| 摘要 |
PURPOSE:To improve data writing efficiency by a method wherein the first control gate, which is connected to a floating gate with an insulating film in between by capacitive coupling, is provided and the second control gate, which is connected to the floating gate by capacitive coupling with an insulating film is provided. CONSTITUTION:As a drain region 11 is extended beneath a floating gate 14 and a part of the floating gate 14 overlaps the drain region 11, electrons which are produced near the drain region 11 by impact ionization can reach the floating gate 14 by traveling the minimum distance. Moreover, as the distance between the drain region 11 and the floating gate 14 is sufficiently reduced, high capacitive coupling between the drain region 11 and the floating gate 14 is provided and, when a high voltage is applied to the drain region 11, the potential of the floating gate 14 is elevated through the capacitive coupling so that electrons can be absorbed by the floating gate 14 easily. With this constitution, injection efficiency of electrons, in other words characteristics of data writing, can be improved. |
