Ultra-low-k porous SiCOH dielectric degradation process before breakdown

The degradation of Ultra Low K (ULK) SiCOH dielectrics before breakdown is investigated. For the first time very early stages of degradation before breakdown have been revealed and a model of the basic process of ULK alteration process under electrical stress is proposed. Two different degradation patterns were found. Tip electrode test structures have been specifically designed for this investigation in order to determine the location of degradation and breakdown. A stepwise increased voltage stress test with a meticulously observed current in the fA range was developed and successfully applied.