Abstract
A method to fabricating split-gated flash device is disclosed. The floating gate is formed on the semiconductor substrate. The floating gate and the semiconductor substrate are partitioned by an oxide layer. The upper surface of the floating gate consists of an oxide area. The two corners of the floating gate consist of an upward-bulged structure. Tunneling oxide layer is formed on the floating gate, on the oxide area, on the oxide gate layer, and on the semiconductor substrate. The tunneling oxide layer than is covered by a material. This upper surface of the material is flat, and has a high selectivity ratio of etching with respect to the tunneling oxide layer. Then the material layer is selectively etched till its upper surface is lower than the bulged structure, so parts of the tunneling oxide layer on the upward-bulged structure is exposed. Etch the exposed tunneling oxide layer selectively to lower its height. The material than is removed. Finally, fabricate the controlling gate, the source, and the drain.