Stacked Image Sensor Wiring for Smaller Pixel Substrate Area
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Solution Overview
Problem
Existing image capturing devices, such as CMOS image sensors, face challenges in reducing the substrate mounting area due to the configuration of photoelectric transducers and pixel transistors on the same semiconductor substrate.
Innovation Solution
The image sensor is designed with a stacked configuration of two semiconductor substrates, where the first substrate contains multiple photoelectric transducers and the second substrate contains a pixel transistor shared by sets of photoelectric transducers. This configuration uses a second wiring that connects to a first wiring via one contact, aggregating multiple first elements and reducing the number of contacts and area required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If photoelectric transducers and pixel transistors are disposed on the same semiconductor substrate, then the device structure is simplified, but the substrate area increases
Solution Approach 1:
The device is divided into two separate substrates: a first substrate containing photoelectric transducers and a second substrate containing pixel transistors. This segmentation allows each substrate to be optimized independently, reducing the overall area requirement while maintaining functional integration through the stacking configuration.
Solution Approach 2:
The invention transitions from a planar two-dimensional layout to a three-dimensional stacked configuration. By stacking the first substrate with photoelectric transducers and the second substrate with pixel transistors vertically, the device achieves area reduction while maintaining connectivity through vertical interconnections.
2Area of stationary object
If multiple photoelectric transducers share one pixel transistor on stacked substrates, then substrate area is reduced, but the number of contacts for wiring increases
Solution Approach 1:
Multiple first elements from different photoelectric transducers are merged and connected to a common second element through a shared wiring path. This merging reduces the number of separate contacts required, as multiple signal paths are consolidated into a single shared connection between the stacked substrates.
Solution Approach 2:
The second element on the second substrate serves as a universal connection point for multiple first elements from different photoelectric transducers. This multi-functional element receives and processes signals from multiple sources through a single interface, reducing the overall contact count while maintaining signal integrity.
3Reliability
If individually stacked substrates are used with shared pixel transistors, then photoelectric conversion efficiency is improved, but wiring area increases due to multiple contacts
Solution Approach 1:
The wiring configuration utilizes the vertical dimension by routing multiple first elements through a single shared contact path in the stacked substrate architecture. This three-dimensional wiring approach reduces the horizontal wiring area while maintaining efficient photoelectric conversion on the first substrate.
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 effectively reduces the substrate's area, improves photoelectric conversion efficiency, and enhances pixel density, thereby addressing the limitations of existing technologies.
Implementation Method 1
a first semiconductor substrate having a pixel region and a second semiconductor substrate having a logic circuit are stacked on top of each other
Data Source
AI summary
A first substrate having a plurality of photoelectric transducers formed on the first substrate, a second substrate having a pixel transistor for each of sets of two or more of the photoelectric transducers as a constituent unit, the pixel transistor being shared by the set and formed on the second substrate, and a second wiring which is connected to a first wiring formed on the second substrate via one contact, and is connected to a plurality of first elements, the first wiring leading to a second element shared by a plurality of first elements among a plurality of elements formed on the first substrate, each of the plurality of first elements being formed for each of the photoelectric transducers are included.