Method for obtaining extreme selectivity of metal nitrides and metal oxides

摘要

Methods for etching metal nitrides and metal oxides include using ultradilute HF solutions and buffered, low-pH HF solutions containing a minimal amount of the hydrofluoric acid species H2F2. The etchant can be used to selectively remove metal nitride layers relative to doped or undoped oxides, tungsten, polysilicon, and titanium nitride. A method is provided for producing an isolated capacitor, which can be used in a dynamic random access memory cell array, on a substrate using sacrificial layers selectively removed to expose outer surfaces of the bottom electrode.

主权项

1. A method of forming a conductor on a substrate, the method comprising:
forming a recess on the substrate; lining the recess with a sacrificial material comprising metal nitride or metal oxide; forming a conductive material within the recess; and removing the sacrificial material with an etch solution comprising an aqueous hydrofluoric acid etchant, wherein a ratio of an etch rate of the sacrificial material in the etch solution to an etch rate of the conductive material in the etch solution is greater than about 500:1.