JPS59190294A - Process for liquid-phase epitaxial growth of semiconductor crystal - Google Patents

Abstract

PURPOSE:To prevent the evaporation of an element having high vapor pressure in the epitaxial growth of a semiconductor crystal, and to obtain a high-quality epitaxial growth layer, by covering the molten liquid containing the semiconductor material to be sujected to the epitaxial growth with a material inert to the molten liquid and having smaller specific gravity than the molten liquid. CONSTITUTION:An n type InP (001) single crystal is used as the substrate 3, and undoped InP and p type InP are grown continuously on the substrate 3. The molten liquid reservoirs 11, 12 are filled with In and InP polycrystals. Especially, the reservoir 11 is added with Zn as a dopant. A B2O3 plate is placed on each growing material in the reservoir 11, 12, and heated in a reaction tube. After the reaction, the substrate 4 is transferred successively under the reservoirs 12 and 11 while cooling slowly the reaction product to room temperature to effect the epitaxial growth of two layers. The molten liquid layers 21 and 22 are covered completely with the layers of B2O3. Since the melting point of B2O3 is sufficiently low compared with the epitaxial growth temperature, and since B2O3 has small specific gravity, it is melted to a liquid having high viscosity during the growing process, and covers the top of the molten liquid layers to fulfill the role of a shield.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a slide boat liquid phase epitaxial growth method for semiconductor crystals.

(Prior Art) In manufacturing compound semiconductor devices such as semiconductor lasers and photodetectors, a slide-boat liquid phase epitaxial growth method is often adopted. An example of a jig used in this liquid phase growth method is shown in FIG.

In the figure, reference numerals 11, 12, and 13 are melt reservoirs containing melts 21, 22, and 23 containing the semiconductor to be epitaxially grown as a solute, and 3 is a slider for moving the semiconductor single crystal 4 that will become the substrate. 5 is a lid to prevent loss of melt due to evaporation. Liquid phase growth is carried out using these jigs, usually in an atmosphere of high-purity hydrogen radicals. therefore,
Before performing this growth, the inside of the reaction tube (not shown) is evacuated and the air contained in the jig (highly dense carbon phase separation is used in many cases) or the melt is removed. I have to be careful. If the bulge is highly sealed during this pre-growth evacuation process, the pressure difference between the inside and outside of the melt reservoir during the initial stage of evacuation will cause the lid to lift and shift. If this state is maintained during the growth process, the lid cannot fulfill its original role of suppressing evaporation of the melt.

m - v & compound semiconductor InP or Ga In
In the liquid phase growth of AsP, AsP is grown using AsP as a solvent.

A semiconductor material such as GaAs or InAs is dissolved as a solute, and the liquid is kept at a high temperature by the heat treatment at this time. Since the melt contains P or (As) with high vapor pressure, if the lid is not completely closed, these components may evaporate and the desired composition may not be obtained.Especially in the long wavelength range. When manufacturing 3-1.6 μm semiconductor lasers and 2-light emitting diodes, there is originally little P content, so the P component evaporates during heat treatment, which changes the composition of the epitaxial growth. There was a problem that the oscillation wavelength shifted significantly. Alternatively, when adding a dopant to the melt, especially when using KZn to obtain a P-type semisolid, InP, f]aIn
, AsP, etc., the vapor pressure of Zn is high at the growth temperature, and Zn often evaporates from the gap in the lid, contaminating the next melt. As a result, it is often difficult to form a Pn junction by liquid phase growth. On the other hand, if the lid is crimped, no air is created inside the melt reservoir, and the internal pressure increases when the temperature rises, causing the melt to flow out from the gap between the bottom of the melt reservoir and the slider. Sometimes.

Therefore, the reproducibility of the lid conventionally used for liquid phase epitaxial growth is poor, and the present invention has been proposed to improve the above-mentioned drawbacks. The purpose of this is to prevent the evaporation of the element during liquid phase epitaxial growth of the substance contained therein, and to obtain a good epitaxial growth layer.

