SILICON OXIDE FILM FORMATION METHOD OF SEMICONDUCTOR DEVICE AND ELEMENT ISOLATION METHOD USING THE METHOD

PROBLEM TO BE SOLVED: To provide the silicon oxide film formation method of semiconductor devices that utilize spin-on glass, fill in the gap between VLSI-class wiring layers with high aspect ratio, and have essentially the same characteristics as a CVD oxide film. SOLUTION: A flat SOG film is formed on a substrate 10 where a trench 12 is formed on an upper surface by applying an SOG solution that has a structure expression of -(SiH2 NH)n - and contains polysilazane. In this case, in the expression, (n) is set to a positive constant. The SOG film is subjected to primary heat treatment for converting to an oxide, the obtained oxide is subjected to secondary heat treatment for congestion, and the SOG film is formed as a silicon oxide film having a flat surface. The oxidation of silicon in an active region is suppressed, thus securing stability in dimensions.