JPH01293611A - Heteroepitaxial growth method - Google Patents

Abstract

PURPOSE:To prevent the propagation of through dislocation of an underlayer on a regrowth interface surface and decrease a crystal defective density by growing a single crystal semiconductor layer further on a regrowth interface surface after the regrowth interface surface is formed on the surface of the single crystal semiconductor layer. CONSTITUTION:A single crystal semiconductor layer 5 of a kind different from silicon is formed on a silicone substrate 1. After a regrowth interface surface 6 is formed on the surface of a semiconductor layer 5, an AlyGa1-yAs layer 7 is formed by MOCVD or MBE, after which a single crystal GaAs layer 8 used as an active layer is grown to a required thickness. An Si substrate 1 is once removed out of a growth device and an AlxGa1-xAs layer 5 is exposed to air in this way, a regrowth interface surface 6 being formed, and a layer 7 is formed thereon. Therefore, at the time of the formation of this layer 7, the through dislocation of the underlayer of the regrowth interface surface 6 is bent chiefly in a lateral direction, and the propagation toward an upper direction is prevented. As a result, the crystal defective density of dislocation in the semiconductor layers 7 and 8 formed on the interface surface 6 becomes low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heteroepitaxial growth method, for example, gallium arsenide (GaA) on a silicon (St) substrate.
It is suitable for application to the heteroepitaxial growth of s).

[Summary of the invention]

In the heteroepitaxial growth method of the present invention, a single crystal semiconductor layer of a type different from silicon is formed on a silicon substrate, a regrowth interface is formed on the surface of the single crystal semiconductor layer, and then the above regrowth interface is formed on the regrowth interface. By growing the single crystal semiconductor layer further, a high quality single crystal semiconductor layer with a low density of crystal defects such as dislocations can be heteroepitaxially grown on a silicon substrate by a simple method.

[Conventional technology]

Heteroepitaxial growth is a technique for growing epitaxial layers using substrates with different lattice constants. Si
The heteroepitaxial growth of a GaAs layer on a substrate is a typical example. However, the lattice constant of GaAs is 5.6534, whereas the lattice constant of St is 5.43086, and the difference between them is as large as about 4%. For this reason, if GaAs is grown directly on an STG plate, this GaAs will grow in the form of an island, and a layered one will not be obtained.Moreover, in this island-like GaAs, there are dislocations near the interface with the Si substrate. There are about 10'2 crystal defects/ci.

Therefore, it can be said that it is difficult to grow a single crystal GaAs layer directly on a St substrate.

Applied Physics, Volume 55, No. 11 (1986) No. 1069
From page 1073, a two-stage growth method is discussed that aims to solve the above-mentioned problems. According to this two-step growth method, a thin amorphous or polycrystalline GaAs layer is first grown on an St substrate, and then this is heat-treated (annealed) to grow in a solid phase and become a single crystal. Single-crystal GaAs lil, which will become an active layer, is grown on the crystallized GaAs layer. However, the density of crystal defects such as dislocations existing in the GaAs layer grown by this two-step growth method is still as high as about 10'1 defects/cia, and its quality is insufficient.

Therefore, in recent years, as a method that can further reduce the crystal defect density, for example, I
Strained superlattice of nGaAs/GaAs system
A method has been proposed in which a strained superlattice is formed and a GaAs layer is further grown on this strained superlattice. According to this method, the strained superlattice allows the threading dislocations in the lower layer of the strained superlattice to be bent in a direction away from the growth direction, so that when further growing a GaAs layer on top of the strained superlattice, The propagation of threading dislocations to this GaAs layer is prevented. As a result, the density of crystal defects such as dislocations in the GaAs layer formed on this strained superlattice becomes as low as about 1O7/d.

[Problem to be solved by the invention]

However, the method for forming a strained superlattice described above requires a complicated and advanced layering technique to form the strained superlattice itself, and also requires other types of growth raw materials.

Therefore, an object of the present invention is to provide a heteroepitaxial growth method that allows a high-quality single crystal semiconductor layer with a low density of crystal defects such as dislocations to be heteroepitaxially grown on a silicon substrate by a simple method.

[Means to solve the problem]

Jpn, J, Appl, Phys, 27 (1
988) In Li2O, GaAs
Once the surface of the layer is exposed to the atmosphere, the previously mentioned InGaA
A problem has been raised that a regrown interface is formed on the surface exhibiting the characteristics of a heterointerface similar to that of a s/GaAs strained superlattice.

