Bias-temperature stress of Al on porous low-k dielectrics

Aluminum has been perceived as a stable electrode for the reliability test of dielectric films. In this letter, using energy dispersive X-ray spectroscopy method, Al ions were detected in the dielectric after Al/SiCOH/SiO2/Si capacitor was subjected to bias-temperature stress (BTS). We investigated the impact of the drifted Al to the stability of the dielectrics by studying the leakage current of the capacitor. We showed that the increase of leakage current after BTS falls into the Poole–Frenkel conduction regime, indicating the Al ions act as electronic traps inside SiCOH. Our results question the compatibility between Al and low-k dielectrics.