| 摘要 |
PURPOSE:To enlarge the area of the part where a floating gate and a control gate overlap with each other and to enable the improvement of writing efficiency by forming the control gate consisting of polycrystalline Si also on side planes of the floating gate. CONSTITUTION:After forming a floating gate 5 and a second gate insulating film 12, a polycrystalline Si layer, an Si nitride layer 14 and a thick photoresist layer 15 are deposited over the whole surface of an element. After that, the photoresist film 15 and the Si nitride film 14 are etched till the surface of the polycrystalline Si layer for forming a control gate on the floating gate 5 is exposed. Then the surface of the exposed polycrystalline Si is oxidized and the excessive Si nitride film 14 is removed. By using the Si oxide film 13 as a mask, anisotropic etching is done to remove the polycrystalline Si layer present except in the periphery of the floating gate 5. Consequently, the polycrystalline Si layer 6 which works as a control gate is formed on side planes of the floating gate 5. |
