Hf-Based High-k Dielectrics: Process Development, Performance Characterization, and Reliability(Synthesis Lectures on Solid State Materials and Devices)

In this work, the reliability of HfO2 (hafnium oxide) with poly gate and dual metal gate electrode (Ru–Ta alloy, Ru) was investigated. Hard breakdown and soft breakdown, particularly the Weibull slopes, were studied under constant voltage stress. Dynamic stressing has also been used. It was found that the combination of trapping and detrapping contributed to the enhancement of the projected lifetime. The results from the polarity dependence studies showed that the substrate injection exhibited a shorter projected lifetime and worse soft breakdown behavior, compared to the gate injection. The origin of soft breakdown (first breakdown) was studied and the results suggested that the soft breakdown may be due to one layer breakdown in the bilayer structure (HfO2/SiO2: 4 nm/4 nm). Low Weibull slope was in part attributed to the lower barrier height of HfO2 at the interface layer. Interface layer optimization was conducted in terms of mobility, swing, and short channel effect using deep submicron MOSFET devices.

Table of Contents:
Introduction.- Hard- and Soft-Breakdown Characteristics of Ultrathin HfO2 Under Dynamic and Constant Voltage Stress.- Impact of High Temperature Forming Gas and D2 Anneal on Reliability of HfO2 Gate Dielectrics.- Effect of Barrier Height and the Nature of Bilayer Structure of HfO2 with Dual Metal Gate Technology.- Bimodal Defect Generation Rate by Low Barrier Height and its Impact on Reliability Characteristics.

About the Author :
Young-Hee Kim was born in Yang-Pyung, Korea, on January 24, 1972, as a son of Yong-Kae Kim and Jong-Rae Lee. He graduated from Sajic High School, Pusan, Korea, and joined Korean Air Force serving as military policeman. In 1995, he got admission in Kyung-Hee University, Suwon, Korea, and in 1999 he received the B.S. degree in electrical and computer engineering. In August 1999, he started his Masters and Ph.D. study in the department of electrical and computer engineering at The University of Texas at Austin. During the graduate work, he contributed to a number of technical publications (34 coauthored papers, in 14 of which he was the first author). In April 2004, he joined IBM T.J. Watson Research Center as a research staff member and has been carrying out exploratory devices integration.Jack C. Lee received the B.S. and M.S. degrees in electrical engineering from University of California, Los Angeles, in 1980 and 1981, respectively; and the Ph.D. degree in electrical engineering fromUniversity of California, Berkeley, in 1988. He is a Professor of the Electrical and Computer Engineering Department and holds the Cullen Trust For Higher Education Endowed Professorship in Engineering at The University of Texas at Austin. From 1981 to 1984, he was a Member of Technical Staff at the TRW Microelectronics Center, CA, in the High-Speed Bipolar Device Program. He has worked on bipolar circuit design, fabrication, and testing. In 1988, he joined the faculty of The University of Texas at Austin. His current research interests include thin dielectric breakdown and reliability, high-k gate dielectrics and gate electrode, high-k thin films for semiconductor memory applications, electronic materials, and semiconductor device fabrication processes, characterization, and modeling. He has published over 300 journal publications and conference proceedings. He has received several patents. Dr. Lee has been awarded two Best Paper Awards and numerous Teaching/Research Awards. Dr. Lee is a Fellow of IEEE.