Method for manufacturing fine-pitch bumps and structure thereof

Abstract

A method for manufacturing fine-pitch bumps comprises providing a silicon substrate; forming a titanium-containing metal layer having a plurality of first zones and a plurality of second zones on the silicon substrate; forming a photoresist layer on the titanium-containing metal layer; patterning the photoresist layer; forming a plurality of copper bumps having a plurality of first top surfaces and a plurality of first ring surfaces; heating the photoresist layer to form a plurality of body portions and removable portions; etching the photoresist layer; forming a plurality of bump protection layers on the titanium-containing metal layer, the first top surface and the first ring surface, each of the bump protection layers comprises a bump coverage portion; plating a plurality of gold layers at the bump coverage portion; eventually, removing the second zones to enable each of the first zones to form an under bump metallurgy layer.

What is claimed is: 
     
         1 . A fine-pitch bump structure at least comprising:
 a silicon substrate having a surface, a plurality of bond pads disposed at the surface and a protective layer disposed at the surface, wherein the protective layer comprised a plurality of openings, and the bond pads are revealed by the openings;   a plurality of under bump metallurgy layers formed on the bond pads, each of the under bump metallurgy layers comprises a bearing portion and an extending portion;   a plurality of copper bumps formed on the under bump metallurgy layers, each of the copper bumps comprises a first top surface and a first ring surface, the bearing portion of each of the under bump metallurgy layers is located under each of the copper bumps, and the extending portion of each of the under bump metallurgy layers is protruded to the first ring surface of each of the copper bumps;   a plurality of bump protection layers formed on the extending portions of the under bump metallurgy layers, the first top surface and the first ring surface of each of the copper bumps, each of the bump protection layers comprises a metallic coverage portion and a bump coverage portion, wherein the bump coverage portion comprises a second top surface and a second ring surface, the first top surface and the first ring surface of each of the copper bumps are covered with each of the bump coverage portions, and each of the extending portions is covered with each of the metallic coverage portions; and   a plurality of gold layers formed at each of the metallic coverage portions, the second top surface and the second ring surface of each of the bump coverage portions, each the gold layers comprises a third top surface.   
     
     
         2 . The fine-pitch bump structure in accordance with  claim 1 , further comprises a plurality of wettable layers formed on the third top surfaces of the gold layers. 
     
     
         3 . The fine-pitch bump structure in accordance with  claim 1 , wherein each of the metallic coverage portions is protruded to the second ring surface of the bump coverage portion and comprises a first outer lateral surface. 
     
     
         4 . The fine-pitch bump structure in accordance with  claim 3 , wherein each of the gold layers comprises a second outer lateral surface coplanar with the first outer lateral surface of each of the metallic coverage portions. 
     
     
         5 . The fine-pitch bump structure in accordance with  claim 3 , wherein the extending portion of each of the under bump metallurgy layers comprises a third outer lateral surface coplanar with the first outer lateral surface of each of the metallic coverage portions.