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US 5,472,562 AGranted
Method of etching silicon nitride
AssigneeAT&T Corp.
InventorDavid H. Ziger
Life of this patent
Estimating the term…
Abstract
Etch baths having phosphoric acid, nitric acid and hydrofluoric acid and used to selectively remove silicon nitride or silicon with respect to silicon oxide have enhanced initial selectivity when silicon is added to the initial bath. The silicon may be added in the form of soluble silicon compounds such a hexafluorosilicic acid or ammonium fluorosilicate.
Claims6
A method of integrated circuit manufacture comprising the steps of:
- forming a silicon oxide surface;
- forming structures on said silicon oxide surface, said structures comprising at least one layer, said layer comprising material selected from the group consisting of silicon and silicon nitride;
- selectively removing said structures relative to said silicon oxide by etching in an etch bath comprising phosphoric acid, hydrofluoric acid, and nitric acid;
- adding soluble silicon to said bath prior to said removing.
1 more element
Dependencies are inferred from the claim text.