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Method for reducing bottom oxygen content of polycrystalline silicon ingot casting

A polysilicon ingot furnace and polysilicon technology, applied in the direction of polycrystalline material growth, chemical instruments and methods, crystal growth, etc., can solve the problem that the quality of the ingot product is greatly affected, the ingot product has high oxygen content, and is easy to form hard Points and other problems, to achieve the effect of easy control of the coating process, good heating effect, and easy control

Inactive Publication Date: 2016-11-09
XIAN HUAJING ELECTRONICS TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, in the solar polysilicon ingot casting process, the crucible spraying process used is Si 3 N 4 material as a spray material, but due to Si 3 N 4 The poor thermal conductivity and instability of the material itself make it easy to form hard spots during the ingot casting process, and the oxygen content at the bottom of the finished ingot is relatively high, which has a great impact on the quality of the product
In addition, Si 3 N 4 Although the material can effectively isolate the reaction between the silicon liquid and the crucible, the Si 3 N 4 After reacting with silicon liquid, a red zone is formed, which is easy to introduce impurity Si 3 N 4 And form a hard point, which has a great influence on the quality of the finished ingot

Method used

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  • Method for reducing bottom oxygen content of polycrystalline silicon ingot casting
  • Method for reducing bottom oxygen content of polycrystalline silicon ingot casting
  • Method for reducing bottom oxygen content of polycrystalline silicon ingot casting

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] like figure 1 A method for reducing the oxygen content at the bottom of the polysilicon ingot is shown, comprising the following steps:

[0048] Step 1, preparation of the coating on the bottom of the crucible, the process is as follows:

[0049] Step 101, preparation of coating spraying liquid: uniformly mixing organic binder, deionized water and boron nitride at a mass ratio of 1:2.2:1 to obtain coating spraying liquid;

[0050] Step 102, spraying: use spraying equipment to evenly spray the coating spray liquid described in step 101 on the inner bottom surface of the crucible 1, and the inner bottom surface of the crucible 1 is 1 m 2 The mass of boron nitride contained in the coating spray liquid sprayed in the area is 100g-150g;

[0051] The crucible 1 is a quartz crucible for a polysilicon ingot furnace;

[0052] Step 103, drying: place the crucible 1 in step 102 horizontally in the drying equipment, and use the drying equipment to spray the coating sprayed on th...

Embodiment 2

[0080] In this embodiment, the difference from Embodiment 1 is that when polysilicon ingots are cast in step 2, the process is as follows:

[0081] Step 201, charging: loading silicon material into the crucible 1 with bottom coating 2 in step 1;

[0082] Step 202, preheating: using the polysilicon ingot furnace to preheat the silicon material in the crucible 1, and gradually raising the heating temperature of the polysilicon ingot furnace to T1; the preheating time is 5 hours, where T1 =1200°C;

[0083] Step 203, melting: using the polysilicon ingot furnace to melt the silicon material loaded in the crucible 1, the melting temperature is T1-T2; where T2=1550°C;

[0084] After the silicon material in the crucible 1 is completely melted, the heating temperature of the polysilicon ingot furnace is controlled at T2, and then the heating power of the polysilicon ingot furnace starts to decrease, and the heating power of the polysilicon ingot furnace stops decreasing And after the...

Embodiment 3

[0133] In this example, the difference from Example 2 is: in step 202, the preheating time is 4 hours and T1=1285°C, P1=100kW; in step 203, T2=1560°C, t=20min, P2=45kW, Q1=650mbar ; In the first step, the holding time is 0.4h; in the second step to the fifth step, T4=1325°C, and the heating time is 0.4h; in the sixth step, T5=1460°C, and the heating time is 3.5h; in the seventh step, T6 =1510°C and the heating time is 3.5h; the heating time in the 8th step is 3.5h; the holding time in the 9th step is 3.5h; the holding time in the 10th step is 4h.

[0134] In the present embodiment, when heating up and pressurizing in the 2nd step to the 5th step, the process is as follows:

[0135] The second step, the first step of raising: raising the heating temperature of the polysilicon ingot furnace 9 from 1285° C. to 1290° C., and the heating time is 5 minutes.

[0136]The third step, the second step of raising: raising the heating temperature of the polycrystalline silicon ingot furna...

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Abstract

The invention discloses a method for reducing bottom oxygen content of polycrystalline silicon ingot casting. The method comprises the following steps: 1, preparation of a crucible bottom coating, wherein a preparation process comprises: 101, preparing a coating spraying solution: uniformly mixing an organic grouting agent, de-ionized water and boron nitride at the mass ratio of 1 to (2 to 2.5) to (0.8 to 1.2) to obtain the coating spraying solution; 102, spraying: uniformly spraying the coating spraying solution on an inner bottom surface of a crucible by adopting spraying equipment and drying to obtain the bottom coating; 103, drying: drying the coating spraying solution sprayed on the inner bottom surface of the crucible by adopting drying equipment to obtain the bottom coating; 2, polycrystalline silicon ingot casting: carrying out the polycrystalline silicon ingot casting by utilizing the crucible with the bottom coating. The method disclosed by the invention is simple in steps, reasonable in design, simple and convenient to realize and good in use effect; one layer of the bottom coating taking the boron nitride as a main raw material covers the bottom of the crucible, so that the bottom oxygen content of the crucible can be effectively reduced, hard inclusion of an ingot casting finished product can be effectively reduced and the quality of the ingot casting finished product is improved.

Description

technical field [0001] The invention belongs to the technical field of polycrystalline silicon ingots, and in particular relates to a method for reducing the oxygen content at the bottom of polycrystalline silicon ingots. Background technique [0002] Photovoltaic power generation is one of the most important clean energy sources with great development potential. The key factors restricting the development of photovoltaic industry are low photoelectric conversion efficiency on the one hand and high cost on the other hand. Photovoltaic silicon wafers are the basic material for the production of solar cells and components. The purity of polysilicon used to produce photovoltaic silicon wafers must be above 6N (that is, the total content of non-silicon impurities is below 1ppm), otherwise the performance of photovoltaic cells will be greatly negative influences. In recent years, the production technology of polycrystalline silicon wafers has made remarkable progress, and the p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B28/06C30B29/06B05D1/02B05D3/02
CPCC30B28/06B05D1/02B05D3/0254B05D2203/30C30B29/06
Inventor 虢虎平刘波波吴增伟贺鹏
Owner XIAN HUAJING ELECTRONICS TECH
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