Multi-Tier Solder Resist Structure for Conductive Bump Separation
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Solution Overview
Problem
As integrated circuits (ICs) evolve with smaller feature sizes and larger footprints, substrate warpage can cause conductive bumps to short or bridge, leading to manufacturing failures and reduced reliability.
Innovation Solution
A multi-tier solder resist structure made of dielectric material, such as epoxy or polymer, is used between adjacent conductive bumps, with varying widths at different heights to prevent bridging and shorting, ensuring better connectivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrate warpage is present during IC manufacturing, then manufacturing complexity increases, but conductive bumps may short or bridge leading to reduced reliability
Solution Approach 1:
The solder resist structure is divided into multiple tiers (first tier, second tier, third tier) with each tier having different widths. This segmentation allows the structure to accommodate substrate warpage while maintaining proper spacing between conductive bumps, preventing shorting and bridging issues.
Solution Approach 2:
The invention introduces a vertical dimension by creating multi-tiered solder resist structures at different heights above the substrate. This dimensional approach allows the solder resist to adapt to substrate warpage without increasing lateral complexity, effectively preventing conductive bump failures.
2Productivity
If feature sizes are reduced to increase IC functionality, then processing power increases, but solder bridge risk increases due to smaller spacing
Solution Approach 1:
By extending the solder resist structure into the vertical dimension with multiple tiers, the invention provides additional spacing control between conductive bumps without reducing their horizontal density. This allows smaller feature sizes to be used while maintaining solder joint integrity through the multi-level resist structure.
Solution Approach 2:
The multi-tier solder resist structure provides localized spacing control between conductive bumps where needed most. Each tier can be optimized independently to provide appropriate clearance for specific bump configurations, enabling higher density layouts while preventing solder bridges.
3Reliability
If multi-tier solder resist structure is implemented, then bridging prevention improves, but manufacturing process complexity increases
Solution Approach 1:
The solder resist fabrication process is segmented into multiple deposition and patterning steps, with each tier being formed separately. This segmentation allows for better process control and quality assurance at each stage, making the complex multi-tier structure manufacturable through standardized semiconductor fabrication processes.
Data Source
AI summary
Some embodiments relate to a semiconductor structure. The semiconductor structure includes a first substrate including a first plurality of conductive pads that are laterally spaced apart from one another on the first substrate. A first plurality of conductive bumps are disposed on the first plurality of conductive pads, respectively. A multi-tiered solder-resist structure is disposed on the first substrate and arranged between the first plurality of conductive pads. The multi-tiered solder-resist structure has different widths at a different heights over the first substrate and contacts sidewalls of the first plurality of conductive bumps to separate the first plurality of conductive bumps from one another.