JPS6234717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a resistance heating method and apparatus used for pulling a single crystal, and particularly to a method and apparatus in which the shape and arrangement of a resistance heating element are improved.

Conventionally, in single crystal pulling, a quartz crucible is placed in a hot zone created by a resistance heating element as shown in Figures 1 and 2, and a single crystal material is placed in the hot zone and melted. It was pulling up the melt. However, when using these resistance heating elements,
The temperature distribution in the zone was not as desired, and the carbon used as a resistance heating element was consumed to a large extent.

FIG. 1 shows a cross-sectional view of an example of a conventional resistance heating body. Since the resistance heating body 1 in this case has a uniform thickness and a uniform cylindrical radius, only a constant temperature distribution can be obtained.

FIG. 2 is also a cross-sectional view of an example of a conventional resistance heating element, and is shown in a patent application publication (1978-39787). The carbon resistance heating body 20 has a variable thickness, and has a multi-stage cylinder with different radii. Therefore, a variety of temperature distributions can be obtained compared to the conventional resistance heating element shown in Figure 1, but the carbon in the thinner parts of the resistance heating element is significantly consumed, and the temperature distribution changes over time. There is a change over time, which is a drawback. Furthermore, when changing the temperature distribution, it is necessary to design and manufacture the carbon by changing its thickness, radius, and height, and install it in the furnace. This can contaminate the furnace with impurities contained in the carbon, making it difficult to achieve the desired high quality. There is also the drawback that single crystal growth cannot be expected.

Furthermore, when using a conventional resistance heating element,
Temperature distribution control is not easy when pulling Si, Ge, etc., and even more so in the liquid capsule pulling method (LEC method) of compound semiconductors such as GaP, InP, GaAs, etc.
In order to cover the melt with B ₂ O ₃ as a sealing liquid that suppresses the decomposition and evaporation of volatile substances such as As and As, it is also possible to use high-pressure inert gas (30 to 50 atm) such as N ₂ gas or Ar gas at high temperatures. Due to the convection phenomenon, the temperature distribution becomes even more complex and difficult to control.

The present invention provides a resistance heating method using a new resistance heating element that improves the drawbacks of the conventional resistance heating element, and also provides a heating apparatus for pulling a single crystal.

The present invention arranges resistance heating bodies inside and outside,
If necessary, the height of the resistance heating element can be adjusted by making the outer resistance heating element extend over the inner resistance heating element, and the height of the resistance heating element can be adjusted as needed. By supplying a certain amount of electric power, a predetermined temperature distribution can be obtained.

The present invention will be explained below based on FIG.

FIG. 3 is a sectional view of the main parts of an example of a single crystal pulling apparatus embodying the present invention. In FIG. 3, a quartz crucible 33 is installed in a graphite susceptor 34A, a melt 31 of a single crystal material is put therein, and a single crystal 32 is pulled up while rotating a pulling shaft 37. Further, a cylindrical heat insulating material 36 is installed coaxially around the outer periphery of the resistance heating elements 35A, 35B, and 35B, and a lower shaft 34B that rotates the quartz crucible 33 monitors the pulling state of the crystal. A peephole 39 is installed. 30 is an inert gas such as N ₂ gas or Ar gas, which is filled in the chamber 38 .

In order to obtain a high quality single crystal using a single crystal pulling apparatus, it is important to control the temperature distribution within the pulling furnace, particularly the temperature distribution near the quartz crucible 33, that is, in the hot zone. The factors that determine the temperature distribution include the resistance heating element 3
There are structures such as 5A and 35B insulation material 36 graphite susceptor 34, among others, resistance heating element 3
The shape and position of number 5 occupies the most important position.

FIG. 4 shows a front view of the heating element and its peripheral equipment of the apparatus of the present invention. Similar to the general structure of a pulling furnace, a crucible 43 is installed in a susceptor 44A and connected to a lower shaft 44B. A heating body is installed on the outside thereof, and has a two-stage, double-layered structure consisting of a lower heating element 45B and an upper heating element 45A in upper and lower stages and a double cylindrical heating element. Electrode plates are attached to the bottom of each heating element, and by adjusting these electrode plates, both the lower heating element 45B and the upper heating element 45A can be easily moved in the vertical direction. By variously changing the arrangement relationship between the crucible, the lower heating element 45B, and the upper heating element 45A, and by independently controlling the input to the lower heating element 45B and the upper heating element 45A,
An optimal temperature distribution is achieved.

For example, by changing the thickness of the upper heating body 55A as shown in FIG. 5, the temperature distribution can be easily changed. A perspective view of the lower heating body 45B is shown in FIG.
The figure shows a perspective view of the upper heating body 45A. These form heating conductor strips 65, 75 having equally spaced slits 66, 76.

According to the present invention, as explained above, the present invention device has two parts that can be easily moved up and down on the outside on the concentric axis with the crucible.
Consisting of a heating element with a double layered structure, by independently controlling the arrangement relationship between these and the crucible and electrical input, it is possible to pull not only single crystals such as Si and Ge, but also GaP, InP, GaAs, etc. Even when pulling a single crystal showing a complicated temperature distribution, a desired temperature distribution can be constructed relatively easily, and a high quality single crystal can be obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views of an example of a conventional resistance heating body. FIG. 3 is a main sectional view of an example of a single crystal pulling apparatus embodying the present invention. 4 and 5 are cross-sectional views of a resistance heating body used in the present invention, and FIGS. 6 and 7 are perspective views of an example of a lower heating element and an upper heating element, respectively, used in the present invention. . In the figure, 10 and 20 are resistance heating elements, and 35
A, 45A, 55A, 75 are upper heating bodies;
35B, 45B, 55B, and 65 are lower heating bodies. 43, 53 are crucibles, 44A, 54A
is a susceptor.

Claims (1)

[Claims] 1. A heating element having a double cylindrical structure is installed concentrically around the outer periphery of the crucible, the inner heating element is set at an intermediate height, and the upper part of the outer heating element is formed into an inverted U shape. , so that it extends above the inner heating element, and is set in advance at a predetermined position in the vertical direction of the furnace, and then by inputting a predetermined electric power to each heating element, the temperature near the crucible is made to have a predetermined distribution. 1. A method for pulling a single crystal, characterized in that pulling is carried out using a single crystal. 2 A heating element with a double cylindrical structure is arranged concentrically around the outer periphery of the crucible, the inner heating element is at an intermediate height, and the outer heating element has an upper part formed in an inverted U shape and placed on the inner heating element. Furthermore, each heating element can be freely set in the vertical direction of the furnace by adjusting the mounting position of the heating element, and the arrangement of the two heating elements and the calorific value of each heating element are 1. A single crystal pulling device characterized by being able to independently control the temperature distribution in the vicinity of the crucible and freely controlling the temperature distribution in the vicinity of the crucible. 3. The device according to claim 2, characterized in that a predetermined temperature distribution can be obtained by changing the entire thickness of the heating body part or by giving a distribution to the thickness. A single crystal pulling device according to claim 2.