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.