Polarity Dependence of the Conduction Mechanism in Interlevel Low-k Dielectrics

Leakage currents of interlevel carbon-doped silicon oxide low-k dielectric in copper interconnect structure are investigated at different temperatures. Remarkable bias polarity dependences of conduction current and breakdown voltage are observed. Different conduction mechanisms are found in different electric field ranges. The conduction phenomena were explained by the asymmetry energy band diagram and surface defects. The bias polarity dependence of breakdown voltage indicates that the breakdown mechanism of interlevel low-k dielectric is attributed to carrier current but not electric field as ascribed by E-model.