Pixel-Array Substrate Layout for Optical Cross-Talk Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Camera image sensors experience optical cross-talk due to light propagating through microlenses and color filters at high incident angles, leading to artifacts in images.
Innovation Solution
A reduced cross-talk pixel-array substrate is designed with a semiconductor substrate, a buffer layer, a metal annulus, and an attenuation layer, where the buffer layer features a recess or aperture above the photodiode region, and the attenuation layer is positioned to reduce light intensity before it reaches the photodiode, preventing optical cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is allowed to propagate through microlenses and color filters at high incident angles, then the image sensor can capture a wider range of light, but optical cross-talk occurs causing artifacts in images
Solution Approach 1:
The patent divides the buffer layer into multiple sections with different thicknesses: a first buffer layer section above the photodiode region and a second buffer layer section above the isolation structure. This segmentation allows differential light attenuation - the thinner first section permits useful light transmission while the thicker second section blocks cross-talk light from adjacent pixels propagating at high angles
Solution Approach 2:
The buffer layer is designed with non-uniform thickness distribution where the first buffer layer section has a different thickness than the second buffer layer section. This local quality variation optimizes light transmission for on-axis light while providing stronger attenuation for off-axis light causing cross-talk, resolving the contradiction between light capture and cross-talk prevention
2Object-affected harmful factors
If the buffer layer thickness is increased to reduce optical cross-talk, then cross-talk is attenuated, but light intensity reaching the photodiode is reduced
Solution Approach 1:
The buffer layer is segmented into a first section with smaller thickness above the photodiode region and a second section with larger thickness above the isolation structure. This segmentation enables the system to achieve cross-talk attenuation through the thicker second section while maintaining adequate light transmission through the thinner first section
Solution Approach 2:
The patent applies partial attenuation by making the buffer layer thickness selective rather than uniformly excessive. The first buffer layer section provides just enough attenuation for cross-talk reduction while the second section provides stronger attenuation, avoiding over-attenuation that would reduce useful light transmission to the photodiode
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 solution effectively reduces optical cross-talk by attenuating incident light, thereby improving image quality by minimizing artifacts caused by light interference between photodiode regions.
Implementation Method 1
The attenuation layer is above the first photodiode region... effectively reduces optical cross-talk by attenuating incident light
Data Source
AI summary
A reduced cross-talk pixel-array substrate includes a semiconductor substrate, a buffer layer, a metal annulus, and an attenuation layer. The semiconductor substrate includes a first photodiode region. A back surface of the semiconductor substrate forms a trench surrounding the first photodiode region in a cross-sectional plane parallel to a first back-surface region of the back surface above the first photodiode region. The buffer layer is on the back surface and has a feature located above the first photodiode region with the feature being one of a recess and an aperture. The metal annulus is on the buffer layer and covers the trench. The attenuation layer is above the first photodiode region.