Method to etch Cu/Ta/TaN selectively using dilute aqueous HF/HCI solution

摘要

Copper can be etched with selectivity to Ta/TaN barrier liner and SiC hardmask layers, for example, to reduce the potential copper contamination. The copper film can be recessed more than the liner to further enhance the protection. Wet etch solutions including a mixture of HF and HCl can be used for selective etching copper with respect to the liner material, for example, the copper film can be recessed between 2 and 3 nm, and the barrier liner film can be recessed between 1.5 and 2 nm.

主权项

1. A method comprising
providing a substrate; forming a dielectric layer above the substrate; forming a plurality of trenches in the dielectric layer; forming a liner layer above the dielectric layer in the trenches, wherein the liner layer comprises at least one of Ta or TaN; forming a copper layer above the liner layer, wherein the copper layer fills in the trenches; planarizing the liner layer and the copper layer so that a portion of the liner layer and copper layers are removed to expose the dielectric layer; and applying an etch solution to the substrate,
wherein the etch solution comprises HF, HCl, and H2O,wherein a concentration of HF is between 0.5 and 0.8 vol %, andwherein a concentration of HCl is between 7 and 10 vol %.