Plasma pretreatment of the Cu seed layer surface in Cu electroplating

Effects of plasma pretreatment to the Cu seed layer on copper (Cu) electroplating were investigated. Copper seed layers were deposited by magnetron sputtering onto tantalum nitride barrier layers before electroplating copper in the forward pulsed mode. The Cu seed layer was cleaned by plasma H2 or N2 prior to electroplating a copper film. Cu films electroplated on the copper seed layer with plasma pretreatment have shown better electrical and physical properties such as electrical resistivities, surface morphologies, levels of impurities, adhesion and surface roughness than those without plasma pretreatment. It is shown that carbon and metal oxide contaminants at the sputtered Cu seed/TaN surface can be effectively removed by plasma H2 cleaning. The degree of the (1 1 1) preferred orientation of the pulsed plated Cu film with plasma H2 pretreatment is as high as that without plasma pretreatment. Also, plasma H2 precleaning is more effective in enhancing the Cu electroplating properties onto the Cu seed layer than plasma N2 precleaning.