Single defect characterization at Si/SiO2 interface
May 21-25, 2017
We carried out a unique and systematic characterization of single Si/SiO2 interface traps using the charge pumping (CP) method, and observed for the first time that two energy levels participate in electron capture/emission processes in a single trap, and the maximum CP current (ICPMAX) from a single trap is not a fixed value of fq, but is in the range of 0≤ICPMAX≤2fq, where f is the gate pulse frequency, and q is the electron charge . This range is expected from the amphoteric nature of Pb0 centers . Although it is widely believed that ICPMAX is given by fqN, where N is the total number of traps contributing to the CP current, we experimentally clarified that this belief is basically incorrect. Based on the systematic characterization of the single traps, we estimated the distribution of the two energy levels of the single traps for the first time . The distribution is reasonably similar to the Pb0 density of states reported previously . We also evaluated the actual number of interface traps in MOSFETs, and showed its variability. Furthermore, we clarified the effect of Coulomb interactions between the traps. By considering the essential nature of the traps (i.e. the presence of two energy levels per trap), factors depending upon the energy levels, and the Coulomb interaction, we were able to correct a widely held misconception and introduce a fundamental refinement of the CP theory. References  T. Tsuchiya and Y. Ono, Jpn. J. Appl. Phys. 54, 04DC01 (2015).  P. M. Lenahan and P. V. Dressendorfer, J. Appl. Phys. 55, 3495 (1984).  T. Tsuchiya and P. M. Lenahan, to be published in Jpn. J. Appl. Phys. 56 (2017).
Toshiaki Tsuchiya, "Single defect characterization at Si/SiO2 interface" in "International Conference on Semiconductor Technology for Ultra-Large Scale Integrated Circuits and Thin Film Transistors VI (ULSIC vs TFT 6)", Yue Kuo (Texas A&M University, USA) Olivier Bonnaud (University of Rennes I, France) Eds, ECI Symposium Series, (2017). http://dc.engconfintl.org/ulsic_tft_6/8