Redistribution Layer Trench Slope for Copper Migration Suppression
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Solution Overview
Problem
Current semiconductor redistribution layer structures fail to maintain dielectric strength voltage due to copper migration between layers, leading to reduced reliability, especially in high-humidity and high-temperature environments.
Innovation Solution
Incorporating a slope in the interconnection trench of the redistribution layer structure, where the maximum opening width of the trench is larger than the redistribution layer width, effectively increasing the distance along the interface where copper migration occurs, thereby maintaining the insulating distance between redistribution layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a copper wire is used instead of gold wire for cost reduction, then manufacturing cost is reduced, but the pad is easily damaged due to copper's higher hardness
Solution Approach 1:
A redistribution layer is introduced as an intermediary component between the copper wire and the pad. This redistribution layer absorbs the mechanical stress and prevents direct contact between the hard copper wire and the vulnerable pad, thereby maintaining pad durability while enabling the use of cost-effective copper wiring.
2Reliability
If a slope is provided on the interconnection trench side face with maximum opening width larger than redistribution layer width, then copper migration is suppressed, but manufacturing complexity increases
Solution Approach 1:
The interconnection trench is designed with an asymmetric cross-sectional shape featuring a sloped side face rather than vertical walls. The maximum opening width of the trench is intentionally made larger than the width of the redistribution layer it encapsulates. This asymmetric geometry creates a mechanical constraint that suppresses copper migration by preventing uniform expansion of copper atoms, while the slope angle and width ratio are optimized to balance manufacturing feasibility with migration suppression effectiveness.
Data Source
AI summary
Reliability of a semiconductor device is improved. A slope is provided on a side face of an interconnection trench in sectional view in an interconnection width direction of a redistribution layer. The maximum opening width of the interconnection trench in the interconnection width direction is larger than the maximum interconnection width of the redistribution layer in the interconnection width direction, and the interconnection trench is provided so as to encapsulate the redistribution layer in plan view.