Image Sensor Pixel Layout With Grid Structure for Higher Quantum Efficiency
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Solution Overview
Problem
As device geometries scale down, the quantum efficiency of image sensors decreases due to reduced photon incidence on photodetectors, leading to performance hindrance.
Innovation Solution
Implementing a grid structure with centralized round source follower transistors and optical filters arranged in a specific pattern to enhance quantum efficiency and reduce noise interference, facilitating faster signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If device geometries are scaled down to reduce size and cost, then manufacturing cost and device size are reduced, but quantum efficiency decreases due to reduced photon incidence on photodetectors
Solution Approach 1:
The patent transitions from planar photodetector arrangements to a three-dimensional stacked architecture where multiple photodetector layers are vertically arranged. This dimensional change allows photons to be detected at different depths and angles, increasing the probability of photon-photodetector interaction and improving quantum efficiency without increasing the device footprint area.
Solution Approach 2:
The patent implements a nested structure where multiple photodetector layers are stacked vertically, with each layer positioned to detect photons that penetrate through previous layers. This nesting arrangement maximizes the use of incident photons by providing multiple detection opportunities at different depths, thereby improving quantum efficiency in a compact volume.
2Measurement precision
If photodetector array density is increased to improve resolution, then measurement precision is improved, but noise interference increases and signal transmission speed decreases
Solution Approach 1:
The patent segments the photodetector array into multiple independent layers, each layer functioning as a separate detection unit. This segmentation allows for independent optimization of each layer's parameters and enables selective readout of signals from different depths, reducing cross-talk and noise interference between adjacent photodetectors while maintaining high spatial resolution.
Solution Approach 2:
The patent introduces intermediate optical elements and signal processing structures between photodetector layers to manage and filter signals. These intermediary components help separate useful signals from noise, reduce cross-layer interference, and enable selective signal transmission, thereby improving signal-to-noise ratio while maintaining high detection precision.
3Measurement precision
If photodetector array density is increased to improve resolution, then measurement precision is improved, but signal transmission speed decreases
Solution Approach 1:
The patent segments the photodetector array into multiple independent layers with separate readout circuits for each layer. This segmentation enables parallel signal processing, where signals from different layers can be read out simultaneously through different channels, thereby maintaining high signal transmission speed even as the total number of photodetectors increases for improved resolution.
Solution Approach 2:
The patent utilizes the vertical dimension by stacking photodetector layers, allowing signals to be transmitted through multiple spatial channels. This three-dimensional arrangement enables parallel signal transmission paths, increasing overall bandwidth and signal transmission speed while maintaining high spatial resolution through the dense vertical packing of photodetectors.
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
The centralized layout of round source follower transistors and optimized filter arrangement increases signal transmission speed and quantum efficiency, improving image sensor performance.
Implementation Method 1
each pixel area contains a photodetector configured to capture optical signals (e.g., light) and convert it to digital data
Data Source
AI summary
An image sensor includes a plurality of photodetectors, a plurality of optical filters, a grid structure and a single round source follower transistor. The photodetectors are disposed on a semiconductor substrate. The optical filters respectively cover at least one of the photodetectors. The grid structure is disposed on the semiconductor substrate and laterally surrounds the optical filters. The grid structure includes a plurality of first elongated grid sections and second elongated grid sections, the first elongated grid sections are arranged parallel to each other and extend in a first direction, the second elongated grid sections are arranged parallel to each other and extend in a second direction, the first and second elongated grid sections intersect each other at intersection points and define at least one closed opening extending in a vertical direction through the intersection points. The single round source follower transistor is disposed in the closed opening.