JPH01268A - Vapor phase growth valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vapor phase growth valve that can epitaxially grow a semiconductor layer with good reproducibility and can form a steep compositional change and impurity distribution.

[Conventional technology]

Conventionally, switching of source gas in vapor phase growth of compound semiconductors, particularly in pyrolytic vapor phase growth (hereinafter referred to as organometallic vapor phase epitaxy) using organometallic compounds and hydrides as raw materials, has been carried out using, for example, three steps as shown in Fig. 2. This is generally done using a directional valve.

The prior art will be explained below with reference to FIG.

Figure 2 is a diagram showing a three-way valve for switching the source gas that is generally used in organometallic vapor phase epitaxy. In the figure, 1 is a raw material gas inlet, 2 is a supply line to the reactor, 3 is an exhaust line, 4 is a cylinder for switching the gas flow path, 5 is a raw material gas flow path,
Reference numeral 6 indicates a raw material gas retention area within the valve, and reference numeral 7 indicates a driving source.

In the figure, when switching the raw material gas, the cylinder 4 is moved by pneumatic or electromagnetic operation using a drive source 7 such as a pneumatic pressure source or an electromagnet, and the raw material gas flow path 5 is moved.
from supply line 2 to discharge line 3 or from discharge line 3 to supply line 2.

This is done by switching. In this case, the raw material gas flow path changes from the shaded area 5 in FIG. 2(a) to the shaded area 5 in FIG. 2(b).

(Problem to be solved by the invention) However, in switching the raw material gas using such three-way pulp, the raw material gas retention area 6 shown in FIG. 2(b) inevitably exists, and this retention This caused the diffusion of the raw material gas, which significantly reduced the reproducibility of the properties of the epitaxial layer and the steepness of the heterointerface.

Furthermore, changing the raw material gas changes the gas flow rate in the supply line, resulting in changes in growth conditions and a problem in that the characteristics of the epitaxial layer change.

In addition, a manifold for vapor phase growth is known in which such three-way valves are aggregated to make the retention area of FIG. In addition, since there is also a change in the gas flow rate in the supply line, the above problem has not been fundamentally solved.

In order to solve the above-mentioned problems, the present invention has a structure in which there is no retention area of source gas in the switching valve and the gas flow rate in the supply line does not change, thereby producing high-quality semiconductor layers with high reproducibility. It is an object of the present invention to provide a valve for vapor phase growth that allows epitaxial growth to be performed well and to form a steep compositional change and impurity distribution.

[Means for solving problems]

To this end, the vapor phase growth valve of the present invention is a raw material gas switching valve used in a vapor phase growth apparatus, in which a gas flow is arranged in an annular manner and has a plurality of gas inlets and a gas supply port and a gas discharge port to the reactor. The gas flow path switching means is arranged in the gas flow path and changes the gas flow path to abruptly switch the raw material gas.

[Effect]

The vapor phase growth valve of the present invention arranges the gas passages in an annular shape, allows the raw material gas and the purge gas to flow in from each gas inlet, and fails to cut the gas passages by the gas passage switching means. When changing the gas flow path, there is no stagnation area of the raw material gas in the supply line to the reactor inside the valve, and the total gas flow rate in the supply line to the reactor does not change, so that the raw material gas can be abruptly switched. Be able to achieve it.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a valve for vapor phase growth according to the present invention, in which (a) is a diagram showing a raw material gas supply state, and (b) is a diagram showing a raw material gas discharge state. In FIG. 1, the same contents as those shown in FIG. 1 are indicated by the same numbers. In addition, 4a and 4b are cylinders, ? Reference numerals a and 7b represent driving sources, and reference numeral 8 represents an inlet for purge carrier gas.

In the figure, the gas flow paths are arranged in an annular manner, and cylinders 4a and 4'b are arranged in each flow path, and drive sources 7a and 7 are respectively arranged.
b.

