JPH023292B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for depositing an epitaxial growth layer from a melt on the surface of a substrate placed on a base plate, and an apparatus for carrying out the method. be.

[Conventional technology]

For liquid phase epitaxy, it is necessary to bring the melt into contact with the epitaxial growth substrate in a hydrogen atmosphere in a high temperature reactor. The melt is often a liquid metal, such as molten gallium. As a result, an epitaxial layer is grown on the substrate by means of a suitable temperature adjustment process.

In conventional methods, contact between the melt and the substrate is effected by mechanical aids. Such auxiliary means include rotating the melting crucible, moving the melt container, or dipping a substrate mounted on a support into the melt in the crucible.

In addition to this, a method using two semiconductor boards is published in ``Journal of Crystal Growth'', 11 .
1971, pp. 101-103). One of these semiconductor plates is somewhat larger, and a smaller semiconductor plate is placed on top of it, with a gap formed between the plates by three protrusions. The melt is deposited as a drop on a gallium arsenide rod and placed by a mechanical device on top of the ridge of the underlying semiconductor plate, whereupon it spreads into the gap by capillary action. However, the application of this method is limited because the amount of molten material inserted is determined physically and cannot be freely adjusted.

[Problem to be solved by the invention]

It is an object of the present invention to provide a method of fused epitaxial growth and an apparatus for carrying out the method that does not require mechanically moving parts.

[Means to solve the problem]

In order to achieve the above object, in the fused epitaxial growth method of the present invention, a second plate is provided above the plate used as the base plate, and at least the surfaces of both plates facing each other are used for fused epitaxial growth. Depending on the melt used, it is not wetted, and the melt used for melt epitaxy and provided with an oxide film is placed in contact with the substrate in the gap formed between the two plates. Then, the oxide film covering the melt is removed in a reducing atmosphere, and then the melt is caused to flow onto the substrate solely by its surface tension.

Further, in another method of fused epitaxial growth of the present invention, a second plate is provided above the plate used as the base plate, and at least the surfaces of both plates that face each other are connected to the fused epitaxial growth method used for fused epitaxial growth. Some bodies are non-wettable, the plates are arranged at an angle to each other to form a wedge-shaped gap between the plates, and the melt epitaxy is used for melt epitaxy and has an oxide layer. is placed on the narrow side of the gap, the substrate is placed on the wide side of the gap, the oxide film covering the melt is removed in a reducing atmosphere, and then the melt flows onto the substrate solely by its surface tension.

Furthermore, in the apparatus for carrying out the method of the present invention, a second plate is provided at a short distance above the plate used as the base plate, so that the molten epitaxy inserted between the two plates is A small gap is formed between the two plates such that the molten material can move between the two plates only by the surface tension, and at least the surfaces of the two plates facing each other are not wetted by the molten material. The apparatus is not equipped with a mechanical sliding mechanism and the melt can be placed in a reducing atmosphere.

The plate used as the base plate and the second plate placed above it may be arranged parallel to each other,
They may also be arranged at an angle to each other.

The plate used as the base plate may have a recess.

[Effect]

In the fused epitaxial growth method of the present invention, the molten material placed in the gap formed between the lower plate used as a base plate on which the substrate is placed and the second plate placed above it It does not wet the surface of the board and therefore remains stationary. When the oxide film of the melt is removed in a reducing atmosphere, the melt moves toward the substrate due to its surface tension, flows onto the substrate, and epitaxial growth occurs.

The fused epitaxial growth apparatus of the present invention is composed of a lower plate used as a base plate on which the substrate is placed, and a second plate placed above it with a slight gap, and a mechanical sliding mechanism. The molten material is not equipped with a molten material, and the molten material is stopped and moved by the surface tension of the molten material.

〔Example〕

Next, the present invention will be explained in more detail with reference to embodiments shown in the drawings.

In the embodiment of FIG. 1, a gap 3 is formed between plates 1 and 2, which are not wetted by the melt, which is made of, for example, graphite, quartz or aluminum oxide and is provided with an oxide layer. These plates 1, 2 are inclined at an angle, with the melt 4 placed on the narrow side of the gap and the substrate 5 placed on the lower plate 2 on the wide side of the gap. In this state, the melt 4 does not wet the plates 1 and 2 and therefore remains stationary. When the oxide film on the surface of the melt 4 is now reduced in a hydrogen atmosphere, the melt 4 moves toward the substrate 5 due to surface tension and flows onto the substrate 5.

As long as the substrate 5 is wetted with the melt, the melt 4 will be absorbed by the substrate 5.
Although it flows above it, it does not reach the plate 2 below. If the amount of melt 4 inserted is greater than that required to coat the substrate, the excess melt flows over the edge of the substrate 5 and out of the gap. This allows accurate metering of the melt.

In the embodiment shown in FIG. 2, plates 1 and 2 are parallel and a uniform gap 3 is created. A melt 4 having an oxide film is inserted into this gap 3 so as to be in contact with the edge of the substrate 5 . In this state, the melt 4 does not move. When the oxide film on the surface of the melt is removed in a reducing atmosphere, the melt 4 flows onto the substrate 5.

Some substrate materials only become wettable with the melt at high temperatures. For example, gallium arsenide and gallium phosphide only become wet with molten gallium at temperatures above 640°C. It is therefore at this temperature that the melt 4 flows onto the substrate 5 if these materials are used.

For example, in order for the additional component to dissolve into the melt only at a high temperature so that all the oxides are reduced, this additional component 6 may be placed on the substrate 5 as shown in FIG. Can be done.

