JPH0428678B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to a liquid phase epitaxial crystal growth apparatus, and particularly to an improvement of a continuous liquid phase epitaxial crystal growth apparatus using an immersion method. In the conventional liquid phase epitaxial crystal growth method, as in the liquid phase crystal growth method using the slide board method shown in FIG. Inert gas is introduced from the inlet 3 and discharged from the gas outlet 4,
After the substrate 7 is immersed in the solution 6 for saturated growth of semiconductor components in the solution tank 5 in the crystal growth furnace 1, the temperature of the growth solution 6 is gradually cooled to crystallize the supersaturated semiconductor component on the substrate 7. It was a way to get him to come out. Note that 8 is a thermocouple. Therefore, since the growth temperature gradually changes in the thickness direction of the liquid phase grown layer on the substrate 7, there is a drawback that the segregation coefficient of impurities or atoms changes, making it impossible to form a crystal grown layer with uniform characteristics. Ta. In addition, the number of epitaxial substrates that can be grown in one crystal growth process is about one, and crystal growth requires operations such as heating → slow cooling → cooling → sample removal, which is extremely complicated. Temperature processes and operations are required, and the time per process is very long.
The drawback was that mass production was difficult. In order to improve mass productivity, a method has been proposed in which multilayer crystals are grown by sequentially immersing substrates attached to a movable shaft into a growth solution in a plurality of crystal growth containers arranged side by side. Kaisho 50-39875
Publication No.). In this method, if raw material crystals are present in the growth solution, good epitaxial growth cannot be achieved, such as fine raw material crystals adhering to the substrate surface or large variations in the thickness of the grown layer. The raw material crystals must be completely dissolved. However, with the method of dissolving all the raw material crystals added to the growth solution and the raw materials for the mixed crystal that form a mixed crystal with the raw material crystals, it is difficult to weigh these raw materials extremely accurately, so It is impossible to reproduce the same saturation and mixed crystal ratio for each growth, and it is impossible to make the thickness and mixed crystal ratio of the epitaxial growth layer the same for each growth in the same crystal growth container. It's impossible. Furthermore, since it is impossible to replenish the raw material solution with the same amount of crystals as the amount of crystals precipitated by growth, this method requires replacing the raw material solution after each growth. The present invention has been made in view of the above, and its purpose is to be able to continuously obtain a large amount of grown layers having a desired film thickness and a desired mixed crystal ratio in a short period of time with good reproducibility; It is an object of the present invention to provide a liquid phase epitaxial growth apparatus which is excellent in mass productivity and does not require replenishing raw materials to a growth solution or replacing a growth solution for each growth. [Summary of the Invention] The present invention is characterized by a first gas replacement chamber that performs inert gas replacement, a plurality of crystal growth furnaces sequentially arranged in series after the first gas replacement chamber, and a crystal growth furnace that performs inert gas replacement. A heater for heating the inside of the growth furnace, a crystal growth container for accommodating a growth solution placed in the crystal growth furnace, and a second crystal growth container provided at the rear stage of the crystal growth furnace.
a gas exchange chamber, and means for transporting a substrate case with a substrate attached thereto from the first gas exchange chamber to the second gas exchange chamber, and the crystal growth container includes a gas exchange chamber in which the substrate case is attached to the growth solution. A crystal growth tank immersed therein communicates with the crystal growth tank and is filled with the raw material solution and accommodates a raw material crystal and a raw material for a mixed crystal that forms a mixed crystal crystal in combination with the raw material crystal. a first heater that heats the raw material crystal dissolving tank to melt the raw material crystals and adjust the degree of saturation of the growth solution; and a second heater that heats the tank to dissolve the mixed crystal raw material and adjust the mixed crystal ratio of the mixed crystal obtained from the growth solution. [Example] The present invention will be described in detail below with reference to the embodiment shown in FIGS. 2 and 3, and FIGS. 4 and 5. FIG. 2 is a front view showing an embodiment of the apparatus of the present invention, and FIG. 3 is a longitudinal sectional view showing an embodiment of each crystal growth container shown in FIG. In FIG. 2, 9a,
Reference numeral 9b denotes a gas exchange chamber having gas inlets 10a, 10b and gas outlets 11a, 11b, respectively.The gas exchange chamber 9a has a substrate loading port 12a and a substrate loading port 12b. 13a, 13b, 13c are crystal growth furnaces provided with gas inlets 14a, 14b, 14c and gas outlets 15a, 15b, 15c, respectively, and crystal growth furnaces 13a, 13b, 13c are provided with heaters 16a, 16b, 16c, respectively It can be heated. Crystal growth vessels 17a, 17b, and 17c are housed in the crystal growth furnaces 13a, 13b, and 13c, respectively, and these crystal growth vessels 17a to 17c
(indicated by 17) is constructed as shown in FIG. In FIG. 3, 18 is a crystal growth tank, 19
20 is a raw material crystal dissolving tank, 20 is a mixed crystal raw material dissolving tank,
The raw material crystal dissolving tank 19 and the mixed crystal raw material dissolving tank 20 are each communicated with the crystal growth tank 18 as shown in the figure, so that each tank is filled with a growth solution. 21 is a raw material crystal melting heater (first heater); 22 is a mixed crystal raw material melting tank heater (second heater);
(heaters), and their temperatures can be controlled independently, as will be described later. Note that there is a partition 23 between the crystal growth containers 17a and 17b, and a partition 23 is provided between the crystal growth containers 17b and 17c.
