SOI Non-volatile Memory

SIMOX silicon-on-insulator (SOI) substrates were implanted with silicon ions at doses of 5 x 10(exp 15) and 1 x 10(exp 16) ions/square cm at 130 keV. At this energy, the majority of the silicon ions were implanted into the buried oxide of the SIMOX substrate. Silicon-oxide-silicon test structures were fabricated on these implanted substrates. Point-contact transistor (PCT) measurements were performed on the test structures and initial threshold voltages determined. A stress voltage was then applied to the test structure for times ranging from 10 millisec to 100 sec. After removal of the stress voltage, PCT measurements were again performed. The threshold voltages shifted by significant and reproducible values. This stress-voltage-induced device switching response forms the basis for a new type of non-volatile SOI memory. The temperature stability of this switching was studied from -50 deg C to +200 C. In addition, the field and time dependence of the switching is also presented.