Method of manufacturing semiconductor device

A method for manufacturing a semiconductor device comprising:

• forming an isolation trench in a surface of a semiconductor substrate;
• coating a solution containing a perhydrosilazane polymer on the semiconductor substrate to fill the isolation trench with the solution;
• heating the solution to form a film containing the perhydrosilazane polymer and which fills the isolation trench;
• and
• oxidizing the film to convert the film into an insulating film containing silicon and oxygen, wherein the oxidizing comprises a first oxidation treatment and a second oxidation treatment, the first oxidation treatment is executed in a water vapor atmosphere at a reduced pressure, and wherein the second oxidation treatment is executed in a water vapor atmosphere at a reduced pressure at a higher temperature than the first oxidation treatment,
• wherein a top portion of the film includes Si—N bonds after the first oxidation treatment and before the second oxidation treatment, and the top portion of the film fails to include Si—N bonds after the second oxidation treatment.

A method for manufacturing a semiconductor device comprising:

• forming an isolation trench in a surface of a semiconductor substrate;
• coating a solution containing a perhydrosilazane polymer on the semiconductor substrate to fill the isolation trench with the solution;
• heating the solution to form a film containing the perhydrosilazane polymer and filling the isolation trench;
• oxidizing the film in a water vapor atmosphere at a reduced pressure to convert the film into an insulating film containing silicon and oxygen;
• and
• filling a silicon oxide film into a part of the isolation trench by an HDP-CVD process before coating the solution containing the perhydrosilazane polymer on the semiconductor substrate.