Improved performance in Ru∕Ta2O5∕Ru capacitors using forming gas annealing

The effects of forming gas (H2∕N2=3%∕97%) annealing (FGA) on Ru∕Ta2O5∕Ru capacitors are studied. It is confirmed that the effects of FGA highly depend on its timing in the preparation sequence. Though FGA after the patterning of the Ru top electrode results in the increased leakage current of the capacitor, FGA prior to the patterning of the Ru top electrode substantially reduces the leakage current and prevents subsequent thermal process-induced peeling between Ta2O5 and Ru, yielding the capacitor with the best electrical characteristics. Such improvements most likely originate from the formation of a stable bonded interface intrinsically linked to Ta2O5 and Ru, and the phase change from TaOx to Ta2O5.