JPH03136236A - Liquid phase epitaxial growth and growth device - Google Patents

Abstract

PURPOSE:To contrive to make the high-yield manufacture of a wafer possible at the time of formation of an epitaxial layer of a multilayer structure by a method wherein a substrate is brought into contact to the surface on the upper side of a raw melt to be cooled and an epitaxial growth of the first layer of the epitaxial layer is made to perform, then, while a GaAs polycrystal is brought into contact to the lower side of the raw melt in a state keeping the substrate intact, it is heated. CONSTITUTION:In a liquid phase epitaxial growth method of forming an epitaxial layer of a multilayer structure on the surface of a GaAs substrate 4, the substrate 4 is brought into contact to the surface on the upper side of the first raw melt 5 in a substrate 2 with prescribed raw melts 5 to 8 housed in a plurality of its opening parts, to to cooled and a first epitaxial layer is grown and thereafter, a GaAs polycrystal 11 is brought into contact to the surface on the lower side of the melt 5 to be heated in the state keeping as the upper side of the melt 5 is brought into contact to the substrate 4, then, the substrate 4 is moved, the substrate 4 is brought into contact to the surface on the upper side of the second raw melt 6, to be cooled and a process of growing a second epitaxial layer is repeated. Thereby, the crystal of the already existing epitaxial layer is not disturbed by a partial fusion and the like at the time of heat-up and the problem of a reduction in the yield of the formation of a substrate grown epitaxially in a multilayer structure can be dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a liquid phase epitaxial growth method and a growth apparatus for forming a multilayered epitaxial layer on the surface of a QaAS substrate for use in electronic devices and optical devices.

"Prior Art" Conventionally, a liquid phase epitaxial growth method using a slide boat has been used to grow a multilayered epitaxial layer on the surface of a semiconductor substrate, particularly a compound semiconductor substrate.

This liquid phase epitaxial growth, as shown in Figure 5,
A semiconductor substrate 4, for example a GaAs substrate 4, is placed between a carbon substrate 1 and a substrate 2 having a plurality of openings 9 (melt reservoirs).
Insert slider 3 with fixed . Melts of raw materials to be epitaxially grown, that is, a first raw material melt 5, a second raw material melt 6, are respectively placed in the opening 9 of the northern base 2.
Accommodates...

For epitaxial growth, a temperature program as shown in FIG. 2 is used. That is, the semiconductor substrate and the raw material melt are heated to a temperature T1, and after the temperature becomes stable, the slider 3 is moved to bring the semiconductor substrate into contact with the first raw material melt 5. Next, when the temperature is lowered from T1 to T2, the first raw material melt 5 crystallizes and grows on the surface of the semiconductor substrate 4, forming an epitaxial first layer. Next, the slider 3 is moved to separate the semiconductor substrate 4 from the first raw material melt 5, the semiconductor substrate is placed on standby between the first raw material melt 5 and the second raw material melt 6, and the temperature is raised to T3. When the temperature stabilizes, the slider 3 is moved to bring the semiconductor substrate 4 into contact with the second raw material melt 6, and when the temperature is lowered from T3 to T4, the second epitaxial layer is formed. This step is the third step.
By repeating the fourth step, an epitaxial layer with a multilayer structure can be formed.

"Problems to be Solved by the Invention" When epitaxial growth is performed using the conventional slide boat method, after forming an epitaxial layer, when the slider is moved to separate the semiconductor substrate, the raw material melt partially remains on the surface of the substrate. do. If there is residual melt, the epitaxial layer in the area with the residual melt melts during the temperature raising process before moving the substrate to the next raw material melt and bringing it into contact, causing the crystals of the epitaxial layer to become disordered and resulting in epitaxial growth. There was a problem in that the yield of substrates decreased significantly.

