Effects of Drift-Region Design on the Reliability of Integrated High-Voltage LDMOS Transistors

Effects of drift-region design on the hot-carrier reliability of n-channel integrated high-voltage lateral diffused MOS (LDMOS) transistors are investigated. LDMOS devices with various dosages of n-type drain drift (NDD) implant and various drift-region lengths (L_d) are studied. Results show that higher NDD dosage can reduce hot-carrier induced on-resistance (R_on) degradation. The shift in damage location is suggested to be the main cause. In addition, longer L_d can reduce R_on degradation significantly because of less lateral electric field. Our analysis indicates that higher NDD dosage and longer L_d are effective for improving the device lifetime of the LDMOS transistors.