Under Bump Metallurgy Ring Wall Structure for Semiconductor Yield
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The intermetallic interface between the aluminum pad, under bump metallurgy layer, and solder ball in conventional semiconductor structures is the most fragile part, leading to separation or damage during ball shear tests, significantly reducing the yield rate in semiconductor manufacturing.
Innovation Solution
A semiconductor manufacturing process involving a silicon substrate with a protection layer, a first seed layer, a buffer layer, and a support layer is implemented, where the first seed layer forms a first under bump metallurgy layer with a ring wall and the buffer layer has a cladding portion, preventing separation from the connection pad by using specific materials like titanium-copper alloy, copper, and Polyimide for enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional semiconductor structure with aluminum pad, under bump metallurgy layer, and solder ball is used, then the manufacturing process is simple, but the intermetallic interface becomes fragile leading to separation or damage during ball shear tests
Solution Approach 1:
The under bump metallurgy layer is segmented into a first under bump metallurgy layer (ring wall structure) and a second under bump metallurgy layer, with the buffer layer positioned between them. This segmentation allows each layer to perform specific functions: the first layer provides mechanical support and prevents pad damage, while the second layer ensures electrical connection, thereby improving overall structural integrity without excessive complexity
Solution Approach 2:
A buffer layer made of copper or nickel is introduced as an intermediary between the first and second under bump metallurgy layers. This buffer layer acts as a transition zone that reduces stress concentration at the intermetallic interface, preventing separation and damage during ball shear tests. The buffer layer mediates the mechanical and thermal stresses between the solder ball and the aluminum pad, significantly improving reliability
2Productivity
If the under bump metallurgy layer is directly connected to the aluminum pad, then the manufacturing process is straightforward, but separation or damage occurs during ball shear tests reducing yield rate
Solution Approach 1:
The first under bump metallurgy layer with ring wall structure is formed preliminarily on the aluminum pad before forming the second under bump metallurgy layer. This preliminary structure provides mechanical reinforcement and stress distribution capability, preventing pad damage during subsequent soldering and ball shear testing processes, thereby improving yield rate
Solution Approach 2:
The patent employs composite material structure with multiple under bump metallurgy layers made of different materials (copper, nickel, or their alloys) combined with a buffer layer. This composite structure leverages the advantageous properties of each material to enhance overall mechanical strength, stress resistance, and electrical conductivity, preventing separation and damage while maintaining manufacturing feasibility
Data Source
AI summary
A semiconductor manufacturing process includes the following steps of providing a silicon substrate having at least one connection pad and a protection layer, forming a first seed layer having at least one first section and at least one second section, forming a first photoresist layer, forming a first buffer layer having a coupling portion and a cladding portion, removing the first photoresist layer, removing the second section of the first seed layer to form a first under bump metallurgy layer, forming a support layer on the protection layer and the first buffer layer, the first under bump metallurgy layer has a first ring wall, the first buffer layer has a second ring wall, wherein the first ring wall, the second ring wall and the cladding portion are cladded by the support layer, and forming a connection portion and covering the coupling portion with the connection portion.