Reduction of the hydrogen degradation in SrBi2(Ta1-xNbx)(2)O-9 by TiN barrier metal

The use of ferroelectric SrBi2(Ta1-xNbx)(2)O-9 (SBTN) as a mainstream form of nonvolatile memory requires that the degradation of its electrical quali ties that is caused by annealing in a hydrogen atmosphere be reduced. Titan ium nitride (TiN) is a candidate for use as a barrier-metal layer against h ydrogen diffusion. The relationship between the degradation in the qualitie s of SBTN and the quality of the TiN barrier metal has been investigated. T iN when sputtered onto SBTN capacitors creates a good barrier under all spu ttering conditions, and maintains the electrical characteristics of the SBT N through annealing in an atmosphere of H-2. Higher density TiN films provi de more effective protection. The characteristics of the degraded capacitor were investigated in terms of its current-voltage characteristic. Remanent polarization can be recovered from, at least partially, by applying a seri es of bipolar pulses. This rejuvenation of the electrical qualities indicat es that degradation arises from a combination of electrical and structural faults. (C) 2000 American Institute of Physics. [S0021-8979(00)04422-4].