Control of Oxygen Content During the Growth of Single Crystal Silicon by Czochralski Method

doi:10.16553/j.cnki.issn1000-985x.2025.0028

Abstract

Abstract: Single crystal silicon by Czochralski method is the raw material for preparing N-type high-efficiency solar cells， and its oxygen content is directly related to the efficiency and stability of solar cells. Reducing the oxygen dissolution rate by changing the crucible wall temperature distribution during the growth of single crystal silicon is an important method for oxygen reduction. This paper proposes three structural solutions of the heater to change the temperature distribution of the crucible wall and studies their effects on temperature distribution， melt flow， crystallization interface shape and oxygen impurity transport by numerical simulation. The results show that when the long side heater is used， the crucible wall temperature increases first and then decreases， and its crystallization interface deflection and oxygen content are the highest， when the short side heater scheme and the insulation ring scheme are used， the crucible wall temperature presents a monotonically increasing distribution， and the crystallization interface deflection and oxygen content are lower， which are closely related to the temperature distribution， the melt flow， and the solubility of the oxygen impurities in the crucible wall and transport properties in the different schemes. A complete set of oxygen transport analysis methods is further summarised and proposed： the exact source and transport process of oxygen at the crystallization interface are clarified by mapping the transport path of oxygen in the melt. This method provides a theoretical basis for reducing the oxygen content inside single crystal silicon.

Key words: monocrystalline silicon for solar energy; Czochralski method; thermal and mass transport; crystallization interface; oxygen impurity; numerical simulation

CLC Number:

O782⁺.5

LI Jiancheng, ZHONG Zeqi, WANG Junlei, LI Zaoyang, WEN Yong, WANG Lei, LIU Lijun. Control of Oxygen Content During the Growth of Single Crystal Silicon by Czochralski Method[J]. Journal of Synthetic Crystals, 2025, 54(9): 1525-1533.

Figures/Tables 12

Fig.1 Schematic diagram of different design options

Table 1 Physical properties parameters of materials

Material	Density /（kg⋅m^-3）	Heat capacity /（J⋅kg^-1⋅K^-1）	Thermal conductivity /（W⋅m^-1⋅K^-1）	Emissivity	Viscosity /（Pa⋅s）	Latent heat /（J⋅kg^-1）
Silicon melt	2 530	1 000	64	0.3	8×10^-4	1 810 000
Argon	—	520.64	0.01+2.5×10^-5T	—	4.95×10^-6	—
Silicon crystal	2 330	1 059	22	0.7	—	—
Quartz	2 650	1 232	4	0.85	—	—
Graphite	2 300	2 019	90	0.8	—	—
Steel	7 900	477	15	0.6	—	—
Carbon felt	2 101	-317+4.03T-2.4×10^-4T²+5.0×10^-7T³	0.334-1.83×10^-4T+2.15×10^-7T²-1.89×10^-11T³	0.45	—	—
Carbon/Carbon composite materials	1 450	1 800	40	0.8	—	—

Fig.2 Grid-independence verification results

Fig.3 Temperature distribution in the silicon melt （Unit： K）

Fig.4 Crucible wall temperature distribution along the Y-axis

Fig.5 Stream function distribution in the silicon melt （Unit： kg/s）

Fig.6 Radial distribution of deflection at the crystalline interface

Fig.7 Oxygen content distribution （unit： ppma） and oxygen transport path in the melt （arrow line）

Fig.8 Distribution of oxygen dissolution rate along the position of the inner wall surface of the crucible in the symmetry plane

Fig.9 Distribution of turbulent viscosity from the center of the crucible bottom to the center of the crystalline interface

Fig.10 Oxygen content at the crystalline interface

Fig.11 Experimental and calculation results of oxygen content

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