduce the dislocation density in this epitaxial T-layer, attempts have been made to add a strained superlattice during epitaxial layer growth and to perform heat treatment after growth. Epitaxy
In the Le layer, the dislocation density is about 106 cm-2.

However, adding a strained superlattice or performing heat treatment has the drawback of making the method for manufacturing the heteroepitaxial layer extremely complicated.

An object of the present invention is to provide a simple method for manufacturing a heteroepitaxial thin film with a low dislocation density, which solves these problems.

[Means for Solving the Problems] The present invention provides a method for manufacturing a heteroepitaxial M film, which comprises performing heteroepitaxial growth on a substrate having a different lattice constant. This is a method for producing a heteroepitaxy X/layer thin film, which comprises growing a buffer layer doped with impurities and then growing a desired epitaxial layer on the buffer layer.

[Function] Most of the misfit dislocations that occur between the GaAs epitaxial layer and the substrate occur when the substrate is in the (100) plane.
It is a pure edge dislocation with Burgers vector parallel to the plane a/2<110>. On the other hand, when the lattice constant of GaAS is a, the Burgers vectors of dislocations in the epitaxial layer include those of a/2<110> and those of a/2<011> lying on the (m) plane. Therefore, it is considered that the dislocation where the Burgers vector is a/2<110> corresponds to the portion where the end of the short Swift dislocation penetrates into the upper part of the epitaxial layer. On the other hand, Burgers Betta 1~
Dislocations with a le of a/2<011> are slip dislocations, and most of them are considered to have occurred due to local stress concentration during epitaxial layer growth.

Therefore, if the yield stress of the crystal in the buff 7 layer can be increased, that is, if dislocations can be made less likely to occur, then at least the Burgers vector will be a/2<01
It is considered that the occurrence of slip dislocations of 1> can be considerably suppressed. A method to increase the yield stress of GaA'S is to increase the yield stress of GaA'S by adding n-type impurity atoms or isoelectronic impurity atoms such as In to 1018 cm-3 during bulk crystal growth.
It is known that this can be achieved by adding it to a high temperature (Journal of Applied Fixtures).

, 19. 822 (1978)). Therefore, if a similar method is applied to the growth of a buffer layer in an epitaxial layer, the dislocation density in the buffer layer can be reduced, and furthermore, the density of dislocations propagating upward in the epitaxial layer grown on it can be reduced. Can be done.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

In this example, a GaAs1 film is formed on a Si substrate using an MO
A method of growing by CVD method will be explained.

FIG. 1 is a schematic cross-sectional view of the heteroepitaxial layer obtained in this example. First, Si substrate 1 is
The surface was cleaned by placing it in arsine diluted with hydrogen at 0C for 2 minutes.

Next, the substrate temperature was set to 420°C, and Ga (C113) 3
, In (Cf13) 3, using Ast13 as raw material, I
2 x 1019 cm' of film thickness 100 G
AAs buffer M2 was grown. Next, increase the substrate temperature to 750
℃, and a GaAs layer 3 having a thickness of 2tIIn was grown.

When the surface of the GaAs layer 3 thus grown was etched with molten KOH at 360 DEG C. for 20 seconds, the dislocation density was found to be 106 Ctn-2.

Note that in this example, G was used as the epitaxial thin film.
Although the description has been made using aAs as an example, the present invention can also be applied to the production of various epitaxial thin films such as InP.

[Effect of the invention 1 As explained above, the dislocation density in the epitaxial layer produced by the method of the present invention is 1
It has been reduced to 1/02 to 103 times, and without adding a strained superlattice or heat treatment as in the past,
A heteroepitaxial film with a low dislocation density can be manufactured by a simple method.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a heteroepitaxial layer 17 according to one embodiment of the present invention. 1...Si substrate 2...GaAS buffer layer 3...GaAs layer

Claims (1)

[Claims] (1) In a method for manufacturing a heteroepitaxial thin film that involves performing heteroepitaxial growth on a substrate with a different lattice constant, a buffer doped with n-type or amphoteric impurities at a concentration of 10^1^8 cm^-^3 or more is added on the substrate. 1. A method for producing a heteroepitaxial thin film, which comprises growing a desired epitaxial layer on the buffer layer after growing the layer.