Low temperature sputter deposition of Ba0.96Ca0.04Ti0.84Zr0.16O3 thin films on Ni electrodes

Abstract

ABSTRACTThe integration of high-K materials, such as ferroelectrics in the paraelectric state, in integrated circuits presents several challenges. If high-K materials are deposited on-chip after or between Al metalization steps, then these challenges include limits on processing gas composition, deposition temperature and electrode material. Specifically, the atmosphere present during deposition and annealing must be oxygen-free; the deposition and annealing temperatures must not exceed 450°C; and the electrode material must be etchable with chemical techniques. We studied rf magnetron sputtered Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) with Ni electrodes because this system meets all the above requirements. The BCTZ deposition process uses pure Ar as the sputter gas and a substrate temperature of 450°C. Subsequent anneals may be performed in a reducing (forming gas) atmosphere with little effect on either the dielectric constant or leakage current. The Ni electrodes provide a good substrate for BCTZ films and are much easier to integrate than Pt films. Observed values for the relative dielectric constant K, exceeding 100, were not as high as for BCTZ films on Pt electrodes, however these values are sufficient to provide a clear advantage over other, non-ferroelectric materials. Overall, the device characteristics observed prove that the Ni/BCTZ/Ni capacitor is a valuable technology for on-chip capacitor applications.