Solid-State Imaging Bonding Layout for Void-Resistant Wafer Joining
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Solution Overview
Problem
Bonding misalignment between semiconductor substrates in solid-state imaging devices leads to variations in bonding strength, resulting in voids and potential separation during the thinning process of the Si substrate.
Innovation Solution
The solution involves a solid-state imaging device design where a first semiconductor substrate with a plurality of conductors is bonded to a second semiconductor substrate, with specific arrangements of overlapping conductors and insulating films in the bonding plane to maintain a constant proportion of bonded areas, ensuring consistent bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bonding misalignment occurs between first semiconductor substrate and second semiconductor substrate, then bonding strength stability decreases, but bonding strength variation increases causing void formation
Solution Approach 1:
The patent applies local quality by creating specific overlapping regions between insulating films in the bonding plane. Instead of uniform bonding across the entire interface, the design concentrates bonding strength in defined areas where insulating films from both substrates overlap, while other regions may have different bonding characteristics. This localized approach ensures that even with misalignment, the critical overlapping regions maintain stable bonding strength.
Solution Approach 2:
The patent implements preliminary action by pre-designing the conductor and insulating film patterns on both substrates before bonding occurs. The overlapping regions are planned and positioned in advance during the substrate fabrication process, ensuring that when bonding takes place, the alignment-critical features are already in their optimal positions. This pre-planning compensates for potential misalignment by having built-in tolerance zones.
2Reliability
If bonding strength varies in the bonding plane, then voids form in the bonding plane, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the bonding plane into distinct functional regions: overlapping regions where insulating films from both substrates meet and provide stable bonding, and non-overlapping regions with different characteristics. This segmentation allows the design to optimize bonding strength in critical areas without requiring complex structures across the entire bonding interface, thereby maintaining reliability while controlling complexity.
3Reliability
If conductors are arranged to overlap in specific regions, then bonding strength stability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses insulating films as intermediary elements between the conductors on opposing substrates. Instead of requiring direct conductor-to-conductor alignment, the insulating films serve as mediators that can overlap and bond independently, providing a more tolerant interface. The conductors are positioned to overlap in regions where their corresponding insulating films also overlap, creating a hierarchical bonding structure where the insulating film alignment is less critical than direct conductor alignment would be.
Data Source
AI summary
A solid-state imaging device capable of preventing variation in bonding strength in a bonding plane between a first semiconductor substrate and a second semiconductor substrate is provided. The solid-state imaging device includes a first semiconductor substrate having a plurality of first conductors, and a second semiconductor substrate bonded to the first semiconductor substrate and having a plurality of second conductors In a bonding plane between the first and second semiconductor substrates, the device includes regions where the conductors overlap, regions where insulating films and the conductors overlap, and regions where the insulating films overlap. The proportion of areas where the first insulating films and the second insulating films are bonded together to the bonding area between the first semiconductor substrate and the second semiconductor substrate is constant before and after the first semiconductor substrate and the second semiconductor substrate are bonded together.