Highly reliable 2.5 nm Ta/sub 2/O/sub 5/ capacitor process technology for 256 Mbit DRAMs

Abstract

A recently developed capacitor process technology can fabricate highly reliable 2.5 nm equivalent thick Ta/sub 2/O/sub 5/ suitable for the cylindrical stacked capacitor of 256 Mb DRAMs. The capacitor process consists of RTN (rapid thermal nitridation) treatment of native SiO/sub 2/ on the cylindrical stacked polysilicon, RTA (rapid thermal annealing) treatment after Ta/sub 2/O/sub 5/ deposition, and the use of a TiN plate electrode formation on the Ta/sub 2/O/sub 5/ film, TDDB (time-dependent dielectric breakdown) tests showed that the 2.5 nm Ta/sub 2/O/sub 5/ capacitor reliability is as high as 10 years and more for 1/2V/sub cc/=1.0 V/100 degrees C operating conditions.<>