IMF2017

The ferroelectric phenomenon involves physically rotating dipoles with an applied electric field. For memory devices, the need to program/erase at high-speed means that a polymer must have a glass transition temperature (T_g) below operation temperature such that the dipoles are not locked in place. Here, we demonstrate a radically new ferroelectric memory device concept based on polar polymers with T_g well above operation temperature. To realize fast operation, program/erase is done with a transient applied electric field and a transient elevated temperature well above T_g. After the program/erase operation, the device returns to operation temperature rapidly. Once cooled, the dipoles are locked in place ensuring long retention. We fabricated a thin-film ferroelectric field effect transistor (FeFET) using a polar polymer, CP1 polyimide (T_g ~ 265 ^oC), as the gate dielectric (15nm) and polysilicon (15nm) channel. The fabricated FeFETs were programmed at ± 4V at 275 ^oC. The device was cooled to room temperature while maintaining the applied electric field. The flat-band voltage shifts significantly and its direction depends on the sign of the applied field during programming. This flat band shift is found to be stable much longer than reported in the literature. Our dual-condition programming (temperature and electrical field) can lead to memory with extremely long retention times while using low cost processing materials that are CMOS compatible and highly scalable.