Time-dependent Dielectric Breakdown in poly-Si CVD Hf02 Gate Stack
نویسندگان
چکیده
In this paper, we present a comprehensive study on long-term reliability of CVD HA), gate stacks with n+-poly-Si gate electrodes. The area dependence and temperature acceleration (Z5-150°C) of TDDB, defect generation rate, and critical defect density of CVD HA), gate stacks are studied. Results show that IO year lifetime of Hm,/ n+-poly-Si gate stack (EOT=14.5.&) is projected for Vg=-Z.OV @25"C and Vg=-l.56V @150°C. This excellent reliability characteristics of H Q gate stack is mainly attributed to the thicker physical thickness of HA),, resulting in significant reduction of tunneling leakage current by a factor of 10'-104 while maintaining comparable Weibull slope factor. In addition, the critical defect density of H Q gate stack is comparable to SiO, with similar physical thickness. However, considering the cumulative impact of temperature acceleration at 15O"C, scaling of an effective gate oxide area of 0.1cm2 and a maximum allowed fraction of failures of O.Ol%, the maximum allowed operating voltage is projected to he only -0.85V for HtO2/poly-Si gate stack with EOT=14.5.&.
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