Plating method and plating apparatus

A method for plating a substrate, comprising:

• providing a substrate having fine trench patterns which are covered with a seed layer;
• disposing said substrate adjacent an anode such that said substrate and said anode face one another and define a plating space therebetween;
• supplying a plating liquid into said plating space, said plating liquid containing metal ions and an additive so as to have an initial additive concentration;
• and
• forming a plated film on a surface of said seed layer by
• (i) applying an electric current between said seed layer and said anode while said plating liquid having said initial additive concentration is in said plating space, and
• (ii) while continuing to apply said electric current between said seed layer and said anode, changing the additive concentration of said plating liquid in said plating space relative to said initial additive concentration by supplying a liquid into said plating space.