JPS61106495A - Si substrate grovided with single crystalline thin film of group iii-v compound and production thereof - Google Patents

Abstract

PURPOSE:To form the high-quality GaAs on an Si substrate by forming a thin film layer of ultralattice structure of group III-V compd. before forming GaAs or the group III-V compd. which is lattice-matched therewith on the Si substrate. CONSTITUTION:The following single crystalline Si substrate is produced wherein one piece of coupling hands forming a bond site of Si has the crystal orientation existing parallel to the substrate. A multilayered structure of thin film layer of ultralattice structure which consists of a single crystalline thin film of solid solution having two compositions of Ge and Si series is formed on the substrate. The average value of lattice number of two solid solutions forming the ultralattice structure is made close to the lattice constant of the small hand between two solid solutions by which the ultralattice structure positioned in the upper side is formed. Furthermore the thin film layer of ultralattice structure of group III-V compd. is formed thereon and the single crystalline thin film layer of group III-V compd. is formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a 51 substrate provided with an m-v compound single crystal thin film and a method for manufacturing the same.

(Conventional structure and its problems) Single crystal GaAs and G are deposited on single crystal Ge and Si, respectively.
Attempts to epitaxially grow aP have shown that the lattice mismatch between the two materials is 0.1% and 0.37%, respectively.
%, and the bandgaps of GaAs and GaP are larger than those of GegSi, so in addition to being promising as a hetero bipolar transistor using them as an emitter, there are many industrially useful uses of the formed GaAs and GaP. It has been used in many ways since ancient times due to its various uses. However, in this system, unlike epitaxy between ■-■ compounds, there were difficult problems that could not be solved by lattice matching alone; an extremely large number of defects such as antiphase structures, twins, and dislocations occurred, and crystal growth did not go well. . In recent years, the cause has become much clearer. First, 197
In 1989, when polar m-v compounds such as GaP and GaAs are epitaxially grown on non-polar diamond-structured materials such as Si and Ga, charges occur at the interface depending on the crystal orientation (for example, ( 1003,
(111)).

It was pointed out that this charge is large enough to have a sufficient effect on the band structure and crystal growth, and since this charge does not occur in (11G), it is suitable for devices and crystal growth. [￥, A, Harrison atal
, Phys. Rev. B 18, 4402 (1978)
).

Then, in 1982, it was discovered that in these epitaxies, not only did interfacial charges not occur, but also where the group ■ and group ■ atoms of the ■-■ compound bonded to the sites of the underlying diamond structure crystal. It has been pointed out that determining the site allocation of group ■ and group ■ atoms is extremely important in order to avoid the occurrence of anti-topological structure, which is a serious problem. Ta. Then, Si,
One of the four bonding hands that make up the bonding site of a crystal with a diamond structure such as Ge exists parallel to the substrate, and one of the four bonding hands exists parallel to the substrate, and the site is oriented upward from the substrate. The crystal plane consists of two types of sites: a site that rests on the bond of The most promising and simplest crystal plane is shown in Figure 1 (211
) was pointed out to be a crystal plane (S, vright
etal, J.

Vac, Sci, Technol, 21,534 (
1982)) @Figure 1 is a diagram of the diamond structure of Si, Ge, or their respective solid solutions viewed from the (11G> direction. 1 is a diagram showing the diamond structure of Si, Ge, or their respective solid solutions viewed from the (11G> direction. Bonds are parallel, 2 is a Si bond site on two bond hands going from the bottom to the top of the substrate, 3 is a Si bond site on two bond hands going from bottom to top of the substrate. show.

Since this crystal plane consists of two qualitatively different types of sites, it is expected that group (1) and group (2) atoms will selectively bond to each site. And actually,
Using a Si(211) substrate, GaP was epitaxially grown by molecular beam epitaxy, and the proposed theory was proven to be correct. As a result, for the first time, GaP with a mirror surface and no anti-phase structure can be formed on a Si substrate.
A single crystal thin film layer was formed. Using this heterostructure, a heterobipolar transistor with the highest ever β value of β=9 was created, but this characteristic was still not sufficient for a transistor. This is because many crystal defects other than the antiphase structure are still included. fact,
There were many parallel linear microstructures on the surface, indicating the presence of internal defects. However, this method solves two fundamental and important problems: eliminating interfacial charges and eliminating the most serious problem, the generation of antiphase structures. If crystal defects other than those caused mainly by lattice mismatch can be removed, we can expect to create a Si substrate with a high-quality GaP single crystal thin film.e When forming GaAs on Ga, , since the lattice mismatch is much smaller than in the case of Si and GaP.

