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 selectively etching a layer of metal nitrides or metal oxide, the method comprising:
heating a substrate having formed thereon a structure comprising a layer of metal oxide or metal nitride; exposing the structure to a buffered hydrofluoric acid etch solution having a pH between about 3.5 and about 5.5; and selectively etching the layer of metal oxide or metal nitride with an etch rate selectivity relative to an exposed layer of silicon greater than or equal to about 2000:1.