Demodulation Pixel Devices With Segmented Floating Diffusion Layers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing pixel devices face limitations in demodulating incident modulated light due to insufficient light intensity, leading to low signal-to-noise ratios and lengthy charge-carrier transport paths, which hinder applications requiring efficient demodulation, such as indirect time-of-flight technologies.

Innovation Solution

The pixel devices incorporate a combination of large photo-detection regions with minimized charge-carrier transport paths using multiple transfer gates and floating diffusion implant layers, allowing for efficient demodulation of incident modulated light by alternately conducting charge carriers to multiple floating diffusion implant layers, reducing transport lengths and enhancing signal acquisition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the photo-detection region is enlarged to collect more light, then light sensitivity is improved, but charge-carrier transport path length increases

Engineering Contradiction:

Improvelight sensitivityVSAvoidcharge-carrier transport path length

Core Design Contradiction:

Illumination intensityVSLength of stationary object

Solution Approach 1:

The pixel device segments the photo-detection region into multiple zones, each associated with a separate floating diffusion implant layer. Charge carriers generated in each zone are collected by its corresponding floating diffusion layer, creating multiple shorter transport paths instead of one long path. This segmentation allows the overall photo-detection region to remain large for high light sensitivity while individual charge-carrier transport paths remain short for fast signal acquisition.

Inventive Principle:

Principle #1Segmentation

2Speed

If multiple transfer gates and floating diffusion implant layers are used to minimize charge-carrier transport paths, then signal acquisition speed is improved, but device complexity increases

Engineering Contradiction:

Improvesignal acquisition speedVSAvoiddevice complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The pixel device merges multiple functional components - transfer gates, floating diffusion implant layers, and photo-detection regions - into a single integrated structure. The transfer gates are positioned between the photo-detection region and floating diffusion layers, creating a unified charge-carrier collection system. This merging achieves fast signal acquisition through multiple short transport paths while maintaining manufacturing feasibility through integration rather than separate components.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the photo-detection region is enlarged to improve light sensitivity, then signal-to-noise ratio is improved, but charge-carrier transport time increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidcharge-carrier transport time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 enables reliable signal production and efficient demodulation of modulated light, even at low light intensities, preserving phase-delays information for distance measurement, thus expanding the applications of pixel devices.

Implementation Method 1

Light incident on the photo-detection region generates charge-carriers which travel through the photo-detection region and are sampled, thereby generating signals with characteristics of the incident light.

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

modulated incident light can generate charge carriers with modulation characteristics representative of the modulated incident light

Methodology Applied

Scientific EffectPhase modulation detection: Phase Modulation

Data Source

PatentEP3365916B1Demodulation pixel devices, arrays of pixel devices and optoelectronic devices incorporating the same

Publication Date: 2020.12.09 HEPTAGON MICRO OPTICS PTE LTD

Figure 1A~1B
Figure 2A~2B
Figure 2C~2D

AI summary

Pixel devices and arrays of pixel devices are operable to demodulate modulated light incident on a photo-detection region of the pixel devices. The pixel devices can include floating diffusion implant layers and transfer gates. The floating diffusion implant layers and transfer gates are disposed such that photo-generated charge carriers can be conducted to the floating diffusion implant layers over minimal charge-carrier transport paths.