JP3010832B2 - Method and apparatus for controlling vapor pressure of compound semiconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to GaAs, InP, G
The present invention relates to a method for controlling a vapor pressure in the synthesis, crystal growth or heat treatment of a compound semiconductor such as aP and CdTe, and an apparatus used for the method.

[0002]

2. Description of the Related Art Compound semiconductors of this kind have a high vapor pressure such as As, P, Te, etc., so that the vapor pressure of such constituent elements can be controlled during synthesis, crystal growth or heat treatment in the manufacturing process. There is a need to do. Conventionally, in order to perform such a vapor pressure control, a compound and a component element having a high vapor pressure are contained in a closed container, and the temperatures of the compound and the component elements are independently controlled. The method was taken.

[0003] For example, a case of GaAs crystal growth will be described as an example. The vapor pressure of As in the vicinity of the melting point of the GaAs melt having a composition ratio of 1: 1 is about 1 atm, and the vapor pressure of Ga is 1/1000 or less. For this reason, in the growth of GaAs crystals, it is necessary to control the vapor pressure of As.

FIG. 2 shows a configuration example of a conventional apparatus for growing a GaAs crystal while controlling the vapor pressure of As by a vertical temperature gradient method. According to this apparatus, the crucible 3 charged with the seed crystal 1 and the GaAs raw material 2 and the quartz container 5 filled with As 4 in a vacuum are set in an electric furnace, and the high-temperature heater 6
After melting the GaAs raw material 2 and the upper end of the seed crystal 1 by heating, the temperature is gradually lowered, so that the crystal grows upward from the seed crystal 1 at the bottom of the crucible 3.

In the above case, the temperature of the As reservoir 7 at the bottom of the quartz container 5 is kept and controlled by the low-temperature heater 8 in the cooling process after the raw material melting process and after the crystal growth, thereby controlling the As vapor pressure. Is being done. When it is desired to make the composition ratio of the GaAs crystal 1: 1, the temperature of the As reservoir 7 is controlled to be 615 ° C. so as to apply an As vapor pressure of 1 atm to the GaAs raw material melt.

[0006]

However, as described above, in the conventional method in which the As vapor pressure control is performed by substituting the temperature control for the As reservoir 7 with the above-mentioned method, particularly, Ga
When an As vapor pressure of 1 atm is applied to the As material melt, the temperature of the upper portion of the material melt at the start of crystal growth has its melting point (1238).
° C), the As vaporizes from the GaAs melt if the applied As vapor pressure is 1 atm, resulting in a Ga-rich composition above the GaAs melt. There is a problem. On the other hand, as the As evaporates, As increases in the As reservoir 7, and especially when the leveling of the As reservoir 7 is insufficient, A
s The effective As temperature, which determines the vapor pressure, rises,
The s vapor pressure is higher than one atmosphere. In this case, the temperature of the upper portion of the raw material melt decreases as the crystal growth proceeds, so that the As vapor pressure also decreases. That is, even if the As reservoir 7 is controlled to be constant, the As vapor pressure fluctuates with the progress of crystal growth, and as a result, it becomes difficult to control the As vapor pressure to be constant.

[0007] Further, since the As vapor pressure cannot be controlled to be constant as described above, the quartz container 5 may be ruptured due to an increase in the As vapor pressure. In particular, in the case of atmospheric pressure, if the vapor pressure of As is intentionally shifted from 1 atm in order to prevent the quartz container 5 from bursting, the control becomes practically impossible. There was an inconvenience.

In view of the above circumstances, the present invention provides a compound semiconductor capable of precisely controlling the vapor pressure of a component element without depending on the temperature control of the component element reservoir in the synthesis, crystal growth, or heat treatment of this kind of compound semiconductor. It is an object of the present invention to provide a vapor pressure control method and apparatus.

