The adhesion of copper films deposited onto aluminum nitride

Good adhesion between copper film and AIN substrate is obtained when the surface of AIN is laser-irradiated prior to copper film deposition and post deposition annealing is conducted. Surface chemistry of AIN substrates before and after laser irradiation and the interfacial reactions of copper film/AIN couples were studied with Auger Electron Spectroscopy (AES) to understand the adhesion mechanisms. The surface of as-received AIN substrates was covered with a thin sheath of Al2O3 Laser irradiation removed the surface Al2O3 layers, smoothened the surface, and decomposed AIN leaving metallic aluminum on the surface. The interfacial reactions in the copper film/AIN couple are affected by the amounts of oxygen and metallic aluminum available at the interface. The adhesion mechanism is the formation of a Cu-O-Al compound at the interface of copper film/AIN couple. Since copper does not react with AIN, laser induced decomposition of AIN seems to be the driving force for the formation of the compound. (C) 1999 Kluwer Academic Publishers.