Method of forming silicon oxide layer in semiconductor manufacturing process using spin-on glass composition and isolation method using the same method

An isolation method of a device for defining an active region of a semiconductor device comprising:

• forming a trench by partially etching an upper portion of a semiconductor substrate;
• coating a spin-on glass (SOG) solution including polysilazane having a structure of —(SiH2NH2)n— where n represents a positive integer, a weight average molecular weight within the range of about 6,000 to about 8,000, and a molecular weight dispersion degree within the range of about 3.0 to about 4.0, onto the semiconductor substrate having a stepped portion formed thereon to form a planar SOG layer burying the trench;
• implementing a first heat treatment of the SOG layer to convert the polysilazane into a silicon oxide;
• implementing a second heat treatment of the converted silicon oxide to densify the converted silicon oxide to form a silicon oxide layer burying the trench;
• and
• defining the active region of the semiconductor device through forming a field oxide burying the trench by partially etching the silicon oxide layer.