Stacked Image Sensor Wiring for Higher Pixel Density
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Solution Overview
Problem
The existing image capturing devices, such as CMOS, have a configuration where photoelectric transducers and pixel transistors are on the same semiconductor substrate, leading to an unsatisfactory reduction in substrate area, and require numerous contacts for wiring, increasing the substrate's surface area.
Innovation Solution
An image sensor design where the substrate with photoelectric transducers and the substrate with pixel transistors are stacked separately, with a shared pixel transistor for multiple photoelectric transducers, and a single contact connection for multiple wiring elements, reducing the number of contacts and substrate area.
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 simple, but the substrate area cannot be reduced satisfactorily
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 substrate area while maintaining functional integration through vertical stacking.
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 reduces the horizontal substrate area while maintaining all necessary functional components.
2Reliability
If a plurality of first elements are commonly connected to a second element using contacts one by one, then the wiring connection is established, but the number of contacts increases causing the area to be large
Solution Approach 1:
Multiple first elements from the first substrate are merged and connected to a single second element on the second substrate through a shared contact structure. This consolidation reduces the number of individual contacts required, thereby minimizing the area occupied by contact regions and wiring infrastructure.
Solution Approach 2:
A single contact structure serves multiple connection functions by establishing electrical connections between multiple first elements and a second element simultaneously. This multi-functional contact design reduces the total number of contacts needed, decreasing the overall wiring area.
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 configuration effectively reduces the substrate area and improves photoelectric conversion efficiency and resolution by minimizing transistor noise and increasing pixel density.
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
An image sensor comprises a first substrate having a first photoelectric transducer and a second photoelectric transducer formed on the first substrate, a first wiring formed on the first substrate and connected to the first photoelectric transducer and the second photoelectric transducer, a second substrate having a pixel transistor formed on the second substrate, the pixel transistor being connected to the first photoelectric transducer and the second photoelectric transducer, a second wiring formed on the second substrate, and a third wiring formed to penetrate the first substrate and the second substrate and connected to the first wiring and the second wiring.