Permanent metal insulator semiconductor memory cell - has silica, silicon nitride, silica and silicon nitride or rutile films to increase efficiency and speed

摘要

Semiconductor memory cell has a semiconductor body coated with consecutive films of (a) SiO2, (b) silicon nitride, (c) silica, (d) insulation (silicon nitride or rutile) and (e) conductor. The pref. thickness of these are (a) under 150 Angstron, (b) under 750 Angstron, (c) under 125 Angstron, (d) under 5000 Angstron, whilst (d) has a dielectric constant of over 15. The new combination of insulating films increases the charge storage retention capacity, so that a permanent memory (RAM) is obtd. The write-in and erase times can be reduced, due to the low p.d. across the rutile, whilst the silica film between the silicon nitride and rutile increases the write-in efficiency. Pref. these layers are between a pair of (source and drain) zones of opposite conductivity type to the body. The memory cell has write-in, readout and erase facilities.