Photoelectric Conversion Layer for Uniform Pixel Sensitivity
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Solution Overview
Problem
Photoelectric conversion devices experience variations in sensitivity due to multilayer film interference effects, leading to inaccuracies in distance measurement in imaging systems, as the amplitude and phase of reflectance vary with layer thickness and refractive index, making it challenging to control and minimize these variations.
Innovation Solution
Incorporating a phase adjustment layer with a fine concavo-convex shape or scattering particles on the dielectric layer, which alters the optical path length based on the position of incident light, reducing interference variations by ensuring the optical path difference is at least ¼ wavelength, thereby stabilizing sensitivity across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a multilayer film structure is used in the photoelectric conversion device, then the device can be manufactured with standard semiconductor processes, but the sensitivity varies due to multilayer film interference effects
Solution Approach 1:
A phase adjustment layer is introduced as an intermediary component between the dielectric layer and the external environment. This layer mediates the optical path of incident light, introducing phase differences that cancel out the interference effects caused by the multilayer film structure, thereby uniformizing sensitivity across different pixels while maintaining the standard multilayer manufacturing process
2Measurement precision
If the thickness and refractive index of dielectric layers are controlled to minimize interference, then sensitivity uniformity improves, but the complexity of manufacturing control increases
Solution Approach 1:
Instead of trying to eliminate the multilayer film interference effect through precise control of layer thickness and refractive index, the invention converts this harmful interference into a beneficial effect by introducing a phase adjustment layer. This layer creates controlled phase differences that actively cancel the interference variations, transforming the manufacturing control problem into a simpler structure-modification approach
3Measurement precision
If a phase adjustment layer with varying optical path length is added, then sensitivity uniformity improves, but the device structure becomes more complex
Solution Approach 1:
The phase adjustment layer is designed with local variations in thickness or refractive index to create position-dependent optical path lengths. This local quality variation allows different regions of the layer to compensate for interference effects specific to their location, achieving sensitivity uniformity across the entire photoelectric conversion device while adding minimal structural 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 phase adjustment layer effectively reduces amplitude variations in light absorption, leading to improved accuracy in distance measurement by minimizing sensitivity differences between pixels and enhancing the stability of imaging systems.
Implementation Method 1
the phase adjustment layer is formed such that the reflected light which has entered the first plane perpendicularly to the photoelectric conversion device and travels from the first plane to the second plane has an optical path length that varies depending on a position where the reflected light is incident on the first plane
Implementation Method 2
Photoelectric conversion devices experience variations in sensitivity due to multilayer film interference effects
Data Source
AI summary
A photoelectric conversion device including a substrate including a charge generation region, a dielectric layer formed on the substrate, and a phase adjustment layer formed on the dielectric layer and having an upper surface and a lower surface. In a cross-sectional view of the photoelectric conversion device, a first plane extends parallel to the substrate in contact with the upper surface of the phase adjustment layer, a second plane is the lower surface of the phase adjustment layer, and the phase adjustment layer is formed such that the reflected light which has entered the first plane perpendicularly to the photoelectric conversion device and travels from the first plane to the second plane has an optical path length that varies depending on a position where the reflected light is incident on the first plane.