Patent ID: 7407855

Claim:
A method of producing a semiconductor element comprising: a process of forming a first oxide film on a semiconductor substrate, a process of forming a semiconductor film and an oxidation stopping film on the first oxide film, a process of forming an opening by patterning the oxidation stopping film, a process of forming an insulating local oxide film by local oxidation of a surface of the semiconductor film exposed through the opening, a process of removing the oxidation stopping film, a process of forming a floating gate of the semiconductor film remaining under the insulating local oxide film, by selective etching of the semiconductor film masked with the insulating local oxide film, a process of cleaning the semiconductor substrate, and a process of transferring the silicon substrate with the floating gate to a chemical vapor deposition device where an initial temperature is kept in a range where oxidation of a surface of the floating gate is restrained, a process of heating the chemical vapor deposition device from the initial temperature to a chemical vapor deposition temperature, and a process of forming a second oxide film covering the floating gate by low pressure chemical vapor deposition, wherein the initial temperature is in range of 400° C.±5° C. and the chemical vapor deposition temperature is in range of 750° C.±5° C.