Copper Edge Seal Ring Structure for FOWLP Interposer Reliability
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Solution Overview
Problem
Fan-out wafer level packages (FOWLPs) require interposers with sufficient mechanical strength to withstand bonding processes, but existing solutions may not adequately prevent moisture, hydrogen, and contaminant ingress.
Innovation Solution
The use of a copper-based edge seal ring structure that blocks lateral ingress of moisture, hydrogen, and contaminants, formed through a process involving copper-based redistribution interconnect structures and dielectric material layers, with a copper edge seal ring structure that vertically extends through the interconnect-level dielectric material layers and laterally surrounds the package-side bump structures and redistribution interconnect structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interposer structures are used, then the interposer can provide basic mechanical support, but it cannot adequately prevent lateral ingress of moisture, hydrogen, and contaminants
Solution Approach 1:
The interposer is segmented into functional zones: a core region containing semiconductor devices, a transition region with gradually varying thickness, and an outer region with the copper edge seal ring structure. This segmentation allows each zone to perform its specific function while collectively providing both mechanical support and environmental protection.
Solution Approach 2:
The interposer employs composite material construction combining organic polymer matrix material with copper-based edge seal ring structures and dielectric material layers. This composite approach integrates the mechanical properties of polymers with the barrier properties of copper and dielectric materials to achieve both structural integrity and contamination prevention.
2Strength
If the interposer thickness is uniformly distributed, then manufacturing is simplified, but mechanical strength at the edges is insufficient to withstand bonding processes
Solution Approach 1:
The interposer features local quality variation through its transition region where the thickness gradually changes from the core to the outer region. This localized thickness variation provides enhanced mechanical strength at the edges where it is most needed for bonding processes, while maintaining a simpler overall structure that is easier to manufacture compared to completely non-uniform designs.
3Reliability
If aluminum is used in the metallic ring structure, then manufacturing is easier, but it does not provide adequate blocking against lateral ingress of contaminants
Solution Approach 1:
The invention changes the material parameter from aluminum to copper in the edge seal ring structure. This parameter change significantly improves the blocking capability against lateral ingress of moisture, hydrogen, and contaminants, while the copper-based structure can be formed using standard electroplating processes that are already prevalent in semiconductor manufacturing, thereby maintaining ease of manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The copper-based edge seal ring structure enhances the mechanical strength of the interposer and provides a contiguous seal that effectively prevents moisture, hydrogen, and contaminant ingress, ensuring the reliability and durability of the FOWLP.
Implementation Method 1
a copper-based edge seal ring structure that blocks lateral ingress of moisture, hydrogen, and contaminants
Data Source
AI summary
An organic interposer includes interconnect-level dielectric material layers embedding redistribution interconnect structures, package-side bump structures located on a first side of the interconnect-level dielectric material layers, at least one dielectric capping layer located on a second side of the interconnect-level dielectric material layers, a bonding-level dielectric layer located on the at least one dielectric capping layer, metallic pad structures including pad via portions embedded in the at least one dielectric capping layer and pad plate portions embedded in the bonding-level dielectric layer, and an edge seal ring structure vertically extending from a first horizontal plane including bonding surfaces of the package-side bump structures to a second horizontal plane including distal planar surfaces of the metallic pad structures. The edge seal ring structure may include a vertical stack of metallic ring structures that are free of aluminum and laterally surround the package-side bump structures and the redistribution interconnect structures.