Under-Bump Pattern Geometry for Reliable Semiconductor Packaging
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Solution Overview
Problem
Current semiconductor packages face challenges in reliability and durability due to issues with the under-bump pattern design, which affects the electrical connections and the overall performance of the semiconductor chip.
Innovation Solution
The semiconductor package incorporates a redistribution substrate with an under-bump pattern, an under-bump seed pattern, and dielectric layers, where the under-bump pattern has a central and edge region design with specific angles and thicknesses, and the under-bump seed pattern covers the sidewall to enhance protection and connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the under-bump pattern is designed with a conventional structure, then the fabrication process is simple, but the reliability and durability of the semiconductor package are reduced
Solution Approach 1:
The under-bump pattern is designed with different thicknesses at different locations: the first thickness at the first region (edge) and the second thickness at the second region (center), where the first thickness is greater than the second thickness. This local variation in thickness provides enhanced protection at the edges where impurities are more likely to enter, while maintaining structural integrity overall, thereby improving reliability without excessive complexity
Solution Approach 2:
The under-bump pattern transitions from a conventional two-dimensional planar structure to a three-dimensional structure with varying thickness and an inclined surface. The angle of inclination is controlled to be between 45 degrees and 60 degrees, creating a wedge-like profile that provides both mechanical strength and protection against external impurities, resolving the contradiction between reliability improvement and structural complexity
2Object-affected harmful factors
If the under-bump pattern has a higher thickness, then the protection against external impurities is improved, but the fabrication precision requirements increase
Solution Approach 1:
The thickness of the under-bump pattern is optimized within specific ranges: the first thickness at the edge region is controlled between 5-15 micrometers, and the second thickness at the center region is controlled between 3-10 micrometers. These parameter specifications provide sufficient protection against external impurities while maintaining manufacturability and avoiding excessive precision requirements that would complicate the fabrication process
3Object-affected harmful factors
If the angle between the bottom surface and sidewall is increased, then the protection capability is improved, but the fabrication complexity increases
Solution Approach 1:
The angle between the bottom surface and the inclined surface of the under-bump pattern is controlled to be between 45 degrees and 60 degrees. This angular parameter optimization provides effective protection against external impurities by creating a geometry that resists contaminant penetration, while remaining within the capabilities of standard fabrication processes and avoiding excessive complexity
Data Source
AI summary
Disclosed are semiconductor packages and their fabricating methods. The semiconductor package comprises a redistribution substrate, a semiconductor chip on a top surface of the redistribution substrate, and a solder terminal on a bottom surface of the redistribution substrate. The redistribution substrate includes an under-bump pattern in contact with the solder terminal, a dielectric layer on a sidewall of the under-bump pattern, an under-bump seed pattern between the dielectric layer and the sidewall of the under-bump pattern, and a redistribution pattern on the under-bump pattern. The under-bump pattern has central and edge regions. A first top surface at the edge region of the under-bump pattern is at a level higher than that of a second top surface at the central region of the under-bump pattern. An angle between the bottom surface and the sidewall of the under-bump pattern is in a range of 110° to 140°.