In Situ Observation of the Interfacial Phase Formation at Si Melt/Silica Glass Interface

In situ observation has been carried out to investigate the interfacial phase of “brownish rings” forming at the Si melt/silica glass interface during Czochralski (CZ) silicon crystal growth. It is found that some small brownish dots appeared at the interface immediately after Si melting, and gradually grew laterally. The growth rate of the interfacial phase increases with increasing temperature, and it only nominally depends on the silica dissolution rate when the dissolution rate is lower than a critical value. The formation mechanism of the brownish rings has been investigated and two formation mechanisms are proposed. (1) Cristobalite forms in the central region of the interfacial phase. (2) The periphery of the interfacial phase is thicker than the central region, and only part of the periphery remains after passing through the triple junction where the dissolution rate is very high.