SILICON EPITAXIAL-GROWTH BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION FROM SIH4/H-2 AT 165-350-DEGREES-C

This paper presents the structural properties and rate expressions of the very low temperature silicon epitaxial growth by plasma enhanced chemical vapor deposition using SiH4/H-2 in a simple vacuum system. The base pressure of the chamber was greater than 3 X 10(-6) Torr. The silicon substrates were ex-situ cleaned by modified spin-etch or HF-dip method prior to wafer loading. An H-2 baking step was carried out prior to epitaxial deposition. Epitaxial films can be grown at 165-350 degrees C. The growth rate is inversely proportional to the hydrogen flow rate as the SiH4 flow rate is fixed. At a fixed H-2/SiH4 flow ratio, the epitaxial growth rate at different process pressures is constant by fixing RF power and substrate temperature. The epitaxial growth rate is linearly proportional to the RF power. The epitaxial growth is mainly controlled by plasma, though an activation energy of about 0.05 eV is measured at 165-300 degrees C, suggesting that more or less surface-reaction effect is involved. Appropriate H-2/SiH4 flow ratio, low RF power, and high substrate temperature are advantageous for high quality epitaxial growth.