Ferroelectric random access memory based on one-transistor–one-capacitor structure for flexible electronics

Abstract

We have demonstrated a low temperature process for a ferroelectric non-volatile random access memory cell based on a one-transistor–one-capacitor (1T1C) structure for application in flexible electronics. The n-channel thin film transistors (TFTs) and ferroelectric capacitors (FeCaps) are fabricated using cadmium sulfide (CdS) as the semiconductor and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer as the ferroelectric material, respectively. The maximum processing temperature for the TFTs is 100°C and 120°C for the FeCaps. The TFT shows excellent access control of the FeCap in the 1T1C memory cell, and the stored polarization signals are undisturbed when the TFT is off. The fabricated 1T1C memory cell was also evaluated in a FRAM circuit. The memory window on the bit line was demonstrated as 2.3V, based on the 1T1C memory cell with a TFT having dimensions of 80μm/5μm (W/L) and a FeCap with an area of 0.2×10−3cm2 using a bit line capacitor of 1nF pre-charged at 17.2V. The 1T1C memory cell is fabricated using photolithographic processes, allowing the integration with other circuit components for flexible electronics systems.