Method for filling via holes in a semiconductor layer structure

A method for filling at least one via hole in a semiconductor layer structure having an interconnect therein spaced from a first surface of the semiconductor layer structure, comprising the steps of:

• opening at least a first auxiliary via hole in said semiconductor layer structure from said first surface down to said interconnect so as to uncover a portion of said interconnect;
• applying a conductive layer having conforming edge coverage on said first surface and into said first auxiliary via hole so as to contact the uncovered portion of the interconnect;
• applying an insulating layer onto said conductive layer so as to fill the first auxiliary via hole;
• providing an opening through said insulating layer and conductive layer, and through said semiconductor layer structure from said first surface down to said interconnect so as to uncover another portion of said interconnect and form a first via hole thereto;
• covering sidewalls of the first via hole with an insulation structure;
• utilizing a portion of said conductive layer on said first surface of said semiconductor layer structure as an auxiliary contact;
• providing an electrolyte, immersing the semiconductor layer structure in the electrolyte, and connecting a power source for an electro-deposition between the electrolyte and said first interconnect by utilizing the auxiliary contact which is in electrical connection with said first interconnect via said conductive layer passing through said first auxiliary via hole;
• filling said first via hole with metal by electro-deposition in the electrolyte;
• and
• removing the insulating layer and conductive layer lying above the first surface of the semiconductor layer structure.