Research on TDDB Physical Mechanism of 28HKMG Mosfet

TDDB (Time dependent dielectric breakdown) issue has been one of the most important reliability issues as the gate dielectrics are changed to HK/IL (HfO 2 /Inter layer SiO 2 ) stack for solving intolerable tunnel leakage problems. In this paper, the physical explanation of TDDB current jump was interpreted through the analysis of trap generation in 28nm HKMG technology. Obviously SILC (Stress induced leakage current) increase on the I-T curve of NMOSFET was found and there existed two current jump phenomenon on NMOS, while SILC effect on PMOSFET was not obvious and only one current jump was observed. The first current jump had a strong correction to shallow traps generated in HK layer during TDDB test and the generation of deep traps result in the second current jump. The deep trap generation was responsible for the permanent damage and the formation of percolation path during the gate oxide degradation. This study provides guidance for TDDB lifetime prediction.