JPS6318857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a boat used in a liquid phase epitaxial growth apparatus.

As is well known, the liquid phase epitaxial growth method is
- group semiconductor crystals, which are compound semiconductor crystals,
It is generally used for its mixed crystals and - group compound semiconductor crystals. Here, as an example, a case where GaAs is epitaxially grown will be explained with reference to FIG.

FIG. 1 is a side sectional view schematically showing a boat used in a conventional epitaxial growth apparatus. In this figure, 1 is a slide boat, 2 is a slider plate, and a GaAs substrate 3 is set on this.
A container 10 has growth melt storage chambers 4, 5, and 6, and stores growth melts 7, 8, and 9 independently. The container 10 and the slider plate 2 are movable relative to each other. Now, n
A case in which n-type GaAs and p-type GaAs are successively epitaxially grown on a shaped GaAs substrate 3 with a steep impurity gradient will be specifically described.

At this time, the GaAs substrate 3 in FIG. 1 is an n-type GaAs substrate (hereinafter referred to as n-GaAs
(referred to as a substrate). The growth melt 7 contains high-purity Ga, high-purity GaAs, and n-type impurities, such as Sn.
It is prepared by adding elements such as or Te. Growth melt 8
and 9 are prepared by adding high purity GaAs and a p-type impurity such as Ge to high purity Ga. In order to provide the growth layer with a steep impurity gradient, the growth melts 8 and 9 are prepared with similar compositions.
GaAs added to Ga is added to Ga at the growth start temperature.
It goes without saying that the amount to be added should be determined by considering the solubility of As and the segregation coefficient of each impurity.

The n-GaAs substrate 3 and the growth melts 7 to 9 prepared in this manner are arranged as shown in FIG. 1, placed in a high-purity atmospheric gas, and heated in an electric furnace.
When GaAs and impurities dissolve in Ga that has reached a predetermined temperature and become a saturated solution, the growth melt 7 and n-
GaAs substrate 3 is brought into contact. By lowering the temperature, n-GaAs is epitaxially grown on the n-GaAs substrate 3. When the desired amount of n-GaAs growth layer is obtained, the container 10 and the slider plate 2 are moved relatively quickly, that is, the n-GaAs substrate 3 and the growth melt 7 are separated, and in this case, the growth melt is The liquid 8 is passed over the n-GaAs substrate 3, and the n-
The next growth melt 9 is brought into contact with the GaAs substrate 3. Since the temperature is lowered, p-GaAs grows epitaxially on the n-GaAs substrate 3. When a predetermined p-GaAs growth layer is obtained, the growth melt 9 is separated from above the growth layer. slide boat 1
is cooled to room temperature and deposited on the n-GaAs substrate 3.
The epitaxial wafer on which GaAs and p-GaAs have been sequentially grown is taken out.

When performing liquid phase epitaxial growth using the slide boat 1 described above, if the bottom surface of the container 10 and the top surface of the crystal of the n-GaAs substrate 3 are made the same surface, the container 10 and the n-GaAs substrate 3 will come into contact. , n-
The GaAs substrate 3 is damaged and a good quality epitaxial crystal layer cannot be obtained. Further, if a slight gap is provided between the bottom of the container 10 and the n-GaAs substrate 3, it is inevitable that the growth melts 7 to 9 will mix with each other. In order to avoid this, two melts having the same composition are used to perform the growth as described above. Although the above explanation assumes that a saturated melt is produced, in reality, there are limitations in accurate and precise control of temperature, accurate weighing of the melt material for growth, etc., and an ideal saturated melt cannot be expected. This means that the thickness of the grown layer cannot be controlled reproducibly. Furthermore, there is a temperature difference between the growth melts 7 to 9 and the n-GaAs substrate 3, and there is also a temperature difference between the growth melts 7 to 9.
This makes it difficult to control the thickness of the growth layer.

This invention was made in an attempt to eliminate the above-mentioned drawbacks of the conventional method by making it possible to produce a saturated melt as a growth melt and reducing the temperature difference between the growth melt and the substrate. This invention will be explained below.

Figures 2 a to c show one embodiment of the present invention, with Figure 2 a being a plan view of the boat, and Figure 2 b being a plan view of the boat.
FIG. 2c is a sectional view taken along line AA in FIG. 2a, and FIG. 2c is a sectional view taken along line BB in FIG. 2a. In these figures, 21 is a substrate, which is set in a growth chamber 22. The growth chamber 22 is connected to a first drainage reservoir chamber 26 through a first growth chamber communication hole 23 and a first drainage chamber communication hole 25 . 29 is the first growth melt storage chamber;
31 is a first piston that can set a base material 33 for saturating the growth melt. 3
Reference numeral 5 designates a first through-hole stopper that closes and opens the first growth chamber through-hole 23. Similarly, 24 is a second growth chamber through hole communicating with the growth chamber 22, 30 is a second growth melt storage chamber, and 32 is a second growth chamber having a base material 34 for saturating the growth melt. 36 is a second through hole stopper that closes and opens the second growth chamber through hole 24. Reference numerals 27 and 28 are a second drainage chamber communication hole and a second drainage storage chamber communicating from the growth chamber 22, respectively.

