EEPROM Flashzelle sowie Verfahren zu deren Herstellung

摘要

A flash EEPROM cell is made by forming films of tunnel oxide 2, polysilicon 3B and a dielectric 14 on Si substrate 1, masking and etching to expose strips of substrate and forming a source 6A and a drain 7A region by injecting first impurity ions. A second oxide film (16 Figure 3B) is grown over source and drain regions, then a second polysilicon film (15), these are masked and etched to expose strips of substrate 1 at right angle to the first strips, second impurity ions being injected to form cell isolation regions (18 Figure 3C). This gives a floating gate 3B and a control gate 15A stacked over it. The dielectric film 14 is oxide 12 and nitride 13. Using this process the silicon substrate is not under-cut.