Semiconductor Package Recess Structure for Underfill Void Reduction
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Solution Overview
Problem
Semiconductor packages face issues such as delamination, cracking, and moisture-induced defects due to voids in the underfill material between the interposer and package substrate, which affect mechanical integrity and yield.
Innovation Solution
Incorporating recesses in the package substrate surface and channels in their bottom surfaces to accommodate semiconductor devices, ensuring a minimum gap for adequate underfill material flow, enhancing structural coupling and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the package substrate surface is made flat to simplify manufacturing, then manufacturing precision is improved, but voids form in the underfill material between the interposer and package substrate, reducing mechanical integrity
Solution Approach 1:
The package substrate is designed with recesses at specific locations where semiconductor devices will be mounted, creating local variations in surface topology. These recesses allow the underfill material to flow underneath the devices and eliminate voids, while the rest of the substrate maintains a flat surface for simplified manufacturing. This local modification resolves the contradiction by addressing the reliability issue only where needed.
Solution Approach 2:
The invention transitions from a two-dimensional flat substrate surface to a three-dimensional surface with recesses. By creating depth variations in the substrate surface, the underfill material can occupy the space underneath semiconductor devices, eliminating voids and improving mechanical integrity without compromising manufacturing feasibility.
2Productivity
If semiconductor devices are mounted directly on the package substrate, then device density is improved, but underfill material cannot flow adequately, causing delamination and cracking
Solution Approach 1:
Recesses are created at specific locations on the package substrate corresponding to semiconductor device positions. These localized recesses provide the necessary space for underfill material flow and device accommodation, while maintaining high device density in the overall package layout. The recesses are strategically placed to enable underfill flow paths without reducing device density.
Solution Approach 2:
The package substrate surface is segmented into raised areas and recessed areas. The recesses create separate zones that accommodate semiconductor devices and allow underfill material to flow underneath them. This segmentation enables adequate underfill penetration while maintaining high device density on the substrate.
3Reliability
If the package structure is made more complex to accommodate additional features, then mechanical integrity is improved, but device complexity increases
Solution Approach 1:
Instead of making the entire package substrate complex with recesses everywhere, the invention applies recesses only at specific locations where semiconductor devices will be mounted. This localized approach improves mechanical integrity by enabling proper underfill flow while minimizing the increase in overall package structure complexity.
Data Source
AI summary
Semiconductor packages and methods of fabricating semiconductor packages include a package substrate having a recess formed in a surface of the package substrate and at least one channel in a bottom surface of the recess. The recess may be configured to accommodate a semiconductor device located over a surface of an interposer that is bonded to the package substrate. Accordingly, a minimum gap distance may be maintained between the semiconductor device and the package substrate, which may ensure that sufficient underfill material may flow between the semiconductor device and the package substrate and within the at least one channel, thereby improving of the structural coupling between the interposer and the package substrate, and reducing the likelihood of package defects, such as delamination, cracking, and/or popcorn defects.