Conductive Pillar with Inner Polymer Core for Stress Relief
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Solution Overview
Problem
Current semiconductor devices face challenges with high stress at interconnect joints due to stiff conductive pillars, leading to high contact resistance and potential joint failure, especially in high aspect ratio interconnects, and existing methods like TSVs and THVs are costly and prone to voids, reducing reliability.
Innovation Solution
The use of conductive z-interconnect structures with an inner polymer core for stress relief, which reduces junction stress and improves reliability by providing both electrical interconnection and mechanical support in semiconductor devices, particularly in fan-out wafer level chip scale packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stiff conductive pillars are used for electrical interconnection, then structural support is provided, but high stress at interconnect joints occurs leading to high contact resistance and potential joint failure
Solution Approach 1:
The conductive pillar is constructed as a composite structure with an inner polymer core and outer conductive material layer. The polymer core provides stress relief and flexibility, while the conductive material layer provides electrical conductivity. This composite structure reduces joint stress and improves reliability while maintaining structural support and electrical interconnection functions.
2Reliability
If TSVs and THVs are used for vertical electrical interconnections, then electrical connectivity is achieved, but the process is costly and prone to voids reducing reliability
Solution Approach 1:
The invention extracts and eliminates the problematic via formation process (TSV/THV) by directly forming conductive pillars on the substrate surface. This eliminates the need for complex via etching, plating, and filling processes, reducing manufacturing cost and complexity while avoiding void formation and improving reliability.
Solution Approach 2:
The polymer core material used in the conductive pillar is a low-cost material that simplifies the manufacturing process. While the polymer core may be consumed or transformed during subsequent processing steps, its temporary presence enables simpler, cheaper fabrication compared to traditional via methods.
3Area of stationary object
If high aspect ratio interconnects are used to reduce device footprint, then integration density is improved, but stress at joints increases leading to contact resistance and joint failure
Solution Approach 1:
The composite structure with polymer core and conductive material layer provides flexibility and stress relief for high aspect ratio interconnects. The polymer core accommodates thermal expansion differences and reduces stress concentration, enabling high aspect ratio structures without joint failure while maintaining small device footprint.
Data Source
AI summary
A semiconductor device is made by providing a sacrificial substrate and depositing an adhesive layer over the sacrificial substrate. A first conductive layer is formed over the adhesive layer. A polymer pillar is formed over the first conductive layer. A second conductive layer is formed over the polymer pillar to create a conductive pillar with inner polymer core. A semiconductor die or component is mounted over the substrate. An encapsulant is deposited over the semiconductor die or component and around the conductive pillar. A first interconnect structure is formed over a first side of the encapsulant. The first interconnect structure is electrically connected to the conductive pillar. The sacrificial substrate and adhesive layers are removed. A second interconnect structure is formed over a second side of the encapsulant opposite the first interconnect structure. The second interconnect structure is electrically connected to the conductive pillar.