Although better crystal growth can be expected than when forming GaP on Si using a substrate with the above-mentioned crystal orientation, a major problem with single-crystal Ge substrates is that it is difficult to clean the surface. Met.

In this case, even if the problems of interfacial charge, site allocation, and lattice matching are solved, various defects occur because it is difficult to clean one surface.

Commonly used (100), (111) and (
11G) and other materials having a diamond structure, such as Si and Ge, have the following problems. (
In the case of 100) and (111) substrates, ■
- When a compound is formed, a charge is generated at the interface, and since the surface is composed of sites of the same type, the site allocation of group ■ and group ■ atoms is not determined, making crystal growth difficult. If a method is found to solve the site allocation problem and good crystal growth is achieved, it will be possible to apply the formed ■-■ compound to devices, but the interface with the underlying non-polar material will be Since a charge is generated, it is not suitable for devices using this interface. In the case of a (110) substrate, no interfacial charge occurs, but the site allocation of group II and group V atoms is not determined. , it is difficult to grow single crystal films with few defects. (110) If some method is found to solve site allocation in the substrate, interfacial charges will not occur, so There are various applications such as devices that use a heterostructure with other materials and devices that use the formed ■-■ compound material as a substrate. Using these crystal planes, GaA of a certain quality can be produced.
Although there are reports that s is formed, it is not sufficient because crystal growth is difficult in principle as described above.

Also, since the GaAs single crystal substrate is at high temperature.

Attempts have been made to grow GaAs epitaxially on inexpensive Si single crystal substrates, but in this case, in addition to problems of interfacial charge and site allocation, the large lattice defect of 4.1% between GaAs and Si. Growth was made more difficult because of the added problem of alignment.

(Objective of the Invention) An object of the present invention is to form GaAs and a m-v compound single crystal thin film lattice matched to GaAs on a single crystal Si substrate. In addition to solving the problem of interfacial charge and site allocation between the formed ■-■ compound and the underlying diamond structure material, it also solves the large lattice mismatch of 4.1% between GaAs and Si, for example. , a device using GeAt5 as a substrate, and a device integrating these devices with a Si device, etc., and a method for manufacturing the same.

(Structure of the Invention) The Si substrate provided with the m-v compound single-crystal thin film of the present invention and the method for manufacturing the same are provided in a crystal orientation in which one of the four bonds constituting the SL bonding site is parallel to the substrate. Ge-S, including Ge and Si, on a single-crystal Si substrate having
A superlattice structure consisting of a single-crystal thin film of solid solutions of two compositions in the i-based structure is formed by forming a superlattice structure in which the average value of the lattice constants of the two solid solutions constituting the superlattice structure is located on the upper side. The lattice constant of the two solid solutions constituting the superlattice structure should be close to that of the smaller one of the two solid solutions that constitute the superlattice structure, and the lattice constant should gradually increase toward the top so that the lattice constant is sufficiently matched to Ga in the top layer. A superlattice structure composed of ■-■ compounds that is lattice-matched to GaAs is formed so that the lattice mismatch gradually decreases upward; and its manufacturing method.

In addition, a Si (211) substrate is used, and GaAs is used as a superlattice structure thin film layer formed between ■-■ compounds.

A superlattice structure thin film layer composed of AlAs and a Mu#xGaz-x solid solution is used.

Furthermore, a single crystal thin film layer of GaAs or an AaxGai-xAs solid solution is used as the single crystal thin film layer of the compound (1)-(2).

(Description of Embodiments) Embodiments of the present invention will be described based on FIGS. 2 to 7.

Figure 2 shows the relationship between the composition and lattice constant of the GexSil-x solid solution and the relationship between the composition and lattice constant of the constituent components of the superlattice structure thin film layer used in Examples 1 and 2, where the horizontal axis is X and the vertical axis is denotes the lattice constant, and 7 to 7 denote the composition and lattice mismatch of the two solid solutions constituting the lattice structure thin film layer formed in this order from the substrate side.

In FIGS. 3 and 4, 1 is a substrate, 2 is a Si buffer layer, and 3 is a single crystal thin film layer of Gea, 5Sia, and s.

4 is a Si single crystal thin film layer, 5, 6, 7, 8, 9, 10° 11 is a superlattice structure thin film layer corresponding to the numbers 1, 2, 3, 4, 5, 6, and 7 in Fig. 2, respectively. 12 is AI. ,
, Ga, , superlattice structure thin film layer made of As-GaAs, 13 is a GaAs single crystal thin film layer, 14 is A-
A single crystal thin film layer of 6, , Ga, , tAs is shown.