The present invention attempts to actively utilize this fact, which has been a problem in the past, for heteroepitaxial growth of a single crystal semiconductor layer on a silicon substrate.

That is, the heteroepitaxial growth method of the present invention,
A single crystal semiconductor layer (5) of a type different from silicon is formed on a silicon substrate (1), and a regrowth interface (6) is formed on the surface of the single crystal semiconductor N (5). A single crystal semiconductor layer (8) is further grown on top of the single crystal semiconductor layer (8).

[Effect]

The regrown interface formed on the surface of a single crystal semiconductor layer is a thin layer with a disordered, distorted crystal lattice, which has a different bonding state between atoms and composition than the inside of the single crystal semiconductor layer, contains impurities, and has a distorted crystal lattice. It is. This regrowth interface is C-V (Capa
citance-voltage) characteristics and DLT S
(Deep Level Transient Cap
From the observation results of deep levels using the acitance 5 pectroscopy method, it is known that the heterointerface exhibits the same characteristics as a strained superlattice.According to the study of the present inventors, this regrown interface is similar to a strained superlattice. Similarly, it has the effect of inhibiting the propagation of threading dislocations.

Therefore, according to the above-mentioned means, when forming a single crystal semiconductor layer on the regrowth interface, threading dislocations in the layer below the regrowth interface are mainly lateralized (towards the surface of the silicon substrate) by the regrowth interface. (parallel direction), and propagation upward (in the direction perpendicular to the surface of the silicon substrate - the growth direction) is prevented. As a result, the density of crystal defects such as dislocations in the single crystal semiconductor layer formed on this regrowth interface is low.

Moreover, this regrown interface can be formed much more easily than a strained superlattice. As a result, a high quality single crystal semiconductor layer with a low crystal defect density can be heteroepitaxially grown on a silicon substrate by a simple method.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. This example is an example in which the present invention is applied to the heteroepitaxial growth of a GaAs layer on an St substrate.

As shown in FIG. 1A, first, for example, metal organic chemical vapor deposition (MO) is applied onto a St substrate l whose surface has been cleaned in advance.
For example, a film can be grown at a growth temperature of 410°C using the CVD (CVD) method or the molecular beam epitaxy (MBE) method. About 200 people form the amorphous GaAs layer 2.

Next, by performing annealing at, for example, 720° C., the amorphous GaAsN2 is grown in a solid phase and made into a single crystal.

As a result, as shown in FIG. 1B, the single crystal GaAs
Layer 3 is formed. The density of crystal defects such as dislocations in this single crystal GaAs layer 3 is as high as about 10''/d.

Next, as shown in FIG. 1C, a single-crystal GaAs layer 4 is grown to a thickness of, for example, about 1 μm on this single-crystal GaAs layer 3 by MOCVD or MBE at a growth temperature of, for example, about 750°C. . The crystal defect density in this single-crystal GaAs layer 4 is also 108 /
It is about d. Thereafter, for example, A11l GaI is deposited on this single crystal GaAs layer 4 by MOCVD or MBE.
-x As layer 5 is formed.

Next, this A1. The St-based trIi, 1 on which the Ga, -XAs layer 5, etc. have been formed is once taken out of the growth apparatus, and this AI is grown.

The surface of the Ga1-x As layer 5 is exposed to the atmosphere. As a result, a regrowth interface 6 is formed on the surface of this AlXGa, -, As layer 5, as shown in the first diagram. Generally speaking, this regrowth interface 6 is thicker (formed) when the AI composition ratio X of the AIX GaI-x As layer 5 is larger. Specifically, this AI composition ratio X is, for example, about 0.5. It can be done.

Next, as shown in Figure 1, M
For example, AI by OCVD method or MBE method.

After further formation of GaI-yAsN7, this Aly
Single crystal G used as active layer in GaI-yAsAlO2
aAsJii8 (for example, from the bottom single crystal GaAs layer 3 to the top single crystal GaAs layer 8)
to a total thickness of about 3.5 μm). Note that the AI composition ratio y of the above-mentioned Aly Ga, -, As layer 7 may be equal to the AI composition ratio X of the above-mentioned AI, GaI-x As layer 5 .

As described above, according to this embodiment, Si is placed outside the growth apparatus.
Take out the board 1 once and set it to A1. Ga, -xAsJi5
By exposing the surface to the atmosphere, a regrowth interface 6 is formed, and on this regrowth interface 6, an AI, Ga, □As layer 7 is formed. , the threading dislocations in the layer below this regrowth interface 6 are bent mainly in the lateral direction by this regrowth interface 6, and are bent upward (
propagation in the growth direction) is prevented.

