Study of poly(vinylidene fluoride-trifluoroethylene) as a potential organic high K gate dielectric

Abstract

Spin cast films of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer deposited on bare Si and SiO2 coated Si substrates were vacuum annealed and treated in supercritical carbon dioxide (scCO2) and the dielectric properties of the films before and after treatments were studied using capacitance-voltage and conductance-voltage techniques on thin film capacitor structures. After annealing, the static dielectric constant (K) for P(VDF-TrFE) was found to be more than double that for SiO2 films and to increase with film thickness and annealing time, and reached a maximum of nearly 10 for thick films on SiO2 or Si substrates. Treating annealed P(VDF-TrFE) films in scCO2 initially decreased K and the refractive index n to as-deposited values that increased and stabilized after reannealing. The changes in P(VDF-TrFE) were attributed to densification and ordering. No systematic differences in interface charges and states were found between treated and untreated samples and with various substrates. The leakage current for P(VDF-TrFE) films was found to be higher than that for SiO2.