FIG. 5 shows the relationship between the composition of the GexSit-x solid solution and the lattice constant, and the relationship between the composition of the constituent components of the superlattice structure thin film layer used in Examples 3 and 4 and the lattice constant.

The horizontal axis is X, the vertical axis is the lattice constant, and 2 to 6 constitute the superlattice structure thin film layer formed in this order from the substrate side.
In FIGS. 6 and 7, which show the composition and lattice mismatch of two solid solutions, numerals 4 to 4 are the same as those shown in FIGS. 3 to 5.

5 to 10 indicate superlattice structure thin film layers corresponding to 1 to 6 in FIG. 6, respectively, 11 is A+2As-GaAs
12 is a GaAs single crystal thin film layer, and 13 is Al. -2G”@*1μS single crystal thin film layer is shown.

Example 1 A Si (211) substrate (reference numeral 1 in Figure 3) with mirror finish similar to that used in the production of general Si devices.
) The surface of the substrate is first cleaned by the following wet process. After the substrate is degreased and cleaned using trichlorethylene, acetone and pure water, H, O, /H, heated to about 150°C, So, (174) immerse in solution to remove surface dirt, then wash thoroughly with pure water, and then
The oxide film on the surface is removed by immersing it in F/H,O (1/10) solution. After this, thoroughly wash with pure water without exposing it to the atmosphere, and heat the NH4OH/H,O,/H,O
(1/1/10) Protect the cleaned surface by immersing it in a liquid and forming an extremely thin silicon oxide film on the surface. This substrate is packed into a molecular beam epitaxy apparatus and heated to 800°C. As a result, the silicon oxide film formed on the surface is completely removed, and the surface of the Si substrate is cleaned.

Next, a Si buffer layer (numeral 2 in Fig. 3) is epitaxially formed on this substrate (numeral 1 in Fig. 3) using a Si molecule beam produced by an electron beam method, and a Si molecule beam and a resistor are formed on the substrate (numeral 1 in Fig. 3). Using a Ga molecule beam prepared by heating, the lattice constant a=5 corresponding to the symbol 1 in FIG.
．． A single-crystal thin film (number 3 in Fig. 3) with a thickness of about 50 mm of a solid solution having a composition of 545 mm Gee, 1 Sla, and s
A thin film layer (5 in FIG. 3) having a repetitive multilayer structure, that is, a superlattice structure, of a single crystal thin film (4 in FIG. 3) of SL having a film thickness of 0.0 mm is epitaxially formed. The lattice mismatch between the two components constituting this superlattice structure is 2.1%. Then, a thin film layer (6 in FIG. 3) having a superlattice structure of a solid solution having two compositions corresponding to 2 in FIG. 2 is epitaxially formed thereon.

In this case, the lattice mismatch between the components is about 1.7%, and the smaller value of the lattice constant is made equal to the average value of the lattice constants of the two components that make up the lower superlattice structure. It's Nitto. In this way, numbers 1 to 7 in FIG.
Multilayer structure of superlattice structure thin film corresponding to
to 11) are epitaxially formed. In this case, the lattice mismatch between the two components forming each superlattice structure is smaller in the upper layer, as shown in Figure 2.
The average value of the lattice constants of these two components is approximately equal to the smaller lattice constant of the next two components constituting the superlattice structure, and the higher the position, the larger the value becomes. On top of this superlattice structure thin film layer, AI6.30ae
,, about 50 single crystal thin film layers of As (reference numeral 1 in Fig. 3).
2) is epitaxially formed, and a GaAs single crystal thin film layer (reference numeral 13 in FIG. 3) is epitaxially formed thereon using Ga and As molecular beams.

As a result, a QaAs single crystal thin film exhibiting a mirror surface and having few defects is formed.

Example 2 In Example 1, Ale, 5Gae, tAs-G
Superlattice structure thin film layer made of aAs (numeral 12 in Figure 3)
A single crystal thin film (numeral 14 in Fig. 4) having compositions of AI, , 3Ga, , and As is placed on top of the All! , epitaxially formed using Ga and As molecular beams. As a result, A, which similarly shows a mirror surface and has few defects, is also 5Ga11.7
A single crystal thin film of As is formed.

