JPH0521361A - Growing method for compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To provide a method for growing a compound semiconductor crystal having excellent crystallinity on a porous silicon substrate. CONSTITUTION:A method for growing a compound semiconductor crystal comprises the steps of making a surface of a silicon single crystalline substrate inclined at an angle of 4 deg. or more from a plane (100) in a direction <011> porous by an anodizing method, etc., in a fluoric acid solution, and then crystalline growing it.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for growing a compound semiconductor crystal on a porous silicon substrate. As a compound semiconductor grown on a silicon substrate, for example, G
Binary III-V group compound semiconductors such as aAs, GaP, InP, AlGaAs, AlGaP, InAlAs, I
III-V of ternary system such as nAlP, GaAsP, GaInP
Group compound semiconductors, and II-V such as ZnS and ZnSe
It is selected from Group I compound semiconductors. Further, these compound semiconductors can be stacked.

[0002]

2. Description of the Related Art Generally, many attempts have been made to grow a compound semiconductor such as GaAs on a single crystal substrate from the viewpoint of cost reduction and hybridization. However, there is a difference in the physical properties between the compound semiconductor and silicon (lattice mismatch, difference in thermal expansion coefficient, the problem of growing a polar substance on a non-polar substance, etc.), so it differs from the normal growth method. A method is needed. For example, methods such as two-step growth, thermal cycle annealing and strained superlattice have been used to grow a single crystal thin film of a compound semiconductor, which is a different material, on a silicon substrate.

[0003]

However, the above-mentioned method using a silicon substrate has a problem that the crystallinity of the grown thin film is inferior to that in the case of growing it on a compound semiconductor single crystal substrate. That is, the problems such as dislocations, residual stress, and warpage that occur due to the differences in physical properties described above cannot be completely solved. Taking dislocation density as an example, GaAs obtained by the LEC method is used.
The dislocation density of the substrate is about 10 ⁴ cm ^-2 , whereas the GaAs crystal thin film grown on the silicon substrate is 10 ⁶ cm.
^It shows a fairly high value of ^-2 .

When a compound semiconductor is grown on a porous silicon substrate, strain due to lattice mismatch can be relaxed and grown, and the introduction of misfit dislocations can be prevented. In addition, porous silicon has a Young's modulus of about 1/10 of that of ordinary silicon, which is highly flexible, and the contact area between the thin film and the substrate can be reduced. So, for example,
Even in a combination of III-V group compound semiconductor and silicon, which have greatly different thermal expansion coefficients, the strain between the two substances can be absorbed in the porous portion, and the dislocation and residual stress of the compound semiconductor layer can be significantly increased. Can be reduced.

Therefore, the present invention solves the above-mentioned drawbacks,
An object of the present invention is to provide a method for growing a compound semiconductor crystal having less dislocations and residual stress on a porous silicon substrate.

[0006]

The present invention provides a method for growing a compound semiconductor crystal on a porous silicon substrate,
Is a method of growing a compound semiconductor crystal, characterized by using the surface of the silicon single crystal substrate is inclined to 4 ⁰ or more angles <011> direction from a (100) plane in porous to crystal growth.

As a method for making the surface of the silicon substrate porous, an anodization method in a hydrofluoric acid solution is preferable. The thickness of the porous layer is not particularly limited, for example,
0. It can be formed with a thickness of several μm to several hundred μm. The pore diameter of the porous layer is, for example, about 20 to 300Å.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention, by performing the growth of a compound semiconductor crystal from the porous and <011> of a silicon single crystal substrate is inclined to 4 ⁰ or more angles to the direction, the surface of the substrate from (100) plane This improves the crystallinity.

T. Ueda, et al. Jpn. J. Appl. Phys. 25 (1986) L
For 789, <011> from the (100) plane of the silicon substrate.
By crystal growth 3-4 ⁰ tilted on the plane in the direction,
It is described that the crystallinity is improved. In this method, by tilting the plane orientation,
One of the types of domains becomes dominant and the crystallinity is improved.

However, when a porous silicon substrate is used, the surface shape and growth mechanism are different. According to the study by the present inventors, the tilt angle of 3-4 ⁰ could not wishing to sufficiently improve the crystallinity. However, the tilt angle of 4 ⁰
It was found that the crystallinity is improved by using the above porous silicon substrate.

[0011]

(Example) (100) of a silicon single crystal substrate
6 ⁰ inclined surface in the <011> direction from the surface to form a porous layer having a thickness of 30μm by anodization in hydrofluoric acid solution, then, along the growth profile of FIG transferred to the reactor initially 420 ° C. To 150 Å by OMVPE method
GaAs thin film was grown, then heated to 550 ° C., a GaAs thin film with a thickness of 2.5 μm was grown by the OMVPE method, and further heated to 650 ° C., a GaAs thin film with a thickness of 2.5 μm by the OMVPE method. Has grown up.

(Comparative Example 1) (10) of a silicon single crystal substrate
0) except having 3 ⁰ inclined surface in the <011> direction from a plane were grown GaAs thin film under the same conditions as in Example.

(Comparative Example 2) (10) of a silicon single crystal substrate
0) 3 ⁰ tilted substrate surface <011> direction from a plane 10
After cleaning at 00 ℃, cool down to 420 ℃, and
A GaAs thin film having a thickness of 150 Å was grown by the MVPE method, further heated to 650 ° C., and a GaAs thin film having a thickness of 5.0 μm was grown by the OMVPE method.

(Evaluation of Photoluminescence) With respect to the GaAs thin films obtained in the above Examples and Comparative Examples, the peak intensity of photoluminescence was compared, and the Ga obtained in the Examples was compared.
The As thin film was 4 times as thick as the thin film of Comparative Example 1 and about 2 times as thick as the thin film of Comparative Example 2, and the crystallinity was improved.

[0015]

According to the present invention, by adopting the above structure, it becomes possible to grow a compound semiconductor crystal having excellent crystallinity using a porous silicon substrate.

[Brief description of drawings]

FIG. 1 is a diagram showing a growth temperature profile adopted in an example of the present invention.

FIG. 2 is a diagram showing a growth temperature profile adopted in Comparative Example 2.

Claims (2)

[Claims] 1. A method for growing a compound semiconductor crystal on a porous silicon substrate, wherein <011 is obtained from the (100) plane.
> Method of growing a compound semiconductor crystal, characterized by the use of 4 ⁰ or more angles inclined surface of the silicon single crystal substrate in a direction in porous to crystal growth. 2. The method for growing a compound semiconductor crystal according to claim 1, wherein the surface of the silicon single crystal substrate is made porous by an anodization method in a hydrofluoric acid solution.