Effect of mechanical stress on LDMOSFETs: Dependence on orientation and gate bias

The effect of mechanical stress on the on-resistance and breakdown voltage of <100> and <110> channel n- and p-type lateral power MOSFETs is investigated. Linear drain current enhancement under uniaxial mechanical stress was measured. The experimentally extracted piezoresistance coefficients (pi-coefficient) were found to be in good agreement with the values predicted by the model. The largest strain induced mobility enhancement in lateral power devices occurs for the strained <100> channel N-laterally diffused MOSFET and <110> channel drain extended PMOSFET. This was determined from the measurement of high gate bias pi-coefficients, pi_<100>=-20times10^-11 Pa^-1 and pi_<110>=50times10^-11 Pa^-1, respectively. It was also shown that the effect of strain on the breakdown voltage in these devices is insignificant (~80 mV for 60 MPa).