Example 3 As in Example 1, after cleaning the surface of the Si (211) substrate (number 1 in Figure 6), a Si buffer layer (number 2 in Figure 6) is epitaxially formed. . On top of that, as in Example 1, Si and Ge, , Sio
,, a superlattice structure thin film layer consisting of a solid solution (reference numeral 5 in Figure 6)
) is epitaxially formed. On top of that, number 2 in Figure 5
A superlattice structure consisting of a single crystal thin film of a solid solution having two compositions having compositions corresponding to numbers 6 to 6 is epitaxially formed in this order as shown by reference numerals 6 to 10 in FIG. In this case, the average value of the lattice constants of the two solid solutions constituting one superlattice structure is approximately 0.0.
The lattice matching is made to be 2%, and the higher the position, the larger the lattice matching becomes, and the uppermost layer is sufficiently lattice matched to Ge. A superlattice structure thin film layer (11 in FIG. 6) made of AlAs and GaAs is epitaxially formed thereon, and a GaAs single crystal thin film layer (12 in FIG. 6) is further epitaxially formed. As a result, a GaAs single crystal thin film having a mirror surface and few defects is formed.

Example 4 In Example 3, Age, Ga,
, a single crystal thin film of tAs composition (13 in Figure 7) is
a, Epitaxial formation using an As molecular beam. As a result, Ago, a with a mirror surface and few defects.
A Ga6, As single crystal thin film is formed.

The Si (211) substrate used in these examples has one bond parallel to the substrate, as shown by reference numeral 1 in Figure 1, so that other diamond structures can be formed on it. Even if a single-crystal thin film layer is formed and GaAs is formed on it, no charge is generated at the interface, and the site where atoms bond is the site on one bond extending upward from the substrate (the first It consists of two qualitatively different types of sites: the site (number 2) in the figure and the site (number 3 in Figure 1) that rests on the two bonding hands extending upward from the substrate. This substrate is suitable for the purpose of the present invention because it has the characteristic that the site allocation of group V atoms is determined. However, there are various other types of substrates that can meet these objectives, such as those with a crystal orientation in which the (211) direction is tilted with respect to the substrate, which is prepared by rotating around the (In) axis from the state shown in Figure 1. For example, (541), (431), (
It is clear from the principle that a substrate such as 3213 can be used.

As shown in Examples 1 to 3 and Examples 4 and 5, in the formation of a multilayer structure with a superlattice structure, the average value of the lattice constants of two solid solutions (including SL and Ge) forming one superlattice structure is 2 that constitutes the superlattice structure adjacent to it.
The lattice constant is made to be close to that of one of the two components.

Although these differences are small and insignificant, as shown in Examples 3 and 4, there is no particular problem as long as the lattice mismatch is within about 0.2%, which is generally required in epitaxial growth.

In the embodiment, A is applied on the multilayer structure of the superlattice structure thin film layer.
1. , , Ga, , tAs-GaAs system or A11A
A thin film layer with an s-GaAs superlattice structure is epitaxially formed, and this serves as a buffer layer to improve the lattice matching with the ■-■ compound formed on top of it and to alleviate the influence of the underlying layer. is fulfilled.

In addition, the AlxGa1-xAs solid solution has GaA in the entire composition range.
Since it is lattice matched to s, the superlattice structure thin film layer shown in the example becomes an extremely good buffer layer. In addition to the examples,
InxGa, -xP solid solution Inx1yGat-x-y
A - - compound such as a P solid solution has a lattice match with GaAs, so it can be used as a component of a buffer layer of a superlattice structure thin film.

In the examples, GaAs and A are used as the ■-■ compounds.
11a, , Ga, , tAs are used, but in addition to these, ①-■ compounds that lattice match with GaAs, such as AmxGal-xAs in all composition ranges, In in specific composition ranges, Ga1-xPJn, l+2. Ga, -x-, P
Solid solutions can also be used.

In the embodiment, a Si buffer layer is formed on the Si substrate, but this is provided to avoid the influence of the substrate surface as much as possible, and is not necessarily necessary, and is not an essential requirement of the present invention. do not have.

Further, in the embodiment, molecular beam epitaxy is used as the epitaxial method, but other methods such as MOCVD may also be used.

° (Effects of the Invention) According to the present invention, interfacial charges are prevented from occurring, anti-phase structure is prevented from occurring by determining site allocation, GaAs or an m-v compound that lattice matches with GaAs. Before the formation of Si
The lattice mismatch of 4.1% between GaAs or GaAs and a lattice-matched ■-■ compound is replaced by a multilayer structure in which the composition of the superlattice thin film layer of a solid solution of Si and Ge is changed stepwise. The following effects can be obtained by solving the problem by inserting it between the m-v compound layer and the m-v compound layer.

