Characteristics of pulse-reverse electrodeposited Cu thin film II. Effects of organic additives

Pulse-reverse electrodeposition is capable of improving the superfilling ability and other properties of Cu in device interconnections. In this research, the influences of pulse-reverse electrodeposition on the properties of Cu thin film were investigated in the presence of organic additives used for Cu superfilling. The anodic step of pulse-reverse electrodeposition gave rise to changes in crystallinity, resistivity, grain size, and surface roughness. Minimum resistivity at the optimum dissolution ratio was observed, revealing a 14% reduction of the resistivity as compared to pulse electrodeposition samples. This was ascribed to the minimization of surface roughness produced by the selective dissolution of SPS-covered Cu as opposed to PEG-Cl^--covered Cu. It was confirmed that the selectivity of the anodic step came from the adsorbates and the anodic potential, resulting in changes in the film properties.