JPS5855392A - Manufacture of semiconductor crystal - Google Patents

Abstract

PURPOSE:To obtain ampuls for well sealing in an easily volatile starting material for use in a Bridgeman method, by filling said material on the bottom of the ampul, overlaying 2 inner tubes on the material, and sealing the ampul by 2 steps. CONSTITUTION:A raw material 12 for manufacture of single crystal, such as a mixture of Rb and Te, is filled in an ampul 11 made of quartz having a tapered end to be sealed, and a first inner tube 12 and a second inner tube 14 each having a flat bottom are overlaid on this material. The ampul 12 is sealed together with the inner tube 14 with a burner 16, while the ampul is evacuated through a cap 15 provided on the opening end of the ampul 11. This is placed in a heating oven 5, the first inner tube 13 is brought into contact with the molten material 12, and the ampul 11 is again sealed together with the tube 13 with the hurner to obtain the ampul 11 sealing in the material 12 without leaving almost any space above the material 12, thus permitting a semiconductor crystals to be manufactured using this ampul.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the manufacturing method of semiconductor crystals, and more particularly to a new method for sealing raw materials in crystal growth angles.

Compound semiconductors containing lead (pb), such as TeIvA/lead tin oxide (Pb1-zsnzTe) crystals, have a narrow energy gap and are used as materials for infrared laser elements.

Such a crystal of Pb1-zSnzTf3 is formed on a crystal of lead telluride ((PI)Te) as a substrate by a liquid phase epitaxial growth method.

Therefore, after forming a single crystal of PbTe, the kite crystal is cut into the shape of a substrate.
The element of chill A/(T13) constituting the crystal is easily evaporated, and when a single crystal is formed using a material containing such an easily evaporated element, the Bridgman method is generally used.

Using such a Bridgman method, the easily evaporable Te
To form a single crystal of pb're containing The materials 2 are each weighed to a predetermined weight and then inserted. Thereafter, the upper end of the amplifier is sealed using a burner 8 while the inside of the ampoule is evacuated using a vacuum bonder. Thereafter, as shown in FIG. 2, an ampoule 1 filled with materials for forming crystals of Pt) and Te is inserted into a heating furnace 5 having a predetermined temperature distribution 4, and the materials of Pb and Te are once melted. As the amplifier P is gradually lowered in the direction of arrow A in the furnace, the molten material is solidified from the sharp tip of the amplifier P.
An attempt is made to obtain a single crystal of bTe.

However, in the conventional method described above, when the upper end of the ampoule is heated with a burner and sealed, the filled Pb and T
There is a drawback that the crystal growth material of e. evaporates and scatters.

In addition, when the upper end of the ampoule is sealed and then melted in a heating furnace, as shown in FIG. In particular, the vapor pressure of Te is higher than that of Pb, so that it exists as a vapor.
The vapor pressure of about ioo.

Since Te is twice as large as Pb in the molten crystal growth material,
The composition of the liquid phase of the nine-crystal growth material that is evaporated and melted is different from the desired composition, resulting in a drawback that the PbTe crystal grown from this liquid phase deviates from the desired composition.

The object of the present invention is to provide a method for manufacturing semiconductor crystals in which the raw material sealing process is improved so as to eliminate the above-mentioned drawbacks.

A method for manufacturing semiconductor crystals to achieve this purpose is as follows:
After filling the amplifier N with its tip sealed with a material for forming a semiconductor crystal, the end of the ampoule is sealed while evacuating the inside of the amplifier μ, and the amplifier ~ is further inserted into a heating furnace. In the method for manufacturing a semiconductor crystal, the material for forming the crystal is heated and melted in the ampoule, and then the molten material is solidified to form a single crystal from the tip of the ampoule. Then, install the first inner tube in the soil, stack the second inner tube on top of the first inner tube, and then remove the ampoule together with the second inner tube while evacuating the inside of the amplifier. After melting and sealing the ampoule, the ampoule is inserted into a heating furnace to heat and melt the material forming the crystal, and the first inner tube is dropped to the liquid level where the crystal is molten.
The ampoule is melt-sealed again together with the inner tube of the ampoule, and pressure is applied to obtain a sealed ampoule for forming a single crystal.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 8 to FIG. 7 are diagrams explaining one embodiment of the method for manufacturing a semiconductor crystal of the present invention in the order of steps.

