JPH0543385A - Carbon heater for furnace for pulling up si single crystal - Google Patents

Abstract

PURPOSE:To provide a carbon heater for a furnace for pulling up an Si single crystal, having sufficient mechanical strength and capable of easily and arbitrarily changing the temperature distribution. CONSTITUTION:The objective heater is composed of a heater main body 1 having cylindrical shape and furnished with alternately formed slits extending from the top edge downward and slits extending from the bottom upward and terminals 3 integrally attached to the heater main body 1. Through-holes 4 are opened at desired positions on each heater segment between two adjacent slits 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a carbon heater used in a Si single crystal pulling furnace.

[0002]

2. Description of the Related Art Si single crystals are mainly manufactured by the Czochralski method. In this method, a polycrystalline silicon raw material is placed in a crucible rotatably supported in a pulling furnace, and the polycrystalline silicon raw material is melted by heating with a cylindrical heater provided on the outer periphery of the crucible. A seed crystal is immersed in and pulled up to obtain an ingot-shaped silicon single crystal.

As a heater for a Si single crystal pulling furnace, as shown in FIG. 5, a heater having a cylindrical shape and slits 2 extending from the upper end to the lower end or from the lower end to the upper end are alternately provided. A carbon heater having a main body 1 and two terminals 3 provided integrally with the heater main body 1 is used. The principle of this carbon heater is 2
A voltage is applied between two terminals 3, and each heater segment sandwiched by two adjacent slits 2 of the heater body 1 is resistance-heated by an electric current flowing vertically.

In order to control the temperature distribution of the silicon melt in the crucible using such a carbon heater, it is sometimes required to obtain a desired temperature distribution in the vertical direction.
For example, when the temperature distribution is changed so that the temperature peak exists on the upper part of the heater, the conventional carbon heater is shown in FIG.
The structure was processed as shown in FIG. FIG. 3 shows a reduction in the wall thickness at the top of the segment. Further, in FIG. 4, the width of the slit is expanded at the upper part of the segment.
In any of the carbon heaters, the temperature distribution is changed so that the temperature peak exists on the upper part of the heater by decreasing the cross-sectional area of the upper part of the segment and increasing the current density.

[0005]

However, the carbon heater having the segment thickness reduced or the slit width widened as shown in FIG. 3 or FIG.
There is a problem that it is difficult to arbitrarily change the temperature distribution.

The present invention has been made to solve the above problems, and provides a carbon heater for a Si single crystal pulling furnace which can maintain mechanical strength and can easily change the temperature distribution arbitrarily. The purpose is to

[0007]

The carbon heater for a Si single crystal pulling furnace of the present invention has a cylindrical shape, and slits extending from the upper end to the lower end and slits extending from the lower end to the upper end are alternately provided. Two adjacent carbon heaters
A through hole is provided at a desired position of the heater segment sandwiched by the two slits.

[0008]

In the carbon heater for a Si single crystal pulling furnace of the present invention, a small through hole is provided in the heater segment to reduce the cross-sectional area of the heater segment and change the temperature distribution in the vertical direction. Since the size of the through hole may be small, the mechanical strength of the heater does not deteriorate so much. Further, since the through hole can be easily processed, the through hole can be provided at a desired arbitrary position of the heater segment, and a desired temperature distribution can be obtained in the vertical direction.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are front views of a carbon heater according to the present invention. Each of the carbon heaters of FIGS. 1 and 2 has an outer diameter of 530 mm, an inner diameter of 470 mm, and a height of 400.
mm, a heater main body 1 having slits 2 extending from the upper end to the lower end and slits 2 extending from the lower end to the upper end alternately, and two terminals 3 integrally provided with the heater main body 1. have.

In the carbon heater (Example 1) of FIG. 1, 270 mm and 300 mm from the lower end of each heater segment sandwiched by two adjacent slits 2 of the heater body 1.
A through hole 4 having a diameter of 10 mm is provided at a position of mm (130 mm and 100 mm from the upper end). The through hole 4 is provided at such a position to reduce the cross-sectional area of the segment, so that the temperature distribution is changed so that the temperature peak exists on the upper part of the heater.

In the carbon heater (Example 2) of FIG. 2, 100 mm and 130 mm from the lower end of each heater segment sandwiched by two adjacent slits 2 of the heater body 1.
A through hole 4 having a diameter of 10 mm is provided at a position of mm. The through hole 4 is provided at such a position to reduce the cross-sectional area of the segment, so that the temperature distribution is changed so that the temperature peak exists in the lower portion of the heater. For comparison with these, the conventional standard carbon heater shown in FIG. 5 was used.

FIG. 6 shows the results of examining the temperature distribution in the vertical direction by energizing these three types of carbon heaters. As is clear from FIG. 6, in comparison with the conventional standard carbon heater, the temperature peak exists in the upper part of the heater in Example 1 and the temperature peak exists in the lower part of the heater in Example 2, respectively.

[0014]

As described above in detail, in the carbon heater for Si single crystal pulling furnace of the present invention, the cross-sectional area of the heater segment is reduced and the temperature distribution in the vertical direction is changed by providing the small through hole. Therefore, the mechanical strength of the heater does not decrease so much, and by providing the through hole at a desired arbitrary position of the heater segment,
A desired temperature distribution can be obtained in the vertical direction.

[Brief description of drawings]

FIG. 1 is a front view of a carbon heater according to a first embodiment of the present invention.

FIG. 2 is a front view of a carbon heater according to a second embodiment of the present invention.

FIG. 3 is a front view of a conventional improved carbon heater.

FIG. 4 is a front view of another conventional improved carbon heater.

FIG. 5 is a front view of a conventional standard carbon heater.

FIG. 6 is a diagram showing a temperature distribution in the vertical direction in Examples 1 and 2 of the present invention and a conventional standard carbon heater.

[Explanation of symbols]

1 ... Heater main body, 2 ... Slit, 3 ... Terminal, 4 ... Through hole.

Claims (1)

[Claims] 1. A carbon heater having a cylindrical shape in which slits extending from an upper end to a lower end and slits extending from a lower end to an upper end are alternately provided, and a desired position of a heater segment sandwiched between two adjacent slits. A carbon heater for a Si single crystal pulling furnace, characterized in that a through hole is provided in the.