JPH0751472B2 - Silicon single crystal pulling equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a silicon single crystal pulling apparatus.

[Conventional technology]

Silicon single crystals used as substrates for semiconductor devices are mainly manufactured by the Czochralski method (CZ method). In principle, the CZ method rotatably supports a crucible in a chamber, loads a silicon raw material into the crucible, melts the silicon raw material in the crucible with a carbon heater provided around the crucible, and melts the silicon. A silicon single crystal ingot is pulled up by immersing a seed crystal rotatably suspended from above in a liquid and pulling it up.

[Problems to be solved by the invention]

By the way, practically, a crucible made of quartz glass is used. This quartz crucible reacts with the silicon melt, and SiO gas is generated as follows.

SiO ₂ + Si → 2SiO This SiO gas reacts with the carbon heater having the highest temperature, and CO gas is generated as follows.

SiO + 2C → SiO + CO As a result, the life of the carbon heater is shortened. Also, CO
Since the gas is taken into the silicon melt, the carbon concentration in the silicon single crystal ingot becomes high, which causes crystal defects to increase.

The present invention has been made to solve the above problems, and prevents the reaction of the SiO gas and the carbon heater, the carbon heater has a long life and the carbon concentration is low and the generation of crystal defects is low in the silicon single crystal. It is an object of the present invention to provide a silicon crystal pulling apparatus capable of manufacturing.

[Means for solving problems]

The silicon single crystal pulling apparatus of the present invention rotatably supports a crucible in a chamber, loads a silicon raw material into the crucible, and heats the silicon raw material in the crucible by a heater provided on the outer periphery of the crucible. In a device for pulling a silicon single crystal by melting and immersing a seed crystal that is rotatably suspended from above in a silicon melt, and pulling this, a carbon fiber is wound between at least a crucible and a heater. A thin cylindrical gas shielding material made of a carbon composite material is provided.

The carbon composite material constituting the gas shielding material used in the present invention can be produced by winding carbon fibers into a cylindrical shape, impregnating a phenol resin or the like, curing the carbon fiber, and then firing the carbon fiber.

[Action]

According to the silicon single crystal pulling apparatus as described above, it is possible to prevent the reaction between the SiO gas and the carbon heater by reacting the gas shielding material with the SiO gas, and to extend the life of the carbon heater. it can.

Since the gas shielding material can be made extremely thin by using carbon fiber having a small fiber diameter, heat transfer from the carbon heater to the crucible is not hindered. Moreover, since the thin gas shielding material can be easily made high in purity, it is advantageous for reducing crystal defects in the silicon single crystal.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a pull chamber 2 is provided above the chamber 1. A rotary shaft 3 is inserted from the lower opening of the chamber 1, and a carbon protective body 4 is fixed to the upper end of the rotary shaft 3 to protect an internal quartz glass crucible 5. A cylindrical carbon heater 6 is provided on the outer periphery of the protective body 4 and is connected to the electrodes 7, 7 inserted from the lower portion of the chamber 1. Between the protective body 4 and the carbon heater 6, a thin cylindrical gas shielding material 8 made of a carbon composite material in which carbon fibers are wound is provided. The gas shielding material 8 is manufactured by winding carbon fiber into a cylindrical shape, impregnating it with a phenol resin, curing it by heat treatment, and further firing it, and its thickness is 3 mm. A heat insulating cylinder 9 is provided on the outer circumference of the carbon heater 6.

Using this silicon single crystal pulling apparatus, the silicon single crystal ingot is pulled as follows. That is, after loading the polycrystalline silicon raw material into the crucible 5,
By energizing the carbon heater 6, the silicon raw material in the crucible 5 is melted, and the pulling shaft 11 suspended from above the pull chamber 2 in the silicon melt 10 is seed chuck 12 at the lower end.
The seed crystal 13 attached to the is soaked and the silicon single crystal ingot 14 is pulled by pulling it.

According to such a silicon single crystal pulling apparatus, the gas shielding material 8 made of a carbon composite material in which carbon fibers are wound, the crucible 5 made of quartz glass, and the SiO gas generated by the reaction of the silicon melt 10 are generated. By reacting, the reaction between the SiO gas and the carbon heater 6 can be prevented, and the carbon heater 6 can have a long life. Further, since the gas shielding material 8 is a thin carbon composite, it can be easily purified and has high purity.
It is advantageous for reducing crystal defects in a silicon single crystal. The gas shield 8 can be manufactured at a much lower cost than the carbon heater 6, and even if it is frequently replaced, the cost does not increase, so that a good silicon single crystal can be always pulled up.

〔The invention's effect〕

As described in detail above, according to the silicon single crystal pulling apparatus of the present invention, the carbon heater has a long life, and the crystal defects in the silicon single crystal can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a silicon single crystal pulling apparatus according to an embodiment of the present invention. 1 ... Chamber, 2 ... Pull chamber, 3 ... Rotating shaft, 4 ... Protective body, 5 ... Crucible, 6 ... Carbon heater, 7 ... Electrode, 8 ... Gas shielding material, 9 ... Insulation Tube, 10
…… Silicon melt, 11 …… Pulling shaft, 12 …… Seed chuck, 13 …… Seed crystal, 14 …… Silicon single crystal ingot.

Claims (1)

[Claims] 1. A crucible is rotatably supported in a chamber, a silicon raw material is loaded in the crucible, and the silicon raw material in the crucible is melted by heating with a heater provided on the outer periphery of the crucible to obtain a silicon melt. In a device for pulling a silicon single crystal by immersing a seed crystal that is rotatably suspended from above into a silicon single crystal and pulling it, at least between the crucible and the heater, a thin carbon composite material made of carbon fiber is wound. A silicon single crystal pulling apparatus, which is provided with a cylindrical gas shielding material.