Rapid Thermal Chemical Vapour Deposition of Epitaxial Si and SiGe

Epitaxy of Si on Si substrates by CVD is an old technique. Developed to improve the performance of bipolar transistors and integrated circuits, it is finding increasing application in CMOS circuits as well. In both cases an epitaxial layer is grown on top of a substrate to contain the active devices. Shrinking device dimensions, laterally as well as vertically, require small transition widths for a change in dopant type or concentration and traditional silicon-epi growth with its high deposition temperatures is becoming more and more incompatible with modern wafer processing. Outdiffusion of dopants and autodoping preclude the use of conventional epi in tailoring dopant profiles in e.g. the base of a bipolar transistor.