There is a partition 24 between the two. 25 is a gas exchange chamber having a gas inlet 26 and a gas outlet 27;
8 is a board exit. The crystal growth furnaces 13a to 13b are arranged in series in multiple stages as shown in FIG. 12a into the gas exchange chamber 9a, and the gas exchange chambers 9a, 9b
After passing through the crystal growth furnaces 13a, 13b, and 13c, and after passing through the gas exchange chamber 25, the substrate exit 28
taken out. In this case, the crystal growth furnaces 13a to 13c are heated by the heaters 16a to 16c, respectively, and the fourth
As shown in the figure, each has a temperature profile suitable for its purpose. The crystal growth vessels 17a to 17c are made of well-washed high-quality graphite boats with a length of 20 cm and a height of 8 cm, the crystal growth tank 18 has a width of 8 cm, the raw material crystal dissolution tank 19 has a width of 5 cm, and a mixed crystal raw material dissolution tank. 20 is width 4
It has a size of cm. Table 1 shows the temperatures of the crystal growth tank 18, mixed crystal crystal dissolution tank 19, and mixed crystal raw material dissolution tank 20 of each of the crystal growth containers 17a to 17c, and the solutes in each of the tanks.

[Table] That is, a source crystal (GaAs or p-GaAs) is placed in the raw material crystal dissolving tank 19 so that a uniform saturated solution is always supplied. Also,
If the mixed crystal to be obtained is a mixed crystal such as GaAlAs, Al is added to the mixed crystal raw material dissolving tank 20 to keep the composition of the mixed crystal constant at a desired temperature. do. In addition, mixed crystal raw material dissolving tank 2
When no raw material is added to the temperature, there is no need to particularly control the temperature. Such a crystal growth container 1
7a to 17c are crystal growth furnaces 13a to 13, respectively.
gas inlets 14a to 14, respectively.
After replacing the inside of the furnace with inert gas by introducing an inert gas from c, the temperature of each crystal growth furnace 13a to 13c is adjusted to a predetermined temperature as shown in FIG. 4, respectively. In this way, the substrate 29 installed in the substrate case 30 is carried through the substrate carrying overhead wire 31 into the gas exchange chamber 9a, which has been substituted with an inert gas, through the substrate loading port 12a, and then the partition plate 12b is opened and carried into the gas replacement chamber 13b, which has been replaced with inert gas, and after being filled with inert gas, the crystal growth furnaces 13a to
The crystals are sequentially transported into the crystal growth vessels 18 of the crystal growth vessels 17a to 17c in the crystal growth chamber 13c, and crystal growth is performed. Note that the substrate carrying overhead wire 31 can be moved intermittently, so that crystal growth can be performed in each crystal growth tank 18 for a predetermined period of time. After crystal growth in each crystal growth tank 18, the substrate 29 is carried into the gas exchange chamber 25 for gas exchange, and then the substrate 29 after crystal growth is taken out from the substrate outlet 28. Next, as shown in FIG. 5, for example, n-GaAs41, p-GaAs42, p-
A solar cell can be obtained by attaching an n-electrode 44 and a p-electrode 45 to a crystal of GaAlAs 43 grown sequentially. The efficiency of this solar cell is
It was 12%. According to the embodiment of the present invention described above, the crystal growth vessels 17a to 17c of each crystal growth furnace 13a to 13c
It is possible to set a temperature difference between the crystal growth tank 18, the raw material crystal dissolution tank 19, and the mixed crystal raw material dissolution tank 20, and the substrate 29 or the crystal grown thereon can be sequentially immersed in the batch-type crystal growth tank 18. By doing so, it is possible to easily grow crystals with good reproducibility even when crystal growth is difficult, and it is possible to obtain semiconductor liquid phase epitaxial crystal plates with uniform growth layer thickness in large quantities in a short time with good reproducibility. can. In particular, when obtaining a crystal plate having a multilayer structure with different compositions, such as a highly efficient light emitting diode or solar cell, this method is industrially more effective than the conventional slide board method. Moreover, since the crystal growth tank 18 does not contain raw material crystals or mixed crystal raw materials, they do not adhere to the substrate surface. Furthermore, the shortage of crystals precipitated from the growth solution is removed from the raw material crystal dissolving tank 19 and the mixed crystal raw material dissolving tank 20.
