A study of Si/SiGe selective epitaxial growth by experimental design approach

Using a half-fraction factorial design with Resolution V, the sensitivity of low-temperature (740–760 °C) Si/SiGe selective epitaxial growth to changes in the factors and their second-order interactions were quantified. Five factors (SiH2Cl2, GeH4, HCl, B2H6 and temperature) at two levels were studied. The responses are Si growth rate, SiGe growth rate and Ge concentration, which were determined using high-resolution X-ray diffraction. Unlike other researchers in this field who usually explore the growth kinetics of Si/SiGe over wide ranges of parameters, the factor levels in this work were kept tight to better reflect typical process variations in a real manufacturing environment. The effects of the main factors and their second-order interactions on the responses were calculated using JMP Statistical Discovery Software. Pareto plots were used to rank these effects. Prediction traces and interaction plots were also used to provide additional information on the importance of the main factors and their interaction effects, respectively. Process engineers should pay most attention to temperature control to ensure stable Si/SiGe growth rates and to GeH4 gas flow control for consistent Ge concentration.