Redistribution Substrate Layout for Thick Under-Bump Reliability
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Solution Overview
Problem
Current semiconductor packages face challenges in achieving enhanced reliability and durability while maintaining a compact size, with existing designs often compromising on these aspects due to limitations in under-bump pattern thickness and redistribution pattern configurations.
Innovation Solution
The semiconductor package incorporates a redistribution substrate with an under-bump pattern having a greater thickness than the redistribution line parts, and a dielectric layer covering the sidewall of the under-bump pattern, along with specific angle and width configurations, to enhance connectivity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the under-bump pattern thickness is increased to enhance reliability and durability, then the manufacturing complexity increases due to additional process steps
Solution Approach 1:
The patent combines the under-bump pattern formation with the redistribution pattern formation into a single etching process. The under-bump pattern and redistribution patterns are etched simultaneously through the dielectric layer, eliminating the need for separate resist patterns and reducing manufacturing complexity while maintaining the enhanced reliability provided by the thicker under-bump pattern
Solution Approach 2:
The single etching process serves multiple functions: it creates the under-bump pattern, forms the redistribution patterns, and defines their relative positions all in one step. This multi-functional approach resolves the contradiction by achieving complex structural requirements without proportionally increasing manufacturing complexity
2Reliability
If the under-bump pattern thickness is increased to enhance reliability, then the package size increases
Solution Approach 1:
The patent applies different thickness characteristics to different regions: the under-bump pattern has greater thickness for reliability, while the redistribution line parts have lesser thickness for compactness. This localized differentiation allows the package to achieve enhanced reliability without proportionally increasing overall package size
Solution Approach 2:
The patent transitions from a two-dimensional planar structure to a three-dimensional structure with varying thicknesses. The under-bump pattern extends deeper than the redistribution line parts, creating a stepped configuration that optimizes both reliability and size by utilizing the vertical dimension strategically
3Manufacturing precision
If multiple resist patterns are used to form under-bump and redistribution patterns separately, then the manufacturing precision improves, but the fabrication process complexity increases
Solution Approach 1:
The patent merges the formation of under-bump patterns and redistribution patterns into a single etching step using one resist pattern. This approach maintains manufacturing precision by ensuring accurate alignment between patterns while significantly simplifying the fabrication process by eliminating multiple resist application and removal cycles
Solution Approach 2:
The single resist pattern is designed in advance to define both the under-bump pattern and redistribution patterns simultaneously. This preliminary design ensures that all patterns are formed with consistent precision requirements met, while the actual fabrication process remains simple and efficient
Data Source
AI summary
Disclosed is a semiconductor package comprising a redistribution substrate, and a semiconductor chip on a top surface of the redistribution substrate. The redistribution substrate includes an under-bump pattern, a lower dielectric layer that covers a sidewall of the under-bump pattern, and a first redistribution pattern on the lower dielectric layer. The first redistribution pattern includes a first line part. A width at a top surface of the under-bump pattern is greater than a width at a bottom surface of the under-bump pattern. A thickness of the under-bump pattern is greater than a thickness of the first line part.