Reduction of the hydrogen degradation in SrBi2(Ta1−xNbx)2O9 by TiN barrier metal

The use of ferroelectric SrBi2(Ta1−xNbx)2O9 (SBTN) as a mainstream form of nonvolatile memory requires that the degradation of its electrical qualities that is caused by annealing in a hydrogen atmosphere be reduced. Titanium nitride (TiN) is a candidate for use as a barrier-metal layer against hydrogen diffusion. The relationship between the degradation in the qualities of SBTN and the quality of the TiN barrier metal has been investigated. TiN when sputtered onto SBTN capacitors creates a good barrier under all sputtering conditions, and maintains the electrical characteristics of the SBTN through annealing in an atmosphere of H2. Higher density TiN films provide 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 series of bipolar pulses. This rejuvenation of the electrical qualities indicates that degradation arises from a combination of electrical and structural faults.