Effect of the Silicon Nitride Coating of Quartz Crucible on Impurity Distribution in Ingot‐Cast Multicrystalline Silicon

Abstract

Multicrystalline silicon ingots were fabricated via the directional solidification method in a vacuum induction furnace using silicon nitride (Si 3 N 4 ) as quartz crucible coating. The effect of Si 3 N 4 coating on the impurity content, transference, and distribution in Si ingots was investigated. The results can be summarized as follows: The impurities contained in Si ingots, including Fe, Ca, Mn, Cu, P, and B, were found to decrease at varying degrees when the inner surface of the quartz crucible was coated with Si 3 N 4 . A mixed layer composted by Si 3 N 4 and Si was observed on the surface of the Si ingot. This mixed layer provided microdefects for the nucleation of metallic impurities. The Fe and N contents in the Si/Si 3 N 4 mixed layer changed with the same tendency, and FeSi 2 particles formed on the Si/Si 3 N 4 crystalline boundary. Both Fe and Ca precipitated in the SiC particles near the Si ingot/Si 3 N 4 -coating interface. *tanyi@dlut.edu.cn

Impurity control in high performance multicrystalline silicon

“…We reviewed several investigations of contamination levels in these media , summarized in Table . The data from different authors scatter, and a few measurements are available for feedstock.…”

Influence of Crucible Thermal Conductivity on Crystal Growth in an Industrial Directional Solidification Process for Silicon Ingots

“…The crucible is usually made of quartz (SiO 2 ) and internally coated with a high-purity layer such as silicon nitride (Si 3 N 4 ) to prevent the impurity contamination from crucible wall [7]. Some researchers also propose the application of silicon nitride crucible, as it can be reused and the source of oxygen contamination is eliminated [8].…”