Shallow trench isolation method

A method of manufacturing a semiconductor device using shallow trench isolation, comprising:

• forming a pad oxide layer on a silicon substrate;
• forming a silicon nitride layer on the exposed surface of the pad oxide layer;
• defining an active area and an isolation area on the substrate;
• forming a trench in the defined isolation area, the trench extending through the mask layer and pad oxide layer and into the substrate;
• forming a photo-resist layer on the exposed surface of the mask layer and in the trench;
• patterning the photo-resist layer such that the photo-resist layer defines a plurality of protrusion areas and a depression area within the defined active area;
• and
• removing a portion of the mask layer in the defined depression area to form a plurality of protrusions in the mask layer;
• depositing a dielectric layer on the exposed surface of the mask layer and in the trench;
• and
• planarizing the dielectric layer by chemical-mechanical polishing.

A method of manufacturing a semiconductor device using shallow trench isolation, comprising:

• forming a pad oxide layer on a silicon substrate;
• forming a silicon nitride layer on the exposed surface of the pad oxide layer;
• forming a first photo-resist layer on the exposed surface of the mask layer;
• applying a photomask to the exposed surface of the first photo-resist layer, the photomask patterned to define an active area and an isolation area in the photo-resist layer;
• and
• removing the first photo-resist layer in the defined isolation area;
• etching a trench in the defined trench area, the trench extending through the mask layer and pad oxide layer and into the substrate;
• removing the remaining portion of the first photo-resist layer;
• forming a second photo-resist layer on the exposed surface of the mask layer and in the trench;
• applying a photomask to the exposed surface of the second photo-resist layer, the photomask patterned to define a plurality of protrusion areas and a depression area within the defined active area;
• and
• removing the photo-resist in the defined depression area;
• and
• etching a portion of the mask layer in the defined depression area to form a plurality of protrusions in the mask layer;
• depositing a dielectric layer on the exposed surface of the mask layer and in the trench;
• planarizing the dielectric layer by chemical-mechanical polishing;
• and
• removing the mask layer and the pad oxide layer to expose the active area defined in the substrate.