Copper was electrodeposited directly onto a sputter-deposited tungsten diffusion barrier layer in an acidic copper–ammonium–citrate (Cu–NH3–Cit) bath. The nucleation characteristic of copper deposits according to applied cathodic potential was investigated. The nucleation mode, nuclei density, and dominant copper species to be preferentially reduced were critically dependent on the applied cathodic potential. Pure instantaneous or progressive nucleation of copper was not observed, but instead, mixed nucleation mechanisms appeared. For low cathodic potentials, the copper deposits, which were reduced mainly from cupric ions, showed consequently a progressive nucleation characteristic despite initial instantaneous nucleation. For large cathodic potentials, the instantaneous nucleation of copper was achieved from the reduction of copper complexes following the early stage of progressive nucleation. The copper nuclei density of 2×1010cm−2 calculated for filling the sub-70 nm damascene structures was approached by applying large cathodic potentials.

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Cu nanowires are directly patterned on W diffusion barrier surface by electrodeposition without using any template. Prior to Cu nanowire growth, a photoresist (PR) film coated over the W surface was mechanically patterned in a random manner with atomic force microscope (AFM) tip. Polycrystalline Cu nanowires in the shape of beaded string were electrochemically formed along line patterns on the W surface. This new approach of Cu nanowire synthesis suggests the feasibility of fabricating Cu interconnects for Si-based electronic devices by direct Cu nanowire patterning.

Cast Ni-Al bronze (NAB) alloy, which is a most common material of ship propeller operating in sea water, is coated with the same NAB alloy by high-velocity oxy-fuel (HVOF) thermal spray process. Application of a HVOF NAB coating to cast NAB can be considered to enhance the resistance to corrosion fatigue failure of a NAB-based ship propeller and repair its damaged location at low cost. Linear sweep voltammetries, potentiostatic corrosion tests, and 80-day immersion corrosion tests are conducted in a 3.5% NaCl solution to investigate the corroding behavior of HVOF-NAB-coated cast NAB. Corrosion pits and microcracks through which the NaCl solution can easily permeate are developed from many pores included in the HVOF NAB coating. More serious corrosion compared to uncoated cast NAB occurs with producing corrosion products of Cu 2 O, Al 2 O 3 , and Fe 2 O 3 . Corrosion fatigue tests of both HVOF-NAB-coated cast NAB and uncoated cast NAB for reference are also conducted in the NaCl solution. Corrosion fatigue strength of the HVOF-NAB-coated cast NAB is measured as 140 MPa, which is much higher than 90 MPa of the uncoated cast NAB.