Bumping process and structure thereof

Abstract

A bumping process includes providing a silicon substrate, forming a titanium-containing metal layer on the silicon substrate, wherein the titanium-containing metal layer comprises a plurality of first areas and a plurality of second areas, forming a photoresist layer on the titanium-containing metal layer, patterning the photoresist layer to form a plurality of opening slots, forming a plurality of bottom coverage layers at the opening slots, proceeding a heat procedure, forming a plurality of external coverage layers to make each of the external coverage layers connect with each of the bottom coverage layers, wherein said external coverage layer and said bottom coverage layer form a wrap layer and completely surround the copper bump, forming a plurality of connective layers on the external coverage layers, removing the photoresist layer, removing the second areas and enabling each of the first areas to form an under bump metallurgy layer.

What is claimed is: 
     
         1 . A bump structure at least includes:
 a silicon substrate having a surface, a plurality of bond pads disposed on the surface, and a protective layer disposed on the surface, wherein the protective layer comprises   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;   a plurality of copper bumps formed on top of the under bump metallurgy layers, and each of the copper bumps comprises a first top surface, a ring surface, and a bottom surface;   a plurality of wrap layers, each of the copper bumps is completely surrounded by each of the wrap layers, wherein the wrap layer comprises a bottom coverage layer and an external coverage layer in connection with the bottom coverage layer, each of the bottom coverage layers is formed on each of the under bump metallurgy layers, each of the external coverage layers is formed on the first top surface of each of the copper bumps and the ring surface, the bottom surface of each of the copper bumps is located on each of the bottom coverage layers, and each of the external coverage layers comprises a second top surface; and   a plurality of connective layers formed on the second top surfaces of the external coverage layers.   
     
     
         2 . The bump structure in accordance with  claim 1 , wherein the material of the connective layers can be gold. 
     
     
         3 . The bump structure in accordance with  claim 1 , wherein the material of the under bump metallurgy layers can be selected from one of titanium/tungsten/gold, titanium/copper, titanium/tungsten/copper, or titanium/nickel (vanadium)/copper. 
     
     
         4 . The bump structure in accordance with  claim 1 , wherein the material of the bottom coverage layers and the external coverage layers can be chosen from one of nickel, palladium or gold.