JPS6240846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a liquid phase epitaxial growth apparatus for semiconductor devices such as GaP.

Generally, when performing liquid phase epitaxial growth of semiconductor devices, the thickness of the solution used for crystal growth is generally adjusted as follows.
In other words, when performing liquid phase epitaxial growth by the sliding method, it is performed by changing the depth of the recess of the sliding plate on which the substrate crystal is placed, and by holding the substrate crystal vertically and allowing the solution to fall. Liquid phase epitaxial growth is performed by changing the spacing between substrate holders on which substrate crystals are placed. For example, when performing liquid phase epitaxial growth on a GaP substrate, it goes without saying that the latter method is more advantageous in terms of mass production than the two methods mentioned above, in which the holders that hold the substrate crystals are lined up vertically. Nor. The outline of the liquid phase epitaxial growth apparatus used in this method will be explained below.

As shown in FIG. 1, the boat body 1 has a box shape, and a solution tank 3 is located above the boat body 1 via a sliding plate 2, and a solution tank 3 is located below the boat body 1 via a sliding plate 4. There is a solution reservoir 5. Protrusions 7 are formed on opposing inner surfaces of the boat body 1 so that holders 6 for holding substrate crystals can be accommodated vertically stacked one on top of the other with a predetermined interval maintained.

Epitaxial growth is performed using the apparatus configured as described above as follows. That is, first, the holders holding the substrate crystals are housed and fixed between the protrusions from the upper opening of the boat body. Layer the solution reservoir, sliding plate, boat body, sliding plate, and solution tank in this order, insert them into a heating furnace, heat them according to a predetermined temperature curve, and move them into the solution tank by sliding the sliding plate. Put the solution into the boat body. A desired crystal is grown by maintaining the solution at a predetermined thickness on the substrate crystal held in the holder and then cooling the boat body. Slide the sliding plate on the bottom of the boat to drop the solution into the solution reservoir. In this way, epitaxial growth is performed on the substrate crystal.

The boat body used when carrying out liquid phase epitaxial growth as described above is usually made of carbon, and can be easily processed to the desired dimensions. However, solutions are extremely sensitive to contamination with harmful impurities, and when a carbon boat body is used, impurities such as sulfur compounds adsorbed by the carbon may enter the solution, making it difficult to prevent contamination of the solution. ,
Furthermore, it is difficult to control the impurity concentration. Furthermore, when making GaP red elements, for example, they must be doped with oxygen, which oxidizes the carbon boat body and shortens its lifespan. To solve these problems, the boat body can be made of an inert material such as quartz, but in this case, it is difficult to form the boat body into a shape that will hold the holder in place due to workability issues. At the same time, improvements have been requested from the viewpoints of quality and workability.

The present invention has been made in view of these points, and it is an object of the present invention to provide a liquid phase epitaxial growth apparatus which prevents solution contamination, provides good quality products, and is highly economical. In other words, the boat body is made of an inert material such as quartz and has a simple shape without a holder holding mechanism, and the holder to be housed inside the boat body is made of the same inert material and the shape is housed in the boat body. When fixing and for solution flow, form protruding edges on the holder surface at both ends along the solution flow direction.

The apparatus of the present invention will be explained below with reference to the drawings. As shown in Fig. 2, 11 is a boat body made of quartz, there is no holder holding mechanism on the inner surface, an opening 25 is provided on the bottom for dropping the solution, and 12 is an opening into which the solution is injected. A sliding plate 14 having a hole 13 is placed above the boat body 11 through the sliding plate 12, and a solution tank having an opening 15 at the bottom for injecting a solution into the boat body 11, and 16 is another sliding plate. The boat body 11 has an opening 17 for allowing the solution to fall below the boat body 11, and 18 is a solution reservoir disposed below the boat body via the sliding plate 16. Holder 2 housed in the board body 11
As shown in FIG. 3, 0 is formed by attaching rectangular parallelepiped quartz members 22 to both end surfaces of a quartz plate-like member 21, respectively. The substrate crystal 23 is held in a recess formed between the edges of both ends.

