JPH05182906A - Hetero epitaxially growing method - Google Patents

Abstract

PURPOSE:To obtain a GaAs epitaxial layer having a low dislocation and high quality by growing a group II element single atomic layer on an As single atomic layer, growing a low temperature GaAs buffer layer thereon and epitaxially growing a GaAs layer on the buffer layer. CONSTITUTION:An Si (100) board 1 is heated to 250 deg.C, and an As single atomic layer 2 is formed thereon. Then, a single atomic layer 3 of group II element such as Zn, Be, Mg, etc., is formed thereon. Thereafter, while a growing temperature remains at 250 deg.C, a low temperature GaAs buffer layer 4 is grown on the layer 3. Then, the growing temperature is raised to 550 deg.C, and a GaAs epitaxial layer 5 is grown. Thus, a two-dimensional grown can be controlled in an initial step of the GaAs epitaxial growth on the board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a heteroepitaxial growth method for epitaxially growing an aAs layer.

[0002]

2. Description of the Related Art A compound semiconductor such as GaAs has a higher electron mobility than Si and has a direct transition type band structure, and is therefore widely used for high speed electronic devices, light emitting devices, light receiving devices and the like. In the field of electronic devices, development and trial production of integrated circuits using high electron mobility transistors (HEMTs) are being carried out. In order to realize a GaAs device that integrates a plurality of such elements, GaA
It is necessary to grow a thin film crystal of a compound semiconductor such as s in a large area while controlling it uniformly. When growing a thin film crystal of a compound semiconductor on a large-area substrate, a GaAs substrate of the same material type is used, but GaAs crystals have a large specific gravity and are fragile. A new problem arises that the device process is restricted. Therefore, a hetero-epitaxial growth technique for growing a thin film crystal of a compound semiconductor using an Si substrate having a large diameter substrate which is easily available, has a low specific gravity and a high mechanical strength has been attracting attention.

However, since GaAs has a lattice constant larger than Si by about 4% and a thermal expansion coefficient about three times larger than that of Si, Ga is
Good quality G on Si substrate compared to when using As substrate
It was impossible to epitaxially grow an aAs crystal. For example, a large difference in lattice constant causes misfit dislocations due to lattice mismatch, and a difference in thermal expansion coefficient causes warp in the wafer in the cooling step after physical growth, so that a flat wafer is obtained. I couldn't.

In order to solve these problems, a growth method called a two-step method has been proposed in which a GaAs epitaxial layer is grown on a Si substrate via an amorphous low-temperature GaAs buffer layer. (M.Akiyama et al. "Jpn.A
ppl.Phsys., 23, (1984) L843) Also, a growth method using a superlattice as an intermediate layer instead of the low temperature buffer layer has been proposed. (Unexamined-Japanese-Patent No. 62-58616) By these methods, the misphyto rearrangement is 10 by now.
^Although reduced to about ⁶ cm ^{-2, the} dislocation density is 10 ⁴ c, which is allowable in a normal GaAs compound semiconductor device.
m ^-2 , dislocation density allowed by laser diode 10 ³
Compared with cm ^-2 , there are more than two or three digits, and it was necessary to improve.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned problems, and has a low dislocation and good quality Ga on a Si substrate.
It is intended to provide a heteroepitaxial growth method capable of obtaining an As epitaxial layer.

[0006]

The present invention provides a method for epitaxially growing a GaAs layer on a Si substrate, comprising:
A first step of growing an As monoatomic layer on the surface of the Si substrate,
s a second step of growing a monoatomic layer of a Group II element such as Zn, Be, Mg, etc. on the monoatomic layer, a third step of growing a low temperature GaAs buffer layer thereon, and a third step of Ga
And a fourth step of epitaxially growing the As layer, which is a heteroepitaxial growth method.

