Title :
A highly reliable ferroelectric memory technology with SrBi2 Ta2O9-based material and metal covering cell structure
Author :
Fajii, E. ; Judai, Yuji ; Ito, Toyoji ; Kutsunai, Toshie ; Nagano, Yoshihisa ; Noma, A. ; Nasu, Toru ; Izutsu, Y. ; Mikawa, Takumi ; Yasuoka, H. ; Azuma, M. ; Shimada, Y. ; Sasai, Y. ; Sato, K. ; Otsuki, T.
Author_Institution :
Semicond. Device Res. Center, Matsushita Electron. Corp., Kyoto, Japan
fDate :
6/1/2001 12:00:00 AM
Abstract :
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 SrBi2(Tax ,Nb1-x)2O9 and Bi2 (Ta x,Nb1-x)O6. 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-μ 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°C, which is promising for commercialization of FeRAM and its embedded LSIs
Keywords :
bismuth compounds; cellular arrays; coercive force; ferroelectric storage; integrated circuit reliability; niobium compounds; passivation; strontium compounds; superlattices; tantalum compounds; 0.6 micron; 2.4 V; 70 degC; Bi2 (Tax,Nb1-x)O6; FeRAM; SrBi2(Tax,Nb1-x)2O 9; SrBi2(TaNb)2O9-Bi2 (TaNb)O6; cell capacitors; coercive voltage; double level metal process; ensured retention; ferroelectric material; ferroelectric memory technology; humidity resistance; metal covering cell structure; mixed superlattice crystal; nitride passivation; reliable characteristics; remnant polarization; Capacitors; Ferroelectric films; Ferroelectric materials; Low voltage; Niobium; Nonvolatile memory; Plasma materials processing; Plasma properties; Random access memory; Superlattices;
Journal_Title :
Electron Devices, IEEE Transactions on