In order to perform liquid phase epitaxial growth using the apparatus of the present invention configured as described above, the substrate crystals are held in a holder, and the substrates are stacked one after another at an angle to the boat body so that they are in close contact with each other. Hold and store the crystal vertically. At this time, the holder is inserted so that the edges at both ends are located along the vertical direction of the boat body. Then solution 1
The solution tank containing No. 9, the sliding plate, the boat body containing the holder 20, the sliding plate, and the solution reservoir are stacked in this order and inserted into a heating furnace (not shown). The operation is performed according to a predetermined heating temperature and heating time to cause liquid phase epitaxial growth on the substrate crystal.

At this time, the holders are stored in parallel in the boat body, and the edges on both ends of the holders allow the multiple holders to be fixed in close contact with each other at a slight inclination. The depth of the recess for holding the crystal can also be determined as desired by appropriately determining the height of the edge forming member. That is, by freely changing the depth of this recess, the thickness of the solution on the substrate crystal can be adjusted. Therefore, during liquid phase epitaxial growth, the thickness of the solution injected from the solution bath onto the substrate crystal can be kept to a predetermined value, and an epitaxially grown layer with stable characteristics without variations can be produced. Furthermore, the boat body and the holder can be easily manufactured using quartz, and since they are made of quartz, there is no fear of impurities being mixed into the solution when performing a prescribed operation, and the characteristics of the epitaxially grown layer can be improved. Furthermore, boats and the like can be used for a much longer period of time than before. As described above, improved quality characteristics and improved economic efficiency can be obtained by the apparatus of the present invention.

Next, FIG. 5 shows the results of liquid phase epitaxial growth of P type GaP using a quartz boat and a carbon boat. The horizontal axis of the figure shows the number of times the boat was used for liquid phase growth, and the vertical axis shows the acceptor concentration and luminous efficiency. P-type epitaxial growth was performed at a maximum temperature of 1050℃, the acceptor concentration was around 20μ at the p-n junction interface, and the luminous efficiency was 0.3mm.
The average value of 10 arbitrarily selected values when 6 mA was applied in the forward direction to the pellet in the mouth was shown. 1 in the diagram
is the luminous efficiency of the one according to the present invention, 2 is the luminous efficiency of the conventional one, 3 is the acceptor concentration of the one according to the present invention,
4 indicates the conventional acceptor concentration.

As can be seen from this figure, the device of the present invention has little variation in acceptor concentration, high luminous efficiency, and has significantly improved characteristics over the conventional device, demonstrating excellent effects.

In addition to the above-mentioned quartz, the boat material is BN
Of course, materials that are stable at high temperatures, such as sapphire or sapphire, are used. Also, depending on the situation, carbon or the like may be used.

Furthermore, in addition to the above-mentioned shapes of the substrate holder, it is of course possible to obtain modified structures other than those shown in the drawings that exhibit similar effects according to the gist of the present invention. For example, as shown in FIG.
A holder with similar improved characteristics can also be obtained by using a holder in which the housing part of the substrate 33 is hollowed out to form a recess 32, and grooves 34 for the solution to flow are provided at both ends of the surface. This shows the excellent effect of reducing

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view schematically showing a conventional liquid phase epitaxial growth apparatus, Fig. 2 is a cross-sectional view schematically showing a liquid phase epitaxial growth apparatus of the present invention, and Fig. 3 is a cross-sectional view schematically showing a liquid phase epitaxial growth apparatus of the present invention. A cross-sectional view of the holder,
FIG. 4 is a plan view of another example, and FIG. 5 is a curve diagram showing the relationship between the acceptor concentration and luminous efficiency of a semiconductor device grown by liquid phase epitaxial growth and the number of times a boat for liquid phase epitaxial growth is used. It is. 11... Boat body, 12, 16... Sliding plate,
14... Solution tank, 18... Solution reservoir, 20... Holder, 21... Plate body part of holder, 22...
Both end edges of the holder, 31...Holder, 32
...Concavity of the holder, 34...Groove of the holder.

Claims (1)

[Claims] 1. A boat body in which a plurality of substrate crystal holders are stacked and stored in close contact with each other at an angle, and a solution tank and a solution reservoir are respectively arranged above and below the boat body via sliding plates. The solution is configured to flow into the boat body and further into the solution reservoir as the sliding plate slides, and projecting edges are formed on both ends of the surface of the holder along the direction in which the solution flows. A liquid phase epitaxial growth apparatus characterized in that a part regulates liquid thickness.