JPH0557237B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for mass-producing liquid phase epitaxial growth of - group compound semiconductors.

Prior Art - Group compound semiconductors such as gallium phosphide and gallium arsenide are currently used in large quantities mainly as light-emitting elements and light-receiving elements, and their manufacturing method, epitaxial growth, is an industrially important technology. It is becoming. Epitaxial growth can be broadly classified into vapor phase growth and liquid phase growth, but liquid phase growth has been thought to require a greater amount of solvent, such as gallium, than vapor phase growth, and is inferior in mass productivity.

In general, liquid phase epitaxial growth of gallium phosphide, gallium arsenide, etc. is carried out by using gallium metal as a solvent and saturating it at high temperature, then bringing the substrate into contact with the solution, and allowing slow cooling to precipitate it. Regarding the liquid phase epitaxial growth method, various apparatuses and methods have been devised, and the slide boat method using a horizontal furnace as shown in FIG. 2, the rotation method, etc. are generally adopted.

Problems to be Solved by the Invention The disadvantages of the prior art include problems with the structure of the equipment and problems with contamination, which make it impossible to take out the reactor until the temperature of the entire growth reactor is below about 100°C. Therefore, the time per growth from setting to removal is 12~
It takes 24 hours, so mass production is poor. Gallium solution is disposable. Alternatively, even when the same gallium solution is used repeatedly, it is necessary to add polycrystals to match the amount that has grown on the substrate crystal, but the amount of polycrystals to be added becomes inaccurate, making it impossible to control the saturated dissolution temperature at a constant level. In particular, if the added amount is insufficient and the saturation dissolution temperature falls below the growth start temperature, problems such as melting of the substrate crystals will occur, making stable continuous operation impossible using the same gallium solution.
Especially in the case of the slide boat method, 1 per board.
A solution is required, and setting up a solution adjustment substrate is complicated.

As a result of various studies, the inventor of the present invention attempted to solve the problem by adopting a vertical immersion method. An advantage of the vertical immersion method is that it is effective to separate the gallium solution bath and the growth jig as shown in Figure 1. Continuous operation is possible if you take care to put in and take out only the ingredients. On the other hand, when a slide boat method, a rotation method, etc. using a horizontal furnace is adopted, it is impossible to extract only the epitaxially grown substrate crystal part because the gallium solution, substrate crystal, etc. are integrated. In addition, as a method to keep the saturation dissolution temperature constant when the same gallium solution is used repeatedly, a saturation container containing a polycrystalline block is heated at a predetermined temperature for a predetermined time.
We devised a unique method to saturate the solution by immersion. Figure 3 shows the immersion time and dissolution amount (Ga100
The relationship between the amount of GaP polycrystal dissolved per gram is shown. It can be seen that the solution becomes saturated after about 50 minutes of soaking time. Therefore, by immersing a saturation container containing polycrystals in a solution at a predetermined temperature for a predetermined period of time, the saturation dissolution temperature can be accurately controlled.

Structure of the Invention The present invention has been made in view of the above study results and facts, and as shown in Fig. 1, the apparatus consists of a growth system equipped with a gallium solution tank and a preliminary chamber that can be shut off from the growth system by a gate valve. By configuring
Using a vertical immersion type growth device that allows the saturation container and growth jig to be taken in and out while the growth system is at high temperature,
A step of saturating the solution by immersing the saturation container containing the polycrystal in a gallium solution bath at a predetermined temperature for a predetermined time (hereinafter referred to as the saturation step), and after the solution was saturated, a substrate crystal was mounted in a preliminary chamber. This method consists of a step of replacing the growth jig and performing growth (hereinafter referred to as the growth step), and provides a mass-produced liquid phase epitaxial growth method that can be operated continuously by repeating the saturation step and the growth step. be.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1a schematically shows a vertical immersion growth apparatus used in the practice of the present invention, which is composed of a growth system 13 and a preliminary chamber 5 that can be shut off by a gate valve 4. . Quartz reaction tube 1
A gallium solution tank 2 is arranged inside the reaction tube, and a heating electric furnace 3 is provided outside the reaction tube. The saturation container 6 containing the polycrystal and the growth jig 7 containing the substrate crystal can be taken out and replaced in the preliminary chamber, and the preliminary chamber has a structure that allows evacuation and gas replacement independently of the growth system. ing.

