Solution-processed conformal coating of ferroelectric polymer film and its application to multi-bit memory device.

Ferroelectric multi-bit storage memory which is fabricated by means of the patterning and double-coating of ferroelectric polymer film is demonstrated. The multi-bit memory device demonstrated here has two thicknesses in a capacitor. Therefore, ferroelectric switching at each thickness arises in different voltage range. The structured capacitor with two different thicknesses is realized by optimizing two processes, i.e., the photo-lithographical patterning of the ferroelectric film and a double-coating method for the formation of the multilayer structure. Not only photo-lithographical patterning but also the double-coating method of ferroelectric film was performed with a solubility-controlled ferroelectric polymer solution created by the addition of an insoluble solvent. From electrostatic force microscopy and displacement-voltage measurements, the fabricated multi-bit storage memory operated as predicted for a multi-bit memory scheme. The solubility-controlling method suggested here will offer additional promising routes to fabricate complex organic devices based on a solution process. [ABSTRACT FROM AUTHOR]