N-channel memory FET with floating memory gate - charged by programmed channel injection has p-zone on drain zone

摘要

n-Channel memory FET ahs a floating memory gate, in which the charge is changed by programmed electron-injecting channel injection, and a control gate, with capacitive effect on the memory gate, as in DT 2445137, esp. for programmed memories of telephone systems. Improvement is that a p-doped auxiliary zone is formed on the drain zone, forming a diode in series with the source-drain section. The drain zone potential floats, the drain terminal being connected to the auxiliary zone and the entire source-drain current always flowing through the auxiliary zone to the drain terminal. Device can act as memory cell without additional selective FET and without complicated forming of both gates. Also, the application of laps to the control gate allows improvement of electrically controlled erasure.