三段式冷却工艺对Al-30%Si合金法提纯太阳能级多晶硅的影响

doi:10.16553/j.cnki.issn1000-985x.2025.0033

摘要/Abstract

摘要： 在合金法提纯太阳能级多晶硅过程中，冷却工艺对初晶硅的形核、生长及杂质分凝具有重要影响。本文探讨了Al-30%Si合金在温度900~600 ℃的冷却工艺，对比了单一速率冷却和三段式冷却工艺对初晶硅形貌和杂质含量的影响，旨在优化Al-Si合金法提纯工艺。实验结果表明，在单一速率冷却工艺下，1 ℃/min的冷却速率能显著增大初晶硅晶粒尺寸，降低初晶硅杂质含量，提高杂质去除率。在三段式冷却工艺下，设置的节点温度越靠近高温区域，初晶硅的晶粒尺寸越大，纯度和收率越高；当节点温度为700 ℃时，可以达到最好的提纯效果，此时初晶硅的尺寸相较于优化前略有减小，但杂质含量与优化前相当，而熔炼时间减少了约62.3%，能耗降低了23.3%。该研究为推进Al-Si合金法提纯太阳能级多晶硅的实用化进程提供了方案并积累了实验数据。

关键词: 太阳能级多晶硅; Al-Si合金法; 冷却速率; 节点温度; 工艺优化

Abstract: During solvent refining for solar-grade polysilicon， the cooling process significantly influences the nucleation， crystal growth and impurity segregation of primary silicon. This study investigated the cooling process of Al-30%Si alloy over a temperature range of 900 ℃ to 600 ℃ and compared the effects of single-rate cooling and three-stage cooling processes on the morphology and impurity content of primary silicon. The main objective is to optimize the solvent refining process. The results indicate that， under the single-rate cooling process， a cooling rate of 1 ℃/min can significantly increase the primary silicon grain size， reduce the impurity content in the primary silicon， and improve the impurity removal rate. In contrast， under the three-stage cooling process， a nodal temperature close to the high-temperature region results in a larger grain size and improves the purity and yield of primary silicon. The best purification effect can be achieved when the nodal temperature is set at 700 ℃. In this case， the grain size of primary silicon is slightly lower， while the impurity content is comparable to that before optimization. At the same time， the optimized process achieves a 62.3% reduction in cooling duration and a 23.3% decrease in energy consumption. This study provides a potential strategy to fabricate solar-grade polysilicon using Al-Si solvent refining， which is of significant experiment accumulation.

Key words: solar grade polysilicon; solvent refining in Al-Si alloy; cooling rate; nodal temperature; process optimization

中图分类号:

O782

唐洪, 狄嘉慧, 杨平平, 李少猛, 施玉洁, 何占伟, 赵紫薇, 高忙忙. 三段式冷却工艺对Al-30%Si合金法提纯太阳能级多晶硅的影响[J]. 人工晶体学报, 2025, 54(8): 1454-1462.

TANG Hong, DI Jiahui, YANG Pingping, LI Shaomeng, SHI Yujie, HE Zhanwei, ZHAO Ziwei, GAO Mangmang. Effect of Three-Stage Cooling Process on the Purification of Solar-Grade Polysilicon by Solvent Refining in Al-30%Si Alloy[J]. Journal of Synthetic Crystals, 2025, 54(8): 1454-1462.

图/表 10

表1 初始原料中杂质含量 (mg·kg-1)

Table 1 Impurity content in raw materials

Impurity	Al	Fe	Cu	B	P	Ti	Mg	Ca
Al	—	926	189.86	50.48	28.05	12.92	2.17	48.82
Si	213.00	136.40	81.90	10.51	55.50	4.51	7.07	20.14

表2 合金样品的热处理工艺

Table 2 Heat treatment process of alloy samples

Sample	Stage-1	Stage-2		Stage-3
Sample	Cooling rate/（℃·min^-1）（900~850 ℃）	Cooling rate/（℃·min^-1）（900~600 ℃）	Cooling rate/（℃·min^-1）（850 ℃~T）	Cooling rate/（℃·min^-1）（T~600 ℃）
N₁	—	0.5	—	—
N₂		1
N₃		4
N₄		7
N₅		11
N₆		15
N₇	Rapid cooling to 850 ℃	—	11	1
N₈
N₉
N₁₀

图1 合金形貌。（a）~（e）的冷却速率分别为1、4、7、11、15 ℃/min；（f）~（i）的节点温度分别为625、650、675、700 ℃；（j）1 ℃/min的显微形貌

Fig.1 Alloy morphology. （a） ~ （e） Cooling rates of 1， 4， 7， 11， 15 ℃/min；（f） ~ （i） nodal temperatures of 625， 650， 675 and 700 ℃；（j） micro-morphology at a cooling rate of 1 ℃/min

图2 不同冷却速率下初晶硅的长度和宽度变化曲线（a），以及粒度系数和收率变化曲线（b）

Fig.2 Average length and width curves （a）， FN and yield curves （b） of primary Si at different cooling rates

图3 不同冷却速率下初晶硅杂质含量变化曲线

Fig.3 Curves of impurity content of primary Si at different cooling rates

图4 初晶硅在不同节点温度下的平均长度和宽度变化曲线（a），以及粒径系数和收率变化曲线（b）

Fig.4 Average length and width curves （a），and FN and yield curves （b） of primary Si at different nodal temperatures

图5 不同节点温度杂质含量变化曲线

Fig.5 Curves of impurity content of primary Si at different nodal temperatures

表3 不同冷却速率及工艺优化后初晶硅杂质含量 (mg·kg-1)

Table 3 Impurity content of primary Si under different cooling rates and process optimizations

Sample	Al	Fe	Cu	B	P
N₂	387.9	1	0.71	5.03	10.99
N₃	387.9	4	2.97	6.88	12.87
N₄	468.7	9	7.71	10.13	14.99
N₅	565.8	24	10.89	13.24	16.58
N₆	485.4	90	12.58	17.39	16.89
N₇	386.1	18	4.92	20.30	20.61
N₈	305.9	20	2.86	15.00	19.76
N₉	285.4	14	1.15	10.10	16.22
N₁₀	278.8	4	0.65	6.40	11.38

表4 工艺优化前、后初晶硅不同性质对比

Table 4 Comparison of different properties of primary silicon before and after optimization

Property		1 ℃/min	T=700 ℃
Size of Silicon/mm	Length	1.56	1.26
Size of Silicon/mm	Width	0.55	0.42
FN		0.66	0.65
Yield/%		58.93	58.41
Refining time/min		300	113
Specific energy consumption/kW		5.46	4.19

图6 工艺优化前、后初晶硅晶粒分布

Fig.6 Distribution of primary silicon grains before and after process optimization

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