JPS62292693A - Liquid epitaxy device - Google Patents

Abstract

PURPOSE:To grow an epitaxial layer in uniform thickness of the surface of a substrate by forcing up a soln. for growth to bring the soln. into contact with plural substrates longitudinally held by a holding part, and then separating the soln. in the holding part and the soln. on the outside of the holding part. CONSTITUTION:A substrate 7 is longitudinally held by a substrate holder 4 in a growth jig 1. A polycrystal for growth is charged into a soln. reservoir 2, and dissolved to obtain a saturated soln. 8. A piston 3 is thrust in to force up the growth soln. 8, hence the soln. is brought into contact with the substrate 7, and then a lower shutter 6 is closed to separate the soln. 8 supplied in the substrate holder 4 from the soln. 8 on the lower piston 3 side. An upper shutter 5 is further closed to separate the soln. 8 in the substrate holder 4 from the soln. 8 at the upper part. At this time, the interval (a) between the upper or lower end of the substrate 7 and the respective shutters 5 and 6 and the distance (b) between the opposed substrates 7 are limited to conform to a<2b. Cooling is continued under said conditions, an equitaxial layer is grown on the substrate 7, and the layer having uniform thickness is obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a liquid phase epitaxial growth apparatus, and particularly to an apparatus for epitaxially growing a substrate in a vertically disposed state.

[Prior Art] Epitaxial growth methods for compound semiconductors such as GaAs include liquid phase growth and vapor phase growth (VPE).

Metalorganic pyrolysis vapor deposition method (MOCVD method).

Although there are methods such as molecular beam epitaxial method (MBE method), liquid phase growth method is most suitable for obtaining a high-quality crystal phase and is widely used at the production level of light emitting diodes and semiconductor lasers. This liquid phase growth method is a method in which crystals are grown by bringing the substrate into direct contact with a solution containing component elements, and the slide boat method is generally used to grow multilayers with a roughly uniform film thickness. .

However, this slide boat method can only manufacture a few wafers at a time, so if you want to increase mass production, you can hold multiple substrates vertically in a growth jig and apply the growth solution to them. A method has been adopted in which growth is achieved by bringing the materials into contact with each other.

This method will be explained with reference to FIG.

First, a growth solution 93 is contained in a solution reservoir 92 located at the bottom of a growth jig 91, and a plurality of substrates 95 are each held vertically by a substrate holding jig 94 located above it. Next, push the piston 96 into the growth solution 9.
3 is pushed upward, thereby avoiding contact between the substrate 95 and the growth solution 93 to perform growth. After that, piston 96
The growth solution 93 is returned to the solution reservoir 92 by pulling .

If such a method is used, growth can be performed on multiple substrates at once. Furthermore, since the growth solution returns to the solution reservoir when growth is low, the growth solution can be reused easily and economically.

[Problems to be Solved by the Invention] However, in the above-described method, during growth, not only the surface of the substrate but also the periphery of the substrate, especially the substrate 95 in FIG.
Since the growth solution contacts the top and bottom of the substrate, the grown epitaxial layer is thicker at the periphery than at the center of the substrate. For example, using a growth jig 91 shown in FIG.
)'Jm is grown to a thickness of about 30 mm, the thickness at the periphery of the substrate 95 becomes more than twice that at the center.

As described above, this method, in which the substrate is vertically arranged and grown, is inferior to the slide boat method in terms of uniformity and quality of the film thickness, and it is difficult to grow an epitaxial layer with high precision.

SUMMARY OF THE INVENTION It is thus an object of the present invention to provide a liquid phase epitaxial growth apparatus which solves the problems of the above-mentioned prior art, has excellent mass productivity, and is capable of growing an epitaxial layer with a uniform thickness.

[Means for Solving the Problems] In order to achieve the above object, the liquid phase epitaxial growth apparatus of the present invention accommodates a growth solution at the bottom of a growth jig, and a plurality of substrate holders located above the growth jig. In an apparatus for epitaxial growth, the substrates are arranged vertically and the growth solution is supplied into the substrate holder by pushing up the growth solution to bring the growth solution into contact with the substrate surface for epitaxial growth. Separation means is provided for separating the growth solution supplied into the substrate holder from the growth solution outside the substrate holder after contact with the substrate holder.

[Function] By providing the above-mentioned separation means, the growth solution inside and outside the substrate holder during growth can be separated into molecules! By doing this, it is possible to prevent the growth solution outside the substrate holder from contributing to growth at the peripheral edge of the substrate. As a result, the epitaxial layer grown on the substrate surface has a uniform thickness without being thicker at the periphery than at the center.

[Example] Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a growth jig used in a liquid phase epitaxial growth apparatus according to an embodiment of the present invention. A solution reservoir 2 for containing a growth solution is provided at the bottom of the growth jig 1, and a piston 3 for pushing up or dropping the growth solution is provided on one side of this solution reservoir 2. . Further, the solution reservoir 2 has an open top, and a substrate holder 4 that can vertically hold a plurality of substrates is provided above the solution reservoir 2 . Further, an upper shutter 5 and a lower shutter 6 are provided along the upper end surface and the lower end surface of the substrate holder 4, respectively, in the form of a flat plate, which can be opened and closed in the horizontal direction, and by closing these, the substrate holder 4 is moved into the growth jig 1. It is constructed so that it is sealed from other parts of the

Using the growth jig 1 having the above configuration, a 30% GaAs epitaxial layer was grown on the GaAS root.

First, GaAs of 50a* x 50m is placed on the substrate holder 4.
A total of 12 plates 7 were held vertically. At this time, the distance between the substrates 7 facing each other was 3IIm. Furthermore, 500 g of Ga and 40 g of GaAs polycrystal were placed in the solution reservoir 2. Note that both the upper shutter 5 and the lower shutter 6 are left open.

