Hydrogen in Si

The study of atomic hydrogen (H) in crystalline silicon (c-Si) over the past three decades has led to a plethora of interesting phenomena. These are of considerable interest in Si technology due to the inevitable presence of hydrogen in many a processing step using plasmas and ion beams. The interaction of H with c-Si encompasses a variety of topics, including dopant-hydrogen complexes, passivation of bulk and interfacial defects, hydrogen-induced defects, and enhancement of thermal donor (TD) formation. Experimental findings in recent years has attested to its potential in improving gate oxide integrity (with deuterium passivation or high-temperature wafer anneal in H₂), reducing post-implant dopant anneal temperature, and formation of deep junctions using hydrogen-enhanced TD’s. Additional phenomena of significance in device processing are trapping and de-trapping of H by defects, interaction with ion implantation damage, and thermal activation of latent defects in hydrogenated c-Si. In considering the applications, two distinct aspects of H in Si must be considered: (i) where H is present transiently or catalytically in one or more of the processing steps, and (ii) where it is permanently ensconced as a passivant in the finished device. This tutorial will review selected topics from the above list, and will also address hydrogen diffusion in Si, its role in related materials such as Ge, as well as SiO₂ and Si₃N₄, interface phenomena and detection techniques.

S. Ashok

S. Ashok received his B.E. (Hons) degree from the P.S.G. College of Technology, Coimbatore, M.Tech. from the Indian Institute of Technology, Kanpur, and the Ph.D. from the Rensselaer Polytechnic Institute, Troy, NY, USA, all in Electrical Engineering. He joined the faculty of the Department of Engineering Science, the Pennsylvania State University, University Park, PA, in 1978, where he has been a Professor since 1987. His research interests over the years include Schottky barriers, semiconductor surface/interface modification, ion implantation, plasma/ion beam process-induced defects, and photovoltaics. In addition to his long-term work on the use of atomic hydrogen in crystalline Si processing, he has in recent years been involved in semiconductor defect engineering and functional nanocavities in semiconductors. He initiated in 1992 and continues to co-organize a symposium on Semiconductor Defect Engineering, that is held triennially at Materials Research Society Spring meetings. He also serves on many program and organizing committees for international conferences. He has held several sabbatical and summer appointments at universities and research labs around the world and given numerous seminars, review talks and short courses.