Non-Prestonian Behavior Study and Development of Advanced Oxide Polish Slurry for Stop-In-Film Applications

Abstract

Non-Prestonian behavior is defined as a non-linear correlation between the removal rate and the polishing pressure. It is believed to be related to dishing, erosion and self-stopping behavior that is observed on pattern wafers. Nojo et al. has reported that “self-stopping polishing” can be achieved when the non-Prestonian behavior was observed. Significant research effort has been made in this field, following this initial report. For example, the effect of chemical additive concentrations and molecule weight of additives, along with abrasive concentration and size on non-Prestonian behavior have been studied. Primarily, blanket wafer performance data has been presented in the majority of published work. Although some researchers had conducted modelling to calculate the effect of non-Prestonian behavior on pattern performance, a comparison between pattern and blanket wafer performance in not available. This is needed to enable a more clear understanding of non-Prestonian behavior. In this presentation, Prestonian behavior was modulated by adjusting chemical concentrations and / or formulation pH. Pattern performance, including oxide removal rate and step height reduction rate, were collected and evaluated. It was determined that non-Prestonian behavior does not necessarily lead to good pattern performance. From the learnings of this systematic study, a high-performance, oxide-polish slurry for stop-in-film applications was successfully developed.