| 摘要 |
PURPOSE:To improve the dielectric withstanding capability of an insulating film and to obtain excellent non-volatile semiconductor memory device leading to the production of high-reliability devices with a high acceptable rate by a method wherein the thin gate insulating film region just under a floating gate is provided not adjoining a field insulating film region. CONSTITUTION:On the surface of a P type semiconductor substrate 11, a field oxide film 12 and a thin oxide film 13 are formed and, through the latter, As ions are implanted for the formation of an N type buried layer 14. Next, the oxide film 13 is removed by using F or the like. A process follows wherein thermal oxidation, patterning of a resist, partial removal of the oxide films, and second thermal oxidation are accomplished for the formation of a relatively thin first insulating film 15 and a relatively thick second insulating film 16. The first, insulating film 15 is not in contact with the field oxide film 12. Next, a floating gate 17, gate oxide film 18, control gate 19 are built for the completion of the required memory device. In a device wherein the gate is a lamination of the two insulating films 15, 16 greatly different from each other in thickness, a current flows in the thinner insulating film 15 generating a stronger electric field. This results in a memory device with its insulation not to be easily broken down due to pinholes and other defects. |
