Atomic Scale Defects Involved in Modern MOS Gate Stack Reliability Problems

Among the most important reliability problems in present day gate stack MOS devices are the negative bias temperature instability (NBTI) which is of particular importance in nitrided gate devices, several instabilities in high-k based devices, among them NBTI and PBTI, and, more generally, hot carrier instabilities.The goal of this presentation will be to introduce attendees to the partial understanding of the atomic scale defects involved in these instabilities which is currently available as a result of recent magnetic resonance and theoretical studies. The presentation will provide a brief introduction to the relevant magnetic resonance techniques as well as a summary of recent relevant magnetic resonance results. It will also include a discussion of some theoretical work, mostly involving density functional theory, which helps to understand both the electronic properties of these defects and to make a direct connection between the magnetic resonance spectra and the defect structure and chemistry. Particularly with respect to NBTI, the presentation will attempt to show how this growing atomic scale understanding may help resolve some apparent contradictions in the recent literature.

Patrick M. Lenahan

P.M. Lenahan earned his B.S. degree from the University of Notre Dame and his Ph.D. from the University of Illinois, Champaign-Urbana. After completing his Ph.D. in 1979, he was a post-doctoral fellow at Princeton University in 1979 and 1980. From 1980 until 1985 he was a member of the technical staff in the Materials Research Directorate of Sandia National Laboratories in Albuquerque, New Mexico. Since 1985 he has been at Penn State University where he is Distinguished Professor of Engineering Science and Mechanics (ESM). ESM is the materials engineering and applied physics department of the Penn State Engineering College; the department also operates an honors degree program for engineering students interested in applied physics. In 2001, he was visiting professor of Electronics and Computer Engineering at Nihon University, Tokyo, Japan (Nihon University is the largest university in Japan). From 2000-2005, he also served as associate editor of the Journal of Electronic Materials. He has authored over 150 publications, approximately 150 conference presentations, and one patent. The publications have been cited approximately 3000 times in the technical and scientific literature. His research has been primarily focused upon the trapping centers in HfO₂, amorphous SiO₂, nitrogen, phosphorous, and boron "doped" SiO₂, silicon nitrides, silicon oxynitrides, Si/SiO₂ interfaces, SiC/SiO₂ interfaces, and silicon grain boundaries with a variety of electrical measurements and electron spin resonance techniques Current interests include NBTI, materials problems in high-k gate dielectrics, and material problems in SiC MOSFETs and BJTs.