Performance analysis of S-parameter in N-MOSFET devices after thermal accelerated tests

An analysis of the degradation occurred in RF life-tests of n-type MOSFETs operated from pulsed bench for a radar application in S-band is introduced. The analysis comes accompanied with experimental results, which are used to facilitate optimization of the robustness of Power RF MOSFETs. The recorded S-parameters before and after degradation allow the observation of the corresponding changes, in the transmission and reflection features, as well as in the miller capacitance, and the transconductance. The physical processes responsible for the observed degradation at different stress conditions are studied by means of ATLAS-SILVACO simulations. These are resulted from the interface state generation (traps), which results in a build up of negative charge at Si/SiO2 interface. More interface states are created due to a located maximum impact ionization rate at the gate edge. This analysis is relevant for power RF MOS devices operating in the RF frequency regime. From our experimental results, hot electron induced RF performance degradation should be taken in to consideration in the design of these devices.