Connection Substrate Recess for Under-Fill Crack-Resistant Packaging
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Solution Overview
Problem
The fabrication of chip-on-wafer (CoW) structures for semiconductor packages often results in stresses that lead to cracks in the under-fill layer, compromising the reliability of the package.
Innovation Solution
A semiconductor package design that includes a package substrate, a connection substrate with a recession on its lower corner, a semiconductor chip on the connection substrate, and connection terminals connecting the package substrate to the connection substrate, with under-fill layers filling gaps between the chips and the connection substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a chip-on-wafer (CoW) structure is fabricated with multiple dies on a silicon interposer, then interconnect density is improved, but stress concentration causes cracks in the under-fill layer
Solution Approach 1:
The patent introduces asymmetry by forming a recess at the lower corner of the connection substrate. This asymmetric structural modification redistributes the stress that would otherwise concentrate at the corner, preventing crack initiation in the under-fill layer while maintaining the high interconnect density of the CoW structure
Solution Approach 2:
The recess is formed in advance during substrate processing, before under-fill material is applied. This pre-formed structural feature acts as a stress buffer that cushions against the thermal and mechanical stresses that develop during subsequent packaging and operation, preventing under-fill layer failure
2Reliability
If under-fill layer volume is increased to fill gaps between chips and connection substrate, then reliability is improved, but material protrusion from substrate sidewall occurs
Solution Approach 1:
The recess creates a localized region with different geometric properties at the lower corner of the connection substrate. This local structural modification allows the under-fill material to be contained within the recess boundaries, enabling sufficient fill volume for reliability without causing unwanted protrusion from the overall substrate sidewall
Solution Approach 2:
The recess introduces a vertical dimension constraint by creating a stepped structure. This dimensional change provides a physical boundary that confines the under-fill material in the vertical direction at the corner region, preventing lateral protrusion while still allowing adequate material volume for gap filling
Data Source
AI summary
A semiconductor package including a package substrate, a connection substrate on the package substrate and having on a lower corner of the connection substrate a recession that faces a top surface of the package substrate, a semiconductor chip on the connection substrate, a plurality of first connection terminals connecting the connection substrate to the semiconductor chip, and a plurality of second connection terminals connecting the package substrate to the connection substrate. The recession is laterally spaced apart from the second connection terminals.