Pulse reverse electrodeposition for metallization and planarization of a semiconductor substrates

A method for filling a microscopic recess in a surface of an electrically conducting substrate with a void-free deposit of metal comprising

• immersing an electrically conductive substrate having a surface and at least one microscopic recess in said surface in an electroplating bath containing ions of a metal to be deposited into said recess, said plating bath being essentially devoid of leveling agents,
• immersing a counter electrode in said plating bath, passing an electric current essentially continuously between said substrate and said counterelectrode for a period of time until said recess has been filled with said metal,
• wherein
• said electric current is a modulated reversing electric current comprising a train of pulses that are cathodic with respect to said substrate and pulses that are anodic with respect to said substrate,
• said cathodic pulses have a duty cycle less than about 50% and said anodic pulses have a duty cycle greater than about 50%,
• the charge transfer ratio of said cathodic pulses to said anodic pulses is greater than one, and
• the frequency of said pulse train ranges from about 10 Hertz to about 5000 Hertz.