Silicon epitaxy using tetrasilane at low temperatures in ultra-high vacuum chemical vapor deposition

• Growth of silicon with tetrasilane via chemical vapor deposition is described.
• Crystalline and amorphous layers are demonstrated.
• Tetrasilane has higher growth rates than lower order silanes.
• Tetrasilane is reactive at temperatures suitable for SiGeSn alloy growth.

The deposition of silicon using tetrasilane as a vapor precursor is described for an ultra-high vacuum chemical vapor deposition tool. The growth rates and morphology of the Si epitaxial layers over a range of temperatures and pressures are presented. The layers were characterized using transmission electron microscopy, x-ray diffraction, spectroscopic ellipsometry, Atomic Force Microscopy, and secondary ion mass spectrometry. Based on this characterization, high quality single crystal silicon epitaxy was observed. Tetrasilane was found to produce higher growth rates relative to lower order silanes, with the ability to deposit crystalline Si at low temperatures (T=400 °C), with significant amorphous growth and reactivity measured as low as 325 °C, indicating the suitability of tetrasilane for low temperature chemical vapor deposition such as for SiGeSn alloys.