``Means for Solving the Problems'' This invention is a liquid phase epitaxial growth method for forming an epitaxial layer with a multilayer structure on the surface of a substrate (wafer 9), in which a raw material melt is applied to a fixed flat carbon substrate and each of a plurality of openings. A structure in which a slider containing a GaAs polycrystal is provided on the upper side between the carbon substrate containing the carbon substrate, and a slider containing a semiconductor single crystal substrate (wafer) on the lower side of the base having an opening. After the temperature of the device is raised and stabilized, the lower slider is moved to bring the substrate into contact with the upper surface of the raw material melt, and the temperature is lowered to allow epitaxial growth of the first layer. In this state, the lower slider is moved to bring the GaAs polycrystal into contact with the lower side of the raw material melt to raise the temperature, and the upper slider is moved to bring the substrate into contact with the second raw material image liquid to lower the temperature. This liquid phase epitaxial growth method and apparatus are characterized in that a second epitaxial layer is grown on the surface of the first epitaxial layer.This operation is repeated to form an epitaxial growth layer having a multilayer structure.

The present invention will be explained below using drawings of specific examples.

FIG. 1 is an exploded view of an example of the device used in the present invention, and the same parts as in FIG. 5, which shows the conventional device, are given the same reference numerals. As shown in the drawing, a slider 10 has two carbon substrates, that is, a flat plate-shaped substrate 1 and a carbon substrate 2 having an opening 9 for accommodating a plurality of raw material melts, and a QaAS polycrystal 11 is fixed on the upper side between them. is being made. A semiconductor substrate (wafer) 4 is placed on the lower side of the hill of the carbon substrate 2.
A slider 3 with fixed . Therefore, when each slider 5, 4 is moved, the upper surface of the raw material melt comes into contact with the semiconductor substrate 4, and the lower surface comes into contact with the GaAs polycrystal.

In the present invention, using such an apparatus, after bringing the substrate 4 into contact with the raw material melt and growing an epitaxial layer on the lower surface, the lower slider 10 is grown while the substrate is in contact with hi of the raw material melt. is brought into contact with the GaAs polycrystal 11, and the temperature is raised. When the temperature becomes stable, the slider 3 is moved to bring the substrate 4 into contact with the next raw material melt, and the temperature is lowered to form the next epitaxial layer. In this way, multiple epitaxial layers are sequentially formed.

"Operation" To grow a multilayer epitaxial layer using the apparatus shown in FIG. 1, a temperature program as shown in FIG. 2 is used.

That is, first, the temperature is stabilized at T1 shown in FIG. 2, the slider 3 is moved to bring the GaAS substrate 4 into contact with the first raw material melt 5, and the temperature is lowered to T2, thereby forming the first epitaxial growth layer. .

Next, without moving the slider 3, that is, the GaAS substrate 4, the slider 10 is moved to bring the GaAS polycrystal 11 into contact with the lower side of the first raw material melt 5. Then, due to the fluctuation of the temperature in the first raw material melt 5, G in the raw material melt.
An aAS cluster (a combination of minute molecules) is formed. This cluster rises to the top of the raw material melt due to the difference in specific gravity within the raw material melt. Therefore, a state is created in which the upper part of the raw material melt is supersaturated (AS) and the lower part is unsaturated, and an epitaxial layer tries to grow on the upper substrate surface.
In the lower part, a phenomenon occurs in which the GaAS polycrystal tries to melt. If the temperature of the raw material melt is increased by 1 at a predetermined temperature increase rate to offset the growth rate at which the epitaxial layer grows on the surface of the substrate, it will rise to T without epitaxial growth on the surface of the substrate. It can be warmed up.

Next, the GaAS substrate is moved by the slider 3 and brought into contact with the second raw material melt 6, and the temperature is lowered from T3 to T4, thereby forming a second epitaxial layer. By repeating this process, an epitaxial layer with a multilayer structure can be formed.

When the apparatus and method of the present invention are used as described above, there is no step of separating the GaAS substrate from the raw material melt and raising the temperature with the raw material melt partially remaining.

Therefore, the crystals of the existing epitaxial layer are not disturbed due to partial melting or the like when the temperature is increased, and the problem of reduced yield of multilayer epitaxially grown substrates can be solved.

``Example'' Using the apparatus shown in FIG. 1 and the temperature program shown in FIG. 4, a substrate for a light emitting diode having two epitaxial growth layers of a single heterostructure as shown in FIG. 5 was manufactured. Ta.

8g of GaAs in 100g of Qa as the first raw material melt
, Zn50# and AI at 300 da were added as a second raw material melt in 100 g of Qa.
7 g+ Te 0.511P, AI 600
A raw material melt containing 1.0 mg of raw material was used. The lower slider contained 10 g of GaAS polycrystal.

