| 摘要 |
PURPOSE:To prevent the lowering of the write efficiency and erase efficiency of a device even when the degree of integration of the device is improved by making the area of a tunnel element small, by a method wherein a doped poly-Si film is connected on the inner wall of a region wherein the tunnel element is formed, an Si film is formed on the poly-Si film in this state, a poly-Si film is connected further thereon, and then this film is turned into an Si oxide film. CONSTITUTION:After source and drain regions 2 and 3 are formed on a semiconductor substrate 1, a gate oxide film 4 is formed, an opening is made in the gate oxide film 4 in a region 5 in which a tunnel element is predetermined to be formed, an Si oxide film 21 is formed on the substrate by oxidation, and thereafter a doped poly-Si film 22 is formed on the substrate 1. after a sputtered poly-Si film 23 is formed further on the substrate, the sputtered poly-Si film 23 and the doped poly-Si film 22 located thereunder are subjected to anisotropic etching, and then the sputtered poly-Si film 23 and a part of the doped poly-Si film 22 located thereunder are oxidized so that the doped poly-Si film 22 be connected in the shape of a ring on the inner wall of the region 5 in which the tunnel element is to be formed. In this state, an Si oxide film 24 is formed. After a poly-Si film 25 is formed further thereon, this poly-Si film 25 is oxidized to form an Si oxide film 26, and a poly-Si film is formed thereon in a prescribed pattern, so as to form a floating gate electrode.
|
