Method of filling intervals and fabricating shallow trench isolation structures

A method for forming shallow trench isolation structures, comprising the steps of:

• providing a substrate having a patterned pad oxide layer, a mask layer and a plurality of trenches thereon;
• forming a first dielectric layer over the mask layer to fill the trenches, wherein the first dielectric layer has a plurality of apertures positioned at a height level higher than an upper surface of the mask layer;
• removing a portion of the first dielectric layer to open up the apertures and form a plurality of openings;
• removing a section of the first dielectric layer off the sidewalls of the openings so that a width of the opening is increased;
• forming a second dielectric layer over the first dielectric layer to fill the openings completely;
• and
• removing the first dielectric layer and the second dielectric layer outside the trenches.

A method of filling intervals, comprising the steps of:

• providing a substrate having at least a first opening thereon;
• forming a first dielectric layer over the substrate to fill the first opening and cover the substrate, wherein the first dielectric layer has at least an aperture located above the opening at a height level higher than an upper surface of the substrate;
• removing a portion of the first dielectric layer to open up the aperture and form a second opening;
• removing a section of the first dielectric layer off the sidewalls of the second opening to increase a width of the second opening;
• and
• forming a second dielectric layer over the first dielectric layer to fill the second opening completely.