(Structure of the Invention) In order to achieve the above object, the present invention provides, in slide boat liquid phase epitaxial growth of compound semiconductors, on a melt containing the semiconductor to be epitaxially grown as a solute.
One of the gist of the invention is a method for liquid phase epitaxial growth of a semiconductor crystal, which is characterized by covering the semiconductor crystal with a substance that has a smaller specific gravity than the melt and does not react with the melt.

In summary, the present invention is characterized in that it does not use a conventional lid and uses a substance that has a lower specific gravity than the melt of the substance to be grown in a liquid phase and does not react with the melt.

According to the present invention, even in the case of a compound semiconductor containing an element with high vapor pressure, the composition of the melt does not change,
Another advantage is that there is no mutual contamination of melts due to evaporation of added dopants.

This material may be any material as long as it does not react with the melt of the material to be subjected to liquid phase growth, has a low specific gravity, and has a low vapor pressure. For example, trioxide? 1tli lti (B20
3), or B2O3 with impurities such as Bi2O3 added to lower the melting point, or Na C1 and KC!
ffi.

There are chlorides such as mixtures of L, OJ, and KaJ.

Of these, B2O3 is chemically used as l, fi,
It is a stable glass substance with a melting point of 4000C! The degree is low. This temperature is the growth temperature (60,000 m
The temperature is sufficiently low compared to the temperature before and after the growth temperature, and it becomes a viscous liquid near the growth temperature.

Next, embodiments of the present invention will be explained with reference to the accompanying drawings. It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements may be made without departing from the spirit of the present invention.

FIG. 2 is an example of a jig used in the liquid phase epitaxial growth method of the present invention. 1.3.4 in the figure shows the same thing as in FIG. 6 is a semiconductor material to be epitaxially grown. Specifically, as the V1 substrate 3, an n-type engineering nP (001
) Using a single crystal, continuous growth of additive-free 1nP, P-type IaP was performed on the single crystal. Melt*Tame 1].

No. 12 was filled with 3y In and 10■ engineering nP polycrystals. In particular, 61 was filled with 2 Mll of Zn as a dopant. Next, a plate of B2O3 was placed on top of the growth material in each melt reservoir. This is shown as 71.72. In this state, the temperature was raised in a rebellious tube and left at 650°C for 211 days. Next, the substrate 4 was moved sequentially under the melt reservoir 62.degree. 61 while being slowly lowered, and epitaxial growth of two layers was performed.

"Cold shoulder at room temperature" Shun tentatively measured the jig, B20371,
72 is the melt 21. ．． It completely covers the top of 22, and the third
It became like the figure. This is because the melting point of B2O3 is sufficiently low compared to the smoker temperature, and since it becomes a highly viscous liquid during simmering and has a low specific gravity, there is enough dust on top of each melt. In addition, by the time the temperature of the melt reaches the melting point of B2O3, the growth material 6 and B
There was a sufficient gap between the 2037 and the melt, and the melt did not protrude from the gap between the liquid reservoir and the slider.Furthermore, the two layers of grown P-InP and non-turbid processed nP showed good growth and bonding. was formed.

(Effects of the Invention) As explained above, in the liquid phase epitaxial growth of a substance containing an element with a high vapor pressure, the present invention can prevent evaporation of the element and obtain a good epitaxial growth layer.

[Brief explanation of the drawing]

Figure 1 shows the conventional liquid phase epitaxial growth using
21st Nee 1. FIG. 3 is an explanatory diagram showing one embodiment of the present invention. 11. 12.13... Melt reservoir, 21 , 22 , 2
3... Melt, 3... Slider, 4... Substrate, 5... Lid, 61.62... Growth material, 71.72... B203
1I! J Applicant Nippon Telegraph and Telephone Public Corporation No. KO [≧5 Figure 2 Figure 3

Claims (1)

[Claims] In the slide boat liquid phase epitaxial growth of compound semiconductors, the characteristic of semiconductor crystal growth is to cover a melt containing the semiconductor to be epitaxially grown as a solute with a substance that has a lower specific gravity than the melt and does not react with the melt. Liquid phase epitaxial growth method.