Conductive vias for redistribution lines in semiconductor devices

A method, comprising:

• forming first and second conductive lines on a substrate;
• forming a dielectric layer on the first and second conductive lines;
• forming first and second conductive vias through the dielectric layer and in contact with the first and second conductive lines, respectively, wherein forming the first and second conductive vias comprises:
• etching first and second openings through the dielectric layer to expose the first and second conductive lines, respectively;
• depositing first and second barrier layers in the first and second openings, respectively;
• and
• depositing first and second conductive layers on the first and second barrier layers, respectively, wherein top surfaces of the first and second conductive layers are substantially coplanar with a top surface of the dielectric layer;
• and
• forming first and second redistribution lines (RDL) on the top surfaces of the first and second conductive vias, respectively, wherein top surfaces of the first and second RDLs are substantially flat.

A structure, comprising:

• a conductive line on a substrate;
• a dielectric layer on the conductive line;
• a conductive via through the dielectric layer and in contact with the conductive line, wherein the conductive via comprises:
• a first barrier layer on a side surface of the dielectric layer;
• a seed layer on the barrier layer;
• and
• a conductive layer surrounded by the seed layer and comprising a first metal;
• a second barrier layer on the conductive via and the dielectric layer;
• and
• a redistribution line (RDL) on the second barrier layer and comprising a second metal different from the first metal, wherein a top surface of the RDL comprises a first portion above the conductive via and a second portion above the dielectric layer, and wherein a first vertical distance between the first portion and the conductive line is substantially the same as a second vertical distance between the second portion and the conductive line.