The following will explain using gallium phosphide (GaPP) as an example.

5 kg of metallic gallium (Ga) in gallium solution tank 2
After vacuum displacement, argon gas (Ar) 3/
Raise the temperature to 1000℃ while flowing water. On the other hand, a saturation container 6 containing GaP polycrystals is set in the preliminary chamber 5, and after the preliminary chamber is evacuated, Ar3/min is injected (see FIG. 1a). When the temperature reaches 1000°C, the gate valve 4 is opened and the saturation container 6 is immersed in the gallium solution bath 2, and maintained at this temperature for 1 hour (see Figure 1b).
After one hour has elapsed, the saturation container 2 is pulled up into the preliminary chamber 5 and the gate valve 4 is closed. Meanwhile, the temperature of the gallium solution bath 2 is lowered to 980°C, which is the growth starting temperature.
After replacing the saturation container 2 with the growth jig 7 equipped with the substrate crystal 8 in the preliminary chamber 5 and replacing the preliminary chamber 5 with vacuum.
Flow Ar3/min (see Figure 1c). The gate valve 4 is opened, and the growth jig 7 is immersed in the gallium solution bath 2 after preheating, cooled to 900° C., and growth is performed (see FIG. 1d). When the temperature reaches 900°C, the growth jig 7 is separated and pulled into the preliminary chamber 5 and the gate valve 4 is closed. At the same time, the temperature begins to rise again to 1000℃. Continuous operation became possible by repeating the above operations as shown in the temperature program shown in FIG.

As described above, the growth system 13 is controlled by the gate valve 4.
By using a vertical immersion growth apparatus equipped with a preliminary chamber 5 that can be shut off, continuous operation is possible for one cycle of about 3 hours, and by using a saturation container 2, the saturation dissolution temperature can be controlled with extreme precision. As a result, stable continuous liquid phase epitaxial growth became possible.

In the above embodiment, GaP was used as an example, but
It is also possible to apply it to GaAs, GaAlAs, etc. It goes without saying that the growth temperature range can be changed appropriately depending on the purpose. Further, by selecting the additive, an N-type growth layer or a P-type growth layer can be obtained, and by changing the amount added, the donor concentration or acceptor concentration can be controlled.

[Brief explanation of the drawing]

Figure 1 shows a vertical immersion growth apparatus, in which a shows the process of dissolving a gallium solution, b shows a process of making a gallium phosphorus saturated solution, c shows a process of replacing and mounting in a preliminary chamber, and d shows an epitaxial growth process. shows. 1...Quartz reaction tube, 2...Gallium solution tank, 3
...Heating furnace, 4...Gate valve, 5...Preliminary chamber, 6...Saturation container, 7...Growth jig, 8...
...Substrate crystal, 9...Gas supply port, 10...Gas discharge port, 11...Gas supply port, 12...Gas discharge port, 13...Growth system. FIG. 2 is a diagram showing a horizontal slide boat method device. DESCRIPTION OF SYMBOLS 1... Heating furnace, 2... Quartz reaction tube, 3... Slide boat, 4... Gallium solution, 5... Substrate crystal, 6... Gas supply port, 7... Gas discharge port. FIG. 3 is a diagram showing the relationship between the dissolution time and the amount of GaP dissolved at 1000°C. FIG. 4 is a diagram showing a temperature program diagram in one embodiment of the present invention.

Claims (1)

[Claims] 1. Vertical immersion type growth apparatus, which consists of a growth system equipped with a gallium solution tank and a preliminary chamber that can be shut off from the growth system by a gate valve, when performing liquid phase epitaxial growth of - group compound crystals using a gallium solution. The process of saturating the solution by immersing the saturation container containing the polycrystal in a gallium solution bath at a predetermined temperature for a predetermined time using a A liquid phase epitaxial growth method characterized by comprising a step of replacing a tool and performing growth.