A method of performing liquid phase epitaxial growth using the apparatus of the present invention shown in FIG. 2 will be described. To simplify the explanation, a case will be described in which p-type InSb and n-type InSb are continuously grown on the p-type InSb substrate 21 using an In melt. First, p-type
The InSb substrate 21 is pretreated and placed in the growth chamber 22 shown in FIG. Next, p-type impurities such as Ge and In are put into the first growth melt storage chamber 29, and a high-purity InSb base material 33 is set on the first piston 31, as shown in FIG. 2b. Set. At this time, the first growth melt storage chamber 29 and the first growth chamber communication hole 23 are separated by a first communication hole stopper 35 . Next, n-type impurities such as Te and In are put into the second growth melt storage chamber 30, and a high-purity InSb base material 34 is set on the second piston 32, as shown in FIG. 2c. Set. At this time, the second growth melt storage chamber 30 and the second growth chamber through hole 24 are separated by a second through hole stopper 36 . The boat prepared as described above is heated to, for example, 280°C and maintained. When kept for a predetermined period of time, the first and second growth melt storage chambers 29 and 30, respectively.
Impurities and InSb are dissolved in In to create a saturated solution. When the saturated solution is created, the first piston 31 is operated, that is, when pressure is applied to the In melt in the first growth melt storage chamber 29, the first conduction hole stopper 35 moves, The In melt enters the growth chamber 22 through the first conduction hole 23 and comes into contact with the p-InSb substrate 21. In overflowing from growth chamber 22
The melt passes through the first drain chamber communication hole 25 and is stored in the first drain reservoir chamber 26 . By lowering the temperature of the boat, the p-type is formed on the p-InSb substrate 21.
InSb grows epitaxially. When the desired growth layer is obtained, the second piston 32 is operated, that is, the In in the second growth melt storage chamber 30 is
When pressure is applied to the melt, the second through hole stopper 36 moves, and the In melt enters the growth chamber 22 through the second through hole 24, displacing the In melt that had previously entered into the second through hole. The second drainage storage chamber 28 is passed through the drainage chamber communication hole 27.
The In melt inside the growth chamber 22 is replaced.
This substituted In melt is a saturated melt because of the InSb base material 34. When cooled to a predetermined temperature, a desired n-InSb epitaxial growth layer is obtained.
According to this method, a layer grown from a saturated melt can be obtained on the substrate 21.

In the embodiments of the present invention, a case where epitaxial growth is performed at a low temperature of 280° C. using InSb as an example has been described, but it is obvious that the invention can be applied to other similar liquid phase epitaxial growth.

Note that the first and second conductive hole stoppers 35 and 36 are reset before performing epitaxial growth. This may be done by using a spring force or the like to return it to its original state. Further, the first and second drain fluid storage chambers 26 and 28 may have a combined volume of one chamber.

As explained in detail above, the present invention provides for each conduction hole that communicates the growth chamber with each growth melt storage chamber.
Each through hole is normally closed, and a through hole stopper is provided that moves by the pressure of the piston to release the closure and communicate the respective growth melt storage chambers with the growth chamber. The conductive hole stopper can be controlled precisely, multiple growth melts will not mix, and the height of the substrate and growth melt can be easily set to several mm in the growth chamber. This means that epitaxial growth proceeds without crystals precipitating anywhere other than on the substrate in the growth chamber, resulting in a uniform epitaxial growth layer. Furthermore, since the growth chamber and the growth melt storage chamber can be brought close to each other, the temperature difference between the substrate and the growth melt becomes extremely small, and the thickness of the growth layer can be controlled with good reproducibility. Further, it has the advantage that it does not require the trouble of accurately weighing and adding a saturation base material in order to prepare a saturated melt for growth.

[Brief explanation of the drawing]

Figure 1 is a side sectional view schematically showing a boat used in a conventional epitaxial growth apparatus, Figures 2 a to c
Figure 2a shows a plan view of the boat, Figure 2b is a sectional view taken along line A-A in Figure 2a, and Figure 2c is a cross-sectional view of the boat in Figure 2a. It is a sectional view taken along the line BB. In the figure, 21 is a substrate, 22 is a growth chamber, 23 is a first growth chamber through hole, 24 is a second growth chamber through hole, 2
5 is a first drainage chamber communication hole, 26 is a first drainage storage chamber, 27 is a second drainage chamber communication hole, 28 is a second drainage storage chamber, and 29 is a first growth solution. Liquid storage chamber, 30
31 is a first piston, 32 is a second piston, 33 and 34 are base materials,
35 is a first conduction hole stopper, and 36 is a second conduction hole stopper. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. It has two or more growth melt storage chambers, and a growth melt saturated base material is attached to each of these growth melt storage chambers so that it can come into contact with the growth melt, and the growth melt can be brought into contact with the growth melt. A growth chamber is provided with a piston for pushing out the growth melt, and is connected to the growth melt storage chamber through a through hole adjacent to each growth chamber. A liquid phase epitaxial device comprising a through hole stopper which closes the hole and is moved by the pressure of the piston to release the closure and communicate between each of the growth melt storage chambers and the growth chamber. growth equipment.