DOUBLE-LEVEL COPPER INTERCONNECTIONS USING SELECTIVE COPPER CVD

Selective copper CVD technique involving hydrogen reduction of hexafluoro acetylacetonate copper has been used to fill vias for fabricating double-level copper interconnect structure. The surface morphology of selectively deposited copper on copper substrate of the via bottom depends strongly on via opening process. A two-step via opening process consisting of an reactive ion etching of the insulating interlayer and a wet removal of the interlayer metal results in smooth copper plug formation by CVD. Double-level copper interconnect structures have been fabricated using this technique and a via resistance as low as 100 mOMEGA has been obtained for a 1 mum diameter via.