| 摘要 |
PURPOSE:To contrive to maintain writing and erasing voltage at a low level by forming an impurity diffusion layer having specific impurity concentration to the exposed section of a substrate and shaping a thin silicon oxide film and a floating gate electrode on the impurity diffusion layer. CONSTITUTION:A gate oxide film 17 is formed in an element region in a first conduction type silicon substrate 11 isolated by a field oxide film 15, a part of the gate oxide film 17 is removed, an impurity diffusion layer 19 having surface impurity concentration within the range 5X10<20>cm<3>-1X10<13>cm<3> is shaped on the exposed section 11 of the substrate, while a thin silicon oxide film 20 is formed on the diffusion layer 19 through thermal oxidation, and a floating gate electrode 21 is shaped on the oxide film 20. Barrier height is lowered largely, and an EEPROM cell using the SiO2 thin-film 20 as a gate oxide film can inject electrons into the floating gate electrode and extract electrons therefrom at low writing/erasing voltage.
|
