Dummy Feature in Redistribution Structure for PoP Stress Mitigation
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Solution Overview
Problem
New packaging technologies for semiconductor devices, such as package on package (PoP), face manufacturing challenges due to stress propagation from heterogeneous materials interfaces, leading to potential damage and reliability issues in the redistribution structure.
Innovation Solution
Incorporating a redistribution structure with active conductive lines and dummy features under the interface between the integrated circuit die and the package layer, which distributes stress and prevents damage to active conductive lines, enhancing the package structure's reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If package on package (PoP) technology is adopted to integrate multiple device dies, then integration density and functionality are improved, but stress propagation from heterogeneous materials interfaces causes damage to redistribution structure
Solution Approach 1:
The patent introduces a dummy feature as an intermediary element between the first and second redistribution lines at the heterogeneous materials interface. This dummy feature acts as a stress mediator that absorbs and distributes the stress generated by thermal expansion mismatches between different materials (substrate, passivation layer, conductive lines), preventing stress concentration that would otherwise damage the active redistribution structure and maintain reliability while enabling PoP integration.
Solution Approach 2:
The patent applies local quality by adding a dummy feature specifically at the critical location where stress concentration occurs (at the heterogeneous materials interface), while leaving other areas of the redistribution structure unchanged. This localized modification provides stress distribution exactly where needed without affecting the overall functionality or increasing unnecessary complexity elsewhere in the device.
2Adaptability or versatility
If heterogeneous materials are used in package structure, then functional integration is improved, but stress concentration at interfaces damages active conductive lines
Solution Approach 1:
The patent converts the harmful stress concentration effect into a beneficial stress distribution mechanism by introducing the dummy feature. The heterogeneous materials still provide their intended functional benefits (different materials for substrate, passivation, and conduction), but the dummy feature transforms the previously harmful interfacial stress into a distributed stress pattern that protects the active conductive lines while maintaining functional integration.
3Adaptability or versatility
If thermal expansion differences between materials are present, then material selection for functionality is improved, but stress propagation during temperature changes damages redistribution structure
Solution Approach 1:
The patent implements beforehand cushioning by pre-positioning the dummy feature in the redistribution structure before thermal stress occurs. This dummy feature serves as a pre-prepared stress buffer that absorbs and mitigates the thermal expansion stresses when temperature changes occur during device operation, protecting the active conductive lines from stress-induced damage and maintaining structural strength.
Data Source
AI summary
Package structures are provided. The package structure includes an integrated circuit die. The package structure also includes a package layer surrounding the integrated circuit die. There is an interface between the integrated circuit die and the package layer. The package structure further includes a redistribution structure below the integrated circuit die and the package layer. The redistribution structure includes active conductive lines electrically connected to the integrated circuit die. The redistribution structure also includes a dummy conductive line between the active conductive lines. The dummy conductive line extends across the interface.