New Strained LDMOS With Ultralow ON-Resistance by Si1−yCySource Stressor for About 20 V Low-Voltage Applications

Abstract

A novel low ON-resistance strained lateral double-diffused MOSFET (LDMOS) with silicon-carbon (Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</sub> C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> ) source is proposed for low-voltage applications. Due to the lattice mismatch between silicon and Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</sub> C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> , the source-side Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</sub> C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> stressor introduces the lateral tensile stress and vertical compressive stress along the conduction path to enhance the electron mobility in the channel and drift regions and hence improves the ON-state characteristics. As the stress relaxation in the drift region, the strain-induced breakdown voltage (BV) deterioration can be neglected. The simulation results show that the ON-resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> ) of the proposed device is decreased by 19.2% compared with the conventional LDMOS without strain at a gate overdrive voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> -V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) of 1 V. At the same time, the novel LDMOS achieves 47% and 28.8% increment in the drive current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D,sat</sub> ) and peak transconductance (G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m,peak</sub> ), respectively, while keeping a nearly identical BV of 23.08 V. Besides, the improved cutoff frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) and transconductance-to-current-ratio (G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> ) are also obtained in the novel LDMOS.