As a result, the number of dislocations, particularly threading dislocations, existing in this AI, Gal-, As layer 7 is reduced, and the crystal defect density is reduced to, for example, about 101/d. Therefore, the crystal defect density in single crystal GaAsjiB formed on Aly GaI-y As1i 7 having a low crystal defect density is similarly low at about 10' pieces/ctA. Moreover, the above-mentioned regrowth interface 6 is formed by removing the Si substrate 1 from the growth apparatus after forming the AIXGap-XAs layer 5, and
It can be easily formed by simply exposing the I-X As layer 5 to the atmosphere. That is, according to this example, high-quality single crystal GaAs1li8 with a low density of crystal defects such as dislocations is
It can be seen that heteroepitaxial growth can be performed on the i-substrate 1 by a simple method.

By using the high-quality single-crystal GaAs layer 8 obtained in this example as an active layer, it becomes possible to manufacture high-performance semiconductor devices such as high-speed semiconductor devices.

Further, by making the high-speed semiconductor element and the optical semiconductor element monolithic, it becomes possible to realize a high-performance optoelectronic integrated circuit (OEIC).

Although one embodiment of the present invention has been specifically described above,
The present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, AlXGa, □As
A regrowth interface 6 is formed by exposing the AsO2 surface to the atmosphere, and this regrowth interface 6 is, for example, AIX
After forming the Gap-g As layer 5, lower the substrate temperature,
It is also possible to form the film by switching the atmosphere in the growth apparatus to, for example, a nitrogen (N2) gas atmosphere in this state. Furthermore, it is not necessary to form the /lly Gap-yAsAs layer 7, and the single crystal Ga layer 7 is formed on the regrowth interface 6.
It is also possible to form the As layer 8 directly. Furthermore, A
IX czal-x As1i5 and AI.

It is also possible to form the regrowth interface 6 directly on the surface of the single crystal GaAs layer 4 without forming the Gap-, As layer 7, and to form the single crystal GaAs layer 8 on the regrowth interface 6.

Also, instead of the amorphous GaAs layer 2, a polycrystalline GaAs layer 2 is used.
It is also possible to use 1i. Furthermore, single crystal G
The aAs layer 4 does not necessarily have to be grown by a two-step growth method.

In addition, in the above-mentioned embodiment, GaA was deposited on the Si substrate.
The case where the present invention is applied to the heteroepitaxial growth of sJi has been described, but the present invention also applies to Ga on a Si substrate.
It is also possible to apply this method to the case of heteroepitaxially growing a single crystal semiconductor layer other than As.

〔Effect of the invention〕

As described above, according to the present invention, after forming a regrowth interface on the surface of a single crystal semiconductor layer, the single crystal semiconductor layer is further grown on the regrowth interface. When forming a single crystal semiconductor layer on a regrown interface, threading dislocations in the layer below the regrown interface are prevented from propagating upward (in the growth direction) by the regrown interface. Therefore, the density of crystal defects such as dislocations in the single crystal semiconductor layer formed on this regrowth interface becomes low. Moreover, this regrowth interface can be easily formed.

As a result, a high quality single crystal semiconductor layer with a low crystal defect density can be heteroepitaxially grown on a silicon substrate by a simple method.

[Brief explanation of the drawing]

FIGS. 1A to 1E are cross-sectional views for sequentially explaining a heteroepitaxial growth method according to an embodiment of the present invention. Explanation of main symbols in the drawings 1: Si substrate, 2: Amorphous GaAs layer, 3.4.8
: Single crystal GaAsN5 5 : Alx Ga5-x
As layer, 6: Regrowth interface, 7: Aly Gap
-y As layer. Agent Patent Attorney Masa Sugiura Tomo - Jitsumiji 4 rows Figure 1 A - ° Fubo, row A Figure 1 B - = Jζ: Ro 1 Gin - Ikuku 1 Tsuri Ichi Miro 14 rows Figure 1 E

Claims (1)

[Claims] After forming a single crystal semiconductor layer of a type different from silicon on a silicon substrate, and forming a regrowth interface on the surface of the single crystal semiconductor layer, the single crystal semiconductor layer is formed on the regrowth interface. A heteroepitaxial growth method characterized by further growing layers.