| 摘要 |
PURPOSE:To ensure highly efficient implantation of ions into a small cell area by a method wherein a floating gate electrode is built in an ion-implanted layer of the second conductivity type, a selective gate electrode is formed in a second gate insulating film, and a drain region and source region of the second conductivity type are formed on the surface of semiconductor to sandwich the floating gate electrode and selective gate electrode. CONSTITUTION:An n type impurity is implanted by the ion implantation method into the surface of a p type substrate for the formation of an n type inversion region 2. A floating gate electrode 4 is built in the n type inversion region 2 through the intermediary of a first gate insulating film 3. With the floating gate electrode 4 acting as a portion of the master, a p type impurity is implanted by the ion implantation method into a portion of the n type inversion region 2, for the formation of a p type region 5. Next, a second gate insulating film 7 is formed on the p type region 5. An insulating film 6 is next formed on the top and sides of the floating gate electrode 4. A process follows wherein a selective gate electrode 8 is formed with an end thereof in contact with the insulating film 6 situated on the floating gate electrode 4. A drain region 9 and source region 10 are formed by implanting an n type impurity so that they may sandwich the floating gate electrode 4 and selective gate electrode 8. |
