JPS621225A - Semiconductor wafer - Google Patents

Abstract

PURPOSE:To grow an InP crystal having excellent quality by forming an intermediate layer consisting of an insulating single crystal by the fluoride of CaF2, BaF2, SrF2, etc. or their mixed crystals between an Si substrate and an InP epitaxial layer. CONSTITUTION:Laminated structure using CaF2 (a lattice constant of 5.46Angstrom ), SrF2 (a lattice constant of 5.80Angstrom ) or BaF2 (a lattice constant of 6.20Angstrom ) as an insulating single crystal capable of lattice-matching with Si (a lattice constant of 5.43Angstrom ) and InP (a lattice constant of 5.87Angstrom ) or their mixed crystals CaxBa1-xF2, CaxSr1-xF2, etc. is formed as an intermediate layer between an Si substrate and an InP epitaxial layer, thus shaping an excellent InP epitaxial layer. A superior InP crystal not acquired by directly forming InP onto the Si substrate can be obtained by employing such as intermediate layer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a semiconductor wafer structure for obtaining a high quality InP single crystal on an St substrate.

<Summary of the Invention> The present invention provides that when growing an InP single crystal on a St substrate, fluoride (CaF2, BaF2) is grown as an intermediate layer.
By using an insulating single crystal of InP (InP) or a mixed crystal thereof, it is possible to grow a high-quality InP crystal.

<Prior art> ■-V group compound semiconductors have optical and electrical properties that cannot be obtained with -■ group element semiconductors (Si, Ge), etc., and LEDs are one of their characteristic devices. (light emitting diode), LD (laser diode), and other electroluminescent devices; and electronic devices such as high-speed FETs, Gunn diodes, and Hall elements. Conventionally, such devices have been fabricated by performing processes such as epitaxial growth on crystalline substrates of ■-V group compound semiconductors (GaAss InPSGaP, etc.), and bulk crystals of IV group compound semiconductors are always required. Become. This bulk crystal has a low yield due to the difficulty of crystal growth, is very expensive, and so far only 2-inch shapes have been obtained, and it is difficult to increase the area. is also in a difficult situation. Furthermore, in the future,
As high-performance devices, three-dimensional circuit elements and functionally separated devices (the signal receiving part is made of ■-■ compound, the signal processing part is made of S
Even when considering the development of devices such as those that i have, it is possible to
Forming a V group compound and further electrically isolating the lower layer and the upper layer through an insulating layer between the St and the -V group compound are important semiconductor element formation techniques.

The present invention employs MOCVD, which enables the formation of multilayer thin films, as a method for growing a -v group compound on the above-mentioned Si single crystal.
InP is epitaxially grown on a Si single crystal substrate by various growth methods such as the method or the MBE method.

<Problems to be solved by the invention> When epitaxially growing InP on a Si substrate, there is a lattice mismatch of about 8%, and there is a problem with anti-7 when growing a diatomic compound on a monoatomic crystal. The occurrence of AIDS ψ domains17 makes crystal growth difficult.

Means for Solving the Problems> Therefore, in the present invention, lattice matching is provided between St (lattice constant 5.43A) and InP (lattice constant 5.87A) as an intermediate layer between the Si substrate and the InP epitaxial layer. It is an insulating single crystal that can be formed (:aF2 (lattice constant 5.46A)
, 5rFz (lattice constant 5.8OA), B aF2 (lattice constant 6.2OA) or its mixed crystal Ca x B a i
-xF2, CaxSr1□xF2, etc. are used to form a laminated structure to form a high quality InP epitaxial layer.

<Example> A first embodiment is shown in FIG.

This wafer structure consists of Si as an intermediate layer 2 on a Si substrate l.
CaFz2t (film thickness 500
The final InP single crystal layer 3 is obtained by forming 5rFz2z (film thickness: 5000 to 100 OOA) with a small mismatch rate with InP.

Further, FIG. 2 shows a second embodiment.

As the intermediate layer 12 between the Si substrate 11 and the InP growth layer 13, a CaF2 layer 121 and a Ca xI Ba 1-
x IF2 layer 122 and CaX 2B a 1-X 2
F2 layer 123 composition gradient layer (1>xi>x2
>0) to achieve lattice matching with InP13 and obtain a high quality single crystal epitaxial layer.

In addition, lattice matching with InP can be made possible by using a multilayer film of compositionally graded layers grown by gradually changing the composition ratio X of CaxBa□-xF2 as an intermediate layer structure.

<Effects of the Invention> By using the intermediate layer structure according to the present invention described above, it is possible to obtain a high-quality InP crystal that cannot be obtained by directly forming InP on a Si substrate. Such semiconductor wafers and growth techniques will be extremely useful in supplying large-area, low-cost InP substrates, and in realizing complex devices such as functionally divided devices.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing an example of an InP single crystal wafer formed on a Si substrate. Explanation of symbols 1: St single crystal substrate, 2: fluoride intermediate layer, 2t: C
aFz, 22: SrF2.3:InP growth layer, 11
:St single crystal substrate, 12:Fluoride intermediate layer, 121:C
aFz,i22: Cax1Srl-x1F2.1
23 e CaxzS r 1-X 2 F 2.13
m InP growth layer. I-P autopsy person 2 types ↓ ↓ stupid ヰ (l yuriri) sa →
Ze! B's 17th call? Figure 1 Figure 2

Claims (1)

[Claims] 1. Ca between the Si substrate and the InP epitaxial layer
A semiconductor wafer comprising an intermediate layer made of an insulating single crystal of a fluoride such as F_2, BaF_2, SrF_2 or a mixed crystal thereof.