| 摘要 |
PURPOSE:To manufacture a titled product with high yield, by reducing the influence due to a process of writing characteristic. CONSTITUTION:When a writing voltage Vw is impressed on a drain region 3 coupled to a floating gate electrode 6 by capacity, against a semiconductor substrate 1, the potential of the floating gate electrode 6 is increased close to approx. Vw, thus the surface potentials of channel regions C4 and C5 are also varied; in particular, the surface potential of the channel region C5 becomes approx. the same as the potential of the drain region 3. On the other hand, the surface potential of the channel region C4 is small, since an Si dioxide film 11 is thick. When electrons are emitted from a source region 2, a part is accelerated as B, at the part wherein the channel region C is contacted on the channel region C, and injected i.e. written into the floating gate electrode 6. When the gate insulation film of the transistor for a logical circuit is utilized as a thick oxide film 11, the process dependency of the writing efficiency is reduced. This insulation film has good accuracy and stable film quality. Therefore, the injection efficiency is determined only by the oxide films 11 and 5, and accordingly is not influenced by the voltages of a selective gate electrode 7 and the oxide film 4. |
