Method for preparing and purifying solar grade silicon crystal

A purification method, a solar-grade technology, applied in crystal growth, chemical instruments and methods, self-melting liquid pulling method, etc., can solve problems such as inability to work, and achieve the effects of increasing productivity, reducing oxygen content, and improving quality

Inactive Publication Date: 2011-05-25
GREENERGY CRYSTAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the quartz crucible can withstand the temperature required for crystal growth (1400-1550°C) for a long time, it cannot work for a long time at the high temperature (1550-1850°C) required for purification

Method used

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  • Method for preparing and purifying solar grade silicon crystal
  • Method for preparing and purifying solar grade silicon crystal
  • Method for preparing and purifying solar grade silicon crystal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] see figure 1 , figure 1 It is a typical longitudinal section of a CZ method crystal pulling furnace. The silicon raw material usually used for growing silicon crystals is placed in the inner crucible, that is, the quartz crucible 2 , heated by the heater 3 , and melted into silicon melt 4 under the protection of the insulation material 8 . The quartz crucible 2 is placed in the outer crucible, that is, the graphite crucible 1 . And the graphite crucible is placed on the crucible shaft 7 that can be lifted. In the CZ method, the crystal growth interface is in the middle of the free surface of the silicon melt 4 . By properly designing the heating power and given the appropriate rotation speed of the crucible shaft 7 and the seed crystal 5, the seed crystal 5 is pulled by the seed crystal rope 9 driven by the traction mechanism to induce the silicon melt 4 to grow into a cylindrical Crystal 6.

[0038] During the growth process of the crystal 6 , the main component o...

Embodiment 2

[0043] Adopt the same technological process of embodiment 1. The difference is that the charging process is carried out by a feeder 14 installed on the furnace cover for side feeding. Such as Figure 4 shown. The silicon raw material 15 stored in the feeder 14 is granular, with an equivalent diameter between 0.5 mm and 15 mm.

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Abstract

The invention discloses a method for preparing and purifying a solar grade silicon crystal, which is characterized in that: the purification and the preparation process of the silicon crystal are performed in a crystal lifting furnace (equipment for growing crystal by using a Czochralski method), and a crucible processed by using a graphite material is used as a container to be directly contactedwith a silicon raw material (and melt obtained after the melting of the silicon raw material). The operation process of the method comprises the following steps: (1) heating the graphite crucible to melt the silicon raw material in the graphite crucible, and evaporating impurities under conditions of a silicon melt temperature of 1,500 to 2,000 DEG C and a silicon melt surface vacuum degree of 0 to 500 Pa; (2) controlling the temperature of the silicon melt to be 1,410 to 1,500 DEG C, and preparing the silicon crystal by seed-crystal induction; (3) when the silicon melt in the graphite crucible is to be used up, heating the crucible to 1,600 to 1,850 DEG C, controlling the silicon melt surface vacuum degree to be 0 to 5 Pa, and evaporating the residual impurities in the silicon melt; (4) reducing the temperature and keeping the temperature in the graphite crucible above 800 DEG , and adding the next batch of silicon raw material into the graphite crucible; and (5) repeating the operations in steps (1) to (4) for continuous production. The silicon crystal produced by the method has low oxygen content, improves the photoinduced attenuation property of solar cells made of boron dopedsilicon crystal and realizes continuous production.

Description

technical field [0001] The invention relates to the field of silicon crystal material preparation, in particular to a method for purifying and preparing solar-grade silicon crystal by using the Czochralski method. Background technique [0002] The Czochralski method (CZ method for short) is a widely used method for silicon crystal growth. The crystal puller is a device for crystal growth using the C Z method. Silicon crystals are the most commonly used materials in the semiconductor industry and the solar photovoltaic industry. [0003] The CZ method is usually to place the inner crucible (quartz crucible) in the outer crucible (generally a graphite crucible formed by combining three or four graphite sheets), and the silicon melt is in the inner crucible (quartz crucible). Cylindrical silicon crystals grow under the induction of seed crystals. The above process is completed in the crystal pulling furnace. [0004] For example, Chinese invention patent 200410061587.3 disc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B15/02C30B29/06
Inventor 李乔马远
Owner GREENERGY CRYSTAL TECH
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