JPH0459694A - Production of compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To obtain a long single crystal having excellent quality by limiting the temperature-lowering range of heating heater on the formation of the shoulder portion of the single crystal on the production of the single crystal of a compound semiconductor by a LEC method. CONSTITUTION:In a method for producing the single crystal of a compound semiconductor by covering a melted liquid 1 with a liquidsealing agent 3 in a high pressure container, pressing the liquid-sealing agent with an inert gas fed from the upper portion of the container and simultaneously slowly lifting a seed crystal 7 from the melted liquid 1 to grow the single crystal (A: shoulder, B: straight body), the following means are adapted. When the shoulder A of the single crystal is formed, the temperature-lowering width of a heater 5 is controlled to be within 1.5 times a temperature-lowering width required for the formation of the straight body of the single crystal. In the above-mentioned method the formation of the shoulder A of the single crystal is performed preferably by changing the lifting rate of the single crystal at a constant rate based on the lifting length lA of the single crystal (up to V1 V2).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a compound semiconductor single crystal, particularly a method for manufacturing a compound semiconductor single crystal using a liquid confinement pulling (LEC) method. be.

[Prior art] For example, when manufacturing a gallium arsenide (GaAs) single crystal, Ga
The so-called LEC method is used, in which the upper part of the As melt is covered with a liquid sealant such as boron trioxide (B203) and grown while applying pressure from the upper part with an inert gas such as N2Ar.

FIG. 4 shows a sectional view of a conventionally used LEC device. In the figure, 1 is GaAs melt, 2
is a GaAs single crystal, 3 is a sealant B O, 4 is a pulling shaft for pulling up the single crystal 2, 5 is a heater, 6 is a crucible,
7 is a seed crystal, 8 is a pulling shaft controller that controls the operation of the pulling shaft 4, and 9 is a temperature controller that changes the input to the heater 5 to control the temperature.

When the melt 1 is formed and seeding with the seed crystal 7 is performed, the pulling shaft 4 is gradually pulled up and the GaAs single crystal 2 is grown. Precise shape control is required because maintaining the dimensions will affect the quality of the element. A pulling shaft controller 8 and a temperature controller 9 shown in the figure are provided for this purpose, and each adjusts the pulling speed of the pulling shaft 4 and the heating temperature of the heater 5 based on preset values input. The outer diameter of the single crystal 2 is controlled to a predetermined size.

[Problems to be Solved by the Invention] As mentioned above, when producing a single crystal of a compound semiconductor such as GaAs, it is important to grow the crystal so that the outer diameter dimension has a predetermined value. A method is used in which the crystal pulling speed and temperature are controlled by a controller. However, even if such a method is used, for example, sudden changes may occur at the solid-liquid interface during crystal pulling, leading to a decrease in quality, or the shoulder of the crystal may be affected due to a delay in the melt temperature relative to the heater temperature. There was a problem that high-quality single crystals could not be grown stably, such as asymmetrical parts.

An object of the present invention is to provide a method for producing a compound semiconductor single crystal, which allows obtaining a long single crystal with excellent quality.

[Means for Solving the Problem] The present invention provides a method for manufacturing a compound semiconductor single crystal using the LEC method. 1.5 of temperature drop width
It is characterized by growing single crystals by controlling the pulling speed to be within 2 times the pulling length and by changing the pulling speed of the crystal at a constant ratio to the pulling length, so that high quality single crystals can be obtained. planning to achieve the goal.

[Function] In the compound semiconductor single crystal manufacturing method of the present invention, when manufacturing, for example, a GaAs single crystal using the LEC method, the crystal pulling speed is increased at a constant rate when forming a shoulder, and When forming the body, control the speed to be constant,
Also, adjust the temperature of the heater while comparing the outer diameter of the crystal with the set value, and especially when forming a shoulder part, make sure that the temperature drop is within 1.5 times that when forming a straight body part. This makes it possible to obtain a single crystal with an ideal shape compared to conventional methods.

[Embodiments] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an embodiment of a GaAs single crystal manufacturing apparatus to which the compound semiconductor single crystal manufacturing method of the present invention is applied.
The same parts as in FIG. 4 are given the same reference numerals. In the same figure, 1o stores data necessary for single crystal production,
This is an arithmetic controller that gives commands to and controls the pulling shaft controller 8 and temperature controller 9 based on this data.

