Performance drifts of N-MOSFETs under pulsed RF life test

This paper presents a reliability life test bench specifically dedicated to high RF power devices for lifetime tests under pulse conditions. The monitoring of RF power, drain, gate voltages and currents under various pulses and temperatures conditions are investigated. A 3000 h pulsed RF life test has been conducted on a dedicated RF S-band test bench in operating modes. The investigation findings of degradations of critical electrical parameters derived from the data treatment after this accelerated ageing tests are presented. Numerous duty cycles are applied in order to stress Lateral-Diffused Metal-Oxide-Semiconductor (LDMOS). It shows with tracking of a set of RF parameters (Pout, Gain and Drain Efficiency: DE) that the dominant degradation phenomenon is linked to hot carriers generated interface states (traps) and trapped electrons. Which results in a build up of negative charge at Si/SiO2 interface and the main cause appear with incidence on RF power device. Physical simulation software (Silvaco-Atlas) has been used to locate and confirm these phenomena.