[0009]

In the method for controlling the vapor pressure of a compound semiconductor according to the present invention, a quartz container in which a compound semiconductor and its constituent elements are vacuum-sealed is sealed in a pressure container. Then, a part (deformation detection unit) of the quartz container is heated to the temperature of the plastic deformation region of quartz, and the amount of deformation of the quartz container is detected by a micrometer. The internal pressure of the pressure vessel is changed according to the amount of deformation of the quartz container, thereby suppressing the deformation of the quartz container, and the internal pressure of the pressure vessel when the deformation of the quartz container is stopped. Read as vapor pressure. Then, as described above, the vapor pressure control is performed by changing at least one of the temperature of the compound semiconductor and the temperature of the element constituting the compound semiconductor in the quartz container according to the measured vapor pressure. Is performed. In the above case, the internal pressure of the pressure vessel is kept constant at a desired value in advance, and the temperature of the compound semiconductor in the quartz vessel and the temperature of the elements constituting the compound semiconductor are kept so that the quartz vessel is not deformed. The vapor pressure control may be performed similarly to the above by changing any one or more.

The apparatus used in the method for controlling the vapor pressure of a compound semiconductor according to the present invention comprises a heater for independently controlling the temperature of the compound semiconductor in the quartz container and the temperature of the elements constituting the compound semiconductor; A pressure gauge that measures
A gas injection / discharge valve for adjusting the internal pressure of the pressure vessel,
A micrometer for detecting the amount of deformation of the quartz container, wherein the temperature of the deformation detecting portion of the quartz container, the amount of deformation of which is detected by the micrometer, is adjusted to the temperature of the plastic deformation region. It is.

[0011]

First, in the apparatus used in the method of the present invention, the temperature of the compound semiconductor in the quartz container and the temperature of the elements constituting the compound semiconductor are independently controlled by the heater. The quartz container is installed in the controllable pressure vessel, and the amount of deformation of the quartz vessel is detected by the micrometer. The internal pressure of the pressure vessel is measured by the pressure gauge. When the internal pressure is higher or lower than a set value, the internal pressure is appropriately adjusted by the gas injection / discharge valve.

According to the method of the present invention using such an apparatus, in measuring the vapor pressure, the phenomenon that the quartz container is deformed based on the pressure difference between the internal pressure (steam pressure) and the external pressure (the internal pressure of the pressure container) is considered. It is detected by the micrometer. Then, when the deformation of the quartz container stops, that is, when the pressure difference between the inside and outside of the quartz container becomes 0, the above-mentioned external pressure is read as the internal pressure of the quartz container. In the above case, in a state where the quartz in the quartz container is at the temperature of the plastic deformation region,
If there is a pressure difference between the inside and outside of the quartz container, the quartz container continues to be deformed, while if the inside and outside pressure difference is 0, the deformation of the quartz container stops. For this reason, it is necessary that the temperature of the deformation detecting section of the quartz container is in the plastic deformation region.

Therefore, the vapor pressure can be measured in real time, and at least one of the temperature of the compound semiconductor and the temperature of the element constituting the compound semiconductor in the quartz container is changed according to the measured vapor pressure. Thereby, the vapor pressure control can be performed. Further, by installing the quartz container in the pressure container, it becomes possible to change the external pressure of the quartz container according to the vapor pressure to be controlled, and to effectively control the vapor pressure even in a pressure region other than the atmospheric pressure. be able to. Further, in the process of measuring the vapor pressure, since the deformation of the quartz container is detected while suppressing the deformation, the rupture of the quartz container can be reliably prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and apparatus for controlling the vapor pressure of a compound semiconductor according to the present invention will be described below with reference to FIG. First, in FIG. 1 showing a schematic configuration of an apparatus used in the method of the present invention, 1 is a seed crystal, 2 is a GaAs raw material, 3 is a crucible, 4 is As, 5 is a quartz container, 6 is a high-temperature heater, 7 is As Reservoir 8 is a low-temperature heater, and the configuration thereof is basically the same as that of the conventional case, and the description thereof will be omitted. In this embodiment, Ga
This is an example of the case of As crystal growth.

