JPS61281100A - Production of silicon single crystal - Google Patents

Abstract

PURPOSE:To obtain the titled single crystal having large diameter and high quality, in high yield, by charging a silicon raw material into a silicon cylinder having higher height than the crucible, putting the cylinder into the crucible, and melting the silicon raw material to effect the growth of a single crystal. CONSTITUTION:A graphite protector 14 is attached to the top of a supporting shaft 13 placed rotatably in the lower chamber 11 of an apparatus for the pulling up of silicon single crystal. A crucible 15 made of e.g. quartz is put into the graphite protector 14 and is made to be heatable with the carbon heater 19. A pull chamber 12 for the pulling up of silicon single crystal is placed above the quartz crucible. A cylinder 16 made of silicon and having higher height than the crucible is inserted into the crucible 15, and a polycrystalline silicon raw material and impurities 17 are charged into the cylinder 16. The apparatus is evacuated while passing an inert gas therethrough, and the carbon heater 19 is electrified with the electrode 18 and heated to melt the raw materials 17 and the cylinder 16. The seed crystal attached to the pulling up shaft is dipped into the molten raw materials while rotating the crucible 15, and a single crystal is pulled up.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in a method for manufacturing silicon single crystals.

[Technical background of the invention]

Silicon single crystals are mainly produced by the Czochralski method. In this method, a crucible is rotatably supported in a chamber, a polysilicon raw material is loaded into the crucible, the polysilicon raw material is heated by a carbon heater placed around the crucible, and then the polysilicon raw material is melted. A silicon single crystal is grown by dipping a seed crystal into silicon and pulling it up.

Conventionally, the charging of polysilicon raw materials into the crucible was done in the second stage.
As shown in the figure, this is simply carried out by filling a polysyncon raw material 2 in the form of a block into a quartz crucible 1, for example.

In the charging method shown in FIG. 2, when the polysilicon raw material is heated and melted, the surface of the molten silicon is considerably lower than the upper end of the crucible l.

[Problems with background technology]

In the above-mentioned Czochralski method, it is clear that in order to increase the production amount of silicon single crystals, it is sufficient to increase the amount of charge of the polysilicon raw material. On the other hand, in order to improve the quality of silicon single crystals, it has been found that it is desirable to reduce the height of the crucible to reduce the temperature gradient of molten silicon. Both of the above-mentioned increases in production volume and improvements in quality lead to improvements in the yield of silicon single crystals.

However, when polysilicon raw materials are charged using the conventional method shown in Figure 2, the positional relationship between the molten silicon and the top of the crucible does not change much depending on the height of the crucible, so the quality of the silicon single crystal is important. When polysilicon raw materials are charged in a low-height crucible using the conventional method, the depth of the molten silicon melt becomes shallow, the amount of charged raw materials decreases, and the production amount of silicon single crystals decreases. Therefore, there was a drawback that the yield of silicon single crystals was not improved as much as expected.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and by increasing the amount of silicon raw material charged into a low-height crucible to improve quality and increase production volume, it is possible to significantly improve yield. The purpose of the present invention is to provide a method for producing silicon single crystals.

[Summary of the invention]

The method for producing a silicon single crystal of the present invention includes accommodating a cylindrical body made of silicon with a height higher than the height of the crucible in a crucible,
The method is characterized in that after a silicon raw material is loaded into the cylindrical body, the silicon raw material and the cylindrical body are melted by heating.

According to this method, even if the height of the crucible is low, by changing the height of the silicon cylindrical body, it is possible to charge an amount of silicon raw material that completely fills the crucible. Therefore, it is possible to improve the quality of the silicon single crystal, increase the production amount, and significantly improve the yield.

In the present invention, the silicone cylindrical body may be a simple cylindrical body or may be a container provided with a bottom surface. Further, the cross-sectional shape of the cylindrical body can be cylindrical or any other arbitrary shape.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described with reference to a lifting device shown in FIG.

In FIG. 1, a lower chamber 11 has openings on its top and bottom surfaces, and a pull chamber 12 for pulling a silicon single crystal is provided above the opening.

A support shaft 13 is rotatably inserted through an opening in the bottom of the lower chamber 11, and supports a graphite protector 14 and a crucible 15 made of quartz or the like inside the support shaft 13 at its upper end.

A cylindrical body 16 formed by welding a silicon rod is housed in the crucible 15, and a polysilicon raw material 17 is contained inside the cylindrical body 16.
is loaded.

Furthermore, electrodes 18 and 18 are inserted into the lower chamber 11 through its bottom surface, and the protector 4 is placed above the electrodes 18 and 18.
It is connected to a carbon heater 8 provided so as to surround the periphery of the carbon heater 8. Furthermore, a heat retaining cylinder 20 is arranged around the outer periphery of the carbon heater 19.

Pulling of a silicon single crystal using the above-mentioned pulling apparatus is carried out as follows. That is, first, polysilicon raw materials and impurities are loaded into a cylindrical body 16 made of silicon housed in a crucible 15, and the pressure is reduced while flowing an inert gas.

Next, the polysilicon raw material 17 and cylinder 16 in the crucible 15 are melted by applying electricity to the carbon heater 19 from the electrodes 18 and 18 to heat them. A silicon single crystal is grown by dipping a seed crystal and pulling it up while rotating the pulling shaft holding the seed crystal.

According to such a method, even when the height of the crucible 15 is low, by changing the height of the cylinder 16, the polysilicon raw material can be charged until the crucible 15 is completely filled when melted.

In fact, if the diameter of the crucible is 14 inches, the height of the crucible will be 250 mm using the conventional charging method for polysilicon raw materials.
1 mm, the maximum charge amount was 25 kg, but in the method of the present invention, the maximum charge amount could be 30 kg when the crucible height was 200 mm. It was also confirmed that it was possible to charge polysilicon raw material in an amount to completely fill the crucible up to the top of the crucible at any height.

Therefore, according to the method of the present invention, it is possible to uniformize the temperature distribution of molten silicon in the crucible, improve the quality of the pulled silicon single crystal, and increase the production amount, thereby significantly improving the yield. .

〔Effect of the invention〕

As described in detail above, according to the method of the present invention, the yield of silicon single crystals can be greatly improved, and furthermore, it can fully cope with the future increase in the diameter of silicon single crystals.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a silicon single crystal pulling apparatus for explaining a method of charging a polysilicon raw material in an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a conventional method of charging a polysilicon raw material. 11... Chang/<-, 12... Sol chamber,
13... Support shaft, 14... Protector, 15... Crucible, 16... Cylindrical body, 17... Polysilicon raw material, 1
8... Electrode, 19... Carbon heater, 20...
・Heat insulation tube.

Claims (1)

[Claims] A crucible is rotatably supported in a chamber, a silicon raw material is melted in this crucible, and a seed crystal is immersed in the molten silicon and pulled up to produce a silicon single crystal. A method for producing a silicon single crystal, which comprises accommodating a tall cylindrical body made of silicon, loading a silicon raw material into the cylindrical body, and then heating to melt the silicon raw material and the cylindrical body.