Real-Time Investigation of Conduction Mechanism With Bias Stress in Silica-Based Intermetal Dielectrics

The real-time conduction mechanism during bias stress of three silica-based intermetal dielectrics in Cu damascene structures was investigated. High-frequency capacitance and $I$ –$V$ measurements were intermittently inserted into the process of bias stress to monitor the conduction mechanism change with time. All experiments show that the capacitance is constant, and the $I$– $V$ curve slope decreases with bias stress and converges to half of the initial value. Based on an extended Frenkel–Poole model with compensation effects, we propose that the changes of the acceptor/donor densities in the dielectrics result in the apparent $I$–$V$ curve slope evolution, but the dominant conduction mechanism is always bulk controlled.