First, predetermined weights of PB and Te as the single crystal forming material 12 are weighed and then filled into a sealed quartz amplifier/L/11 shown in FIG. 8, which has a sharp tip and is sealed.

Thereafter, a flat-bottomed first inner tube 1 is inscribed in the inner wall of the amplifier p.
8 is placed so that the flat bottom part is in contact with the single crystal forming material. Thereafter, the second inner tube 14 having a flat bottom and in contact with the inner wall of the amplifier/L'LL was stacked and installed on the first inner tube 18, and the cap 1 was then placed on the ampoule.
While evacuating the inside of the amplifier μ with a vacuum pump (not shown) via the tube 6, the surrounding area of the second inner tube 14 is heated with the Ganubhana 16, and the amplifier ytt is heated together with the second inner tube. Melt and seal. This prevents the components of the material in the ampoule from evaporating during heating.

The state formed in this manner is shown in FIG.

Thereafter, as shown in FIGS. 2 and 6, the ampoule is inserted into a heating furnace 6 having a temperature gradient as indicated by 4 in FIG.
Once the crystal material 12 is melted, the amplifier 〃 is gradually lowered into the furnace, and the tip of the amplifier μ is removed as shown in FIG. l! The solidified crystal material 12 is solidified. In this way, when the crystal material is melted, the first inner tube 1
B falls to the molten liquid level and is written on the surface of the crystal material which has solidified after melting, so that the space above the K crystal material almost disappears. Also, if it is held in the state shown in Figure 6,
The crystalline material present in vapor form in the upper space is also assimilated and precipitated on the solid surface below. Thereafter, as shown in FIG. 6, the ampoule and the first inner tube IB are heated and melted using a gas burner 16 to seal them, thereby obtaining a sealed structure as shown in FIG. 7.

In this way, the first inner tube IB is installed in the amplifier Ivl IK close to the crystal material, and the crystal material is loaded into the amplifier μ in a state where there is almost no space above the crystal material. It turns out.

Thereafter, the ampoule was reinserted into the heating furnace shown in FIGS. 2 and 6 to once melt the crystal material, and then the ampoule was gradually lowered into the furnace to solidify the crystals rising at the tip of the ampoule. to obtain a single crystal.

In this way, since there is almost no space above the crystalline material in the ampoule, it is possible to eliminate easily evaporable components from evaporating into the space when the crystalline material is heated, thereby eliminating fluctuations in the composition of the molten crystalline material. Furthermore, when the amplifier p is melted and sealed using a burner, there is almost no space above the crystal material inside the amplifier μ, so the crystal material is heated and easily evaporated components are prevented from escaping. The advantage is that a highly reliable semiconductor crystal with a stable composition can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional single crystal manufacturing method, FIG. 2 is a schematic diagram of a single crystal manufacturing apparatus, and FIGS. 8 to 7 show an embodiment of the single crystal manufacturing method of the present invention. It is a figure showing a process. In the figure, L, 11 is an ampoule, 2.12 is a crystal forming material, 8, 16 are gas burners, 4 is a temperature distribution, 6 is a heating furnace, 6 is a liquid phase, 7 is an upper space, 18 is a first inner tube ,! 4
indicates the second inner tube, and 16 indicates the cap. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] After filling an angle with a sealed tip with a material for forming a semiconductor crystal, the curved end of the ampoule is sealed while evacuating the inside of the ampoule, and the ampoule is then inserted into a heating furnace to form a crystal. In the method for manufacturing a semiconductor crystal in which the material for forming the crystal is heated and melted and then the melted material is sequentially solidified from the tip of the amplifier μ to form a single crystal, the material for forming the crystal is filled into the angle, and then the material for forming the crystal is filled into the angle. Place a first inner tube on top, stack a second inner tube on top of the first inner tube, and then melt and seal the ampoule together with the second inner tube while evacuating the inside of the angle. Thereafter, the ampoule is inserted into a heating furnace to heat and melt the material forming the crystal, and the first inner tube is dropped to the surface of the molten crystal. A method for manufacturing a semiconductor crystal, characterized in that a sealed ampoule for forming a single crystal is obtained by melt-sealing.