JPH0751474B2 - Silicon single crystal pulling equipment - Google Patents

Description

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

[Prior Art] Silicon single crystals used as substrates for semiconductor devices are mainly manufactured by the Czochralski method (CZ method). This CZ method, in principle, rotatably supports the crucible in the chamber, melts the silicon raw material in the crucible, and immerses the silicon melt in a rotatably suspended seed crystal from above. By pulling up the silicon single crystal ingot. At this time, the silicon raw material in the crucible is heated by a cylindrical carbon heater provided on the outer periphery of the crucible protector (carbon crucible), and is melted while being kept warm by a heat retaining cylinder provided on the outer periphery of the carbon heater. .

By the way, heretofore, as a heat insulating tube, a multi-layered woven cloth of carbon fibers has been used.

[Problems to be solved by the invention]

However, when using a heat-retaining tube in which a woven carbon fiber cloth is wound in a cylindrical shape, small pieces of carbon fiber easily fall off from the surface, so this may float in the chamber and fall into the silicon melt. is there. As a result, there is a problem that the carbon concentration in the pulled silicon single crystal becomes high and crystal defects are increased. The above-mentioned detachment of the small pieces of carbon fiber becomes a problem particularly when they occur on the inner peripheral surface of the heat insulating cylinder.

The present invention has been made to solve the above-mentioned problems, and prevents the small pieces of carbon fiber from falling off the surface of the heat insulating cylinder, preventing an increase in the carbon concentration in the silicon single crystal and reducing the crystal defects. An object of the present invention is to provide a silicon single crystal pulling apparatus capable of performing the above.

[Means for solving problems]

The apparatus for pulling a silicon single crystal of the present invention rotatably supports a crucible in a chamber, loads a silicon raw material into the crucible, and heats the crucible by a heater provided on the outer periphery of the crucible. In a device for pulling a silicon single crystal by melting the silicon raw material in the crucible while keeping the temperature in a heat-retaining cylinder, immersing a seed crystal rotatably suspended from above in the silicon melt and pulling it up, It is characterized in that a cylindrical body made of a carbon composite material in which carbon fibers are wound is closely attached to at least the inner peripheral surface of the heat insulating cylinder.

In the present invention, the carbon composite material that constitutes the cylindrical body that is installed in close contact with the heat insulating cylinder is manufactured by winding carbon fiber into a cylindrical shape, impregnating it with resin, and then firing it.

Note that not only the inner peripheral surface of the heat insulating cylinder but other exposed portions may be covered with the carbon composite material.

[Action]

According to the silicon single crystal pulling apparatus as described above, the cylinder itself, which is installed in close contact with the heat-retaining cylinder, has high mechanical strength even though it is thin and lightweight, and carbon fibers fall off from its surface. There is no such thing. Then, this cylindrical body has a function of preventing a small piece of carbon fiber from falling off from the surface of the heat insulating cylinder. Therefore, it is possible to reduce the carbon concentration in the silicon single crystal and reduce the crystal defects without the small pieces of carbon fiber falling into the silicon melt.

〔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. A heat insulating cylinder 8 is provided on the outer periphery of the carbon heater 6, and a cylindrical body 9 made of a carbon composite material in which carbon fibers are wound is closely attached to the inner peripheral surface thereof.

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

According to such a silicon single crystal pulling apparatus, the heat insulating cylinder 8
The cylindrical body 9 itself, which is installed in close contact with, has high mechanical strength, and carbon fibers do not fall off from the surface thereof. Since the cylindrical body 9 prevents the small pieces of carbon fiber from falling off the surface of the heat insulating cylinder 8, the small pieces of carbon fiber do not drop into the silicon melt. Moreover, this cylindrical body is thin, and the purification treatment is easy and high purity is easily obtained. Therefore, the carbon concentration in the silicon single crystal 14 can be reduced to reduce crystal defects.

〔The invention's effect〕

As described in detail above, according to the silicon single crystal pulling apparatus of the present invention, it is possible to prevent an increase in carbon concentration in the silicon single crystal,
It is possible to provide a silicon single crystal pulling apparatus capable of reducing crystal defects.

[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 ... Insulating cylinder, 9 ... Cylindrical body ,Ten……
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, the crucible is heated by a heater provided on the outer periphery of the crucible, and is kept warm by a heat retaining cylinder provided on the outer periphery of the heater. While melting the silicon raw material in the crucible, in a device for pulling a silicon single crystal by immersing a seed crystal rotatably suspended from above in a silicon melt and pulling it up, at least the inside of the heat retaining tube A silicon single crystal pulling apparatus, wherein a cylindrical body made of a carbon composite material in which carbon fibers are wound is installed in close contact with the peripheral surface.