The flowage bias sputter method for planarized aluminum interconnections in VLSIs

A novel planarizing technology, Flowage Bias sputter (FB sputter), has been developed. Well below its melting point, Al flows into grooves through plastic deformation by applying negative substrate bias in the plasma atmosphere. With this newly found mechanism, high speed formation of completely planarized Al film has been accomplished, either by exposure to the plasma atmosphere of deposited Al films (bias-treatment), or by sputter deposition under application of negative substrate bias (bias-deposition). Thin Al film deposition prior to the bias deposition (two step deposition) provides high quality (low resistivity, high specular reflectivity) films without radiation damage. Using bias-deposition, two level interconnections with sub-micron ridges, valleys and via-holes were successfully fabricated.