A detailed study aimed at investigating the interfacial structure of Cu films deposited on high purity aluminum nitride (AlN) substrate, which controls the adhesive strength of the deposited Cu film, is described. In this system, the Cu films are deposited by uniform coating of nanosized Cu2O particles onto the substrate, oxidation of Cu2O to CuO by heat-treatment in air, and subsequent reduction to metallic Cu followed by electroless Cu plating. Effect of the treatment condition on the structure of composite layer formed on the AlN substrate was investigated by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, which show that the interfacial structure depends significantly on the annealing conditions. Upon heat-treatment above 800degreesC in air, an CuAl2O4 and/or alpha-Al2O3 phase is formed on the AlN surface. The adhesive strength of the deposited Cu film increased with increasing the annealing temperature, and maximum strength observed is ca. 4 kg per 2x2 mm(2) (kg/4 mm(2)), much greater than that obtained by conventional electroless plating process. The formation of an interfacial oxide layer is suggested to be responsible for high adhesive strength through chemical interaction. The use of Cu2O particles as deposition seeds having chemical bonding with AlN substrate can be crucial in this methodology, which has important implications for practical manufacture of Cu-based electronic devices fabricated on AlN substrate. (C) 2003 The Electrochemical Society.