Two-Step Cyclic Etching of Copper Thin Films Using Acetylacetone/O₂ Gases

Two-step cyclic etching of copper thin films was carried out using acetylacetone/O-2 gases and Ar plasma. The copper film surfaces were first modified by exposing them to acetylacetone/O-2 gases and the modified layers were removed via Ar-ion sputtering. The surface modification step was optimized by varying the flow rate of the acetylacetone/O-2 gases and exposure time. The removal step was optimized by varying the dc-bias voltage to the substrate as well as sputtering time. The surface modification and removal of the modified layers were confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The etch per cycle was estimated to be in the range of 0.7-3.0 nm. The cyclic etching of the copper films using acetylacetone/O-2 gases and Ar sputtering revealed good etch profiles with an etch slope of 70 & DEG; without redepositions. It is proposed that the cyclic etching using acetylacetone/O-2 gases and Ar can be a suitable method to delineate the fine patterns on copper films.