Improved read stability and writability of negative capacitance FinFET SRAM cell for subthreshold operation
Journal
Proceedings - IEEE International Symposium on Circuits and Systems
Journal Volume
2019-May
Date Issued
2019
Author(s)
Zheng Z.-A
Abstract
In this work, we compare the read stability and writability between 6T negative capacitance FinFET (NC-FinFET) SRAM cell and the baseline 6T FinFET SRAM cell in the subthreshold and superthreshold operations. In the subthreshold operation (VDD = 0.4V), NC-FinFET SRAM cell shows better read, write, and hold static noise margins than FinFET SRAM cell. During read operation at VDD = 0.4V, pass-gate (PG) NC-FinFET becomes weaker due to the negative differential resistance (NDR) in the saturation region, which reduces the read disturb voltage of NC-FinFET SRAM cell. During write operation at VDD = 0.4V, PG NC-FinFET with internal voltage amplification becomes stronger in the linear region, and pull-up NC-FinFET with NDR effect becomes weaker in the saturation region, which improves the writability of NC-FinFET SRAM cell. In other words, negative capacitance effect resolves the conflict between read stability and writability for subthreshold operation. For the superthreshold operation (VDD = 1V), NC-FinFET SRAM cell still exhibits 1.73 times larger RSNM (= 183mV) than FinFET SRAM cell, and adequate WSNM (= 198mV). 6T NC-FinFET SRAM cell performs superior stability for both subthreshold and superthreshold operations. ? 2019 IEEE
Subjects
Capacitance; Cells; Cytology; Ferroelectric materials; Negative resistance; Stability; Static random access storage; Threshold elements; Internal voltage; Negative capacitance; Negative capacitance effect; Negative differential resistances; Saturation region; Static noise margin; Subthreshold operation; Write operations; FinFET
Type
conference paper