Method of producing semiconductor device with viscous flow of silicon oxide

A method of producing a semiconductor device comprising the steps of:

• depositing a second thin film on a semiconductor substrate or a first thin film;
• forming a pattern on said second thin film by a first photoresist, and etching said second thin film, using said first photoresist as a mask, to form a second thin film pattern, said second thin film extending by a first length on said semiconductor substrate or said first thin film to form a first step;
• depositing a third thin film on an entire surface including said second thin film;
• etching said third thin film, using a second photoresist on said third thin film as a mask, to form a third thin film pattern covering said second thin film, said third thin film extending by a second length on said second thin film to form a second step, wherein said first step and said second step resulting respectively from said second thin film pattern and said third thin film patter are formed on the surface of an end portion of said third thin film pattern;
• depositing a silicon oxide film on said third thin film, said silicon oxide film containing impurities;
• and
• causing said silicon oxide film to viscously flow by a heat treatment;
• wherein a value obtained by subtracting the thickness of said third thin film from the length by which said third thin film pattern extends on said second thin film pattern to the outward periphery of said third thin film pattern is not less than two times larger and not more than ten times larger than the thickness of deposition of said silicon oxide film.

A method of producing a semiconductor device comprising the steps of:

• forming an interlayer insulation film on a semiconductor substrate including a switching transistor, and forming a contact window reaching an active region of said switching transistor;
• depositing first polycrystalline silicon containing impurities in such a manner that said first polycrystalline silicon is in contact with said active region of said switching transistor through said contact window;
• forming a pattern on said first polycrystalline silicon by a first photoresist, and etching said first polycrystalline silicon, using said first photoresist as a mask, to form a first polycrystalline silicon pattern;
• forming a dielectric film on a surface of said first polycrystalline silicon, and further depositing second polycrystalline silicon on said dielectric film and on said first polycrystalline silicon layer, said second polycrystalline silicon containing impurities;
• forming a pattern on said second polycrystalline silicon by a second photoresist, and etching said second polycrystalline silicon, using said second photoresist as a mask, to form a second polycrystalline silicon pattern;
• depositing a silicon oxide film on said second polycrystalline silicon, said silicon oxide film containing impurities;
• and
• causing said silicon oxide film to viscously flow by a heat treatment;
• wherein the length by which said second polycrystalline silicon pattern extends on said interlayer insulation film outward from said first polycrystalline silicon layer is not less than two times larger and not more than four times larger than the thickness of said first polycrystalline silicon film.