PDAF Pixel Diffuser Layout for Near-Infrared Focus Detection
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Solution Overview
Problem
Complementary metal-oxide semiconductor (CMOS) image sensors with phase detection autofocus (PDAF) struggle to enhance near-infrared (NIR) radiation sensitivity due to electromagnetic radiation (EMR) shields that block NIR radiation, reducing angular response discrimination between PDAF pixels and complicating phase difference determination.
Innovation Solution
The image sensor design incorporates EMR diffusers laterally spaced within the PDAF pixel regions, allowing more NIR radiation to be transmitted and increasing angular response discrimination by diffusing incident NIR radiation, enabling improved focus condition determination through phase difference comparison between PDAF pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If EMR shields are added to improve visible light detection, then visible light sensitivity is improved, but device complexity increases
Solution Approach 1:
The EMR shields are designed to serve multiple functions simultaneously: they block visible light from reaching NIR-sensitive pixels to prevent cross-talk, they provide structural support for the pixel array, and they define the optical paths for both visible light and NIR PDAF operations. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving visible light sensitivity improvement.
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 design enhances NIR radiation PDAF performance by increasing NIR sensitivity and angular response discrimination, allowing for more accurate focus determination and improved autofocus capabilities in NIR applications.
Implementation Method 1
EMR diffusers laterally spaced within the PDAF pixel regions, allowing more NIR radiation to be transmitted and increasing angular response discrimination by diffusing incident NIR radiation
Data Source
AI summary
Various embodiments of the present disclosure are directed towards an integrated chip. The integrated chip includes a first photodetector disposed in a first pixel region of a semiconductor substrate and a second photodetector disposed in a second pixel region of the semiconductor substrate. The second photodetector is laterally separated from the first photodetector. A first diffuser is disposed along a back-side of the semiconductor substrate and over the first photodetector. A second diffuser is disposed along the back-side of the semiconductor substrate and over the second photodetector. A first midline of the first pixel region and a second midline of the second pixel region are both disposed laterally between the first diffuser and the second diffuser.