Seal Ring Keep-Out Layout for Reliable Hybrid Bonding
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Solution Overview
Problem
In wafer-to-wafer bonding technologies, existing methods face challenges in achieving reliable and strong bonding due to tolerance variances and delamination issues, particularly when using hybrid bonding techniques, which can result in reduced bonding yield and increased bond failure rates.
Innovation Solution
The design of dies is altered by removing dummy bond pads from the layout and mechanically or electrically coupling them to a seal ring structure, creating a keep out zone to improve surface uniformity and bonding interface, allowing for fusion bonding of dielectric layers and direct metal-to-metal bonding without eutectic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dummy bond pads are included in the layout, then the bonding interface has more uniform pattern density, but the bonding yield decreases and delamination issues occur
Solution Approach 1:
The patent removes dummy bond pads from the bonding interface layout to eliminate the source of delamination and bonding failures. This extraction of problematic elements resolves the contradiction by prioritizing bonding reliability over pattern density uniformity, as the dummy pads were causing more harm than benefit to the overall bonding quality
Solution Approach 2:
The patent applies different quality requirements to different regions of the bonding interface. Active bond pads maintain their standard design for electrical functionality, while the regions where dummy pads would have been located are now kept clear to ensure bonding reliability. This local differentiation resolves the contradiction by allowing uniformity in critical areas without compromising overall yield
2Strength
If hybrid bonding is used with metal pads and oxide surfaces, then bonding strength is improved, but tolerance variances cause delamination and bond failure
Solution Approach 1:
The patent removes dummy bond pads in advance before the bonding process to prevent potential delamination and failure. This preliminary action eliminates the root cause of tolerance-related bonding issues, allowing the hybrid bonding to achieve both high strength and high reliability without the compromising effect of misplaced or misaligned dummy pads
Solution Approach 2:
The patent converts the potential harm of having dummy bond pads (which cause delamination and failure) into a benefit by strategically removing them. This creates larger clear bonding areas that improve both the strength and reliability of the hybrid bond, turning a design element that caused problems into an opportunity for enhanced bonding performance
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 enhances bonding yield and reliability by providing a uniform bonding interface, reducing bond failure rates and improving the strength of hybrid bonds between wafers, chips, or dies, regardless of size mismatches.
Implementation Method 1
In the fusion bonding, an oxide surface of a wafer is bonded to an oxide surface or a silicon surface of another wafer
Implementation Method 2
In the hybrid bonding, the metal pads of two wafers are bonded to each other through direct metal-to-metal bonding
Implementation Method 3
In the eutectic bonding, two eutectic materials are placed together, and are applied with a high pressure and a high temperature. The eutectic materials are hence molten. When the melted eutectic materials are solidified, the wafers are bonded together
Data Source
AI summary
A structure includes a first die and a second die. The first die includes a first bonding layer having a first plurality of bond pads disposed therein and a first seal ring disposed in the first bonding layer. The first bonding layer extends over the first seal ring. The second die includes a second bonding layer having a second plurality of bond pads disposed therein. The first plurality of bond pads is bonded to the second plurality of bond pads. The first bonding layer is bonded to the second bonding layer. An area interposed between the first seal ring and the second bonding layer is free of bond pads.