JPS6281712A - Liquid growth device - Google Patents

Abstract

PURPOSE:To contrive the improvement in characteristics of a grown film by preventing the mixing of Si included in a reactor tube into the grown film by providing an interpolation pipe composed of either of carbon and boron nitride or combination of those inside the reactor tube composed of SiO2 and arranging a substrate and a jig inside the interpolation pipe. CONSTITUTION:Inside a reactor tube 1 of SiO2, an interpolation pipe 4 composed either of carbon C and boron nitride BN or combination of those is provided and a substrate S used for growth and a jig composed C for holding a material, i.e., a melt M, i.e., a slide board 3 are arranged inside the interpolation pipe 4. The interpolation pipe 4 consists of inside the interpolation pipe 4. The interpolation pipe 4 consists of high-purity C or high-purity BN, e.g., polycrystalline BN (PBN) and it is of cylindrical form having the external diameter which can be inserted in the reactor tube 1 and the length which can involve a region to be heated by a heater 2. It is inserted in the reactor tube 1 and inside that, the slide board 3 is arranged. A thickness of about 2-3mm will do if the material to be used is compact. Also, a double structure comprising the outside of C and inside of BN is available.

Description

[Detailed Description of the Invention] [Summary] In a liquid phase growth apparatus for growing compound semiconductors or mixed crystal semiconductors, an inner tube made of one or a combination of carbon and boron nitride is provided inside a reaction tube made of silicon dioxide. By providing this, it is possible to prevent the silicon contained in the reaction tube from being mixed into the grown film during growth, and it can also be used to remove silicon contained in the growth raw material.

[Industrial application field]

The present invention relates to the configuration of a liquid phase growth apparatus for growing a compound semiconductor or a mixed crystal semiconductor.

In electronic devices using m-v group compound semiconductors or their mixed crystal semiconductors, for example, optical devices such as double heterojunction lasers, avalanche photodiodes, and PIN diodes, and high-speed active devices such as field effect transistors and Gunn diodes. , the semiconductors used are often formed by liquid phase growth.

In this case, in order to obtain a grown film with excellent characteristics, it is necessary to minimize the incorporation of unnecessary impurities.

[Conventional technology]

FIG. 3 is a sectional side view of a main part of a conventional example of a liquid phase growth apparatus that performs the liquid phase growth described above.

In the figure, 1 is silicon dioxide (S) such as quartz glass.
i02), 2 is a resistance wire heater for heating, and 3 is a jig called a slide boat made of high-purity carbon and used to hold the substrate S and raw material (melt) M used for growth. .

The semiconductor is grown by holding the substrate S and melt L-M in a boat 3, and by flowing high-purity hydrogen (H2) into the reaction tube 1 at a growth temperature (600 to 900°C, melt M becomes a molten liquid). and melt M onto the substrate S by operating the boat 3.
This is carried out by bringing the semiconductors into contact with each other and depositing a semiconductor in the form of a film on the substrate S.

The reason for flowing the above-mentioned H2 here is to maintain the cleanliness inside the reaction tube 1.

[Problem that the invention seeks to solve]

The semiconductor to be grown is a III-V compound semiconductor or a mixed crystal semiconductor thereof, such as gallium arsenide (GaAs).
, indium phosphide (InP), indium gallium arsenide (InGaAs), indium gallium arsenide phosphide (I
nGaAsP), residual impurities present in the grown film include sulfur (S), silicon (Si), and tellurium (Te).
), zinc (Zn), and magnesium (Mg);
Indium (Ga), indium (In), GaAs-, indium arsenide (InAs), InP, etc. are mixed therein.

Among the above elements, S % Tes Zn, which has a high vapor pressure,
Mg, etc. can be removed by subjecting Mel l-M to high temperature heat treatment in vacuum before using it for growth.

However, since Si has a low vapor pressure, it is difficult to remove it by the above method, and it remains in the M (M) and becomes a residual impurity that is mixed into the grown film and is an unnecessary impurity.

Furthermore, when growing using the growth apparatus shown in the conventional example,
5i02, which is the material of the reaction tube 1, is reduced by H2, and the Si generated by the reaction 5i02+ 2 H2→Si+ 2 H20 further increases the Si concentration of Mel l-M.

For this reason, Si is the main component of residual impurities in the grown film, making it difficult to reduce the residual impurities that degrade the characteristics of the grown film.

In particular, using In solvent, InP, InGaAs,
In the growth of InGaAsP, the segregation coefficient of Si is very large (approximately 30), which poses a very serious problem.

[Means for solving problems]

FIG. 1 is a sectional side view of a main part of an embodiment of a liquid phase growth apparatus according to the present invention.

The above problem is solved by having an inner tube 4 made of carbon (C) and boron nitride (BN) or a combination thereof inside the reaction tube 1 made of 5io2, as shown in FIG. This problem is solved by using the liquid phase growth apparatus of the present invention in which a jig or slide boat 3 made of C for holding the substrate S to be used and the raw material or melt M is placed inside the inner tube 4.

