Impact of time dependent dielectric breakdown and stress induced leakage current on the reliability of (Ba,Sr)TiO3 thin film capacitors for Gbit-scale DRAMs

Time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) are investigated for the reliability of (Ba0.5Sr0.5)TiO3 (BST) thin films. TDDB characteristics show a lifetime longer than 10 years at +1V for BST films with an SiO2 equivalent thickness (teq) of 0.70 nm. The breakdown is strongly affected by leakage current properties, and does not depend on the dielectric constant. SILC is studied at +1V in time domain after stress charge injection into BST films. 10 year operation for Gbit-scale DRAMs can be guaranteed in spite of the charge loss caused by SILC