Silicon is an excellent material for microelectronics, power electronics and solar cells. For these applications, silicon films and surfaces are convenient. But, its production needs significantly high level process technology and engineering. This book provides the scientific approaches to the actual semiconductor silicon production problems. By separating and classifying the phenomena into chemistry, physics and chemical engineering, really simple understanding is possible. The silicon epitaxial growth and doping are the combination of chemical reactions occurring under the gas flow and temperature fields. The etching and surface contamination are similar. Rapid thermal process and flash lamp annealing are simple physics. For solving the cross linked chemistry and physics, numerical calculations are the useful and powerful tool. From the work considering the classical and advanced chemistry utilizing hydrogen, trichlorosilane, chlorine trifluoride and other gases, scientists and engineers will find a new route shedding future materials process development.