[Effect]

In the liquid phase growth apparatus having the above configuration, since the slide boat 3 is shielded from the inner surface of the reaction tube 1 by the inner tube 4, the reaction tube 1
Even if 5iOz, which is the material of There is no need to increase the Si4 degree of l-M.

Needless to say, C and BN, which are the materials of the internal tube 4,
If a high-purity material that is chemically stable against gases such as H2 is used, there is no fear that impurities will be generated therefrom and mixed into the melt M.

Therefore, if this device is used, St, which enters the grown film as a residual impurity, can be replaced by Si, which is included in the mel)M from the beginning.
This is less than when using the conventional device.

However, the present device can also be used to remove Si contained in the melt M before growth.

That is, since the Si in the reaction tube 1 no longer enters the mel l-M, by adding a small amount of water (N20) or oxygen (02) to the inflow Hz and heat-treating it, Si+ 2 Hz 0-= The reaction 5i02+2Hz or 2H2+02-2H2°Si+2H20→5i02+2Hz contributes to the removal of Si from the melt M.

Thus, if growth is performed using this apparatus using the melt M from which Si has been removed, the amount of St that enters the grown film is significantly reduced, making it possible to obtain a grown film with few residual impurities, that is, with excellent properties.

〔Example〕

Embodiments will be described below with reference to FIG. 1 and a side sectional view of a main part in FIG. 2 showing another embodiment.

The liquid phase growth apparatus shown in FIG. 1 is the same as the conventional apparatus shown in FIG. 3, with an internal tube 4 added thereto.

The inner tube 4 is made of high purity C or high purity BN, such as polycrystalline B.
Made of N (PBN), the outer diameter can be inserted into the reaction tube 1,
It has a cylindrical shape with a length that includes the area heated by the heater 2, and is inserted into the reaction tube 1 and has a slide boat 3 inside.
is placed. The thickness is 2~2 if the material used is dense.
About 3 friends is enough. - Also, the outside is the above C1 and the inside is the above BN
It may have a two-layer structure.

Formation of a grown film using this apparatus is the same as in the conventional example. The function of the internal intubation tube 4 at that time is as described above.

In addition, in order to remove Si from melt M using this device, only melt l-M is held in port 2, a small amount of N20 or 02 is added to the Hz flowing into reaction tube 1, and melt l-M is The temperature at which the Si in the
It is sufficient to heat it to about 700°C and hold it for several tens of hours.

By the way, the results of comparing the growth of InP when using the conventional apparatus (without removing Si from the melt M) and when using the apparatus according to the above embodiment (when removing Si from the melt M) are as follows. The carrier concentration of the film grown by the latter is about one order of magnitude lower than the former, and the mobility at 77K is about twice as high.

The liquid phase growth apparatus shown in FIG. 2 is the same as the apparatus shown in FIG. 1, in which the inside and outside of the inner tube 4 are completely partitioned off.

That is, by changing the shape of the reaction tube 1 and aligning the length of the inner tube 4 with the reaction tube 1, the inner tube 4 partitions the inside and outside of the tube,
Gas cannot flow between the inside and outside.

Accordingly, gas can be inflowed into and out of the internal tube 4 independently.

Hz is allowed to flow into the inside of the inner tube 4 as in the previous embodiment, but an inert gas such as nitrogen (N2) or argon (Ar) is flowed into the outside so that the SiO2 in the reaction tube 1 does not react with H2. It is desirable to do so.

By doing so, it is possible to completely prevent Si in the reaction tube 1 from entering the melt M.

This device can also be used to remove Si from the melt M in the same way as the device in the previous embodiment, and can obtain effects similar to or better than the device in the previous embodiment.

〔Effect of the invention〕

As explained above, according to the configuration of the present invention, in a liquid phase growth apparatus for growing a compound semiconductor or a mixed crystal semiconductor, Si contained in the reaction tube is prevented from being mixed into the grown film, and furthermore, Si contained in the reaction tube is prevented from being mixed into the growth film. It can also be used to remove Si contained therein, and has the effect of making it possible to improve the characteristics of the grown film.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a main part of an embodiment of the present invention, FIG. 2 is a side sectional view of a main part of another embodiment of the present invention, and FIG. 3 is a side sectional view of a main part of a conventional example. . In the figure, 1 is a reaction tube, 2 is a heater, 3 is a slide boat (jig), 4 is an internal tube, M is a melt (raw material), and S is a substrate.

Claims (1)

[Claims] A reaction tube (1) made of silicon dioxide has an inner tube (4) made of one or a combination of carbon and boron nitride, and a substrate (S) and a raw material (M) used for growth.
A jig (3) made of carbon for holding the inner tube (4)
) A liquid phase growth apparatus characterized in that it is placed inside a.