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Zone melting furnace for purifying crystalline silicon and method for purifying crystalline silicon

A technology of crystalline silicon and zone melting furnace, which is applied in the field of silicon preparation technology and equipment, and can solve the problems of small size of the melting zone, many impurities, and single crystal silicon can not meet the purity requirements, etc.

Active Publication Date: 2011-05-04
YINGLI GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, due to the low purity and many impurities in the processing waste of the above-mentioned polysilicon or metallurgical silicon, the single crystal silicon prepared by the Czochralski method or the zone melting method in the prior art cannot meet the purity requirements
Although the zone melting furnace can purify crystalline silicon, the zone melting furnace in the prior art is equipped with a single-turn induction heating coil, so the volume of the formed melting zone is small and the purification effect is limited

Method used

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  • Zone melting furnace for purifying crystalline silicon and method for purifying crystalline silicon
  • Zone melting furnace for purifying crystalline silicon and method for purifying crystalline silicon
  • Zone melting furnace for purifying crystalline silicon and method for purifying crystalline silicon

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preparation example Construction

[0049] Such as image 3 As shown, the process flow chart of the crystalline silicon preparation method provided by the present invention includes:

[0050] S101: a rough selection process for polysilicon raw materials;

[0051] S102: the selection process of magnetic separation or flotation of polysilicon raw materials;

[0052] S103: performing one or more cleaning processes of high-purity water cleaning, pickling, alkali cleaning, cleaning agent cleaning, and ultrasonic cleaning on the polysilicon raw material;

[0053] S104: preparing crystalline silicon by Czochralski method using polysilicon after the cleaning process as a raw material;

[0054] S105: purifying the crystalline silicon rods by vacuum zone melting or hydrogen zone melting;

[0055] After testing the purified crystalline silicon rods, the crystalline silicon can be purified again with a zone melting furnace, or the process can be terminated.

Embodiment 1

[0058] The polysilicon raw material is a polysilicon mixture of wire saw silicon powder and metallurgical silicon ingot;

[0059] The polysilicon mixture is first roughed in a screening machine;

[0060] Select the polysilicon mixture after rough selection in a magnetic separator with a magnetic field strength of 3000 Oersted;

[0061] For the selected polysilicon mixture, use HNO with a mass ratio concentration of 65% 3 , 40% HF, high-purity water, pickling with a mixed solution with a ratio of 3:1:10, and then cleaning with high-purity water;

[0062] The cleaned polysilicon mixture is placed in a crucible in a Czochralski furnace, and a P-type dopant is added. The Czochralski furnace is a CG-3000 Czochralski furnace made in the United States, and then the crucible is heated to 1550° C. After the polysilicon mixture is melted into a molten state, the seed crystal rotation mechanism is started, the seed crystal is lowered, and the seed crystal is welded to the molten body, ...

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Abstract

The invention provides a method for purifying crystalline silicon, comprising a furnace body and an induction heating device which is arranged in the furnace body. The induction heating device comprises a multi-loop induction coil and an induction short circuit ring; the induction short circuit ring comprises an induction short circuit upper ring which is arranged above the multi-loop induction coil and an induction short circuit lower ring which is arranged below the multi-loop induction coil. The multi-loop induction coil can provide larger power so as to increase a melting area of a crystalline silicon rod and obtain the crystalline silicon with high purity. In order to prevent the melting area from dropping off after the melting area is increased, the upper part and lower part of the multi-loop induction coil are provided with two induction short circuit rings so that a part of a leakage magnetic field generated by the multi-loop induction coil generates high-frequency current on the two induction short circuit rings; the high-frequency current respectively generates an induction magnetic field; the tension of the liquid surface of the melting area is increased by action force generated by the induction magnetic field on the induction short circuit ring and a melting area magnetic field of the crystalline silicon rod, thereby preventing the melting area from dropping off.

Description

technical field [0001] The invention relates to a silicon preparation process and device, in particular to a zone melting furnace for purifying crystalline silicon and a method for purifying crystalline silicon. Background technique [0002] High-purity crystalline silicon is the main raw material for the preparation of electronic components and solar cells, and is an important electronic information material. In the prior art, various methods for preparing crystalline silicon have been disclosed, such as the Czochralski method and the zone melting method. [0003] In the Czochralski method, the cleaned polysilicon material is loaded into a quartz crucible of a single crystal furnace, and the polysilicon material is heated to melt in a reasonable thermal field to obtain a melt. Then take a seed crystal and fully weld it with the melt, rotate and lift the seed crystal at a certain speed, under the induction of the seed crystal, control the crystal growth conditions and dopin...

Claims

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Application Information

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IPC IPC(8): C30B13/20
Inventor 高艳杰
Owner YINGLI GRP
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