Comparative Study of Negative Capacitance Ge pFETs With HfZrO<italic>x</italic>Partially and Fully Covering Gate Region

Abstract

We report a comparative study of the negative capacitance (NC) Ge pFETs with HfZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> (HZO) partially and fully covering gate region. Utilizing the layout with HZO partially covering the gate, the internal voltage gain dV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">int</sub> /dV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> > 10 is demonstrated in NC Ge pFETs, which is attributed to the NC effect induced by HZO film. NC transistor demonstrates the hysteresis above 2 V, the sub-60 mV/decade subthreshold swing, and the improved drive current over internal-gated MOSFET. As the area of HZO is increased to fully cover the gate, the increased ferroelectric capacitance C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> produces the much better capacitance matching between C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> and the MOS capacitance of TaN/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ge channel, contributing to the elimination of hysteresis of the NC Ge pFET. NC Ge pFETs with the gate fully covered by HZO achieve a much higher gate capacitance peak and a 36% enhancement in drive current compared to the devices with HZO partially covering gate.