The QaAS substrate was attached to the upper slider, and as shown in Fig. 4, the temperature was stabilized at Tl-900°C, and then brought into contact with the first raw material melt, and the temperature was lowered at a rate of 1° to T2-850°C.
The first layer of the epitaxial layer was formed by epitaxial growth while lowering the temperature at C/w.

Next, the GaAS polycrystal was brought into contact with the raw material melt, and the temperature was raised to TS-870°C at a heating rate of 0.01°C/body.

Next, the GaAS substrate was moved and brought into contact with the second raw material melt, and the temperature was lowered to T4-600°C at a cooling rate of 1°C/Jin to grow a second epitaxial layer.

For comparison, the same GaAS substrate (wafer) was used, and after the first layer was epitaxially grown as in the conventional method, the GaAS substrate was separated from the raw material melt without bringing the GaAS polycrystal into contact with the first raw material melt. T2-85 with
The temperature was raised from 0°C to T3-870°C, and then the temperature was lowered by contacting with the second raw material melt to produce a substrate having a two-layer epitaxial layer with a single heterostructure similar to that described above.

A light emitting diode was made from the substrate (wafer) with the epitaxial layer obtained. 1000 from wafer
Each LED chip was extracted and the brightness was measured and compared. At that time, chips with a diameter of 500 mcd or less were considered defective.

The results are shown in the table below.

From the results shown in the table, it can be seen that when the method of the present invention is used, the number of defective chips is reduced compared to the conventional method, and the yield is improved.

"Effects of the Invention" As explained in detail above, when the method and apparatus of the present invention are used, during the epitaxial growth process when manufacturing a substrate having a multilayered epitaxial layer, the raw material fusion that leaves the previously formed epitaxial layer can be used. The next epitaxial layer can be grown without being damaged by melting or the like due to the liquid, and this has the effect of making it possible to manufacture wafers with high yield when manufacturing epitaxial layers with a multilayer structure.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a cross section of an apparatus for implementing the method of the present invention, and FIG. 2 is a graph showing a temperature program for epitaxial growth of a multilayer structure. FIG. 3 is a graph showing a temperature program for epitaxial growth of a single heterostructure in the example, and FIG. 4 is an explanatory diagram showing a cross section of a wafer with a single heterostructure. FIG. 5 is a conceptual diagram showing a cross section of a conventional liquid layer epitaxial growth apparatus. 1: Carbon substrate 2: Carbon substrate with openings 3.10 Nislider 4+ 14: oaAs substrate (wafer) 5, 6
．． 7. 8: Raw material melt 9: Opening 11: GaAS polycrystal 12.
13: Epitaxial growth layer

Claims (1)

[Claims] 1. In a liquid phase epitaxial growth method for forming an epitaxial layer with a multilayer structure on the surface of a GaAs substrate (wafer), a first raw material melt in a substrate containing a predetermined raw material melt in a plurality of openings; After the substrate is brought into contact with the upper surface and the temperature is lowered to grow the first epitaxial layer, a GaAs polycrystal is brought into contact with the lower surface of the raw material melt and raised while the upper surface is in contact with the substrate. warm up, then move the substrate to the second
Liquid phase epitaxial growth method 2 characterized by repeating the step of bringing the substrate into contact with the upper surface of the raw material melt and lowering the temperature to grow a second epitaxial layer, a multilayered epitaxial layer on the surface of the GaAs substrate (wafer) In a liquid phase epitaxial growth apparatus for forming a GaAs polycrystal, the GaAs polycrystal in contact with the raw material melt is placed on the upper side when the carbon base is slid between a fixed flat carbon base and a carbon base containing a raw material melt in each of a plurality of openings. A liquid phase epitaxial growth apparatus 3 characterized in that it has two sliders, each having a slider housed in a carbon substrate having an opening, and a slider having a semiconductor single crystal substrate (wafer) fixed to the lower side on a carbon substrate having an opening. , using the apparatus of claim 2, the temperature of the growth apparatus is raised while the GaAs substrate is in contact with the upper side of the raw material melt and the GaAs polycrystal is in contact with the lower side before growing the second layer and subsequent layers. The liquid phase epitaxial growth method according to claim 1, wherein