Impact of time dependent dielectric breakdown and stress induced leakage current on the reliability of (Ba,Sr)TiO/sub 3/ thin film capacitors for Gbit-scale DRAMs

Time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) are investigated for the reliability of (Ba/sub 0.5/Sr/sub 0.5/)TiO/sub 3/ (BST) thin films. TDDB characteristics show a lifetime longer than 10 years at +1 V for BST films with an SiO/sub 2/ equivalent thickness (t/sub eq/) 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.