Title :
Impact of time dependent dielectric breakdown and stress-induced leakage current on the reliability of high dielectric constant (Ba,Sr)TiO3 thin-film capacitors for Gbit-scale DRAMs
Author :
Yamamichi, Shintaro ; Yamamichi, Akiko ; Park, Donggun ; King, Tsu-Jae ; Hu, Chenming
Author_Institution :
Function Mater. Res. Labs., NEC Corp., Kanagawa, Japan
fDate :
2/1/1999 12:00:00 AM
Abstract :
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 1/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 SiO2 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 DRAMs 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
Keywords :
DRAM chips; barium compounds; capacitors; leakage currents; permittivity; semiconductor device breakdown; semiconductor device reliability; strontium compounds; (BaSr)TiO3; 1 V; 10 yr; 50 nm; Gbit-scale DRAM; charge loss; dielectric constant; electrical stress; lifetimes; long-term reliability; reliability; stress-induced leakage current; thin-film capacitors; time dependent dielectric breakdown; Binary search trees; Capacitors; Dielectric breakdown; Dielectric thin films; Electrodes; High-K gate dielectrics; Ion beams; Leakage current; Sputtering; Strontium;
Journal_Title :
Electron Devices, IEEE Transactions on
