Patent ID: 9136167
Filing Date: 2015-09-15
Classification: H01L

Abstract:
1. A method of making a pillar structure, the method comprising: forming a first under-bump-metallurgy (UBM) layer formed on a pad region of a substrate, wherein the first UBM layer includes sidewalls; forming a second UBM layer on the first UBM layer, wherein the second UBM layer includes a sidewall surface, an area of the first UBM layer is greater than an area of the second UBM layer; forming a copper-containing pillar on the second UBM layer, wherein the copper-containing pillar includes a sidewall surface and a top surface; and forming a protection structure on the sidewall surface of the copper-containing pillar and on an entirety of the sidewall surface of the second UBM layer, wherein the protection structure does not cover the sidewalls of the first UBM layer, and the protection structure is a non-metal material.