JPS58127320A - Device for liquid-phase epitaxial growth - Google Patents

Abstract

PURPOSE:To prevent the extraordinary growth of crystals in the peripheral part of a substrate by a method wherein the central part of the substrate having an appropriate area, other than the peripheral part, is covered with an insulating film whose melting point is sufficiently higher than the temperature of growing, and a substrate formed of a material having the same quality with that of said substrate is arranged on a melt. CONSTITUTION:A slider 2, which forms the bottom of a melt cistern 1a, is inserted slidably into the main body 1 of a carbon boat, and a substrate 3 whereon growth is to be made is fitted and supported by a recess 2a for holding 2a of the slider. The substrate 3 has an area somewhat larger than that of the melt cistern 1a and is held between the main body 1 of the boat and the slider 2 so that it does not rise up from the bottom of a melt 4. The central part of the main body 5a of a substrate 5 formed of GaAs is covered with an insulating film 5b formed of SiO2 or the like. When liquid-phase epitaxial growth is made in such a device, the growth is made, in the central part of the melt 4, only on the substrate 3, while it proceeds, in the peripheral part thereof, both on the substrate 3 and in the exposed part of the main body 5a of the substrate 5. Therefore, the speed of growth of crystals in the peripheral part becomes smaller than that in the central part. This difference becomes remarkable when the ratio of the thickness of the melt 4 to that of a growing layer is small, and thus the extraordinary growth of crystals in the peripheral part can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a liquid phase epitaxial growth apparatus using a sliding carbon boat.

Generally, when a compound semiconductor is grown by liquid phase epitaxial growth on a single-crystal growth substrate by slowly cooling a melt saturated with solute atoms using a sliding type carbon, heat dissipates from the carbon wall of the melt reservoir. Since the temperature is large, a two-dimensional temperature gradient occurs in the melt near the substrate surface. As a result, abnormal crystal growth occurs on the substrate near the carbon wall where the temperature is relatively low.

Such abnormal crystal growth on the periphery of the substrate impedes the smooth removal of the melt, causing poor wipe-off, scratches on the surface of the growth area, and damage to the edges of the carton, especially in continuous multilayer epitaxial growth. In some cases, it may cause deterioration of crystallinity.

In order to avoid these problems, a carburetor main body 1 forming a melt wetted wall as shown in FIG. A car consisting of a slide 2 that also serves as a holder? In the support cart, as shown in FIG. 2, the opening area of one melt reservoir 1a is made larger than that of the substrate 3 to be grown, so that the surface of the substrate 30 can be sufficiently covered with the melt 4, and the surface of the substrate 30 is
It is possible to reduce the temperature distribution of the melt 4 within the plane. However, this is because the substrate, which has a lower density than the melt, floats into the melt, and the source of solute per unit area of the substrate becomes larger at the periphery of the substrate, resulting in abnormal growth. It's inconvenient.

Furthermore, in order to avoid the above-mentioned inconvenience, some methods attempt to prevent the substrate 3 from floating by obliquely polishing the peripheral portion 3a of the substrate 30, as shown in FIG. Because extra processing is added to the item,
This method not only increases the number of steps but also increases the possibility of introducing new crystal defects into the substrate.

The present invention has been made in view of the above-mentioned circumstances, and includes a substrate having an appropriate area, the center of which is covered with an insulating film having a melting point sufficiently higher than the growth temperature, and which is made of the same material as the material to be grown. By providing a liquid phase epitaxial growth apparatus in which the above is fitted into a slide-type Cargontate melt reservoir and placed on top of the melt, it is possible to grow crystals of compound semiconductors over a wide range of composition ratios. The purpose is to prevent the occurrence of abnormal crystal growth around the substrate.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5.