(1) Since high-quality GaAs or a ■-■ compound lattice-matched thereto can be formed on a Si substrate, devices can be manufactured at low cost using expensive ■-■ compounds such as GaAs.

(2) Furthermore, as an effect of using a Si substrate, a new device that integrates the above device and an SL device can be manufactured.

[Brief explanation of the drawing]

Figure 1 is a diagram of the diamond structure of solid solutions such as Sa and Ge, Figure 2 is a diagram of the relationship between the composition and lattice constant of G6X511-X solid solution, and Figures 3, 4, 6, and 7 are diagrams of the present invention. A conceptual diagram of the cross section of the material formed by Ge, S
Relationship between solid solution composition and lattice constant and implementation of i1+! 3
．． 4 is a diagram showing the relationship between the composition of the constituent components of JIMM and the lattice constant. Patent applicant: Matsushita Electric Industrial Co., Ltd. Figure 2 Figure 3 ■ Figure 4 Figure 5 Figure 6 ■ Figure 7

Claims (12)

[Claims] (1) Ge-Si based 2 A superlattice structure consisting of a single-crystal thin film of a solid solution with a composition of The lattice constant should be close to the smaller one of III to be formed and lattice matched with GeAs on top of it so as to become smaller stepwise.
I characterized by having a structure in which a superlattice structure thin film layer composed of -V compounds is formed, and a single crystal thin film layer of a III-V compound lattice-matched to GeAs is formed thereon.
A Si substrate with a II-V compound single crystal thin film. (2) A Si substrate provided with a III-V compound single crystal thin film according to claim (1), characterized in that a Si (211) substrate is used. (3) As a superlattice structure thin film layer formed between III-V compounds, GaAs, AlAs and Al_xGa_1
Claim (1) characterized in that a superlattice structure thin film layer composed of ____x solid solutions is used.
A Si substrate with a III-V compound single crystal thin film. (4) A Si substrate provided with a III-V compound single crystal thin film according to claim (3), characterized in that a Si (211) substrate is used. (5) GaAs as a single crystal thin film layer of III-V compound
Claim (3) characterized in that a single crystal thin film layer of Al_xGa_1_-_xAs solid solution is used.
A Si substrate provided with the III-V compound single crystal thin film described in 1. (6) A Si substrate provided with a III-V compound single crystal thin film according to claim (5), characterized in that a Si (211) substrate is used. (7) Single-crystal Si with a crystal orientation in which one of the four bonding hands constituting the Si bonding site is parallel to the substrate
A multilayer structure of a superlattice structure thin film layer consisting of a single crystal thin film of a Ge-Si solid solution with two compositions, including Ge and Si, is formed on the substrate, and the lattice constants of the two solid solutions constituting the superlattice structure are The average value of is made to be close to the smaller lattice constant of the two solid solutions constituting the superlattice structure located on the upper side, and it increases stepwise in the upper direction so that it is sufficiently lattice-matched to Ge in the top layer, and constitutes a superlattice structure 2
epitaxially forming the two solid solutions so that the lattice mismatch gradually decreases upward, and epitaxially forming a superlattice structure thin film layer formed between GeAs and a III-V compound lattice-matched thereon, A method for manufacturing a Si substrate provided with a III-V compound single crystal thin film, comprising epitaxially forming a GeAs lattice-matched III-V compound single crystal thin film layer thereon. (8) A method for manufacturing a Si substrate provided with a III-V compound single crystal thin film according to claim (7), characterized in that a Si (211) substrate is used. (9) As a superlattice structure thin film layer formed between III-V compounds, GaAs, AlAs and Al_xGa_1
A method for manufacturing a Si substrate provided with a III-V compound single crystal thin film according to claim (7), characterized in that a superlattice structure thin film layer formed between _-_xAs solid solutions is used. (10) A method for manufacturing a Si substrate provided with a III-V compound single crystal thin film according to claim (9), characterized in that a Si (211) substrate is used. (11) As a single crystal thin film layer of III-V compound, GaA
S comprising a III-V compound single crystal thin film according to claim (9), characterized in that a single crystal thin film layer of a solid solution of S or Al_xGa_1_-_xAs is used.
A method for manufacturing an i-board. (12) A method for manufacturing a Si substrate provided with a III-V compound single crystal thin film according to claim (11), characterized in that a Si (211) substrate is used.