JPH0786159A - Growing method of compound semiconductor - Google Patents

Abstract

PURPOSE:To prevent substances adhering to the inside of furnace from falling by growing a single crystal Si layer on an Si substrate at a specified temperature or below, further growing a GaAs buffer layer by a specified thickness or less at a specified temperature or below, conducting the annealing at a temperature within a specified range, and then epitaxially growing a III-V compound semiconductor thereon. CONSTITUTION:The substrate temperature is set at 800 deg.C or below and hydrogen gas is fed into a reaction furnace together with disilane thus forming a single crystal Si layer on an Si substrate. The substrate temperature is then set at 450 deg.C and trimethyl gallium is fed into the reaction furnace together with arsine thus growing a GaAs butter layer by 50nm thick or less. Annealing is then conducted with the substrate temperature being set in the range of 700-800 deg.C. Subsequently, trimethyl gallium and arsine are fed to epitaxially grow a III-V compound semiconductor, i.e., a GaAs single crystal. This method eliminates troubles, e.g. falling of substances adhering to the inside of furnace and mechanical malfunction of the system, and produces a high quality compound semiconductor stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a growth method for epitaxially growing a III-V group compound semiconductor such as GaAs on a Si substrate.

[0002]

2. Description of the Related Art III-V group compound semiconductors such as GaAs are excellent as materials for high-speed electronic devices because they have a higher electron mobility than Si. However, as a substrate used for device fabrication, Si having a larger diameter than that of GaAs is available at a low cost. Therefore, it is necessary to use the advantages of both of these to make II of GaAs etc. on the Si substrate.
Research and development has been conducted on a method of epitaxially growing a group IV compound semiconductor to form a device.

As a basic growth technique in this case, a two-stage growth method (Japanese Patent Publication No. 2-36059, Japanese Patent Publication No. 2-36060, M. Akiyama et al., J. Crystal Growth vol.77 (19
86) p.490) is well known. This two-step growth method is
Metal-organic vapor phase epitaxy (MOVPE), which is a method for growing II-V group compound semiconductors, molecular beam epitaxy (MBE)
Method), chemical beam epitaxy method (CBE method), etc., but here, MOVPE
A case where the two-step growth method is carried out will be described.

FIG. 1 shows an example of a temperature sequence of the two-step growth method, which will be described. First, the Si substrate is HF
To remove the surface oxide film, wash with water and dry it, and then install in a reaction furnace. H ₂ gas is flowed as a carrier gas in the reaction furnace.

In the first step of the two-step growth method, the Si substrate is heated to 950 ° C. and heat-treated for 10 minutes (see FIG. 1). The purpose of this step is to remove the surface oxide film of the Si substrate by the above-mentioned pretreatment, but the oxide film is formed again by the time it is installed in the reaction furnace, so that this oxide film is removed.

In the second step, the temperature of the substrate is lowered to 450 ° C. (shown in FIG. 1), and after the temperature is stabilized, trimethylgallium (TMGa) and arsine (AsH ₃ ) are introduced into the reaction chamber and the substrate is placed on the substrate. A GaAs buffer layer is grown to a thickness of 20 nm. AsH ₃ is continuously introduced into the reaction furnace after this step until all steps are completed.

In the third step, the substrate temperature is raised to 750 ° C. and annealed for 5 minutes (FIG. 1).

In the fourth step, the substrate temperature is set to 650 ° C. (FIG. 1), TMGa is introduced again after temperature stabilization, and desired GaAs is grown. After that, the introduction of TMGa is stopped and the temperature is lowered.

[0009]

In the above two-step growth method, the substrate temperature is set to 900 ° C. or higher in order to remove the oxide film in the first step, and the fourth step is to grow. This is to solve the problem of poor reproducibility of GaAs characteristics. On the other hand, if the temperature is set to 900 ° C or higher, the deposits inside the reaction furnace will peel off and fall off easily. There is a problem that it contributes to surface defects.

Further, in a revolving-type reactor (a device in which each substrate itself rotates at the same time as a susceptor having a plurality of substrates arranged on the circumference rotates) which has recently been developed as a reactor, Since mechanical rotating parts such as gears are used for rotation, when they are heated to a high temperature, thermal expansion of these causes a problem that rotation stops. Further, in some cases, there is a problem that parts are destroyed due to an excessive load applied to the rotating shaft.

