Time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) are investigated for the reliability of (Ba, Sr)TiO3 (BST) thin films. Both time to breakdown (TBD) versus electric field (E) and TBD versus l/E plots show universal straight lines, independent of the film thickness, and predict lifetimes longer than 10 y at +1 V for 50 nm BST films with an SiU2 equivalent thickness of 0.70 nm. SILC is observed at +1 V after electrical stress of BST films; nevertheless, 10 y reliable operation for Gbit-scale DRAM's is predicted in spite of charge loss by SILC. Lower (Ba + Sr)/Ti ratio is found to be strongly beneficial for low leakage, low SILC, long TBD, and therefore greater long-term reliability. This suggests a worthwhile tradeoff against the dielectric constant, which peaks at a (Ba + Sr)/Ti ratio of 1.05.
- (Ba, Sr)TiO
- High dielectric constant