Interposer Support Structure for Semiconductor Junction Reliability
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Solution Overview
Problem
Existing semiconductor package structures face challenges in maintaining junction reliability between upper and lower connection bumps while ensuring a constant distance between the interposer substrate and the package substrate, which affects the overall performance and reliability of stacked semiconductor packages.
Innovation Solution
A semiconductor package structure is designed with a support structure comprising a metal core ball and a ball cover layer that gradually decreases in thickness from the interposer substrate to the package substrate, providing electrical connectivity and mechanical support between the substrates, and a molding layer for sealing, thereby enhancing junction reliability and maintaining a consistent distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a support structure is added to maintain constant distance between interposer substrate and package substrate, then mechanical support and distance maintenance are improved, but device complexity increases
Solution Approach 1:
The support structure integrates multiple functions into a single component: the ball cover layer simultaneously provides mechanical support, maintains constant distance between substrates, and offers stress relief. This merging of functions improves reliability without proportionally increasing device complexity, as one structure accomplishes what would otherwise require multiple separate components.
Solution Approach 2:
The support structure uses a composite design consisting of a metal core ball surrounded by a ball cover layer made of different material properties. This composite structure combines the mechanical strength of the metal core with the protective and stress-distributing properties of the ball cover layer, achieving enhanced reliability while keeping the overall structure efficient and integrated.
2Reliability
If ball cover layer thickness is reduced to improve electrical connectivity, then junction reliability is improved, but mechanical support capability deteriorates
Solution Approach 1:
The ball cover layer is designed with non-uniform thickness, being thinner at the top surface near the interposer substrate and gradually thicker toward the bottom near the package substrate. This local variation in quality optimizes electrical connectivity at the critical junction interface while maintaining sufficient mechanical support capability in the lower regions, thus resolving the contradiction between electrical performance and mechanical strength.
Solution Approach 2:
The thickness parameter of the ball cover layer is strategically varied across different locations rather than maintaining a uniform thickness. By changing this geometric parameter locally, the design achieves optimal electrical connectivity where the layer is thinner while preserving mechanical support where greater thickness provides strength, thereby balancing both requirements.
Data Source
AI summary
A semiconductor package structure includes a semiconductor chip on a package substrate; a lower connection bump on the package substrate; and an interposer substrate on the lower connection bump on the package substrate and an upper surface of the semiconductor chip. The semiconductor package structure includes an upper connection bump on a lower surface of the interposer substrate; and a support structure on a lower surface of the interposer substrate, spaced apart from the upper connection bump to provide support between the package substrate and the interposer substrate. The upper connection bump and the lower connection bump constitute a connection bump structure, and the support structure includes a metal core ball and a ball cover layer surrounding the metal core ball, wherein the ball cover layer is formed to gradually decrease in thickness in a direction from the interposer substrate to the package substrate cross-section.