JP2805865B2 - Vapor phase growth method of phosphorus compound semiconductor crystal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for vapor-phase growing a phosphorus compound semiconductor crystal on a semiconductor substrate using an organic metal source gas.

(Prior Art) A conventional metal organic chemical vapor deposition method is a method in which a semiconductor substrate is transferred to a growth chamber via a preparation chamber or a transfer chamber, and an organic metal source gas is thermally decomposed on the substrate to grow a crystal. . The method of exchanging the semiconductor substrate in the growth chamber is to individually evacuate the growth chamber and the transfer chamber, and then open the two partitions to exchange them.
A method of exchanging both by opening the partition after setting both at atmospheric pressure, and a method of exchanging while flowing gas from the growth chamber to the transfer chamber are adopted.

(Problems to be Solved by the Invention) In the metalorganic vapor phase epitaxy method, a substance having a high vapor pressure, for example, phosphorus, is deposited in a growth chamber during a crystal super process,
In the above-described method of exchanging semiconductor substrates, there is a problem that when the partition between the transfer chamber and the growth chamber is opened, the deposits diffuse into the transfer chamber and contaminate the semiconductor substrate.

An object of the present invention is to solve the above-mentioned problems and to provide a method for vapor-phase growth of a phosphorus compound semiconductor crystal, which makes it possible to replace a semiconductor substrate while avoiding contamination of the semiconductor substrate by the deposits. .

(Means for Solving the Problems) According to the present invention, after a semiconductor substrate is mounted on a susceptor in a transfer chamber and the substrate is transferred into a growth chamber together with the susceptor, a source gas containing at least an organic metal is deposited on the substrate. And introducing a constant flow rate of an inert gas or hydrogen gas from the transfer chamber to the growth chamber while transferring the substrate between the transfer chamber and the growth chamber. A method for vapor-phase growth of a phosphorus compound semiconductor crystal characterized by flowing toward

(Operation) FIG. 1 is an explanatory diagram for explaining the vapor phase crystal growth method of the present invention. FIG. 3A shows a state during crystal growth or standby, and FIG. 3B shows a state during transfer of the semiconductor substrate. This crystal growth apparatus mainly comprises a reaction chamber 1, a transfer chamber 8 and a preparation chamber 11, as shown in FIG.
A susceptor 2 supported on a shaft 4 is arranged in the reaction chamber 1,
The semiconductor substrate 3 is held at the center of the reaction chamber 1. The source gas is introduced from an inlet 5 at the top of the reaction chamber 1, thermally decomposes on the surface of the semiconductor substrate 3 to grow crystals, and is exhausted from an exhaust port 6 below. Meanwhile, the opening and closing bottom 7 of the growth chamber 1
Is closed. After the crystal growth is completed, the supply of the raw material gas is stopped, and the residual gas in the growth chamber 1 is exhausted.
As shown in FIG. 2B, the opening / closing bottom 7 is lowered, an inert gas or hydrogen gas is introduced from the gas inlet 9, and exhausted from the transfer chamber 8 through the reaction chamber 1 through the exhaust chamber 6 as indicated by a dotted arrow. I do. In the meantime, the semiconductor substrate 3 on the susceptor 2 is exchanged with a new cassette 12 by the transfer arm 13. By the flow of the inert gas or the hydrogen gas, it is possible to prevent the contaminants deposited during the growth from diffusing from the growth chamber to the transfer chamber, and to prevent the transfer chamber from being contaminated, and consequently a new semiconductor substrate from being contaminated. In addition, as the inert gas, nitrogen gas or the like can be used, and the supply amount of the inert gas is
It must be set to a value that is higher than the diffusion rate of contaminants. After replacing the semiconductor substrate, the susceptor 2 is returned to the growth chamber 1 again, the opening and closing bottom 7 is closed to start crystal growth, and the semiconductor substrate on which a predetermined epitaxial layer is formed is transferred from the transfer chamber 8 to the preparation chamber 11. The substrate is returned to the substrate cassette 12, and the gate valve 10 is closed, and then taken out of the apparatus.

Example An InP epitaxial layer was vapor-phase grown on a semiconductor substrate in a reaction chamber having an inner diameter of 200 mm using the apparatus shown in FIG. To replace the semiconductor substrate, open and close the bottom of the growth chamber 20 mm, introduce hydrogen gas at 3 / min from the gas inlet of the transfer chamber, and let hydrogen flow into the reaction chamber. Could not.

The supply amount of the hydrogen gas was determined as follows. The opening area of the opening and closing bottom is about 125.6cm ² (2πrh = 20 × 3.14 ×
2) Since the diffusion coefficient of phosphorus has not been accurately determined, the diffusion coefficient of carbon dioxide gas in air is larger than that of phosphorus, and the diffusion coefficient is 0.135 cm ² / sec. When the distance L and the diffusion speed S are obtained, L = 2 (Dt) ^1/2 = 0.73 cm S = L / t = 0.73 cm / sec. When the supply amount V of the inert gas corresponding to the diffusion speed is obtained, Since V ≒ 92 cm / sec = 5.5 / min, it was supplied at the above 6 / min.

(Effect of the Invention) According to the present invention, by adopting the above configuration, it is possible to prevent the substrate surface from being contaminated with deposits when transferring the semiconductor substrate to the growth chamber, and to provide a clean substrate surface. Epitaxial growth can now be performed.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are views for explaining a semiconductor substrate exchange operation of the present invention.

────────────────────────────────────────────────── (5) References JP-A-63-99524 (JP, A) JP-A-58-210843 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C30B 1/00-35/00 H01L 21/205

Claims (1)

(57) [Claims] A semiconductor substrate is mounted on a susceptor in a transfer chamber, and the substrate is transferred together with the susceptor into a growth chamber. Then, a source gas containing at least an organic metal is introduced onto the substrate to form a phosphorus compound semiconductor crystal. In the method of vapor-phase growing a substrate, a constant flow rate of an inert gas or a hydrogen gas is flowed from the transfer chamber toward the growth chamber while the substrate is transferred between the transfer chamber and the growth chamber. Vapor growth method of phosphorus compound semiconductor crystal.