LDMOS Transistor High-Frequency Performance Enhancements by Strain

Abstract

The effects of mechanical stress on the dc and high-frequency performances of laterally diffused MOS (LDMOS) transistors with different layout structures were investigated by using the wafer bending method. A 3.1% peak cutoff frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fT</i> ) enhancement is achieved for the multifinger device under 0.051% biaxial tensile strain. For LDMOS with annular layout, the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fT</i> enhancement is increased to 3.7% due to the various channel directions. Our results suggest the strain technology can be adopted in LDMOS for RF applications. The transconductance and gate capacitance were also extracted to clearly demonstrate the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fT</i> variations.