Solid-State Image Sensor Layout for Shared Floating Diffusion
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Solution Overview
Problem
The configuration of solid-state imaging elements with shared floating diffusion regions for vertical and planar transistors complicates simultaneous optimization, leading to suboptimal conversion efficiency and potential color mixture due to charge short-circuits.
Innovation Solution
The implementation of a configuration where adjacent pixels share a floating diffusion, allowing for separate optimization of vertical and planar transistors and reducing the likelihood of charge short-circuits, thereby enhancing pixel processing and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared floating diffusion region is used for both vertical and planar transistors, then device complexity is reduced, but manufacturing precision deteriorates due to inability to simultaneously optimize both transistor types
Solution Approach 1:
The patent divides the pixel structure into distinct regions: a first pixel with a vertical transistor and its dedicated floating diffusion region, and a second pixel with a planar transistor and its dedicated floating diffusion region. This segmentation allows each transistor type to be independently optimized without interference from the other type, resolving the contradiction between device complexity reduction and manufacturing precision maintenance.
2Ease of manufacture
If vertical and planar transistors share the same floating diffusion region, then ease of manufacture improves, but reliability deteriorates due to potential charge short-circuits causing color mixture
Solution Approach 1:
The patent implements spatial segmentation by providing separate floating diffusion regions for vertical and planar transistors. The first floating diffusion region is exclusively for the vertical transistor, while the second floating diffusion region is exclusively for the planar transistor. This physical separation eliminates the risk of charge short-circuits between different transistor types, thereby maintaining reliability while still allowing both transistor types to coexist in the same imaging device.
3Productivity
If photoelectric conversion regions are positioned between light incident surface and vertical transistor, then conversion efficiency improves, but device complexity increases due to additional structural constraints
Solution Approach 1:
The patent applies local quality by optimizing the photoelectric conversion region placement specifically for the vertical transistor configuration. The photoelectric conversion region is positioned between the light incident surface and the vertical transistor in the first pixel, allowing maximum light absorption and conversion efficiency for that specific transistor type without imposing universal structural constraints on the entire device.
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 enables fine processing of pixels and optimizes conversion efficiency while minimizing color mixture, allowing for improved performance in generating color signals from shared photoelectric conversion regions.
Implementation Method 1
A solid-state imaging element of a vertical spectral type is proposed to be capable of generating a plurality of color signals from one pixel region by laminating a plurality of photoelectric conversion portions (photodiodes (PDs), etc.) in a depth direction of a substrate
Data Source
AI summary
An imaging device and an electronic apparatus including an imaging device are provided. The imaging device includes a substrate and a photoelectric conversion film disposed above the substrate. A first pixel includes a first photoelectric conversion film region, first and second photoelectric conversion regions formed in the substrate, and a vertical transistor for the first photoelectric conversion element. A second pixel includes a second photoelectric conversion film region, first and second photoelectric conversion regions formed in the substrate, and a vertical transistor for the first photoelectric conversion element. The imaging device also includes a first floating diffusion. The first floating diffusion is shared by the first photoelectric conversion regions of the first and second pixels. A portion of the first photoelectric conversion regions of the respective pixels is between a light incident surface of the substrate and the vertical transistor for the respective pixel.