Effects of Chemical Treatments on the Electrical Behaviors of Ferroelectric Poly(vinylidene fluoride-trifluoroethylene) Copolymer for Nonvolatile Memory Device Applications

Abstract

Ensuring the sound ferroelectric behaviors of the ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] after various fabrication processes routinely performed for the device integration is very important for the practical nonvolatile memory applications using P(VDF-TrFE). In this work, the changes in the electrical and physical properties of the P(VDF-TrFE) thin film were investigated, assuming that some chemical treatments are involved in the fabrication processes for P(VDF-TrFE)-based memory devices. Although the treatments in the conventional developer and acids fortunately caused no critical damage to the film, it was found that the use of some resist strippers provides harsh conditions to the film. They caused the degradation in the crystallinity and surface roughness, and hence large increases in coercive field and leakage current were observed. Among the chemicals tested in this work, we proposed 1-methoxy-2-propanol as the best resist stripper. Metal–ferroelectric–metal capacitors and metal–ferroelectric–insulator–semiconductor diodes were also fabricated using the proposed patterning methods, in which no critical degradation in ferroelectric memory effects was observed when the size of capacitor decreased to 30 ×30 µm2. We conclude that these experimental studies can give us a useful solution to realizing memory arrays and related integrated circuits by exploiting P(VDF-TrFE)-based nonvolatile memory devices.