FIG. 3 shows a melt reservoir showing a sliding car board of an apparatus for performing liquid phase epitaxial growth on a GaAs substrate according to an embodiment of the present invention using a melt made of a Qa solution containing impurity elements of A/ and As. A cross section is shown. In FIG. 3, reference numeral 1 denotes a carton body that forms the wall of the melt reservoir 1a, and 2 a carton that forms the bottom of the melt reservoir 1a and is inserted into a groove that slides smoothly against the gate body 1, and further supports the growth substrate 3. This is a slider that fits into and supports the holding recess 2m. The substrate 3 has an area slightly larger than the cross-sectional area of the melt reservoir 1a, and its peripheral portion protrudes from the melt reservoir 1a and is held between the gate body 1 and the slider 2, so that it does not rise above the bottom of the melt 4 in the melt reservoir a. 5 is a substrate fitted into the melt reservoir 1a and placed on the melt 4, and as shown in the bottom view of FIG. 5, this substrate 5 has a predetermined composition ratio. kl, As
Qa solution or melt 4 containing impurity elements consisting of
Si with a melting point sufficiently higher than 900°C
o, (melting point 1470'C), A40s (melting point 2030'C)
The main substrate 5 is made of QaAs, which is the same material as the growth substrate 3, with an insulating film 5b made of 5iC (melting point 2200°C), etc.
The central portion of a is covered except for the peripheral portion of a suitable area.

When liquid phase epitaxial growth is performed using the apparatus according to the embodiment of the present invention as described above, liquid phase epitaxial growth is performed only on the growth target substrate 3 located below the central portion of the melt 4; In the peripheral area, crystal growth progresses on both the substrate 3 to be grown and the exposed portion of the main substrate 5a of the substrate 50 disposed above the melt 4. For this reason, the crystal growth rate at the periphery of the growth substrate 3 is lower than that at the center, especially in the case of epitaxial growth where the ratio of the thickness of the melt 4 to the thickness of the epitaxial growth layer to be obtained is small. Since the solute supply source is small, the difference in crystal growth rate between the peripheral area and the central area of the growth substrate becomes significant. Therefore, abnormal crystal growth at the periphery of the growth substrate, which occurs when attempting to obtain an epitaxially grown layer at the center with a predetermined thickness, is reduced. Moreover, since the growth substrate itself has not been subjected to any special processing other than normal surface treatment, the surface is not damaged or contaminated, and crystal growth proceeds at a good interface.

As explained above, the liquid phase epitaxial growth apparatus of the present invention has a substrate in the melt reservoir of a sliding carden cart, the center part of which is covered with an insulating film having a high melting point except for the peripheral part, and which is made of the same material as the substrate to be grown. Since they were fitted and placed on the melt, using this device it is possible to reduce abnormal crystal growth around the growth substrate, and since no special processing is applied to the growth substrate itself. , it is possible to perform epitaxial growth in good conditions without introducing new defects into the growth substrate and without contaminating the solid-liquid interface, and is particularly applicable to continuous epitaxial growth with many hetero interfaces. A great effect can be obtained.

[Brief explanation of drawings]

Figure 1 shows a sliding carbon point for continuous multilayer liquid phase growth.
FIGS. 2 and 3 are cross-sectional views of the melt reservoir showing different ways of using the conventional cartridge.
FIG. 4 is a sectional view of the melt reservoir of a sliding type carbon plate according to an embodiment of the present invention, and FIG. 5 is a bottom view of a substrate placed on the melt according to an embodiment of the present invention. ...Boat body, 1a...Melt reservoir, 2...Slider, 2a...Holding recess, 3...Growth substrate, 4
...melt, 5...substrate placed on the melt, 5a
... Substrate main body, 5b... Insulating film. Patent applicant Oki Electric Industry Co., Ltd.

Claims (1)

[Claims] A slide type carmen is provided with a main body for forming a melt wet wall, and a slider that is slidably inserted into the boat main body to form the bottom of the melt pool and support the growth plate. - In a liquid phase epitaxial growth apparatus using a melt tank, a substrate having an appropriate area, the center of which is covered with an insulating film having a melting point sufficiently higher than the growth temperature, and made of the same material as the substrate, is fitted into a melt reservoir. 1. A liquid phase epitaxial growth apparatus characterized in that the apparatus is arranged above a melt.