| 摘要 |
PURPOSE:To facilitate the working of electrode wirings and to reduce a stepwise difference by burying an erase gate in an internal surface layer of an isolation region, forming the top of the region in a 2-layer structure of a floating gate and a control gate, and alleviating the unevenness of a base on which the wirings are formed. CONSTITUTION:When the width of a groove 21 is indicated by a, a polysilicon 23 which becomes an erase gate 5 is so deposited in thickness of a/2 on a field oxide film 3 as to fill it in the groove 21. Then, the silicon 23 is etched, and the polysilicon remains only in the groove 21. Thereafter, a polysilicon 25 to become a floating gate is so formed on the upper surface of the film 2 as to oppose at its end through a thin insulating film 11 thereto. A polysilicon 27 to become a control gate 15 is eventually formed through a gate oxide film 13 on the silicon 25 as a 2-layer structure. Thereafter, an interlayer insulating film is laminated on the silicon 27, contact holes for connecting a source region, a drain region and gates to electrode wirings are opened, and the electrodes are wired on the interlayer insulating film. Thus, unevenness of the base on which electrode wirings are to be formed is alleviated.
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