Semiconductor Package Conductive Ring Sealing UBM Interface
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving reliable mechanical integration and high component density in semiconductor packaging due to issues with adhesion and delamination between dielectric layers and under bump metallurgy (UBM) in redistribution structures, particularly in Package-on-Package (PoP) technology.
Innovation Solution
A conductive ring is formed around the perimeter of openings in the dielectric layer, sealing the interface between the UBM and the dielectric layer, and conductive connectors are formed on the UBM, preventing flux from entering the interface during reflow, thereby enhancing adhesion and mechanical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Package-on-Package (PoP) technology is used to increase integration density and reduce footprint, then component density and functionality are improved, but adhesion and delamination issues between dielectric layers and under bump metallurgy worsen
Solution Approach 1:
A conductive ring is introduced as an intermediary element between the dielectric layer and under bump metallurgy (UBM). The conductive ring is formed around the perimeter of openings in the dielectric layer and seals the interface between the UBM and dielectric layer, preventing flux from entering and causing delamination while maintaining electrical connectivity.
Solution Approach 2:
The conductive ring is formed in advance before the reflow process. By pre-forming the conductive ring that seals the interface between the dielectric layer and UBM, the structure is prepared to prevent flux penetration during the subsequent reflow process, thereby preventing adhesion issues before they occur.
2Reliability
If conductive connectors are formed on UBM without sealing the interface, then electrical connectivity is achieved, but flux enters the interface during reflow causing delamination and reducing mechanical reliability
Solution Approach 1:
The interface sealing function is segmented from the conductive connector function. The conductive ring provides interface sealing around the perimeter of openings, while conductive connectors are formed on the UBM for electrical connectivity. This segmentation allows each element to perform its specific function without interfering with the other.
Solution Approach 2:
Different regions of the UBM structure are given different functions: the perimeter region is sealed by the conductive ring to prevent flux penetration, while the center region accommodates conductive connectors for electrical connectivity. This local differentiation of quality ensures both mechanical reliability and electrical functionality.
Data Source
AI summary
In an embodiment, a device includes: an integrated circuit die; a first dielectric layer over the integrated circuit die; a first metallization pattern extending through the first dielectric layer to electrically connect to the integrated circuit die; a second dielectric layer over the first metallization pattern; an under bump metallurgy extending through the second dielectric layer; a third dielectric layer over the second dielectric layer and portions of the under bump metallurgy; a conductive ring sealing an interface of the third dielectric layer and the under bump metallurgy; and a conductive connector extending through the center of the conductive ring, the conductive connector electrically connected to the under bump metallurgy.