Solid hermetic via and bump fabrication

Abstract

A method of forming an electrically conductive via with bumps on both sides of a substrate wherein there is provided a substrate having a pair of opposing surfaces and a via extending between the opposing surfaces. A layer of a material capable of forming a seed for receiving thereon a plating material is provided on one of the surfaces extending to the via. The structure is then placed into an electroplating bath, preferably gold-containing, to electroplate the walls of the via. The electroplated material is then heated to a temperature above its flow or melting temperature in a reducing atmosphere for a time sufficient to cause the electroplated material to fill the via and any voids within the via. The step of heating the electroplated material is preferably to a temperature at least 10 degrees C. above its flow or melting temperature of the electroplated material. The reducing atmosphere is from about 5 percent to 100 percent hydrogen and the remainder preferably nitrogen. The step of electroplating can include electroplating of sufficient electroplated material in the via to provide a bump on at least one of the surfaces heating.

Dependencies are inferred from the claim text.