Using this device, a 6-inch diameter P B N (Pylol
iticboron n1trid) Rupo 6 to Ga5
6 kg of As and 38 oo of liquid sealant BB2O were placed in a furnace, filled with high-purity Ar gas, and heated with a heater 5 to produce a GaAs melt 1. Next, the pulling shaft controller 8 is operated according to a command from the arithmetic controller 10, and the pulling shaft 4,
Therefore, seeding was performed by lowering the seed crystal 7.

When the seeding was completed, the pulling shaft 4 was pulled up by operating in the opposite direction to the previous one, and a single crystal was formed in the order of the shoulder A1 and the straight body B (FIG. 1). In this way, a GaAs single crystal with a diameter of 3 inches was obtained.

FIG. 2 shows the relationship between the pulling length 1 and the pulling speed V at this time, where the horizontal axis shows the pulling length 1 and the vertical axis shows the pulling speed V. 1.1 in the same figure represents the pulling length of the B single crystal shoulder portion A and straight body portion B, respectively.

Further, the dotted line indicates V-constant when using the conventional control method.

As shown in the figure, in the case of this embodiment, a shoulder portion is formed 1
During the period -1A, the pulling speed (2) is increased as shown by V1-V2, and control is performed so that ym is constant during the period -1B since the straight body portion is formed. On the other hand, for the temperature, adjust the power of the heater 5 according to the shape of the shoulder and gradually lower it in accordance with the lifting operation. , good results were obtained by keeping it within 5 times. In the conventional method, as shown by the dotted line in Figure 2, v was constant, so the shape around the shoulder became asymmetrical, and the ratio of the above temperature drop width was 2 to 2.
It was 5 times more.

In this way, in this example, it is possible to obtain a good shape for both the shoulder part and the straight body part, and for example, the straight body part diameter is 82 mm.
When manufacturing a GaAs single crystal of
The deviation when using the conventional method can be within ±
This was a significant improvement compared to 4.5 mrn.

FIG. 3 shows the relationship between the pulling length 1 and the diameter of each part of the crystal, where the solid line shows the case of this embodiment and the dotted line shows the case when the conventional method was used. DA is the diameter of the shoulder, D is the diameter of the trunk, D
c represents the diameter of the bottom. It can be seen that the single crystals are formed into a conical shape and a cylindrical shape, respectively, and have no irregularities as shown by the dotted line (conventional method), resulting in a highly accurate single crystal.

[Effects of the Invention] As described above, according to the present invention, the following effects can be obtained.

(1) High quality single crystals can be obtained without unevenness on the crystal surface.

(2) Yield during wafer manufacturing can be significantly improved due to improved quality.

(3) The cost of devices can be reduced by improving the wafer yield.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a manufacturing apparatus to which the compound semiconductor single crystal manufacturing method of the present invention is applied, FIG. 2 is a characteristic curve diagram showing the relationship between pulling length and pulling speed, and FIG. 3 4 is a characteristic curve diagram showing the relationship between the pulling length and the diameter of each part of the single crystal, and FIG. 4 is an explanatory diagram of a manufacturing apparatus in which the conventional method is applied. DESCRIPTION OF SYMBOLS 1: GaAs melt, 2: Single crystal, 4: Pulling shaft, 5: Heater, 8: Pulling shaft controller, 9: Temperature controller, 10. Arithmetic controller. 4th day chain As melt 2. Single crystal 5: He 78.31 old control, i*j, the control of the unknown way, l two bows 11 ball;: 1 chi 1 [speed D, diameter of worn parts

Claims (1)

[Scope of Claims] 1. A compound in which a melt melted in a high-pressure container is covered with a liquid sealant, and a seed crystal is gradually pulled up from the melt while pressurizing from above with an inert gas to grow a single crystal. In the method for manufacturing a semiconductor single crystal, when forming the shoulder portion of the single crystal, the temperature drop width of the heater is set to within 1.5 times the temperature drop width necessary for forming the straight body portion of the single crystal. A method for producing a compound semiconductor single crystal, characterized by controlling the compound semiconductor single crystal. 2. Manufacturing a compound semiconductor single crystal according to claim 1, wherein the formation of the shoulder of the single crystal is performed by changing the pulling speed at a constant rate with respect to the pulling length of the single crystal. Method.