Double-level copper interconnections using selective copper CVD

A study is made of selective copper chemical vapor deposition (CVD) using hydrogen reduction of bis-hexafluoro acetylacetonate copper to fill vias of double-level copper interconnections. The surface morphology of the selectively deposited copper on the substrate copper in the via bottom depends strongly on the via opening process. The two-step via opening process comprising reactive ion etching of the insulating interlayer and wet removal of the interlayer metal results in smooth copper plug formation by CVD. Double-level copper interconnection is demonstrated using this technique. Electrical measurement showed that the via resistance of a 1-μm hole was about 100 mΩ