JPH07242486A - Production of iii-v compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To efficiently produce single crystals and polycrystals of a III-V compd. semiconductor. CONSTITUTION:Two units of growth boats 20, 30 housing crystal raw materials of group III elements are arranged on both sides of a group V element 40 and are encapsulated into a reaction tube 10. This reaction tube 10 is inserted into a furnace core tube 51 of a heating furnace 50 provided with a temp. gradient in the axial direction of the furnace and the crystals 22, 32 crystallized from melts 21, 31 formed by heating of the crystal raw materials are grown in the furnace axis direction from the central part of the reaction tube 10 toward both ends. As a result, two units of the growth ports 20, 30 are encapsulated into one unit of the reaction tube 10 and crystal growth is effected and, therefore, the single crystals or polycrystals are grown efficiently with a floor area smaller than in the case of using two units of the reaction tubes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a compound semiconductor single crystal or polycrystal of III-V group by a boat method.

[0002]

2. Description of the Related Art Single crystals and polycrystals of compound semiconductor materials are
It is manufactured by the liquid sealing pulling method, the boat method, etc. In the liquid sealing pulling method, a crucible containing a melt is set in a high-pressure container pressurized with an inert gas such as N ₂ or Ar, and a single crystal or a polycrystal is pulled from the melt. Although this method is suitable for the production of large single crystals and polycrystals, it requires a high-pressure gas container and therefore uses expensive equipment. Further, since expensive inert gas such as N ₂ and Ar purified to high purity is consumed, the obtained single crystal or polycrystal of the compound semiconductor becomes a very expensive product. In this respect, according to the boat method, single crystals and polycrystals can be manufactured with relatively low equipment cost and manufacturing cost. In the boat method, a growth boat containing a single crystal or polycrystal raw material is contained in a reaction tube such as a quartz tube and heated with a temperature gradient along the longitudinal direction of the reaction tube. A melt is generated on the high temperature side, and a single crystal or a polycrystal grows from the melt as the temperature becomes lower.

[0003]

In the boat method, only one growth boat is enclosed in one reaction tube. Since a single crystal or a polycrystal is grown in this reaction tube with a temperature gradient, the heating zone is short and the temperature distribution of the generated melt tends to be non-uniform. As a result, defects such as cracks, pores and sparse parts occur in the obtained single crystal or polycrystal. Therefore, the yield is low and, as a result, the manufacturing cost is increased. The present invention has been devised in order to solve such a problem, and by adopting a method of growing a single crystal or a polycrystal from a melt from the central part of the reaction tube toward both ends, it is sufficient. The objective is to produce a high quality single crystal or polycrystal by taking various heating zones.

[0004]

The method for producing a III-V group compound semiconductor crystal according to the present invention has the following objectives.
Two growth boats containing a group III element crystal raw material are placed on both sides of the group V element and enclosed in a reaction tube, and the reaction tube is attached to a furnace core tube of a heating furnace having a temperature gradient in the furnace axis direction. It is characterized in that a crystal which is inserted and crystallized from a melt generated by heating the crystal raw material is grown in a furnace axis direction from the central portion of the reaction tube toward both ends. In the semiconductor crystal manufacturing apparatus according to the present invention, as shown in FIG. 1, two growth boats 20 and 30 are enclosed in one reaction tube 10. The growth boats 20 and 30 are set on both sides of the group V element 40 arranged in the center of the reaction tube 10. The reaction tube 10 is
It is arranged inside a furnace core tube 51 inserted into the heating furnace 50.
In the heating furnace 50, the position facing the group V element 40 is at the low temperature part 5
2 _L , melts 21 and 3 stored in the growth boats 20 and 30
The heater 52 has a high temperature portion 52 _{H at} a position facing 1. The furnace shell of the heating furnace 50 is provided with a heat radiating portion in order to control the temperature distribution, heating conditions, heat radiating conditions, etc. while observing the growth state of the single crystals or polycrystals 22, 32 crystallized from the melts 21, 31. A combined viewing window 53 is provided. A heat insulating material 54 is lined in a portion other than the viewing window 53.

