Investigation on Annealing and Etching Effects for Pt/Bi3.15Nd0.85Ti3O12/Pt Ferroelectric Capacitors

Abstract

The annealing and etching effects of Pt/Bi3.15Nd0.85Ti3O12/Pt ferroelectric capacitors were studied. Bi3.15Nd0.85Ti3O12 (BNdT) thin films were obtained by a sol–gel method. At an annealing temperature of 650 °C, BNdT films crystallized well in nitrogen atmosphere, but remained amorphous in oxygen atmosphere. For capacitor fabrication, Pt top layers were etched by ion beam etch (IBE) to form top electrodes, and the BNdT ferroelectric films were etched by reactive ion etch (RIE) utilizing two different gases: SF6 and HC2ClF4. Degradation was discovered after top electrode etching, and could be partly recovered by rapid thermal annealing in oxygen at 650 °C. RIE etching damage was not prominent in both groups, though SF6 etched group was a bit superior to HC2ClF4 group. Nevertheless, HC2ClF4 group became noticeable inferior to SF6 group after a furnace annealing in nitrogen at 650 °C for 40 min. This was attributed to the influence of hydrogen, which was induced by RIE process in HC2ClF4 group. Instead, when oxygen was employed as the atmosphere of furnace annealing, both groups finally possessed similar ferroelectric properties, namely the RIE etching damage in HC2ClF4 group had been recovered.