Dummy Micro Bump Layout for Void-Free 3D Die Underfill
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Solution Overview
Problem
Current 3D IC fabrication methods face limitations in achieving high integration density due to physical constraints and inefficiencies in underfill material distribution, leading to trapped voids and reduced reliability of semiconductor devices.
Innovation Solution
The introduction of dummy micro bumps between adjacent dies in a 3D IC stacking configuration enhances the flowability of underfill material by creating finer gaps, reducing the risk of trapped voids and improving the mechanical connection between dies and the base substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 3D IC fabrication methods are used, then integration density can be increased through stacking, but trapped voids form in underfill material reducing device reliability
Solution Approach 1:
The patent introduces a capillary wick structure as an intermediary element between the stacking dies. This wick structure serves as a mediator that actively draws underfill material through capillary action into regions that would otherwise be difficult to fill, preventing trapped voids while maintaining the 3D stacked configuration.
Solution Approach 2:
The patent replaces traditional mechanical filling methods with capillary action-based filling. Instead of relying solely on external pressure or gravity to distribute underfill material, the capillary wick structure utilizes surface tension and capillary forces to automatically draw material into the gaps between dies, eliminating voids without complex mechanical systems.
2Productivity
If more devices are integrated into one chip, then circuit density increases, but design complexity increases
Solution Approach 1:
The patent transitions from two-dimensional planar integration to three-dimensional stacking architecture. By utilizing the vertical dimension, multiple devices can be integrated into a single chip volume without increasing lateral footprint, thereby increasing circuit density while managing design complexity through standardized stacking interfaces.
3Manufacturing precision
If underfill material is dispensed without capillary structures, then manufacturing process is simple, but underfill material distribution is uneven creating voids
Solution Approach 1:
The capillary wick structure enables self-service filling where the underfill material is automatically drawn into the gaps between dies through capillary action without requiring external control systems. The structure itself performs the distribution function, eliminating the need for complex manufacturing control while achieving uniform material distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the reliability and yield of semiconductor devices by ensuring better capillary attraction and even underfill material distribution, thereby enhancing the mechanical connection and thermal management within the semiconductor device.
Implementation Method 1
dispensing an underfill material into gaps between the plurality of dies, the conductive joints, the dummy micro bumps, and the dummy pads
Data Source
AI summary
A method of fabricating a semiconductor device is provided. The method includes providing a die stacking unit that includes a plurality of dies stacked on each other, and a plurality of conductive joints connected between each two adjacent dies. The method includes providing a plurality of dummy micro bumps and dummy pads between the two adjacent dies and between the conductive joints. The dummy micro bumps and the dummy pads are connected to one of the two adjacent dies but not to the other, and the dummy micro bumps are formed on some of the dummy pads but not on all of the dummy pads. The method includes dispensing an underfill material into gaps between the plurality of dies, the conductive joints, the dummy micro bumps, and the dummy pads.