[0005] high-temperature portion heater -52 _H, as three-dimensional temperature distribution is controlled highly accurately, divided into four parts along the circumferential direction of the heating furnace 50. Each heater, which is divided into four parts, is equipped with a thermocouple installed at the required location.
Alternatively, the voltage applied to each heater is adjusted according to the degree of crystal growth that can be observed through the viewing window, and the temperature gradient and crystal growth rate at the solid-liquid interface are controlled with high accuracy.
The high temperature heater 52 _H controls the temperature distribution in the furnace axis direction (X axis), the boat width direction (Y axis), and the vertical direction (Z axis) with high accuracy. Therefore, the temperature gradient and the movement of the melting point can be easily manipulated, and homogeneous and dense single crystals or polycrystals 22 and 32 having no defects such as cracks, pores and sparse parts can be synthesized with good reproducibility. The low-temperature heater 52 _L is conventionally provided at one end of the reaction tube, and is easily affected by the external environment to cause temperature fluctuations. On the other hand, in the present invention, since the low temperature heater 52 _L is arranged at the center of the reaction tube 10, there is no temperature fluctuation and the temperature distribution can be controlled uniformly. As a result, the heating temperature of the zone in which the group V element 40 is arranged is precisely controlled, and the vapor pressure of the group V element 40 is properly controlled. As a result, the melts 21 and 31 will not overflow from the ends of the growth boats 20 and 30.

The single crystal or polycrystalline raw material contained in the growing boats 20 and 30 is heated by the high temperature heater 52 _H to become the melts 21 and 31. Since the melts 21 and 31 are heated by the high temperature heater 52 _H with a temperature gradient that increases from the center of the heating furnace 50 to both sides, solidification proceeds in the arrow direction starting from the seed crystals 23 and 33. .
At this time, the group V element 40 is heated by the low temperature heater 52 _L to be vaporized, sent through the holes of the capillaries 11 and 12 to the growth boats 20 and 30 arranged on both sides, and melt 21 and It is taken in by 31. The melts 21 and 31 are solidified following the crystal orientations of the seed crystals 23 and 33, and the seed crystals 2
Predetermined single crystals 22 and 32 grow from the 3 and 33 sides. Further, when the crystals are grown on the growth boats 20 and 30 without installing the seed crystals 23 and 33, polycrystals are similarly crystallized from the melts 21 and 31.

As described above, when the group V element 40 is collected at one location in the center of the reaction tube 10 and the two growing boats 20 and 30 are arranged on both sides of the group V element 40, only one growing boat is used. The heater 52 can be designed with a necessary minimum length and good heat insulation property as compared with the case of using two enclosed reaction tubes. Therefore, heat is efficiently used for crystal growth, and the time required for melting is shortened. Further, the installation area can be reduced as compared with the case where two heating furnaces 50 are installed.

[0008]

【Example】

Example 1: As a Group III element, 3.6 kg of Ga was housed in each of the growth boats 20 and 30 having a semicircular cross section with a diameter of 90 mm and a length of 600 mm. As group V element 40, As of 7.8 kg was allowed to stand still in the center of the reaction tube 10, and the growth boats 20 and 30 were arranged on both sides of the group V element 40 and sealed in the reaction tube 10. The reaction tube 1 is placed in the furnace core tube 51 of the heating furnace 50.
0 is inserted and the temperature in the heating furnace 50 is set to the melting point of GaAs of 12
Heated to a temperature above 38 ° C. Heating boat 2 by heating
The single crystal raw material Ga contained in 0, 30 is melted, and A
s (group V element 40) is gasified and reacts with Ga, resulting in GaA
s melts 21 and 31 were produced. The voltage applied to the high temperature heater 52 _H was adjusted to obtain a temperature distribution with a furnace axial temperature gradient of 2.5 ° C./cm suitable for growing the single crystals 22 and 32. Under these conditions, the melts 21 and 31 are brought into contact with the seed crystals 23 and 33 installed at the tips of the growth boats 20 and 30, and the single crystals 22 and 32 are made into the starting points from the seed crystals 23 and 33 and the reaction tubes 10 are formed.
Was grown in the furnace axis direction from the center to both sides.