Further, in the drawing, 9 is a pressure vessel for housing the whole quartz vessel 5 therein, 10 is a pressure gauge for measuring the internal pressure of the pressure vessel, and 11 and 12 are for injecting or discharging gas into or from the pressure vessel 9. Respectively, an injection valve and a discharge valve. Here, the pressure in the pressure vessel 9 is measured with a pressure gauge 1
0, and if the measured value is lower than the desired set value, the injection valve 11 is opened to introduce gas,
If the pressure is higher than the set value, the discharge valve 12 is opened to discharge the gas, whereby the internal pressure of the pressure vessel 9 can be controlled.

Reference numeral 13 denotes a fixing jig provided on the top of the quartz container 5 for a micrometer described later, and 14 denotes the quartz container 5 mounted and fixed on the fixing jig 13.
Is a micrometer that detects the amount of deformation of Although a high-precision and lightweight one is selected as the micrometer 14, the micrometer 14 has a probe 14 for the micrometer 14, which is formed of a quartz cap for sealing the quartz container 5.
a comes into contact, and only the needle pressure of the needle 14a is applied.

In the above case, as described later, the deformation detecting unit 1
The temperature of 5 is 1200 to 1 in the case of GaAs crystal growth.
The temperature is set to 300 ° C., and in this temperature range, the deformation detecting section 15 is in the plastic deformation region. On the other hand, when the synthesis, crystal growth, or heat treatment of the compound semiconductor is performed at or below the plastic deformation temperature range of quartz, the deformation detection unit 15 maintains the plastic deformation temperature (1200 to 1300 ° C.) to maintain the temperature. A heater is appropriately installed in the vicinity of the deformation detection unit 15.

Next, a specific method for controlling the vapor pressure of a compound semiconductor using the apparatus of the present invention configured as described above will be described. First, a PBN crucible 3 loaded with 3 kg of a GaAs raw material 2 and a seed crystal 1 is inserted into a quartz container 5 in which 8 g of As4 is placed at the bottom thereof.
The inside is evacuated to 10 ^-6 Torr and sealed. Then, the quartz container 5 is set at a predetermined position in the pressure container 9, and the micrometer 1 is fixed by the fixing jig 13.
4 is attached to the top of the quartz container 5. In this case, the needle 14 a of the micrometer 14 is brought into contact with the center of the deformation detector 15.

The temperature of the As reservoir 7 is 615 ° C., and the temperature of the seed crystal 1 and the GaAs raw material 2 thereover are 1238 to 127 ° C.
The temperature is raised to 0 ° C. From the heating process, the amount of deformation of the quartz container 5 was measured using the micrometer 1.
4, the set value of the internal pressure of the pressure vessel 9 is increased as the quartz vessel 5 expands and deforms. After the completion of the temperature raising process, the internal pressure of the pressure vessel 9 was 1.203 kg / cm ² when the deformation of the quartz stopped in a state where the GaAs raw material 2 and the seed crystal 1 were melted. After this,
The internal pressure of the pressure vessel 9 is gradually reduced to 1.000 kg / cm ^2. During this time, the temperature of the As reservoir 7 is reduced as the quartz vessel 5 expands and deforms. When the deformation of the quartz stopped at 0.000 kg / cm ² , the temperature of the As reservoir 7 was 608 ° C. On the other hand, the temperature of the deformation detecting unit 15 at this time is 1260 ° C.

From the state where the GaAs raw material 2 and the upper part of the seed crystal 1 are melted, the set temperature of the high-temperature heater 6 is set to 0.
Crystal growth was performed by lowering the temperature at a rate of 6 ° C. In this crystal growth process, the set value of the internal pressure of the pressure vessel 9 is set to 1.0.
The temperature is kept constant at 00 kg / cm ^2, and the temperature of the As reservoir 7 is increased in response to the deformation of the quartz container 5 and the shrinkage (recess) of the quartz container 5. Crystal growth has ended. The temperature of the As reservoir 7 when the deformation of the quartz stopped in this state was 615 ° C. The control accuracy of the internal pressure of the pressure vessel 9 during crystal growth is ± 0.003k
g / cm ² , and the deformation detector 15 of the quartz container 5.
Is a maximum of about 2 mm.