[0011]

As a result of various studies in view of these problems, the present invention has developed a method for growing a compound semiconductor which has excellent reproducibility of GaAs semiconductor characteristics and eliminates surface defects of the substrate. is there

That is, the present invention provides a method for growing a compound semiconductor in which a compound semiconductor is epitaxially grown on a Si substrate in a reaction furnace in a non-oxidizing atmosphere.
The first step of growing a single crystal Si layer at a temperature of 00 ° C or lower, and G at a temperature of 450 ° C or lower on the formed single crystal Si layer.
A second step of growing the aAs buffer layer to a thickness of 50 nm or less, a third step of annealing the GaAs buffer layer at a temperature of 700 to 800 ° C., and a third step on the GaAs buffer layer.
And a fourth step of epitaxially growing a group-V compound semiconductor. Also, the above
III-V group compound semiconductors include GaAs and AlGa
There may be mentioned any one kind or two or more kinds of laminated structures selected from the group of As and InGaAs.

[0013]

As described above, in the present invention, the Si substrate is heated to a temperature of 800 ° C. or lower in the first step. Therefore, problems such as separation of deposits in the furnace and failure of the rotating system caused by conventional heating above 900 ° C will not occur. On the other hand, as described above, the surface oxide film on the Si substrate cannot be sufficiently removed at the substrate temperature of 800 ° C. or lower. However, in the present invention, since the single crystal Si layer is newly formed on the Si substrate in the reaction furnace, the GaAs buffer layer formed in the subsequent second step is formed on the Si layer having no surface oxide film. Thus, substantially the same effect as that obtained by performing the conventional first step is produced.

[0014]

EXAMPLES The present invention will be further described below based on examples.

(Example) A semiconductor sample A was obtained by epitaxially growing a GaAs compound semiconductor on a Si substrate placed in a reaction furnace in the next step of →→→.

[0016]: a substrate temperature of 750 ° C., and the carrier gas into the reactor and H ₂ gas with disilane (Si
₂ H ₆ ) was flowed at a flow rate of ₂ cc / min for 10 minutes to form a single crystal Si layer. : TMGa 16cc in reaction furnace with substrate temperature 450 ℃
/ min, AsH ₃ was flown at 480 cc / min to grow a GaAs buffer layer to a thickness of 20 nm. : Set substrate temperature to 750 ° C and add 100 AsH ₃ to the reactor.
Annealing was performed for 10 minutes while flowing cc / min. : TMGa 160cc / min, A with substrate temperature 650 ℃
A GaAs single crystal was epitaxially grown to a thickness of 3 μm by flowing sH ₃ at 480 cc / min.

(Conventional Example) As a conventional example, the above-mentioned conditions are changed to the following conditions' by the conventional two-step growth method to obtain Ga.
As compound semiconductor sample B was obtained. ′: The substrate temperature was set to 950 ° C. and the substrate was heated in a carrier gas (H ₂ ) for 10 minutes.

(Comparative Example) In the above two-step growth method
Was changed to the following "" to obtain a GaAs compound semiconductor sample C. ": The substrate temperature was 750 ° C. and heating was performed in a carrier gas (H ₂ ) for 10 minutes.

Each of the above GaAs compound semiconductor sample A
First, the surface conditions of the samples A to B were compared, and the samples A and B of the examples and the conventional examples were both mirror-finished.
The surface of the comparative sample C in which the surface oxide film on the Si substrate was not sufficiently removed was cloudy and was a defective product.

Next, Table 1 shows the results of Hall measurement performed on Samples A and B.

[0021]

[Table 1]

As described above, it can be seen that the compound semiconductor obtained by the method of the present invention and the one obtained by the conventional two-step growth method have almost the same characteristics. This is because a single crystal Si layer without a surface oxide film was formed on the Si substrate by introducing Si ₂ H ₆ into the reaction furnace in the step of the present invention, and therefore Si was not used when starting the above step. It means that the Si layer without oxide film is exposed on the substrate.
This is because the same effect as when the first step is performed by the step growth method is exhibited.

[0023]

As described above, according to the present invention, although the semiconductor characteristics are the same as those of the conventional one, the problems such as the fall of the deposits in the reaction furnace and the mechanical failure of the apparatus itself are eliminated, and the quality is excellent. It has effects such as stable production of compound semiconductors.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a temperature sequence of a conventional two-step growth method.

Claims (2)

[Claims] 1. A method of growing a compound semiconductor in which a compound semiconductor is epitaxially grown on a Si substrate in a reaction furnace in a non-oxidizing atmosphere, wherein a single crystal Si layer is grown on the Si substrate at a temperature of 800 ° C. or lower. A step of growing a GaAs buffer layer on the formed single crystal Si layer at a temperature of 450 ° C. or less to a thickness of 50 nm or less, and the GaA
s The buffer layer is annealed at a temperature of 700-800 ℃
A method of growing a compound semiconductor, comprising: a step; and a fourth step of epitaxially growing a III-V group compound semiconductor on the GaAs buffer layer. 2. The III-V group compound semiconductor is GaA.
The method for growing a compound semiconductor according to claim 1, wherein the compound semiconductor has a laminated structure of one or more selected from the group consisting of s, AlGaAs and InGaAs.