It can be constantly supplied by melting raw material crystals and raw materials for mixed crystals. Furthermore, continuous use is possible without replacing the growth solution. The size, material, etc. of each part of the device can be appropriately selected to suit the purpose, and gas replacement with inert gas may be performed after evacuation. This is preferable because it removes impurity gases. In this case, when the movement of the substrate transport overhead line 31 is stopped, if the gas replacement chambers 9a and 9b are vacuum-sealed and the gas exchange chambers 9a and 9b are evacuated, the vacuum can be easily created. Allow reducing gas to flow. [Effects of the Invention] As explained above, according to the present invention, the saturation level of the growth solution can always be set to a predetermined state without replenishing raw materials or replacing the growth solution for each growth. Therefore, it is possible to continuously obtain a large amount of multi-layered growth layers of a desired thickness in a short period of time with good reproducibility. In addition, since it is possible to easily set the mixed crystal ratio of the growth solution to a predetermined state, it is possible to continuously epitaxially grow mixed crystals with a desired mixed crystal ratio with good reproducibility. This method has a significant industrial effect when obtaining a crystal plate having a multilayer structure with different compositions, such as for solar cells.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a conventional liquid phase crystal growth method using the slide board method, FIG. 2 is a front view showing an embodiment of the liquid phase epitaxial crystal growth apparatus of the present invention, and FIG. 2 is a vertical cross-sectional view showing an example of each crystal growth container shown in FIG. 2, FIG. 4 is a diagram showing the temperature profile of each crystal growth furnace shown in FIG. 2, and FIG. FIG. 2 is a schematic diagram of a semiconductor device using a crystal growth plate obtained by the above-mentioned method. 9a, 9b, 25: gas replacement chamber, 13a-13
c...Crystal growth furnace, 16a-16c...Heater, 17a-17c...Crystal growth container, 18...
Crystal growth tank, 19... Raw material crystal dissolution tank, 20...
Mixed crystal raw material dissolving tank, 21... Raw material crystal dissolving tank heater (first heater), 22... Mixed crystal raw material dissolving tank heater (second heater), 29... Substrate, 3
0... Board case, 31... Base transport overhead wire.

Claims (1)

[Claims] 1 a first gas replacement chamber that performs inert gas replacement;
For accommodating a plurality of crystal growth furnaces sequentially arranged in series after the first gas exchange chamber, a heater for heating the inside of the crystal growth furnace, and a growth solution placed in the crystal growth furnace. a crystal growth container, a second gas exchange chamber provided at the rear stage of the crystal growth furnace, and means for transporting a substrate case with a substrate attached from the first gas exchange chamber to the second gas exchange chamber. The crystal growth container includes a crystal growth tank in which the substrate case is immersed in the growth solution, and a crystal growth tank that communicates with the crystal growth tank and is filled with the raw material solution and that contains raw material crystals and the raw material crystal. A raw material crystal dissolving tank and a mixed crystal raw material dissolving tank for accommodating raw materials for a mixed crystal, respectively, which form a mixed crystal by a combination of the above, and the raw material crystal dissolving tank is heated to melt the raw material crystal and grow. a first heater that adjusts the degree of saturation of the growth solution, and a second heater that heats the mixed crystal raw material dissolving tank to dissolve the mixed crystal raw material and adjust the mixed crystal ratio of the mixed crystal crystal obtained from the growth solution. 1. A liquid phase epitaxial crystal growth apparatus for continuously growing multilayer crystals on a substrate, characterized by comprising a heater.