Next, this growth jig 1 was placed in a reaction tube (not shown), and after replacing the inside of the reaction tube with hydrogen gas, the temperature inside the furnace was raised to 800°C using an external electric furnace (not shown). A growth solution 8 is formed by dissolving GaAs polycrystals in Ga in the solution reservoir 2 to a saturated state.

Thereafter, the temperature inside the furnace is lowered at a cooling rate of 1° C./min, and when the growth solution 8 reaches a supersaturation degree of 4° C., the piston 3 is pushed in to push the growth solution 8 upward (see FIG. 2).

After contacting the substrate 7 and the growth solution 8 in this way, the lower shutter 6 is closed and the growth solution 8 supplied into the substrate holder 4 is transferred from the growth solution located on the lower piston 3 side. Separate (see Figure 3).

Next, the upper shutter 5 is closed to separate the growth solution 8 in the substrate holder 4 from the growth solution above (see FIG. 4). Cooling is continued in this state to grow an epitaxial layer on the substrate 7.

After the growth is completed, the upper shutter 5 and the lower shutter 6 are opened.
are successively opened, and then the piston 3 is pulled to drop the growth solution 8 into the solution reservoir 2, returning the state as shown in FIG. Then, the growth jig 1 was pulled out of the reaction tube, and the manufactured epitaxial wafer was taken out from the substrate holder 4. When manufacturing wafers subsequently, growth can be started again by simply using the growth solution 8 in the solution reservoir 2 and placing a new substrate.

When the film thickness of 12 epitaxial wafers manufactured in this way was measured, each was within a range of 304 ± 10%, and the in-plane variation was within ± 10%, indicating excellent uniformity. .

As shown in FIG. 5, the smaller the distance a between the upper or lower end of the substrate 7 and each shutter when the upper shutter 5 and the lower shutter 6 are opened, the more uniform the epitaxial layer will be on the substrate 7. In particular, it was found that uniformity similar to that of the above embodiment can be obtained when the relationship a<2b is satisfied with respect to the distance Mb between the opposing substrates 7.

Further, in the above embodiment, the upper shutter 5 and the lower shutter 1? Although the ivy 6 has a flat plate shape, the shape is not limited to this, and as shown in FIG. 64 can also be used. In this case, as shown in FIG. 6, the piston 3 is pushed in with the openings 62 of the shutters 63 and 64 aligned with the gap 61 of the substrate holder 4, and the growth solution 8 is brought into contact with the substrate 7. As shown in FIG. 7, the shutters 64 and 63 are sequentially moved slightly to the left to separate the growth solution 8 in each gap 61 of the substrate holder 4 from the others. In this way, the growth solution can be separated by only slightly moving each shutter.

In addition, in order to separate the growth solution inside and outside the substrate holder,
As shown in FIG. 8, fixing plates 82 and 83 are provided which touch the upper and lower parts of the substrate holder 81, respectively.
It may be configured such that the substrate holder 81 moves between and 83. In this case, as shown in FIG. 8, with the mounting plate 85 in the substrate holder 81 positioned directly above the solution reservoir 84, the piston 86 is pushed in, thereby supplying the growth solution 87 into the substrate holder 81. The growth solution 87 is separated by moving the plate holder 81 in the direction of the arrow.

The device of the present invention is a ■-V group compound semiconductor containing GaAs, a mixed crystal compound semiconductor such as GaAuAs, and a II-rV compound semiconductor.
It can be applied to liquid phase epitaxial growth of group compound semiconductors and their mixed crystals.

[Advantageous Effect 1] As explained above, according to the present invention, the following excellent effects of rAI are exhibited.

(1) It is possible to grow an epitaxy cell layer with the same uniformity of film thickness as the slide boat method even though the method uses a method in which the substrates are arranged vertically and the growth is mixed.

(2) That is, high-quality epitaxial wafers with uniform film thickness can be manufactured with good mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a growth jig used in a liquid phase epitaxial growth apparatus according to an embodiment of the present invention, FIGS. 2 to 4 are process diagrams showing the operation of the embodiment, and FIG. A partially enlarged view showing the positional relationship between the held substrate and the upper and lower shutters, FIGS. 6 to 8 are configuration diagrams of growth jigs used in other embodiments, and FIG. 9 is a conventional growth jig. It is a block diagram of a jig. In the figure, 1 is a growth jig, 3 is a piston, 4 is a substrate holder, 5 is an upper shutter, 6 is a lower shutter, 7 is a substrate, and 8
is the growth solution. Figure 3 Figure 4

Claims (4)

[Claims] (1) A growth solution is stored in the bottom of the growth jig, and a plurality of substrates are arranged vertically in a substrate holder located above the growth jig, and the growth solution is pushed up into the substrate holder. In an apparatus for epitaxial growth by supplying a solution and bringing the growth solution into contact with the substrate surface, after the substrate and the growth solution come into contact, the growth solution being supplied into the substrate holding part and the growth outside the substrate holding part are removed. 1. A liquid phase epitaxial growth apparatus, characterized in that it is provided with a separation means for separating the liquid from the solution. (2) The apparatus according to claim 1, wherein the separating means comprises shutters that are provided at the upper and lower parts of the substrate holding section so as to be openable and closable, respectively. (3) The first aspect of the present invention is characterized in that the separating means comprises fixing plates that are in contact with the upper and lower parts of the substrate holder, respectively, and the substrate holder is provided so as to be movable between the fixing plates. Apparatus described in section. (4) Distance a between the upper end or lower end of the substrate and the separation means, and distance b between the substrates facing each other within the substrate holder.
The device according to any one of claims 1 to 3, characterized in that and satisfies the relationship a<2b.