Seal Ring Layout for Reliable Hybrid Bonding Without Dummy Pads
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Solution Overview
Problem
Existing wafer-to-wafer bonding technologies face challenges in achieving reliable and strong bonding due to tolerance variances from die processing, particularly with hybrid bonding methods, which can be exacerbated by the presence of dummy bond pads in close proximity.
Innovation Solution
The design of dies is altered to remove dummy bond pads from the layout, especially in areas over a seal ring structure, and in some cases, these dummy bond pads are mechanically and electrically coupled to the seal ring, enhancing the bonding process by reducing tolerance variances and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dummy bond pads are present in close proximity to the bonding interface, then the bond pad layout can be simplified and manufacturing can be easier, but tolerance variances from die processing are exacerbated and bonding reliability deteriorates
Solution Approach 1:
The patent removes dummy bond pads from the bonding interface area, extracting the problematic elements that cause tolerance variance issues. This allows the remaining active bond pads to be positioned optimally without the compounding effect of dummy pads in close proximity, thereby improving bonding reliability while maintaining manufacturing simplicity through the streamlined layout.
Solution Approach 2:
The patent applies different quality requirements to different regions of the die: active bond pads are positioned in areas with controlled tolerance characteristics, while dummy bond pads are either removed or positioned in regions that do not adversely affect the bonding interface. This local differentiation optimizes the bonding reliability without compromising overall manufacturing ease.
2Manufacturing precision
If dummy bond pads are removed from the layout, then tolerance variances are reduced and bonding yield increases, but the bond pad layout design becomes more complex
Solution Approach 1:
By removing dummy bond pads from the bonding interface region, the patent eliminates the source of tolerance variance exacerbation. Although this requires redesigning the bond pad layout, the resulting configuration achieves superior manufacturing precision and bonding yield by preventing the compounding of tolerance errors that would occur with dummy pads in close proximity.
3Reliability
If dummy bond pads are mechanically and electrically coupled to the seal ring, then bonding reliability is improved and yield increases, but the device structure becomes more complex
Solution Approach 1:
The patent merges dummy bond pads with the seal ring structure by mechanically and electrically coupling them. This integration serves multiple functions simultaneously: the dummy pads continue to provide layout regularity and stress distribution benefits, while their coupling to the seal ring eliminates tolerance variance issues at the bonding interface and improves bonding reliability, all within a unified structural design.
Solution Approach 2:
The seal ring structure is given multiple functions: it provides its traditional sealing and structural support roles, and additionally serves as an electrical and mechanical coupling element for the dummy bond pads. This multi-functionality improves bonding reliability through better tolerance control while avoiding the need for separate structures that would increase device complexity.
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.