JPS62158314A - Substrate for compound semiconductor single-crystal thin film - Google Patents

Abstract

PURPOSE:To obtain a compound semiconductor substrate of large area showing little transformation, by superposing a thin film of silicon-germanium mixed crystal (Si1-xGex, 0<=x<=1) and a thin film of silicon-germanium (Si1-yGey, 0<=y<=1) different in composition from the former to form a strain superlattice on a silicon substrate. CONSTITUTION:A thin film 102 of Si1-xGex(0<=x<=1) and a thin film 103 of Si1-yGey(0<=y<=1, xnot equal to y) being different in composition from Si1-xGex are superposed sequentially on a single-crystal Si substrate 101, so as to form a strain superlattice. In the strain superlattice, the thin film 102 having a large amount of Si is formed immediately on the single-crystal Si substrate 101, and the thin film 103 having a large amount of Ge is formed as the final thin film of the lattice, respectively. Each film has a very thin superlattice structure, and therefore an internal stress is relaxed by each thin film. Therefore, a transition point does not appear, and thus a single-crystal substrate having a surface of crystal being substantially in accord with the lattice constant of a compound semiconductor of GaAs, ZnSe or the like can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a single crystal substrate for forming a single crystal thin film of a l-V group compound semiconductor such as GaAs and a single crystal thin film of a Zn5en-Vl group compound semiconductor. 0 [Summary of the Invention] The present invention relates to a single crystal substrate for forming an l-V group compound semiconductor single crystal thin film such as GaAs and a Zn5el-Vl group compound semiconductor single crystal thin film, on a single crystal silicon semiconductor substrate. S i 1-) (Gex (0≦x≦1) ultrathin film and 5it-yGe)'(0≦y≦1*xsy)'? H
By forming a strained superlattice formed by sequentially and repeatedly stacking films, the lattice constant of GoAs (5,6565λ) or the lattice constant t! of Zn5e can be changed. 1 (5,667A) on the surface, and the strained superlattice relieves the internal stress caused by the difference in lattice constants, resulting in dislocation defects. This makes it possible to provide a large-area single-crystal substrate with a small amount of damage.

[Conventional technology]

Conventional compound semiconductor single crystal thin film substrates are made of GaAs + In, which has a lattice constant close to that of the thin film.
A single crystal substrate such as P was used.

Or, I, E-E-E, Electron Device, Letters (I, E-E-Electro
1984 ED of nDevice Letters) magazine
As seen in the paper described in Vol. D-5, page 207, a method is used in which Ge is formed as an intermediate layer on a single-crystal Si substrate, and a compound semiconductor single-crystal thin film such as Ga'As is formed thereon. was.

[Problems and objects to be solved by the invention] However, in the above-mentioned conventional technology, when using a single crystal substrate such as GaAS or InP, it is necessary to manufacture single crystal materials of elements with different vapor pressures. L<, it is not possible to make a large single crystal substrate, and there are many transition points on the surface of the single crystal substrate, defects occur in compound semiconductor thin films such as GaAs grown on this substrate, and light emitting elements, When manufacturing devices such as FETs, there have been problems such as extremely low yields or high unit costs of single crystal substrates, increasing device manufacturing costs.

In addition, a substrate formed by forming a Ge single crystal thin film as an intermediate layer on a single crystal Si substrate is cheaper than a single crystal St substrate and can be manufactured with a large area. It has the advantage of having no transition point, but the lattice constant of Si single crystal is 5.43071, and the lattice constant of Ge single crystal is s.
, 6 sy 4 A, the lattice constant mismatch is large, and the surface of the Ge single-crystal thin film has the problem of a large number of transition points.

The present invention is intended to solve these problems, and its purpose is to create a substrate for compound semiconductor single crystal thin films that is inexpensive, can be made into a large-area substrate, and has an extremely low transition point on the substrate surface. It's there to provide.

[Means for solving problems]

The compound semiconductor single-crystal thin film substrate of the present invention includes a 5il-XGex (0≦x≦1) thin film and a 5ii-yGey having a different composition from the 5i1-zGex on a single-crystal silicon substrate.
(0≦y≦1.
, o≦x(0,5), but the final thin film of the strained superlattice has a germanium-rich thin film (Si1-yGey, 0.5<y≦
1) It is characterized by a force of 4A.

[Effect]

When growing a single crystal thin film on a substrate, if there is misalignment in the lattice constant, internal stress will occur in the film and as the film becomes thicker, the elastic limit will be exceeded and a transition point will occur. , according to the above configuration of the present invention, 5il-zGex and S
There is a lattice constant mismatch between the i The stress is relaxed in each thin film, and a transition point does not occur, resulting in a good quality film, and the final Ge thin film with a superlattice structure
Since the composition can be almost 1, GaAs + Zn5
It is possible to produce a single crystal substrate having a crystal surface that almost matches the lattice constant of a compound semiconductor such as e.

〔Example〕

FIG. 1 is an example of a main cross-sectional view of a compound semiconductor single-crystal thin film substrate in an embodiment of the present invention, in which (101) is a single-crystal Si substrate, and directly above it is SiO, 6Ge.
[The mixed crystal thin film (102) of L4 is formed with a film thickness of 10 to 100λ. □After that, a mixed crystal thin film (106) of SiO, IGe (19) is formed with a film thickness of 10 to 100λ, and thereafter (102).

