Pixel Sensor Diffusion Layers for Broad-Wavelength Quantum Efficiency
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Solution Overview
Problem
Existing CMOS image sensors with diffusion structures do not optimally distribute incident light across a broad range of wavelengths, leading to less than optimal quantum efficiency (QE) performance for certain wavelengths.
Innovation Solution
Incorporating multiple vertically arranged layers of diffusion structures above the photodiode, each layer designed to distribute and refract incident light effectively, with specific shaping and sizing to enhance QE across a broader wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer of diffusion structures is used, then the device complexity is reduced, but the quantum efficiency performance across broad wavelengths deteriorates
Solution Approach 1:
The diffusion structure is divided into multiple vertically arranged layers, each with potentially different geometries and optical properties. This segmentation allows each layer to handle specific wavelength ranges or light distribution patterns, collectively achieving broad-spectrum high efficiency without requiring a single overly complex structure
Solution Approach 2:
The solution transitions from a single-layer (2D planar) diffusion structure to a multi-layer (3D vertical) architecture. By adding the vertical dimension with multiple stacked layers, the patent achieves enhanced light distribution across broad wavelengths while maintaining manageable complexity through modular layer design
2Reliability
If multiple vertically arranged layers of diffusion structures are incorporated, then the quantum efficiency across broad wavelengths is improved, but the device complexity increases
Solution Approach 1:
The multi-layer diffusion structure is segmented into discrete functional layers, each optimized for specific optical tasks. This segmentation enables independent design and optimization of each layer while maintaining overall system performance, making the complexity manageable through modular architecture
Solution Approach 2:
Each diffusion layer is designed to perform multiple functions: light refraction, wavelength-specific distribution, and photon absorption enhancement. This multi-functionality reduces the need for additional specialized components, achieving broad-spectrum QE improvement without proportionally increasing overall device complexity
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 multiple layers of diffusion structures increase the likelihood of photon absorption, enhancing QE and improving sensor performance across various wavelengths.
Implementation Method 1
The plurality of vertically arranged layers of diffusion structures distributes incident light by refraction
Data Source
AI summary
A plurality of vertically arranged layers of diffusion structures are included above a photodiode of a pixel sensor. Each layer of diffusion structures distributes incident light by refraction to provide a greater amount of distribution of the incident light than a single layer of diffusion structures. For example, a top layer of diffusion structures may distribute incident light by refraction, and a bottom layer of diffusion structures may further distribute the distributed incident light from the top layer of diffusion structures before the incident light enters the photodiode of the pixel sensor. This increases the length of the path of travel of photons of the incident light, thereby increasing the likelihood that the photons will be absorbed in the photodiode. Thus, the plurality of vertically arranged layers of diffusion structures may further increase the quantum efficiency (QE) of the pixel sensor.