Polycrystalline silicon ingot, preparation method thereof, and polycrystalline silicon wafer

• US 9,562,304 B2
• Filed: 03/28/2013
• Issued: 02/07/2017
• Est. Priority Date: 04/01/2012
• Status: Expired due to Fees

• Current Assignee: Jiang Xi Sai LDK Solar High-Tech Co., Ltd.
• Original Assignee: Jiang Xi Sai LDK Solar High-Tech Co., Ltd.
• Inventors: Hu, Dongli, He, Liang, Wan, Yuepeng, Lei, Qi, Chen, Hongrong, Zhang, Tao, Zhong, Dejing
• Primary Examiner(s): Zimmer, Anthony J
• Application Number:
  US14/389,452
• Publication Number:
  US 20150056123A1
• Time in Patent Office: 1,412 Days
• US Class Current: 1/1
• CPC Class Codes: C30B 11/00 Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method C30B13/00, C30B15/00, C30B17/00, C30B19/00 take precedence; under a protective fluid C30B27/00
• CPC Class Codes: C30B 11/003 Heating or cooling of the melt or the crystallised material
• CPC Class Codes: C30B 11/006 Controlling or regulating
• CPC Class Codes: C30B 11/02 without using solvents C30B11/06 takes precedence
• CPC Class Codes: C30B 11/04 adding crystallising materials or reactants forming it in situ to the melt
• CPC Class Codes: C30B 11/14 characterised by the seed, e.g. its crystallographic orientation
• CPC Class Codes: C30B 28/06 by normal freezing or freezing under temperature gradient
• CPC Class Codes: C30B 29/06 Silicon
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/16 including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/03682 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/182 Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
• CPC Class Codes: Y02E 10/546 Polycrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Disclosed is a preparation method of a polycrystalline silicon ingot. The preparation method comprises: providing a silicon nucleation layer at the bottom of a crucible, and filling a silicon material above the silicon nucleation layer; heating the silicon material to melt same, adjusting the thermal field inside the crucible to make the melted silicon material to start crystallization on the basis of the silicon nucleation layer; and when the crystallization is finished, performing annealing and cooling to obtain a polycrystalline silicon ingot. By adopting the preparation method, a desirable initial nucleus can be obtained for a polycrystalline silicon ingot, so as to reduce dislocation multiplication during the growth of the polycrystalline silicon ingot. Further disclosed are a polycrystalline silicon ingot obtained through the preparation method and a polycrystalline silicon wafer made using the polycrystalline silicon ingot as a raw material.

Claims

1. A method for preparing polycrystalline silicon ingot, comprising:

(1) laying a microcrystalline nucleating source layer at the bottom of the crucible, the microcrystalline nucleating source layer is microcrystalline silicon and/or amorphous silicon;

thickness of the microcrystalline nucleating source layer is a first height;

the microcrystalline nucleating source layer is the nucleating source of silicon material layer;

(2) feeding silicon onto the microcrystalline nucleating source layer, melting the silicon to form molten silicon by heating, wherein a solid-liquid interface formed after the silicon is melted completely reaches the surface of the microcrystalline nucleating source layer or is deep into the microcrystalline nucleating source layer and the height to the bottom of the crucible is greater than or equal to 1 mm, regulating a thermal field to achieve supercooled state to grow crystals from the molten silicon on the base of the microcrystalline nucleating source layer;

(3) after the crystallization of molten silicon is completely finished, performing annealing and cooling to obtain polycrystalline silicon ingot.

2. The method for preparing polycrystalline silicon ingot according to claim 1, when solid-liquid interface formed after the silicon is melted completely is deep into the microcrystalline nucleating source layer and the height to the bottom of the crucible is greater than or equal to 5 mm, regulating the thermal field to achieve supercooled state to grow crystals from the molten silicon on the base of the microcrystalline nucleating source layer.

3. The method for preparing polycrystalline silicon ingot according to claim 1, wherein the first height is in a range of 1-150 mm.