Semiconductor Cavity Underfill Confinement for High Density I/O Pads
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Solution Overview
Problem
The increasing miniaturization of semiconductor dies and the need for higher I/O pad density in packaging pose challenges, such as limited pad pitch leading to solder bridges and underfill bleeding, which complicates packaging and reduces yield.
Innovation Solution
A semiconductor structure and method involving a cavity in the package's upper surface to confine underfill, allowing for increased I/O pad redistribution and reduced contamination, using a carrier substrate with buffer layers, through vias, and redistribution layers to facilitate greater flexibility in I/O pad placement and underfill containment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pitch of I/O pads is decreased to increase pad density, then the number of I/O pads that can be packed increases, but solder bridges may occur
Solution Approach 1:
The patent transitions from traditional fan-in packaging where I/O pads are limited to the die surface area to fan-out packaging where the package substrate area is larger than the die area. This dimensional expansion allows I/O pads to be redistributed over a larger area, increasing pad density without decreasing pitch to the point of causing solder bridges. The package substrate acts as an extended platform that accommodates higher pad counts while maintaining adequate spacing.
2Productivity
If fan-in packaging is used to maintain simple packaging process, then throughput is greater and cost is lower, but the number of I/O pads is limited due to die area constraints
Solution Approach 1:
The invention employs fan-out packaging where the package substrate area exceeds the die area, enabling I/O pads to be redistributed over a larger surface. This dimensional expansion allows significantly higher I/O pad counts to be accommodated while maintaining a streamlined packaging process. The larger package substrate provides additional real estate for pad redistribution without fundamentally changing the packaging workflow.
Solution Approach 2:
The packaging process is divided into distinct stages: die attachment to the package substrate, followed by I/O pad redistribution layer formation. This segmentation allows the die to be packaged first, then the I/O pads to be systematically redistributed over the larger package substrate area, enabling high pad density while maintaining process efficiency and throughput.
3Quantity of substance
If I/O pads are redistributed to greater area to increase pad density, then the number of I/O pads packed increases, but underfill bleeding may occur
Solution Approach 1:
The patent implements underfill confinement structures (such as barriers or channels) before the underfill application process. These pre-formed structures guide and contain the underfill material, preventing it from bleeding outward during the dispensing and curing processes. This preliminary containment measure enables safe underfill application even when I/O pads are redistributed over larger areas with higher density.
4Area of stationary object
If known-good-dies are packaged after sawing to enable fan-out packages, then I/O pad redistribution to greater area is possible, but packaging complexity increases
Solution Approach 1:
The packaging process is segmented into distinct operational phases: die singulation and selection, die attachment to package substrate, I/O pad redistribution layer formation, and underfill application. This segmentation transforms a potentially complex monolithic process into manageable discrete steps, each with clear objectives and procedures. The known-good-die approach is integrated as a preliminary sorting step that enables subsequent fan-out packaging without overwhelming process complexity.
Data Source
AI summary
A structure and method of forming are provided. The structure includes a dielectric layer disposed on a substrate. The structure includes a cavity in the dielectric layer, and a plurality of contacts positioned in the cavity and bonded to the substrate. A component is bonded to the plurality of contacts. Underfill is disposed in the cavity between the dielectric layer and the component. A plurality of connectors is on the dielectric layer, the connectors being connected through the dielectric layer to a conductor that is at a same level of metallization as the plurality of contacts.