Method for forming an improved field isolation structure using ozone enhanced oxidation and tapering

A method for forming a field isolation structure for a semiconductor device comprising:

• forming a silicon substrate having active areas and isolation areas;
• forming a mask on the substrate having openings aligned with the isolation areas and solid portions aligned with the active areas;
• placing the substrate in a reaction chamber heated to a temperature of between 600.degree. C. to 1300.degree. C. and containing an oxidation atmosphere comprising ozone and oxygen combined in a ratio of ozone to oxygen of between 0.5% to 25% by volume for a time period sufficient to grow a field oxide of a desired thickness in the isolation areas;
• and
• dry etching a surface of the field oxide to form a tapered surface using a process selected from the group consisting of sputter etching, ion milling, reactive ion etching and plasma etching.

A method for forming a field isolation structure for a semiconductor device comprising:

• forming a silicon substrate, having active areas and isolation areas;
• forming a mask on the substrate to protect the active areas;
• forming a field oxide in the isolation areas using the mask and an oxidation atmosphere comprising ozone and oxygen combined in a ratio of ozone to oxygen of 0.5% to 25% by volume;
• removing at least a portion of the mask;
• and
• dry etching a portion of the field oxide to form a faceted surface Using a process selected from the group consisting of sputter etching, ion milling, reactive ion etching and plasma etching.

A method for forming a field isolation structure for a semiconductor device comprising:

• forming a silicon substrate having active areas and isolation areas;
• forming a mask on the substrate having openings on the isolation areas and solid portions on the active areas;
• forming a field oxide in the isolation areas using an oxidation atmosphere comprising oxygen and ozone;
• and
• chemically mechanically planarizing a surface of the field oxide to form a tapered surface.

A method for forming a field isolation structure for a semiconductor device comprising:

• forming a silicon substrate having active areas and isolation areas;
• forming a mask on the substrate having openings on the isolation areas and solid portions on the active areas;
• forming a field oxide in the isolation areas using an oxidation atmosphere comprising oxygen and ozone, said field oxide including corner portions;
• implanting a dopant into the field oxide;
• and
• dry etching the corner portions of the field oxide to form a tapered surface.