Thereafter, the set temperature of the high-temperature heater 6 is increased by one hour.
It cools down to 800 ° C at a rate of 20 ° C,
In this cooling process, the temperature of the As reservoir 7 is kept constant at 615 ° C. Subsequently, the set temperatures of the high-temperature heater 6 and the low-temperature heater 8 were lowered to room temperature at a rate of 180 ° C./hour to perform cooling.

In the above-described embodiment, in the temperature raising step, the upper part of the seed crystal 1 and the GaAs on the seed crystal 1 were controlled while controlling the internal pressure of the pressure vessel 9 to 1.000 kg / cm ^2.
The raw material 2 is heated to a temperature of 1238 to 1270 ° C., and the deformation of the quartz container 5 is detected from this process, and the temperature of the As reservoir 7 is increased as the quartz container 5 contracts. As a result, the As vapor pressure becomes 1.000 kg / c.
It can be controlled in m ^2. Further, even when the leveling of the As reservoir 7 is insufficient, the vapor pressure can be controlled by adjusting the temperature of the As reservoir 7 according to the measured vapor pressure value.

[0023]

As described above, according to the present invention, in the synthesis, crystal growth or heat treatment of a compound semiconductor, the vapor pressure control is performed in real time without substituting the temperature control of the constituent element (eg, As) reservoir of the compound semiconductor. , And the measured vapor pressure can be fed back to control the vapor pressure. Further, it is possible to effectively prevent accidents such as rupture of the quartz container in the synthesis, crystal growth, heat treatment, etc. of the compound semiconductor in the quartz container, thereby realizing an extremely safe apparatus. There is.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of a GaAs crystal growth apparatus used for a compound semiconductor vapor pressure control method according to the present invention.

FIG. 2 is a longitudinal sectional view showing a schematic configuration of a conventional GaAs crystal growth apparatus.

[Explanation of symbols]

 Reference Signs List 1 seed crystal 2 GaAs raw material 3 crucible 5 quartz container 6 high temperature heater 7 As reservoir 8 low temperature heater 9 pressure container 10 pressure gauge 11 injection valve 12 discharge valve 13 fixing jig 14 micrometer 15 deformation detector

Claims (2)

(57) [Claims] An element constituting a compound semiconductor or a quartz container in which a compound semiconductor and its constituent elements are vacuum-sealed is heated to a predetermined temperature in a pressure vessel, and a deformation amount of the quartz container is detected by a micrometer. At least one of the temperature of the compound semiconductor in the quartz container, the temperature of an element constituting the compound semiconductor, or the internal pressure of the pressure container is changed according to the amount of deformation of the quartz container, thereby reducing the deformation of the quartz container. While suppressing, the internal pressure of the pressure vessel when the deformation of the quartz container is stopped is read as the vapor pressure of the compound semiconductor, and the temperature of the compound semiconductor in the quartz container and the compound semiconductor according to the vapor pressure A method of controlling the vapor pressure of a compound semiconductor, wherein at least one of the temperatures of the elements constituting the compound is changed. 2. A heater for independently controlling the temperature of a compound semiconductor in a quartz container and an element constituting the compound semiconductor;
A pressure gauge that measures the internal pressure of the pressure vessel, a gas injection / discharge valve that adjusts the internal pressure of the pressure vessel, and a micrometer that detects the amount of deformation of the quartz container are provided. 2. The apparatus according to claim 1, wherein the detected temperature of the deformation detecting section of the quartz container is adjusted to a temperature of a plastic deformation region.