Wide Under Bump Metallization for Flexible RDL Interconnects
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving smaller and more creative packaging techniques for semiconductor dies due to limitations in reducing feature size and integrating more components within a given area, necessitating innovative solutions for improved contact resistance and flexibility in routing redistribution lines.
Innovation Solution
The formation of under bump metallizations (UBMs) with a large width that overlap multiple redistribution lines, providing a greater contact area and mechanical support, while also forming extension portions to interface with more surfaces, thereby reducing delamination risk and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but the contact resistance increases and manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The under bump metallization extends in the lateral dimension beyond the vertical connection point, creating an extended footprint that overlaps multiple redistribution lines. This dimensional extension allows the UBM to interface with multiple conductive paths simultaneously, reducing contact resistance without requiring smaller feature sizes.
Solution Approach 2:
The under bump metallization merges multiple redistribution lines by overlapping and electrically connecting to multiple lines simultaneously. This merging approach consolidates multiple signal paths into a single robust connection point, improving electrical contact while maintaining the original feature dimensions.
2Quantity of substance
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but routing flexibility of redistribution lines is reduced
Solution Approach 1:
The under bump metallization utilizes the lateral dimension to create an extended structure that can overlap multiple redistribution lines. This additional spatial dimension provides routing flexibility by allowing the UBM to connect to different line configurations without changing the vertical connection geometry.
Solution Approach 2:
The under bump metallization serves multiple functions simultaneously: it provides vertical electrical connection, lateral mechanical support, and multi-line interfacing capability. This multi-functionality allows a single structure to adapt to various routing configurations while maintaining integration density.
3Volume of moving object
If smaller packaging techniques are implemented, then device size is reduced, but mechanical support and structural reliability are compromised
Solution Approach 1:
The under bump metallization extends laterally beyond the vertical connection point, utilizing the horizontal dimension to provide mechanical support. This extended footprint distributes mechanical stresses across a larger area, strengthening the structure without increasing the vertical profile or overall device volume.
Solution Approach 2:
The under bump metallization is formed in advance to provide pre-established mechanical support and structural reinforcement. This preliminary structural preparation ensures that subsequent packaging and assembly processes can proceed with enhanced mechanical stability, even in compact device configurations.
Data Source
AI summary
In an embodiment, a device includes: a passivation layer on a semiconductor substrate; a first redistribution line on and extending along the passivation layer; a second redistribution line on and extending along the passivation layer; a first dielectric layer on the first redistribution line, the second redistribution line, and the passivation layer; and an under bump metallization having a bump portion and a first via portion, the bump portion disposed on and extending along the first dielectric layer, the bump portion overlapping the first redistribution line and the second redistribution line, the first via portion extending through the first dielectric layer to be physically and electrically coupled to the first redistribution line.