JPS60118700A - Production of semiconductor crystal - Google Patents

Abstract

PURPOSE:To reduce crystal grain boundary contained in the interior and improve the quality of the crystal, by preparing a crystal ingot, and heat-treating the ingot in a vapor atmosphere of component elements contained in the crystal ingot. CONSTITUTION:A raw material element is sealed in a quartz ampule under reduced pressure, and the whole is melted in a heating furnace and then passed through a zone having a temperature gradient in the furnace to grow crystals from the tip part and prepare a crystal ingot 13, e.g. cadmium tellurium crystal ingot. The resultant crystal ingot 13 is then contained in a vacuum closed vessel 11 having a temperature gradient, and a component element 15, e.g. cadmium, contained in the crystal ingot 13 is simultaneously contained in the high-temperature side of the closed vessel 11. The crystal ingot 13 is then heat-treated in a vapor atmosphere of the component element 15 to give the aimed semiconductor crystal with little crystal grain boundary contained in the interior thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing a semiconductor crystal, and more particularly to a processing method for further improving the quality of a semiconductor crystal containing a component element having a high vapor pressure.

(bl Conventional technology and problems The pull-L pull method is used to create semiconductors and crystals.

There are various growth methods such as the zone melting method and the Bridgman method, but when the crystal component contains an element with a high vapor pressure, the growth method is the Brinnonman method or the zone melting method in a closed tube. suitable for growth.

The n-viH compound semiconductor has many component elements with high atomistic pressure, such as cadmium telluride (CdTe), which forms the crystal.Mium (Cd') is an element with an extremely high atomistic pressure. CdTe crystal is a well-known semiconductor crystal that is widely used as a growth substrate for l1gcdTe crystals used as infrared sensors, or as element substrates for ultraviolet sensors and optical modulators, and whose demand is expected to increase further in the future.

A schematic diagram of a growth apparatus for growing a CdTe crystal ingot 1- as shown in FIG. 1 by the Brynonman method is shown in FIG. That is, tellurium (Te) weighed in a ratio of 1:1.
After vacuum-sealing and 1-mium (Cd) into a quartz ampule 1, the quartz ampule 1 is inserted into a vertical cylindrical heating furnace 2 and the entire quartz ampule 1 is melted at a high temperature (approximately 1150° C.). Next, when the quartz ampule 1 is gently lowered and passed through the temperature gradient zone B in the heating furnace 2, the CdTe crystal solidifies and grows from the tip T of the ampule 1, forming a cubic crystal. Implant l-3 is formed. In this case, the temperature gradient zone B has a temperature gradient centered around the melting point of CdTe (1092°C), and the quartz amplifier has a diameter of 10 to 50 mmφ and a length of about 100 mm. is used.

By the way, the crystal ingot grown in this way is not necessarily a high-quality crystal, but often contains crystal grain boundaries inside, and can generally be said to be in a polycrystalline state. In particular, many grain boundaries with an inclination of 1° or less occur in Te compound crystals. These causes are said to be due to temperature fluctuations, supercooling, inclusion of impurities, vacancies, etc.

(C) Object of the Invention The present invention proposes a heat treatment method for improving the quality of a crystal ingot containing many grain boundaries.

(di Structure of the Invention The purpose is to create a crystal implant), in a vapor atmosphere of the component elements contained in the crystal ingot,
A method of heat-treating the crystal ingot, for example, placing Cadmira J, tellurium (Cd) in a vacuum sealed container with a temperature gradient.
Te) Accommodating the crystal ingot and at the same time accommodating the cadmium (Cd) element on the high-temperature side of the hermetically sealed container, and injecting the tellurium (CdTe) crystal in a vapor atmosphere of the (cd) This is achieved by a method of heat treating an ingot.

(e+ Example of invention Examples will be described in detail below with reference to two drawings.

Fig. 2 is a schematic sectional view of the heat treatment apparatus according to the present invention;
The figure shows the temperature distribution map. In Figure 2, 1
1 is a quartz ampoule (vacuum sealed container).

12 is a cylindrical heating furnace, 13 is a CdTe crystal ingot, 1 is a small container 14 with a small hole inside the quartz ampoule 11
is attached, and Cd element 15 is accommodated therein.

This quartz ampoule 1 having a double tube structure is held by a support rod 16. Further, the CdTe crystal ingot 13 accommodated in the quartz amplifier monthly charge 1 has a diameter of 5Qm++φ.

The cylindrical tube of the heating furnace is several tens of millimeters long and has a diameter of about 60 to 70 mm. For example, the heating furnace 12 is formed to have a temperature distribution as shown in FIG.
Place the Cc1 element 15 at the position, and place the CdTe crystal ingot 13 at a temperature of 600°C with the one closest to 5 having a temperature gradient of 300°C. Heat treatment is performed for about 100 hours.

Then, the grain boundaries are significantly reduced and at least 5
Grain boundaries with an inclination angle of less than ° are extremely sigma,
In addition, all grain boundaries having an inclination angle of 1° or less disappear.

Therefore, the CdTe crystal ingot 13 has a high quality as fine grain boundaries disappear, and a device using such a crystal substrate has improved performance such as improved detection sensitivity.

(f) Effects of the Invention As can be seen from the description of the above embodiments, according to the present invention, a high-quality crystal substrate can be obtained, which has an extremely large effect on improving the performance of semiconductor devices. It is something that can be achieved.

It goes without saying that the present invention provides similar effects to semiconductor crystals other than the above-mentioned CdTe crystal.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a growth apparatus using the Bridgman method, Figure 2
The figure is a schematic sectional view of a heat treatment apparatus according to the present invention, and FIG. 3 is a temperature distribution diagram thereof. In the figure, ■ is a quartz ampoule, 2.12 is a heating furnace, and 3°13
is CdTe crystal ingonol, and moon is quartz 7 used in the present invention.
Ampoule (vacuum sealed container) 1] 4 is a small container inside an ampoule 15, 15 is a Cd element, and 16 is a support rod. Figure 1, Figure 2, Schiff, Figure 3 - U51

Claims (2)

[Claims] (1) A method for producing a semiconductor crystal, which comprises producing a crystal ingot and then subjecting the crystal ingot to heat treatment in a vapor atmosphere of component elements contained in the crystal ingot. (2) A cadmium telluride crystal ingot is housed in a vacuum sealed container with a temperature gradient, and at the same time, 1 inch of mium element is housed on the high temperature side of the sealed container, and the cadmium tellurium crystal ingot is placed in the cadmium vapor atmosphere. A method for manufacturing a semiconductor crystal according to claim 1, characterized in that a crystal ingot is subjected to heat treatment.