Process stability of SiGe heterostructures for BiCMOS applications

Abstract
Silicon-germanium heterostructures have introduced the opportunity to engineer the energy gap of Si, leading to a wide range of microelectronics device applications. During epitaxial layer growth as well as technology process steps, structural defects may appear or be enhanced affecting device performances. We have studied the as grown potential defects before and after thermal treatments and ion implantation used in a BiCMOS technology under development. Preliminary results show a clear correlation between structural defects such as misfit dislocations in the commensurate layers and the junction leakage current in the final Heterojunction Bipolar Transistor (HBT). These results allow us to optimize the growth parameters in order to have a wider process window and a better process yield. Keywords : CVD, Epitaxy, SiGe heterosmictures, BiCMOS process, HBT