Design, fabrication, and analysis of enhanced mobility silicon germanium transistors

Silicon-germanium is a very compatible material with silicon. It can improve the performance of the current silicon-based semiconductor devices. A temperature measurement system based on infrared light absorption by the silicon wafer was constructed for a Rapid Thermal Processing Chemical Vapor Deposition system. The details of the temperature measurement system are described here. This system can provide very sensitive temperature measurement for the important 650 – 850 °C range. A relaxed silicon-germanium structure with very smooth surface was grown successfully using this temperature measurement system. A new way to improve the growth of the structure was found. It was also found what the optimum temperature condition for the growth of the structure should be. MOSFETs based on silicon-germanium were fabricated and measured. PMOSFET with a buried channel of silicon-germanium-carbon was fabricated vii and measured to quantify its characteristics. A new method to calculate hole mobility of a buried channel of silicon-germanium-carbon has been proposed. This method requires the low temperature measurement of the device and computer simulation of the device. When this method was used for our PMOSFET, the result successfully revealed hole mobility characteristics of silicon-germanium-carbon. This study also could quantify these characteristics using the well-known Lombardi mobility model for silicon. This device study demonstrated enhanced hole mobility for a certain range of a germanium in silicon-germanium-carbon.