First, when supplying raw material gas, drive sources 7a and 7b
is operated to drive the cylinders 4a and 4b to the position shown in FIG. A purge carrier gas having the same flow rate flows in from the inlet 8, passes through the discharge line 3, and is discharged.

Next, in the case of discharging the raw material gas, the cylinders 4a, 4b are driven to the positions shown in FIG. 1(b) by the drives fi7a, 7b. In this case, the raw material gas that has flowed in from the inlet 1 is discharged through the discharge line 3. At this time, the purge carrier gas having the same flow rate as the raw material gas has flowed in from the lower introduction port and is discharged through the supply line 2. Flows into the reactor.

In this way, the gas flow path is arranged in an annular shape, the two cylinders are driven simultaneously, and all the raw material gas remaining in the valve is purged by the inflow of the purge carrier gas, so that the raw material gas remains in the valve. The area becomes a structure that does not remain. In addition, since the raw material gas and the purge carrier gas are set at the same flow rate, the total gas flow rate flowing into the reactor does not change due to switching of the raw material gas.
Since the supply line and the discharge line of the switching valve can be made common for each source gas, it is also possible to aggregate them and downsize them.

〔Effect of the invention〕

When undoped GaAs was grown using the organometallic vapor phase growth apparatus equipped with the vapor phase growth valve according to the present invention as described above, it was n-type with a residual carrier concentration of 1014 to 10.
"C11-" epitaxial layer was obtained with good reproducibility,
In addition, the undoped GaAs epitaxial layer immediately after P-type impurity doping also showed n-type with a residual carrier concentration of 1014 to 10" 1 m-', confirming that a high-quality epitaxial layer could be obtained with good reproducibility. .

In addition, as a result of epitaxially growing heterostructures of CaAs, Alo, sCaa, and s AS and measuring the steepness of compositional changes, the transition region of both was estimated to be 1 to 2 atomic layers (5 people), which is extremely It was confirmed that a steep interface was formed.

In the above embodiments, metal organic vapor phase growth of GaAs and AjGaAs was explained as an example, but the present invention is applicable to GaAa, Af
It goes without saying that the present invention is not limited to fiGaAs, and is not limited to the shape or pressure of the reactor at all, and can be applied to the vapor phase growth of all single crystals, polycrystals, amorphous materials, and metals.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a valve for vapor phase growth according to the present invention, and FIG. 2 is a diagram showing a three-way valve for switching source gases used in conventional metal organic vapor phase growth. 1... Raw material gas inlet, 2... Supply line, 3...
・Discharge line, 4.4a, 4b...Cylinder, 5...
- Raw material gas flow path, 6... Raw material gas retention area, 7.7a
17b... Drive source, 8... Carrier gas inlet for purge. Applicant Hamamatsu Photonics Co., Ltd. Representative
Person Patent Attorney Masanobu Hirukawa (I)
(0) Figure 2

Claims (4)

[Claims] (1) In a source gas switching valve used in a vapor phase growth apparatus, a gas flow path arranged in an annular shape having a plurality of gas inlets, a gas supply port and an exhaust port to the reactor, and a gas flow path in the gas flow path. A valve for vapor phase growth comprising a gas flow path switching means arranged to change the gas flow path and abruptly switch source gases. (2) The vapor phase growth valve according to claim 1, wherein the gas flow path switching means comprises a plurality of cylinders driven by a drive source. (3) Let the raw material gas flow in through one of the multiple inlets, and let the purge carrier gas flow in at the same flow rate as the raw material gas through the other one, and connect the supply line to the reactor inside the valve when changing the gas flow path. 2. The valve for vapor phase growth according to claim 1, wherein there is no retention region of raw material gas in the reactor, and the total gas flow rate in the supply line to the reactor does not change. (4) A plurality of gas flow path switching means and an annular gas flow path are incorporated into a single block, and the supply line and the discharge line are common, respectively, and the size is reduced by aggregating them, Claim 1 Vapor phase growth valve described.