Trench-diffusion corner rounding in a shallow-trench (STI) process
AssigneeVLSI Technology, Inc.
InventorChristopher S. Olsen
Life of this patent
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Abstract
An isolation structure on an integrated circuit is formed using a shallow trench isolation process. On a substrate, a trench is formed. A thermal anneal is performed to oxidize exposed areas of the substrate to provide for round corners at a perimeter of the trench. The thermal anneal in performed in an ambient where a chlorine source is added to O.sub.2 in order to minimize facets while creating the round corners. Oxidation time is lengthened by introducing an inert gas during the thermal anneal.
Claims15
A method for forming an isolation structure on an integrated circuit comprising the following steps:
- (a) on a substrate, forming a trench;
- and,
- (b) performing a thermal anneal to oxidize exposed areas of the substrate to provide for round corners at a perimeter of the trench, including the following substeps:
- (b.1) adding a chlorine source to O.sub.2, when performing the thermal anneal in order to minimize facets while creating the round corners, and
- (b.2) lengthening oxidation time by introducing an inert gas during the thermal anneal.
A method for forming an isolation structure on an integrated circuit comprising the following steps:
- (a) on a substrate, forming a layer of buffer oxide;
- (b) forming a layer of nitride on the layer of buffer oxide;
- (c) patterning the layer of nitride and the layer of buffer oxide to form a trench area;
- (d) etching the substrate to form a trench within the trench area;
- and,
- (e) performing a thermal anneal to oxidize exposed areas of the substrate to provide for round corners at a perimeter of the trench, including the following substeps:
- (e.1) adding a chlorine source to O.sub.2, when performing the thermal anneal in order to minimize facets while creating the round corners, and
- (e.2) lengthening oxidation time by introducing an inert gas during the thermal anneal.
Dependencies are inferred from the claim text.