Exploring the Performance of 3-D Nanosheet FET in Inversion and Junctionless Modes: Device and Circuit-Level Analysis and Comparison
V. Bharath Sreenivasulu, Aruna Kumari Neelam, Sekhar Reddy Kola, Jawar Singh, Yiming Li
Abstract
In this article, the performance of 3-D nanosheet FET (NS-FET) in inversion (INV) and junctionless (JL) modes is demonstrated and compared at both device and circuit levels. In JL mode, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> rises with an increase in temperature compared to the downfall trend in INV mode. In addition, compared to JL mode, the INV mode exhibits a better negative temperature coefficient of threshold voltage (d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> /dT). Further, the mixed mode circuit simulations are carried out using the Cadence Virtuoso platform through the Verilog-A model. From the analysis, it is observed that an increase of 20% gain in INV mode compared to JL mode for a common source (CS) amplifier. JL mode NS-FETs achieve higher CMOS inverter switching current ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> ) and lower energy-delay products (EDP) as temperature rises. A three-stage ring oscillator (RO) is designed, and the oscillation frequencies ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSC</sub> ) of 43.39 GHz and 38.8 GHz are obtained with INV and JL modes. Although JL NSFET offers less intrinsic capacitances, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSC</sub> is high for INV mode due to higher <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> . Furthermore, reducing supply voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> ), the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSC</sub> falls by 67% with INV and 62.6% with JL modes. These results will give a better understanding of this emerging NS-FET at both device and circuit levels at advanced technology nodes.