Structural and sensing characteristics of Pr2O3 sensing membrane for pH-ISFET

In this paper, the physical and sensing properties of physical vapor deposition Pr₂O₃ dielectrics deposited on Si substrate were explored. A 30 nm Pr₂O₃ dielectric was grown on the p-type Si (100) wafer by reactive RF sputtering from a praseodymium target with a argon-to-oxygen (Ar/O₂) flow ratio of 10/4. Post deposition annealing of the samples was carried out using a conventional rapid thermal annealing (RTA) system in O₂ ambient for 30-s at different temperatures. A 300-nm Al was deposited on the backside of Si wafer by thermal evaporator. The sensing area was defined by a photosensitive epoxy. The pH sensitivities of Pr₂O₃ sensing films were all extracted by capacitance-voltage (C-V) curves of EIS structures. C-V curves for various pH buffer solutions of Merck Inc. were measured through Ag/AgCl reference electrode by Hewlet-Packard 4284A.