Polishing method and apparatus

An apparatus for polishing a copper layer on a semiconductor substrate to form copper wiring on the semiconductor substrate, said apparatus comprising:

• a first polishing tool having a polishing surface for first polishing a copper layer, which layer includes copper on a barrier metal layer that is in grooves and on a surface of a semiconductor substrate in which the grooves are formed, by bringing the copper layer into sliding contact with said polishing surface;
• an eddy current sensor for determining when the copper layer has been polished by said first polishing tool to a predetermined thickness so as to stop the first polishing of the copper layer;
• a second polishing tool having a polishing surface for second polishing the copper layer after stoppage of the first polishing of the copper layer, by bringing the copper layer into sliding contact with said polishing surface of said second polishing tool;
• and
• an optical sensor for determining when the copper and the barrier metal layer have been removed by said second polishing tool from the surface of the semiconductor substrate, but not from the grooves, so as to stop the second polishing of the copper layer.

An apparatus for polishing a substrate, comprising:

• a polishing tool providing a polishing surface;
• a top ring for holding a substrate while the substrate is in contact with and moved relative to said polishing surface so as to polish the substrate;
• a first sensor to measure a film thickness of the substrate;
• and
• a second sensor to measure a film thickness of the substrate,
• wherein said first sensor is of a type that is different than that of said second sensor.