JPH0585881A - Pull system for single crystal - Google Patents

Abstract

PURPOSE:To provide the title system designed to raise the rate of pull of single crystal and decrease the defects in the single crystal by arranging reflective plates in tiers so as to enclose single crystal to prevent heating the single crystal and maintain the uniformity of melt's temperature. CONSTITUTION:A quartz crucible 2 supported by a susceptor 1 is filled with a silicon melt 4 heated by a heater 3. The lower surface of a silicon single crystal 5 is in contact with the melt's surface and the single crystal 5 is pulled, via a seed chuck 6, by a seed wire 7. Besides thermal insulating materials 15, 16, a reflective plate supporting table 20 is installed and equipped with reflective plates 20 in tiers (e.g. three tiers) through a beam 18 and wire 19. These plates serves so as to reflect the thermal radiation emitted from the surface of the silicon melt 4 toward the silicon single crystal 5 to the region where the above surface contacts with the quartz crucible 2, heating this region subject to temperature fall to uniformize the temperature of the silicon melt 4 and also preventing the radiation toward the single crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for pulling a single crystal by the Czochralski method (CZ method).

[0002]

2. Description of the Related Art Generally, for manufacturing a single crystal by the CZ method, for example, a raw material for a crystal is put into a crucible arranged in a susceptor, and this is heated and melted, and then a seed crystal is immersed in the melt,
It is carried out by rotating this and pulling it upward to grow a single crystal at the lower end of the seed crystal.

In the production of this single crystal, the pulling speed of the single crystal is increased, thereby improving the productivity and reducing the defects in the pulled single crystal. To raise the temperature, it is effective to improve the uniformity of the temperature distribution of the melt and to increase the temperature gradient in the pulling direction of the single crystal being pulled. Conventionally, as a measure for this, heat radiated upward from the melt surface (single crystal side) is applied to the melt surface side, especially to the contact side between the melt that tends to decrease in temperature and the crucible filled with the melt. It has been proposed to provide a reflecting plate that reflects toward the target (eg, Japanese Examined Patent Publication No. 57-4011).
No. 9).

[0004]

The above-mentioned reflector is useful for making the temperature of the melt uniform, but according to the experiments of the present inventor, this reflector also becomes hot during pulling of the single crystal, and this reflector is too high. Acts as a secondary heat source and rather heats the single crystal being pulled up, resulting in a decrease in the temperature gradient in the pulling direction of the single crystal.

In view of the above-mentioned circumstances, the present invention improves the uniformity of the temperature distribution of the melt and prevents the single crystal from being radiated with heat resulting from the melt. The purpose is to provide a device.

[0006]

A single crystal pulling apparatus according to the present invention for achieving the above object is a single crystal pulling apparatus according to the Czochralski method. It is characterized in that it is provided with a plurality of reflecting plates that reflect heat radiated upward from the surface toward the melt surface side.

[0007]

Since the single crystal pulling apparatus of the present invention is provided with the reflecting plates stacked in a plurality of stages, for example, even when the lowermost reflecting plate is heated, the lowermost reflecting plate is directed toward the single crystal side. The heat radiated by the next reflection plate is reflected by the next reflection plate, which prevents the single crystal from being heated by the heat radiated from the high-temperature melt, and the uniformity of the temperature of the melt is ensured. The temperature gradient in the crystal pulling direction can be maintained, and the pulling speed of the single crystal can be improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of a single crystal pulling apparatus according to an embodiment of the present invention. The quartz crucible 2 supported by the susceptor 1 is filled with the silicon melt 4 heated by the heater 3. The surface of the silicon melt 4 is in contact with the lower surface of the silicon single crystal 5, and the silicon single crystal 5 Is pulled up by the seed wire 7 via the seed chuck 6. In addition, the heat insulating material 1 is provided adjacent to the heater 3 so that the heater 3 does not heat any direction other than the silicon melt 4.
5, 16 are provided.

A reflecting plate support 17 is provided on the heat insulating material 15, and multiple (three in this example) reflecting plates 20 are attached via beams 18 and wires 19. The multiple reflection plate 20 reflects heat radiated from the surface of the silicon melt 4 toward the silicon single crystal 5 toward a region where the surface of the silicon melt 4 and the quartz crucible 2 are in contact with each other. As a result, the region where the temperature tends to decrease is heated and the temperature of the silicon melt 4 is made uniform.

Further, the multiple reflection plate 20 cannot completely reflect the heat radiated toward the multiple reflection plate 20. Therefore, the lowermost reflection plate 20a of the multiple reflection plate 20 is gradually gradual. The reflecting plate 20a becomes a secondary heat source and radiates heat toward the silicon single crystal 5 as well, but this heat is reflected by the reflecting plate 20b at the next stage, and the reflecting plate 20a reflects the silicon single crystal. The heat radiated in the direction 5 is reflected by the reflection plate 20c, whereby the heat radiated from the surface of the melt 4 toward the silicon single crystal 5 is prevented from reaching the silicon single crystal 5.

FIG. 2 is a diagram showing an example of the temperature distribution in the pulling direction of the silicon single crystal being pulled up. This Figure 2
45 kg of silicon was charged into a crucible having an inner diameter of 16 inches, and the crucible was rotated at a speed of 6 rpm on average to 1.
This is data when a silicon single crystal is pulled at a speed of 0 mm / min. Silicon melt 4 and silicon single crystal 5
The temperature at the interface with and is 1420 ° C., and in the case where the multiple reflection plate 20 shown in FIG. 1 and other reflection plates are not provided, there is a temperature distribution in the pulling direction as shown in Graph A. Graph B is
2 shows a temperature distribution in the case where a single reflection plate is provided instead of the multiple reflection plate 20 shown in FIG. 1, and the reflection plate serves as a secondary heat source and the silicon single crystal 5 is heated up instead. .

Graph C is a graph showing the temperature distribution in the case where the multiple reflection plate shown in FIG. 1 is provided, and the heat radiated from the surface of the silicon melt 4 toward the silicon single crystal 5 is reflected. As a result, the cooling of the silicon single crystal proceeds,
The temperature distribution has a large gradient in the pulling direction.
The apparatus for pulling a single crystal of the present invention can be widely used for manufacturing a silicon single crystal and various kinds of single crystals using the CZ method.

[0013]

As described above, the apparatus for pulling a single crystal of the present invention reflects the heat radiated upward from the melt surface, which is arranged surrounding the single crystal, toward the melt surface side. Since the reflection plates are stacked in a plurality of stages, the single crystal is prevented from being heated due to the heat radiated from the high temperature melt, and the temperature of the melt can be made uniform. A large temperature gradient can be maintained in the pulling direction of the single crystal, which can improve the pulling speed of the single crystal and reduce defects.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a single crystal pulling apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a temperature distribution in a pulling direction of a single crystal being pulled up.

[Explanation of symbols]

1 Susceptor 2 Crucible 3 Heater 4 Melt Liquid 5 Single Crystal 20 Multiple Reflector

Claims (1)

[Claims] 1. A single-crystal pulling apparatus by the Czochralski method, wherein a plurality of stages are provided surrounding the single crystal and reflecting heat radiated upward from the melt surface toward the melt surface side. An apparatus for pulling a single crystal, comprising: