Research Of Hot-carrier Degradation Mechanism And Lifetime Model For 600V LDMOS

The Lateral Double Diffused MOS has been widely used in PIC for its high breakdown voltage,low on-resistance and easy compatible with standard CMOS process.As it is always working in the condition of strong electric field,large current and high frequency,the hot carrier reliability problem is very serious.The 600V LDMOS applied in half-bridge driver was faced with very serious reliability risk for its miserable condition.Thus,a detailed research on the degradation mechanism and lifetime model for 600V high voltage LDMOS is urgently needed.The degradation mechanism of 600V high voltage LDMOS applied in half-bridg driver chip was investigated by TCAD and I-V characteristic.It showed that the main degradation mechanism is the interface state formation and hot hole injection into the drift region closing to the end of poly gate under the low V_gs high V_ds.The gate duty-cycle-accelerated stress was adopted to investigate the degradation mechanism under low V_gs high V_ds because of the narrow Safe Operation Area.The main degradation mechanism is the interface formation and hot electron injection into the surface close to drain under high V_gs high V_ds.In addition,the impact on degradation mechanisim of gate pulse duty cycle?shrot edge?frequency and temperature was researched.It was discovered the short pulse edges enhance the decrease of on-resistance(R_on)due to transient hot holes injection into bird's beak.Finally,a hot-carriers degradation model about R_on was given based on the degradation machanisim of600V LDMOS.In a certain range of stress condition,the experiment results verified the accuracy of the proposed model.The conclusions and methodology in this thesis have profound guiding siginificance for the further study on hot carrier reliability of the power device.