Suppression of short channel effects in FinFETs using crystalline ZrO₂ high-K/Al₂O₃ buffer layer gate stack for low power device applications

The electrical characteristics of FinFETs with a crystalline ZrO₂/Al₂O₃ buffer layer gate stack and a crystalline ZrO₂ high-K dielectric single layer, along with different fin widths and gate lengths, are investigated. Compared with the FinFETs with a single layer of crystalline ZrO₂ high-K dielectric, the gate stack comprising the crystalline ZrO₂/Al₂O₃ buffer layer on FinFETs leads to the suppression of short channel effects in terms of a low drain induced barrier lowering, reduced threshold voltage roll-off, and improved subthreshold swing. The ON/OFF current ratio and gate leakage current of FinFETs are also improved by the crystalline ZrO₂/Al₂O₃ buffer layer gate stack. The improvement of electrical characteristics is ascribed to the reduced interface state density and gate leakage as a result of the insertion of an Al₂O₃ buffer layer between ZrO₂ and Si. The results demonstrate that the crystalline ZrO₂/Al₂O₃ buffer layer structure is a promising high-K gate stack for next-generation nanoscale transistors. (paper)