Isolation structure formation for semiconductor circuit fabrication
First Claim
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1. A method for forming a trench isolation structure in a semiconductor substrate, comprising the steps of:
- (a) forming in said semiconductor substrate a first portion of a trench having a first width;
(b) applying a photoresist layer to said semiconductor substrate;
(c) masking said photoresist layer to define a region for a second portion of said trench within said first portion, said second portion having a second width less than said first width;
(d) forming in said region said second portion of said trench deeper than said first portion; and
(e) after forming said first and second portions of said trench, filling both said first portion and said second portion of said trench with material in a single processing step.
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Abstract
The deposition of oxide over a semiconductor substrate to fill trenches provides for simpler isolation processing for semiconductor circuit fabrication. Both shallow and deep trenches are etched in a semiconductor substrate for the formation of both device isolation structures and well isolation structures. Oxide is then deposited using chemical vapor deposition over the substrate, filling both the shallow and deep trenches. The resulting oxide layer over the substrate is then planarized, thus forming shallow and deep trench isolation structures in the substrate.
137 Citations
25 Claims
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1. A method for forming a trench isolation structure in a semiconductor substrate, comprising the steps of:
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(a) forming in said semiconductor substrate a first portion of a trench having a first width; (b) applying a photoresist layer to said semiconductor substrate; (c) masking said photoresist layer to define a region for a second portion of said trench within said first portion, said second portion having a second width less than said first width; (d) forming in said region said second portion of said trench deeper than said first portion; and (e) after forming said first and second portions of said trench, filling both said first portion and said second portion of said trench with material in a single processing step. - View Dependent Claims (2, 3, 12, 13, 14)
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4. A method for forming isolation structures in a semiconductor substrate comprising the steps of:
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(a) forming a first trench and a first portion of a second trench in said semiconductor substrate, said first trench and said first portion of said second trench having a first depth; (b) applying a photoresist layer to said semiconductor substrate; (c) masking said photoresist layer to define a region for a second portion of said second trench within said first portion while protecting said first portion and said first trench; (d) forming a second portion of said second trench in said region, said second trench having a second depth greater than said first depth; and (e) simultaneously filling said first trench and said second trench with material. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 15, 16, 17)
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18. A method for forming isolation structures in a semiconductor substrate comprising the steps of:
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(a) forming over the semiconductor substrate a first layer having a first material; patterning the first layer to form a patterned first layer having at least a first opening for a first trench and a second opening for a second trench; (c) forming in the semiconductor substrate said first trench having a first depth while simultaneously forming in the semiconductor substrate an upper portion of said second trench; (d) applying a photoresist layer to said semiconductor substrate; (e) masking said photoresist layer to define a region for a lower portion of said second trench within said upper portion; (f) forming in said region said lower portion of the second trench, the second trench having a second depth greater than the first depth; (g) forming over the semiconductor substrate a second layer having a second material to simultaneously fill the first trench and the second trench with the second material; and (h) polishing the second layer using the patterned first layer as a polish stop to form the isolation structures. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification