A highly reliable ferroelectric memory technology with SrBi/sub 2/Ta/sub 2/O/sub 9/-based material and metal covering cell structure

A multilevel metal process-based highly reliable ferroelectric memory (FeRAM) has been developed. Highly reliable characteristics have been attained by two techniques. One is a newly developed ferroelectric material with mixed superlattice crystal of SrBi/sub 2/(Ta/sub x/,Nb/sub 1-x/)/sub 2/O/sub 9/ and Bi/sub 2/ (Ta/sub x/,Nb/sub 1-x/)O/sub 6/. Which provides an elevated remnant polarization while keeping a low coercive voltage. The other is a metal covering memory cell structure which makes the use of plasma silicon nitride (p-SiN) passivation possible without reduction of the ferroelectric thin film by a hydrogen plasma during p-SiN deposition, which results in no B degradation of the characteristics of cell capacitors. The FeRAM cell capacitors with the above newly developed ferroelectric material and metal covering structure have been fabricated by using a 0.6-/spl mu/ double level metal process. The fabricated cell capacitors show highly reliable characteristics such as the ensured retention of data written at a low voltage of 2.4 V and humidity resistance for 10 y under a high temperature of 70/spl deg/C, which is promising for commercialization of FeRAM and its embedded LSIs.