Stacked Photoelectric Conversion Layout for Flat Substrate Bonding
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Solution Overview
Problem
The bondability between semiconductor substrates in photoelectric conversion devices is low due to uneven bonding surfaces and stress during dicing, leading to potential separation and gaps.
Innovation Solution
Incorporating conductive patterns with both wiring and dummy members on the substrates, particularly dummy members on the outer sides of the bonding surfaces, to improve flatness and bondability, reducing gaps and enhancing bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wiring patterns are used without dummy members, then device complexity is reduced, but bonding surface flatness deteriorates leading to poor bondability
Solution Approach 1:
The patent applies the copying principle by introducing dummy members that replicate the structural characteristics of functional wiring members without performing electrical functions. These dummy members are positioned in non-circuit regions to mirror the thickness and material properties of actual wiring, thereby maintaining bonding surface flatness without adding functional complexity. The dummy members serve as structural copies that fill voids and level the bonding surface.
Solution Approach 2:
The patent applies local quality by selectively placing dummy members only in specific regions where bonding surface flatness is compromised, such as outer side regions and areas with insufficient wiring density. Rather than uniformly increasing complexity across the entire device, the dummy members are strategically positioned to address local flatness issues, thus improving bonding precision without unnecessarily increasing overall device complexity.
2Reliability
If dummy members are added to improve bonding surface flatness, then bondability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies the merging principle by integrating the formation of dummy members with the existing multi-layer conductive pattern fabrication process. Dummy members are formed alongside functional wiring members using the same sequential deposition and patterning steps, combining two functions (structural support and electrical conduction) into a unified manufacturing flow. This approach improves bondability while minimizing the increase in manufacturing complexity by reusing existing process steps.
Solution Approach 2:
The patent applies parameter changes by adjusting the material composition, thickness, and positioning parameters of dummy members to match the bonding requirements. By carefully controlling these parameters, the dummy members achieve the desired bonding surface flatness without requiring fundamentally different manufacturing processes. The parameters are optimized to balance bondability improvement with ease of manufacture.
3Productivity
If wiring members are densely packed in circuit regions, then electrical functionality is improved, but bonding surface flatness deteriorates in outer regions
Solution Approach 1:
The patent applies copying by placing dummy members in outer non-circuit regions that replicate the thickness and material properties of the densely packed wiring members in circuit regions. This creates a structural mirror image that balances the bonding surface profile, ensuring that the flatness in outer regions matches that of the functional circuit regions, thereby maintaining overall bonding precision.
Solution Approach 2:
The patent applies asymmetry by recognizing that circuit regions and outer regions have different wiring density requirements. Rather than forcing uniform wiring distribution, the design allows asymmetric wiring patterns in functional areas while compensating with dummy members in non-functional areas. This asymmetric approach preserves electrical functionality in circuit regions while restoring bonding surface flatness in outer regions.
Data Source
AI summary
A photoelectric conversion device in which first and second substrates are bonded to each other is provided. The first substrate includes a first semiconductor layer having light receiving elements. The second substrate includes a second semiconductor layer having a circuit element for processing a signal generated by the light receiving elements. The photoelectric conversion device includes an electrode pad for external connection, an opening extending to the electrode pad, and a conductive pattern located between the first and second semiconductor layers. The conductive pattern includes wiring members that are used to drive the photoelectric conversion device and dummy members that are not used to drive the photoelectric conversion device. The dummy members include a dummy member located on an outer side relative to the opening in a plan view relative to a boundary between the first and second substrates.