Failure analysis of hot-electron effect on power RF N-LDMOS transistors

Comparative reliability of hot carrier induced electrical performance degradation is reported in power RF LDMOS transistors after novel methods for accelerated ageing tests with electrical and/or thermal stress. The effects of the reliability degradation mechanisms on the S-parameters and in turn on static and dynamic parameters are pointed out. The analysis of the experimental results is presented and the physical processes responsible for the observed degradation at different stress conditions are studied by means of 2D ATLAS-SILVACO simulations. The RF performance degradation is explained by the transconductance and miller capacitance shifts, resulting from the interface state generation and trapped electrons, with a build up of negative charge at Si/SiO₂ interface.