In order to ensure that excess melt flows out only after the melt has coated the substrate 5 in the parallel plate gap as shown in FIG. 2, the apparatus of FIG. 4 can be used. In this device, the substrate 5 is placed against the edge of a recess 7 in the plate 2, and the excess portion of the melt placed on the other side of the substrate 5 flows into this recess. The melt is continuous with the melt portion filling the recess 7 and overlying the substrate 5, as shown in FIG. In order to prevent the melt filling the depression 7 from influencing the deposition conditions on the substrate 5, substrate material is placed in the depression 7 and the melt is saturated with this material.

In order to prevent the additional component 6, which melts into the melt only at high temperatures, from coming into contact with the substrate 5, this component is placed in a recess 7 as shown in FIG.

It is not necessary that the substrate be wetted by the molten mixture resulting from dissolution of the additional component 6. Therefore, the present invention is also effective when using a non-wetting melt. An example of the components is plates 1 and 2 of gallium graphite, melt 4 of gallium, substrate 5 of gallium arsenide, and additional component 6 of aluminum. This example satisfies all the requirements for fusion epitaxy of ternary gallium arsenide/aluminum arsenide. Further additional components can be introduced into the recess 7 after the end of the epitaxy process. This allows addition melt epitaxy ("Inst.Phys.Conf." series, No. 24, 1975, 145
Depending on the type of additional components, this can be either heteroepitaxy with different crystal compositions or homoepitaxy with the same crystal composition but with different doping. This growth process can be repeated as many times as necessary.

In an actual example, silicon was added as an additional component to the above material combination of graphite, gallium, and gallium arsenide/aluminum arsenide in the first epitaxy process to create a pn junction within the epitaxial layer. It is a well-known fact that silicon is an amphoteric dopant. In this case, aluminum is introduced into the recess 7 as additional component 6 prior to the second epitaxy step.

This method produces a device having the structure shown in FIG. In FIG. 6, the vertical axis represents the aluminum concentration K, and the horizontal axis represents the distance d of the epitaxial layer from the substrate surface. Therefore, the boundary between the substrate and the epitaxial layer serves as the coordinate origin.
The position of the pn junction is indicated by a dashed line 8. The structure of FIG. 6 is suitable as a light emitting diode, the light emitting wavelength of which can be chosen between 650 nm and 950 nm. A second epitaxial layer 10 grown on the first epitaxial layer 9 is transparent to the generated light and is used as a window for light emission. This layer can also act as an injection-limiting layer to influence the emission light spectrum and the switching time.

〔Effect of the invention〕

According to the present invention, since no mechanical movable device is required for covering the substrate with melt, the method and device are extremely simple, and the cleanliness of the device and substrate can be maintained at a high level. Consequently, it is possible to obtain an epitaxial layer without crystal disturbance without contaminating the substrate material, and the manufacturing process can be automated to a large extent.

[Brief explanation of drawings]

1 to 5 each show a cross-sectional view of a different embodiment of the invention, and FIG. 6 shows a cross-sectional view of a different embodiment of the invention. 1... Base plate, 2... Second plate, 3... Gap, 4
...Melting body, 5...Substrate.

Claims (1)

[Claims] 1. In a method for growing an epitaxial layer on a substrate 5 placed on a plate 2 used as a base plate, a second plate 1 is provided above the plate 2 used as a base plate. , at least the mutually opposing surfaces of both plates 1, 2 are not wetted by the melt 4 used for melt epitaxy, and in the gap 3 formed between the plates 1, 2. A melt 4 used for melt epitaxy and provided with an oxide film is placed in contact with the substrate 5, the oxide film covering the melt 4 is removed in a reducing atmosphere, and then the melt 4 is placed in contact with the substrate 5. A fused epitaxial growth method characterized by flowing onto a substrate 5 only by surface tension. 2 In a method of growing an epitaxial layer on a substrate 5 placed on a plate 2 used as a base plate, a second plate 1 is provided above the plate 2 used as a base plate, and both plates 1 and 2 are grown. at least mutually opposite surfaces of the plates 1, 2 are not wetted by the melt 4 used for fused epitaxy, and the plates 1, 2 are arranged at an angle to each other. A wedge-shaped gap 3 is formed between them, a melt 4 used for fused epitaxy and provided with an oxide layer is placed on the narrow side of the gap 3, and a substrate 5 is placed in the gap 3.
A fused epitaxial growth method characterized in that the oxide film covering the melt 4 is removed in a reducing atmosphere, and then the melt 4 is caused to flow onto the substrate 5 only by its surface tension. 3. In an apparatus for growing an epitaxial layer on a substrate placed on a plate 2 used as a base plate, a second plate 1 is placed at a small distance above the plate 2 used as a base plate. By providing such a small gap 3 between the two plates 1 and 2, the molten material 4 for molten epitaxy inserted between the two plates 1 and 2 can move between the two plates 1 and 2 only by its surface tension. At least the mutually opposing surfaces of both plates 1 and 2 formed between the plates 1 and 2 are not wetted by the melt 4, and the device is not equipped with a mechanical sliding mechanism, and the melt 1. A fused epitaxial growth apparatus, characterized in that No. 4 can be placed in a reducing atmosphere. 4. The device according to claim 3, characterized in that both plates 1 and 2 are arranged parallel to each other. 5. The device according to claim 3, characterized in that both plates 1, 2 are arranged at an angle to each other. 6. Device according to claim 4, characterized in that the lower plate 2 has a recess 7.