Structure Optimization And Anylysis Of Hot-carrier Effect For RF LDMOS Device

High-voltage radio frequency power LDMOS device is widely used in wireless communication and radar system. It is subjected to hot-carrier effect and temperature effect due to its high-voltage and high-power working condition. On one hand, hot-carrier effect and temperature effect affect the character of the device out of working condition. On the other hand, long-playing hot-carrier injection and temperature effect degrade device’s life, even cause device breakdown. In order to improve reliability of the device, it’s importance to study the effects of the device.The device in this thesis is metal trench sinker RF LDMOS device, which uses metal instead of heavily doped P+ to save the effective area of the device. Its double source field plates not only decrease the feedback capacitance between gate and drain, but optimize the electric field in the channel and drift region which weaken the hot-carrier injection.Aging-test and computer simulation by Silvaco TCAD are used to study the hot-carrier effect on DC character(including threshold voltage, transconductance, saturation current and on-state resistance). Optimization of device structure(length of field plate, drift region and poly gate) and process(dose of implantation in drift region) is done to decrease hot-carrier injection in the channel and drift region, which enhances device reliability.Thermal stress test and computer simulation are done to study the temperature effect. There is serious self-heating effect owning to power dissipation while the device is working at high-power condition. In this thesis, experiment is done in various temperatures to study the effect of temperature on device character; optimization is also done to improve the temperature effect on device.