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 (π-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 π-coefficients, π 〈100〉 =−20×10 −11 Pa −1 and π 〈110〉 =50×10 −11 Pa −1 , respectively. It was also shown that the effect of strain on the breakdown voltage in these devices is insignificant (∼80mV for 60MPa).