(103) is a cross-sectional view when 10 to 100 thin films of (103) are alternately and repeatedly layered. The final surface thin film is (103)
The composition has a large amount of QEl. Each St 1
The composition of the -xGex thin film is 0.1 < x < 0.5 for the thin film corresponding to the (102) layer, and the composition of Six -yGey *I equivalent is 0.5 < y for the thin film corresponding to the (103) layer.
It is possible to form a film within the range of <1.0. These S i 1-
The zGex layer can be formed using pyrolytic chemical vapor deposition, molecular epitaxy, ion cluster beam method, etc., but pyrolytic chemical vapor deposition, which can easily form a film on a large area substrate, is possible. The growth method has many advantages.

However, in the pyrolytic chemical vapor deposition method, when formed at a high substrate temperature, a diffusion phenomenon of Ge atoms occurs and it is often difficult to fabricate a superlattice structure. Hydrogenated silicon (SinH21-4-2+ n
-z + 3 + 01. ) etc. raw materials -) f Select f
It is necessary to

Figure 2 shows Six manufactured by the above-mentioned pyrolysis chemical vapor deposition method.
This is an example in which the concentration distribution of Si atoms and Ge atoms in the strained superlattice in the film thickness direction was measured using Auger electron spectroscopy. Because it is grown at a low substrate temperature of 830°C to 900°C, it is possible to ensure the steepness of the composition at each interface, and the superlattice structure alleviates lattice constant mismatch.
A substrate surface with almost no pine transfer was obtained.

FIG. 3 shows a compound semiconductor single crystal thin film substrate manufactured using the present invention. 1 is a cross-sectional perspective view of an example of an AAGaAa/GaAs double p-heterojunction semiconductor laser; FIG. (3
On the n-type single crystal Si substrate of (02), the n-type 5 of (303)
A il-zGex strained superlattice is formed, and then (304
) n-type AAGaAs.

(305) mon-doped GaAs active layer, (
506) P-type AlGaA, s, (so7) P-type Ga
AJ layer lla next, liquid phase epitaxial method, MO-C
It is grown by a compound semiconductor thin film growth method such as the VD method or the 'MBE method. In this case, MO can be grown uniformly over a large area.
-CVD method has many advantages.

After that, an insulating film such as sio, 1si3N4, etc. is formed, and P-type GaAs is formed into stripes by photolithography.
(30B) is formed by a step in which the film surface is exposed,
The main structure of the semiconductor laser was fabricated by depositing electrodes that could provide ohmic contact on the front surface and the back surface of the Si substrate. Since a large-area substrate of 3 inches to 5 inches with a low transition point can be obtained, many semiconductor chips can be obtained in one manufacturing process.In terms of characteristics, it is also possible to manufacture on a conventional single-crystal substrate such as GaAS. A product comparable to that of a semiconductor laser was obtained.

〔Effect of the invention〕

As described above, according to the present invention, S 11-xGe
By forming the x-strained superlattice on the Si substrate, it is possible to provide a large-area compound semiconductor substrate with few dislocations.

Furthermore, since single-crystal Si substrates can be manufactured in large-area substrates such as 6-inch and 8-inch diameters, a large number of light emitting devices and integrated circuits can be manufactured.
Since it can be obtained at low cost, it has the effect of significantly reducing the cost of manufactured devices.

Furthermore, it is possible to create integrated circuits in which Si elements and compound semiconductor elements such as GaAS are mixed, so the electrical drive is carried out by the Si element, and the optical drive parts such as light emission and light reception are carried out by the GaAs-based elements. - It has the effect that it is easy to realize an electrical integrated circuit (OEIC).

[Brief explanation of drawings]

FIG. 1 is a main cross-sectional view of a compound semiconductor single crystal thin film substrate according to the present invention. FIG. 2 is a distribution diagram of the atomic number concentration of Si+Ge valley elements in the film thickness direction of the compound semiconductor single crystal thin film substrate according to the present invention. FIG. 3 is a main cross-sectional perspective view of a semiconductor laser manufactured using the compound semiconductor single crystal thin film substrate according to the present invention. (101)...Single crystal Si substrate (102)-8i1-xGeXA'J film (0≦x<0.
5)(103)-8it-yGOX 'I'Jp film (0,5(y≦1)(302)...n-type single crystal Si substrate (303)/n-type 5tl-) (Gex strained superlattice More than a layer of Nyogogyuan lacquer gI Yuaki (7) 1 m base 14 eaves 1 figure 2 3 ρ 2.1 Done even piece S Keyaki Chonobu book line spear) Enkigo No. 3 figure

Claims (1)

[Claims] In a compound semiconductor single crystal thin film substrate for forming a III-V group and II-VI compound semiconductor single crystal thin film, a silicon-germanium mixed crystal (hereinafter, Si_1_-_xGe_x, 0≦ x≦1) thin film, and a silicon germanium (Si_1_−_yGe_
A strained superlattice is formed by sequentially stacking thin films (y, 0≦y≦1), and in the strained superlattice, a thin film with a large amount of silicon (Si
_1_−_xGe_x, 0≦x≦0.5), but the final thin film of the strained superlattice contains a thin film with a large amount of germanium (Si_1
A substrate for a compound semiconductor single crystal thin film, characterized in that _-_yGe_y, 0.5<y≦1) are formed.