The melting point shift and temperature distribution can be made to proceed as designed during crystal growth, and the two growth boats 2
15.6 kg of GaAs single crystal was obtained corresponding to a capacity of 0,30. The crystal growth rate at this time is 10 mm /
It was time. The obtained GaAs single crystal was a homogeneous and dense single crystal having no defects such as cracks, pores, and sparse portions because rapid growth was suppressed. Training boat 2
Polycrystals were grown from the melts 21 and 31 under the same conditions except that the seed crystals 23 and 33 were not installed at the tips of 0 and 30. The obtained GaAs polycrystal was a homogeneous and dense product without defects such as cracks, pores, and sparse portions.

Example 2: In5.9 as a group III element
kg has a semicircular cross section with a diameter of 80 mm and a length of 510 m
They were housed in m. As the group V element 40, 6.1 kg of As was allowed to stand still in the center of the reaction tube 10, and the growth boats 20 and 30 were arranged on both sides of the group V element 40 and sealed in the reaction tube 10. Furnace core tube 51 of heating furnace 50
The reaction tube 10 is inserted into the heating furnace 50 and the temperature inside the heating furnace 50 is set to InA.
The melting point of s was heated to a temperature of 943 ° C. or higher. The single crystal raw material In contained in the growing boats 20 and 30 is melted by heating and reacts with gasified As to form an InAs melt 2
1,31 were generated. The voltage applied to the high temperature heater 52 _H was adjusted to obtain a temperature distribution having a furnace axial temperature gradient of 2.4 ° C./cm suitable for growing the single crystals 22 and 32. Under this condition, the melts 21 and 31 are brought into contact with the seed crystals 23 and 33 installed at the tips of the growing boats 20 and 30, respectively.
Single crystals 22 and 32 were grown in the furnace axial direction from the center of the reaction tube 10 toward the both sides, starting from 33. The movement of the melting point and the temperature distribution could be made to proceed as designed during the crystal growth, and the overflow and rapid growth of the melts 21 and 31 were suppressed. The obtained InAs single crystal had a weight of 17.8 kg corresponding to the capacities of the two growth boats 20 and 30, and was a homogeneous and dense single crystal free from defects such as cracks, pores and sparse parts. It was The crystal growth rate at this time is 8 m
It was m / hour. Single crystals and polycrystals of GaP, InP, etc. could also be manufactured by the same method in a pressure resistant container.

[0011]

INDUSTRIAL APPLICABILITY As described above, in the present invention, two growth boats are arranged on both sides of the group V element and sealed in the reaction tube, and a single crystal or a polycrystal crystallized from the melt produced. Crystal growth is allowed to proceed in the furnace axial direction from the center of the reaction tube to both sides. Thereby, a large amount of single crystals and polycrystals can be efficiently and inexpensively manufactured with a small installation area. Further, since the heating zone is required to have the minimum necessary length, a precise design can be achieved, heat can be effectively used, and temperature distribution can be set with high accuracy. for that reason,
Homogeneous and dense single crystals and polycrystals without defects such as cracks, pores, and sparse parts can be obtained.

[Brief description of drawings]

FIG. 1 is a semiconductor crystal manufacturing apparatus used in an embodiment of the present invention.

[Explanation of symbols]

10: Reaction tube 20, 30: Growth boat 21,
31: melt 22, 32: single crystal or polycrystal 23,
33: Seed crystal 40: Group V element 50: Heating furnace 51:
Furnace core tube 52: Heater 52 _H : High temperature part 52
_L : Low temperature part

Claims (1)

[Claims] 1. A furnace core tube of a heating furnace in which two growth boats containing a crystal raw material of a group III element are arranged on both sides of a group V element and enclosed in a reaction tube, and a temperature gradient is given in a furnace axial direction. The reaction tube is inserted into the reaction tube, and crystals crystallized from a melt produced by heating the crystal raw material are grown in the furnace axial direction from the central portion of the reaction tube toward both ends.
-Method for producing Group V compound semiconductor crystal.