Photoelectric Conversion Substrate Bonding With Dummy Conductive Patterns
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Solution Overview
Problem
The bondability between substrates in photoelectric conversion devices is compromised by low flatness of bonding surfaces, leading to potential separation during dicing due to stress, affecting both circuit and non-circuit regions.
Innovation Solution
Incorporating a conductive pattern with both wiring and dummy members on the substrates, where dummy members improve the flatness of bonding surfaces and reduce gaps between substrates, enhancing bondability and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding surfaces are formed without dummy members, then device complexity is reduced, but bondability between substrates deteriorates due to low flatness
Solution Approach 1:
The patent applies this principle by using dummy members that serve a temporary structural function during bonding. These dummy members are not intended for long-term functional use but rather to provide immediate flatness improvement for bonding. After serving their purpose in enhancing bondability, they can be removed or left as non-critical structures, embodying the concept of using simple, expendable elements to solve a specific problem.
Solution Approach 2:
The patent changes the physical parameters of the bonding surface by introducing dummy members that alter the flatness and surface topology. This parameter change directly addresses the bondability issue by creating a more uniform bonding interface, allowing the bonding process to proceed effectively despite the added structural element.
2Reliability
If dummy members are added to improve flatness, then bondability increases, but manufacturing precision requirements increase
Solution Approach 1:
The dummy members are incorporated into the conductive pattern structure before the bonding process occurs. This preliminary action of adding flatness-enhancing elements prior to bonding allows the bonding surfaces to achieve the necessary flatness without requiring extremely precise manufacturing control during the actual bonding operation. The flatness correction is done in advance through the dummy member structure.
3Reliability
If dummy members are placed on outer side relative to opening, then bondability at boundary improves, but device area increases
Solution Approach 1:
The patent applies local quality by placing dummy members specifically at the boundary region outer side relative to the opening, rather than uniformly distributing them across the entire substrate. This localized placement targets the specific area where bondability is most critical (the boundary region) while minimizing the overall area increase. The dummy members are concentrated where they provide maximum bonding benefit rather than being spread throughout the device.
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.