| 摘要 |
PURPOSE:To manufacture an EPROM which can erase by ultraviolet rays with less leak of accumulated charges even when formed in high integration with a good reprducibility, by forming the film thickness of oxide films formed from the surface of a gate to the both sides equivalent to the gate oxide film one or over that particularly in the periphery of a floating gate. CONSTITUTION:Of the SiO2 film 14 formed from the surface of each gate to source and drain regions, the film thickness of the periphery 14a of the floating gate FG in particular is formed equivalent to the film thickness (500Angstrom or less) of the gate oxide film 1 or larger, e.g. 800-1,000Angstrom . This oxide film 14 is adhered approximately in evenness and has a very good film quality. The growth of the SiO2 film 14 on the surface of each gate is performed by applying an oxidation treatmet, e.g. at 1,000 deg.C for 30min in dry O2. Thereat, simultaneously, the film thickness of the SiO2 film 14a in the periphery of the floating gate FG becomes much larger than that of the gate oxide film 1. Therefore, even when contriving to the high integration of an EPROM by forming a gate length or channel length and a gate oxide film thickness respectively to small sizes, leak decrease resulting in the good retention of charges. |
