JPS60166300A - Method for epitaxial growth - Google Patents

Abstract

PURPOSE:To carry out the epitaxial growth preventing the thermal deformation of a semiconductor substrate, by covering the semiconductor substrate with a cover made of a GaAs crystal during the period to keep at a high temperature, and holding the assembly in an atmosphere admixed with phosphine. CONSTITUTION:The semiconductor substrate 4 is covered with the cover 5 made of a GaAs single crystal, and the state is maintained until the epitaxial growth is started. When the temperature of the atmosphere reaches a prescribed level, the jig 3 is shifted rightward to effect the contact of the semiconductor substrate 4 rightward to effect the contact of the semiconductor substrate 4 successively with the molten liquids 6a and 6b for growth contained in the molten liquid holder 2. The atmosphere in the reaction tube 1 is H2 gas containing about 100ppm of PH3 gas. During the period to keep at a high temperature prior to the growth, the semiconductor substrate 4 is protected by the cover 5 and the partial pressure of P caused by the thermal decomposition of PH3. Accordingly, the thermal decomposition of the semiconductor substrate is suppressed, and the degradation and deformation of the crystal near the surface of the semiconductor can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improved method for epitaxial growth on the surfaces of InPi6 and InGaAsP based semiconductors.

(Prior art) In recent years, 1nP and InGaAsP-based semiconductors have become increasingly important as materials for light-emitting elements and light-receiving elements, which are key devices in optical fiber communications, and improvements in epitaxial growth technology are being actively pursued in various fields. There is.

Under these circumstances, epitaxial growth is not limited to simply flat crystal surfaces, but is also required for the production of high-performance semiconductor devices, such as growth on processed surfaces such as lattice grooves and mesa-like protrusions. Epitaxial growth technology is also becoming increasingly sophisticated.

Conventionally, In
When epitaxially growing an InGaAsP mixed crystal with a composition on P or close to InP, InP crystal or GaAsP is used to prevent deformation of the semiconductor substrate surface due to thermal decomposition.
Countermeasures have been taken, such as placing a cover made of crystal over the semiconductor substrate and increasing the partial pressure of P by mixing PH into the atmosphere to prevent P volatilization. However, it was not possible to prevent the thermal deformation of the semiconductor substrate during high temperature maintenance, which affected the epitaxial growth conditions.

(Objective of the Invention) An object of the present invention is to provide an epitaxial growth method that eliminates the above-mentioned drawbacks and can prevent thermal deformation of a semiconductor substrate without substantially affecting epitaxial growth conditions.

(Structure of the Invention) The structure of the present invention is a method for epitaxially growing a semiconductor substrate having an InGaAsP thread semiconductor containing InP on its surface, during which the semiconductor substrate is held at a high temperature prior to the start of epitaxial growth.
It is characterized in that it is covered with a cover made of aAs crystal and that 8 phosphines (PHs) are mixed into the holding atmosphere.

(Example) The present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a phase epitaxial growth apparatus using an embodiment of the present invention. The semiconductor substrate 4 is made of InP single crystal and is placed at a predetermined position on the jig 3 made of carbon. A cover 5 made of GaAs single crystal is placed over the semiconductor substrate 4, and maintained in this state until epitaxial growth is started. When the temperature of the atmosphere reaches a predetermined value, move the jig 3 to the right and remove the melt holder 2.
Epitaxial growth is performed by sequentially bringing the semiconductor substrate 4 into contact with the growth melts 16a and 6b provided inside. This is a method well known as a normal liquid phase epitaxial growth method. In this example, the atmospheric gas in the reaction tube L was 1 (2 gases and PH with a concentration of about 100 pIm).

It uses gas.

In this embodiment, as described above, during the high-temperature holding period prior to growth, the semiconductor substrate 4 is protected by the cover 5 and the 2-minute positive generated by the thermal decomposition of the PH3 gas, suppressing thermal decomposition of the semiconductor substrate and suppressing the semiconductor surface. Deterioration of crystal quality and shape deformation in the vicinity are prevented.

FIG. 2 shows the effect of preventing thermal deformation of a semiconductor substrate according to this embodiment. m2 diagram (a) is InP before heat treatment
The substrate 20 (in Figure 2) shows the 1nP substrate 20 after undergoing a thermal history comparable to that of ordinary liquid phase epitaxial growth, which uses a cover made of GaAs crystal, PH, and gas. The figure shows the case using the conventional method. Striped mesa 2 formed on InP substrate 20
In No. 1, the corner portion 22 disappears due to thermal decomposition during the high temperature holding period, and the bottom portion 2:3I is deposited due to the action of decomposition products. On the other hand, according to the method of the above embodiment, no deformation of the striped mesa 21 occurs even by the same heat treatment. Of course, etch bits or roughness due to thermal decomposition do not occur on the surface of the InP substrate 20 other than the striped mesa 21.

The protective effect of the semiconductor substrate in this example is G a A
As partial pressure and minute O produced by thermal decomposition of s-crystal
InGaA, which has a very slow growth rate in the vicinity of the semiconductor substrate, is produced by a partial pressure, a partial pressure supplied from PH, and a partial pressure supplied from the gas.
This is achieved by creating an atmosphere for growing spP yarns. Therefore, the PH3 gas concentration must be higher than a certain value determined by the holding temperature of the semiconductor substrate. For example, if the PH3 gas 'fA' degree is too low, the formation of a growth atmosphere is inhibited, resulting in a reduction in the protection effect of the semiconductor substrate.
It causes surface roughness. Under the reported growth conditions, the preferred value of PH3 concentration for InP substrate is 10-500 ppm.
It is.

(Effects of the invention) Finally, if we absorb the effects and advantages of the present invention, 1n
Thermal deformation of the P yarn or InGaAs P yarn substrate can be prevented, and stable epitaxial growth can be performed even on a semiconductor substrate having an uneven structure on the surface1.

[Brief explanation of drawings]

FIG. 1 is a diagram of a Y-type epitaxial growth apparatus for one embodiment of the present invention, and FIG. 2 is a diagram for explaining thermal deformation of a semiconductor substrate. In the figure, l is a reaction tube, 2 is a melt holder, 3 is a jig, 4 is a semiconductor substrate, 5 is a cover, 6a and 6
b is a growth melt, 20 is an InP substrate, 21 is a striped mesa, 22 is a corner, and 23 is a bottom portion. 51baAb2 43 (a) (b)

Claims (1)

[Claims] A method of epitaxial growth on a semiconductor substrate by bringing a melt having a desired composition into contact with a semiconductor substrate having an InGaAsP thread semiconductor layer containing 1nP on the surface.
During the high-temperature holding period of the semiconductor substrate prior to the start of epitaxial growth, GaAs is applied to the semiconductor substrate.
An epitaxial growth method characterized by covering with a cover made of crystal and mixing phosphine (Pus) in a holding atmosphere.