Transient Imprint Memory Effect in MOS Memories

This work reports on a transient effect which caused a pattern stored in a MOS memory to be imprinted when exposed to a high dose rate. The imprinted pattern can be restored in the memory by simply exposing the device with the complementary pattern in it to a single pulse with a dose rate in excess of the upset threshold. CMOS/SOS memories of 5T and 6T storage cell design and CMOS/BULK samples were tested for this effect. The Boeing LINAC was used to provide 10 MeV electron pulses of 20 ns width. Results showed that the magnitude of the "Transient Imprint Memory Effect" depended on the accumulated dose delivered by radiation pulses. The data upset threshold increased when the stored pattern was maintained constant for repeated exposures during the imprint procedure.