Demands for low-temperature, defect-free, thin silicon epitaxial films have produced significant progress in process modeling and process design. This review paper discusses recent developments with new additional data, with an emphasis on autodoping, defect control, and process-device interactions, as they relate to bipolar applications. A brief discussion of a low-temperature epitaxial process is provided, and calculations are presented to illustrate the advantages of low epitaxial temperatures in terms of profile tolerance and device performance.