Ferroelectric Fluoride Memory FET Development

摘要

This Interim Technical Report covers the development and integration of BariumMagnesium Fluoride (BMF) ferroelectric thin films for incorporation into the gate dielectric of a metal-insulator-silicon field effect transistor, capable of functioning in a non-volatile, nondestructive-readout (NDRO) ferroelectric random access memory (FERRAM). Also provided is a detailed description of the test vehicles implemented for the study of fabrication process integration and optimization and the resultant properties of 'ferroelectric/(semiconductor) memory FET (FEMFET) and related structures'. Tne BMF films were deposited by co-evaporation in ultra high vacuum from barium fluoride and magnesium fluoride effusion sources. A substrate temperature of 200 deg C during deposition followed by an anneal in hydrogen at 480 deg C resulted in polarization orientation closest to the preferred. Film samples exhibited polarization, Ps, as high as 4.55 micro-C/sq cm. The permittivity varied from a value of 9 at 5 kHz to 8.4 at 500 kHz. This compares closely with the average value of 10 reported for bulk single crystals. The ferroelectric switching speed of the thin film was approximately 45 nanoseconds.