Redistribution Structure Layout to Prevent Seed Layer Delamination
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Solution Overview
Problem
Existing semiconductor packaging techniques face challenges in achieving high integration density and reliability due to issues such as delamination of seed layers during the formation of vias, which are exacerbated by copper diffusion from conductive features during reflow processes.
Innovation Solution
A semiconductor package design involving a first redistribution structure with offset vias and conductive connectors, where the second via is longer than the first via, and the conductive connectors are aligned with the second via, preventing lateral extension of the intermetallic compound and reducing copper diffusion from the conductive features, thereby avoiding seed layer delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging techniques are used, then manufacturing simplicity is maintained, but seed layer delamination occurs during via formation
Solution Approach 1:
The patent applies asymmetry by creating vias of different lengths (first via and second via) within the same redistribution structure. The second via extends deeper than the first via, allowing differential control of copper diffusion paths. This asymmetric via configuration prevents seed layer delamination by managing intermetallic compound formation at different depths, resolving the contradiction between maintaining simple manufacturing and preventing delamination.
Solution Approach 2:
The patent segments the via structure into multiple distinct via elements (first via, second via) with different characteristics. Each via is positioned at specific locations relative to conductive features, creating segmented diffusion barriers. This segmentation allows independent control of copper diffusion in different regions, preventing delamination while maintaining overall structural manageability.
2Reliability
If copper diffusion is allowed during reflow, then intermetallic compound formation occurs, but lateral extension causes seed layer delamination
Solution Approach 1:
The patent applies local quality by positioning specific via types at specific locations relative to conductive features. The first via is positioned to allow controlled intermetallic compound formation, while the second via is positioned to prevent lateral copper diffusion. This localized quality control ensures that intermetallic compounds form where needed for connection integrity while preventing lateral diffusion that would cause delamination.
Solution Approach 2:
The patent uses the via structure as an intermediary element between the conductive features and the seed layer. The via acts as a mediator that controls copper diffusion - allowing vertical diffusion for intermetallic compound formation while the via configuration blocks lateral diffusion paths. This intermediary structure resolves the contradiction between needing intermetallic compounds for connection integrity and preventing lateral diffusion that causes delamination.
3Productivity
If integration density is increased through PoP technology, then component density improves, but packaging complexity increases
Solution Approach 1:
The patent applies universality by creating a redistribution structure that performs multiple functions simultaneously. The same structure provides electrical redistribution, mechanical support, and differential control of copper diffusion through its asymmetric via configuration. This multi-functionality allows the package to achieve high integration density through PoP technology while managing complexity through a unified structure that handles multiple requirements.
Solution Approach 2:
The patent applies the nested doll principle by integrating multiple functional elements within a compact redistribution structure. The asymmetric vias are nested within the dielectric material, which is itself part of the larger package substrate. This nesting allows high integration density to be achieved while keeping the overall packaging structure manageable through hierarchical organization of components.
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
This design enhances the reliability of semiconductor packages by preventing delamination of seed layers and maintaining structural integrity, improving the overall performance and longevity of the devices.
Implementation Method 1
copper is diffused from the second via
Data Source
AI summary
A device includes a first redistribution structure comprising a first conductive line and a second conductive line. An integrated circuit die is attached to the first redistribution structure. A first via is coupled to the first conductive line on a first side, and a first conductive connector is coupled to the first conductive line on a second side opposite the first side. A second via is coupled to the second conductive line on the first side, and a second conductive connector is coupled to the second conductive line on the second side. The first via directly contacts the first conductive line without directly contacting the first conductive connector. The second via directly contacts the second conductive line and directly contacts the second conductive connector.