A Metal-Insulator-Semiconductor (MIS) Device Using a Ferroelectric Polymer Thin Film in the Gate Insulator

Abstract

A nonvolatile MIS memory device using a ferroelectric polymer thin film in the gate insulator is proposed. In the gate electrode of the device, a ferroelectric polymer thin film is sandwiched between two insulator films to prevent carrier injection into the polymer thin film. Al-SiO2-P (VDF/TrFE)-SiO2-Si capacitors were fabricated to evaluate the basic characteristics of the device by C-V measurement, and ferroelectric polarization reversal was observed in the capacitors. Based on the C-V measurements, MIS transistors were fabricated using a process which virtually self-aligns the effective gate area to the source/drain. It was shown that the MIS transistor could be electrically programmed and erased. The on/off ratio of the transistor was greater than 106.

Ferroelectric nanomesa formation from polymer Langmuir–Blodgett films

“…6,7 The VDF copolymers typically crystallize from solution to form a jumble of crystalline lamellae with highly folded chains and dimensions of order 25 nm along the chains and 1 -10 m perpendicular to the chains. 1 Annealing and drawing can improve crystallinity and microstructure, even to the point of producing highly oriented crystals with predominately straight chains.…”

Reactive ion etching of poly(vinylidene fluoride-trifluoroethylene) copolymer for flexible piezoelectric devices

“…An electrospun method was employed to fabricate PVDF nanofibers for sensors and energy harvesters [5,13]. For fabrication of nonvolatile memory devices, low-temperature fabrication approaches including Langmuir-Blodgett deposition [14,15] and spin coating methods [16] were developed. The spin coated P(VDF-TrFE) films, intrinsically tending to form phase I crystal with a high remanent polarization, are widely used in recent researches [6,17,18].…”

Nonvolatile memory element based on a ferroelectric polymer Langmuir–Blodgett film

“…5 In 1986, Yamauchi reported the operation of two promising devices that incorporated 73% VDF copolymer P͑VDF-TrFE 73:27͒ films, which were formed by solvent spinning on a silicon substrate. 6 However, both devices required operating voltages of at least 30 V. In order to reduce the operating voltage below 5 V, similar devices would require polymer films less than 25 nm thick, too thin for reliable fabrication by solvent spinning, so further progress seemed unlikely at the time. A major breakthrough was the fabrication of ferroelectric films of VDF copolymers by Langmuir-Blodgett ͑LB͒ deposition, 7 resulting in ferroelectric films as thin as 1 nm that can be switched with as little as 1 V. [8][9][10] Here we report the fabrication and operation of a metal-ferroelectricinsulator-semiconductor ͑MFIS͒ memory element that incorporated a ferroelectric polymer LB film.…”