[0007]

The present inventors have paid attention to the growth mode at the initial stage of GaAs growth on the Si substrate, in addition to the above technical problems due to the lattice mismatch and the difference in the coefficient of thermal expansion. When GaAs is grown on a Si substrate, GaAs grows like islands,
It was then known that defects such as Mitsufit dislocations would be introduced when the islands coalesce. It is considered that the cause of this three-dimensional island-like growth is the mismatch of charges generated at the interface between the Si substrate and the GaAs layer. That is, a dangling bond, which is a bond, is generated in the process in which a group III or V atom is bonded to the surface of Si, which is a nonpolar semiconductor, to form a crystal lattice. Causes an extremely large charge mismatch at the interface with the Si substrate, and in order to stabilize this charge mismatch in terms of energy, GaAs growth near the interface is a three-dimensional island shape. Growth is believed to occur. Therefore, by neutralizing the charge on the interface between the Si substrate and the GaAs layer, it is possible to reduce the charge from the initial stage of GaAs growth to 2
High-quality GaAs that can promote three-dimensional layered growth
We succeeded in obtaining a thin film and completed the present invention.

In the present invention, Si and II are formed by inserting a group II atom as a monoatomic layer at the interface between the Si substrate and the GaAs layer.
It is possible to eliminate the charge mismatch generated between the group I atom and the group V atom, and obtain a high-quality GaAs epitaxial layer with low dislocation. FIG. 1 shows a sectional structure of an As monoatomic layer, a Zn monoatomic layer on a Si substrate, and a laminated structure in which a GaAs epitaxial layer is formed on a low-temperature GaAs buffer layer, which is one embodiment of the present invention. FIG. 2 shows the bonding state of atoms in the vicinity of the Si substrate interface.

[0009]

EXAMPLE A GaAs layer was epitaxially grown on a Si substrate in the laminated structure shown in FIG. 1 by using the molecular beam epitaxial method (MBE method). As the first step, after heating the Si (100) substrate 1 set in the MBE apparatus to 250 ° C., the substrate is irradiated with only As molecular beams, and the As substrate is irradiated with As.
The monoatomic layer 2 was formed. Then, as a second step, a Zn monoatomic layer 3 was formed on the As monoatomic layer 2 by irradiating a Zn molecular beam of a group II atom source at the same temperature. In the third step, the As molecular beam and the Ga molecular beam are simultaneously irradiated while keeping the growth temperature at 250 ° C., and low temperature GaAs is formed on the Zn monoatomic layer 3.
The buffer layer 4 was grown to 200Å. As and G at this time
The molecular beam intensity ratio (flux ratio) of a was 10, and the growth time was 5 minutes. After that, the growth temperature was raised to 550 ° C. and the GaAs epitaxial layer 5 was grown to about 3 μm. At this time, the As / Ga flux ratio was 10, and the growth rate was 1 μm / h. (Obtained GaA
Could you describe the experimental results such as dislocation density of s epitaxial layer and confirmation of two-dimensional growth? )

[0010]

According to the present invention, by adopting the above structure, the charge mismatch generated at the interface between the Si substrate and the GaAs epitaxial layer can be eliminated, and the initial process of GaAs epitaxial growth on the Si substrate can be eliminated. At 3
Since the two-dimensional growth can be controlled by suppressing the three-dimensional island growth, it has become possible to obtain a high-quality GaAs epitaxial layer with low dislocation.

[Brief description of drawings]

FIG. 1 was obtained by the heteroepitaxial growth method of the present invention,
FIG. 3 is a cross-sectional view showing an example of a laminated structure in which a GaAs epitaxial layer is formed on a Si substrate.

FIG. 2 is an explanatory diagram showing a bonded state of atoms in the vicinity of the interface of the Si substrate of FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroya Kimura 1-1-1 Kunyo Kita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Mitsuru Shimazu 1-1 Kunyo Kita, Itami City, Hyogo Prefecture No. 1 Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Two Shirakawa 1-1, Kunyo Kita, Itami City, Hyogo Prefecture Sumitomo Electric Industries Itami Works

Claims (1)

[Claims] 1. A method of epitaxially growing a GaAs layer on a Si substrate, comprising: a first step of growing an As monoatomic layer on a Si substrate surface; and Zn, B on the As monoatomic layer.
e, a second step of growing a group II element monoatomic layer such as Mg, a third step of growing a low-temperature GaAs buffer layer thereon, and a fourth step of epitaxially growing a GaAs layer on the buffer layer. A heteroepitaxial growth method comprising: