Effect of Post Plasma Oxidation on Ge Gate Stacks Interface Formation

Abstract

This work investigates the application of slot plane antenna plasma oxidation (SPAO) during dielectric depositionto processTiN/AlO/ZrO2/Ge MOS capacitors. The impact of SPAO exposure on effective oxide thickness (EOT), leakage current, interface state density (D it), C-V hysteresis, oxide breakdown characteristics have been studied. Considerable degradation of electrical properties has been observed with SPAO being performed before AlO/ZrO2 gate stack deposition. When SPAO is performed in between AlO/ZrO2deposition, moderate increase in EOT and significant decrease in D it was observed, which can be attributed to the formation of a thicker GeOX layer. On the other hand, when SPAO is performed after the deposition of both the high-k layers, higher D it was observed suggesting that a thinner GeOX layer formation. Time zero dielectric breakdown (TZDB) characteristics indicate that plasma exposure after and in between AlO/ZrO2 deposition enhances the dielectric quality by film densification due to plasma exposure. It was demonstrated that improved dielectric and interface quality can be achieved when ALD-AlO/ZrO2 gate stacks were exposed to SPAO.