A significant improvement in memory retention of MFIS structure for 1T-type ferroelectric memory by rapid thermal annealing

摘要

A Rapid Thermal Annealing (RTA) process has improved crystallinity of the ferroelectric SrBi{sub}2Ta{sub}2O{sub}9 (SBT) thin film in Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structures. The RTA temperature and time were ranged from 600 to 1000℃ and 30sec to 1min, respectively. XRD patterns showed clear preferential perovskite SBT(115) peaks for the temperature range. The RTA makes larger grain size of around 180nm but much smaller surface roughness of around 5nm due to short annealing time than the furnace annealing. Leakage current density through the MFIS is below 5 × 10{sup}(-8)A/cm{sup}2, and is fairly reduced especially at the low electric field region by decreasing RTA time. Finally, a very long retention time of 6 × 10{sup}5 sec (i.e. 1week) was obtained by the RTA with 1000 ℃ for 30sec. The extrapolated retention time from the data was 3.3 × 10{sup}7sec(i.e.about 1year).