Analysis of the degradation mechanism of Pt/SrBi2(Ta/Nb)(2)O-9/Pt capacitors during reductive annealing

Degradation mechanism of the Pt/SrBi2Ta2xO9/Pt and Pt/SrBi2(Ta1-x/Nb-x)(2)O -9/Pt capacitors exposed to the hydrogen attack has been analyzed. The capa citors were fabricated from thin-films consisting of SrBi2Ta2xO9 (1 less th an or equal to x less than or equal to 1.1) and SrBi2(Ta1-x/Nb-x)(2)O-9 (0 less than or equal to x less than or equal to 1) (SBTN) that were formed us ing a sol-gel process. In most capacitors, SBTN thin-films were short-circu ited while annealing in the reducing atmosphere. In contrast, excessive Ta addition could hold back the short circuit. Analysis of the degradation mec hanism were carried our by means of the XRD, TEM and XPS, which revealed th at the most significant alteration took place in the vicinity of crystal gr ain boundaries. It was also found that the film with excessive Ta concentra tion contains the pyrochlore phase in the grain boundary layers. These find ings suggest that the stabilization of grain boundary layers is effective t o realize capacitors resistant to process conditions.