Method for forming a copper film on a substrate

The fabrication of electronic devices on semiconductor substrates, such as ultra large scale integration (ULSI) device fabrication, has resulted in integrated circuit (IC) chips having substantial miniaturization of electronic device dimensions. Conventional aluminum/silicon oxide (Al/SiO2) interconnect architectures have proven inadequate to meet the demand for higher interconnect performance (e.g., IC speed and reliability lifetime) needed to support increasingly miniaturized electronic device fabrication with higher chip integrated densities. To support further miniaturization, industry has chosen copper metalization to replace aluminum. Adhesion of a copper film, such as a copper interconnect, to a substrate underlayer, such as a substrate diffusion barrier, is enhanced with adhesion promotion techniques. The adhesion promotion techniques can repair the interface of the copper film and the substrate to enhance adhesion of the copper film for high-yield formation of inlaid copper metal lines and plugs. For instance, thermal annealing of a seed layer, including a copper seed layer, an alloy seed layer or a reactant seed layer, can repair contamination at the interface of the seed layer and the substrate. Alternatively, the adhesion promotion techniques can avoid contamination of the interface by depositing an inert seed layer, such as a noble (e.g., platinum) or passivated metal seed layer, or by depositing the seed layer under predetermined conditions that minimize contamination of the interface, and then depositing a bulk copper layer under predetermined conditions that maximize throughput. Alternatively, the adhesion promotion techniques can avoid the formation of an interface by graduated deposition of a first material and copper.