Characterization of HfO2 dielectric films with low energy SIMS

This work investigated optimal conditions for SIMS analyses of HfO2/Si and TiN/HfO2 interfaces as well as nitrogen distributions in HfO2 films. It was demonstrated that SIMS profiling from the back side of wafers was desirable to eliminate artificial tails of Hf+ and Ti+ as often observed during profiling from the front side. The data suggested good thermal stability of the interfaces in this study. Meanwhile, accurate characterization of shallow nitrogen in HfO2 was achieved by using a low energy O2 + beam at oblique incidence and detecting 30NO secondary ions. It was revealed that nitrogen was mainly incorporated into the top part of the HfO2 films through plasma nitridation and could be released rapidly during post nitridation anneal at a high temperature.