PDAF Image Sensor Layout for Near-Infrared Angular Discrimination

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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 incident 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 from the PDAF pixel regions, diffusing incident NIR radiation and allowing more of it to be transmitted, thereby increasing NIR sensitivity and angular response discrimination between PDAF pixels for improved focus determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If EMR shields are placed over PDAF pixel regions to block harmful radiation, then protection from electromagnetic radiation is improved, but NIR radiation transmission is reduced and angular response discrimination is degraded

Engineering Contradiction:

ImproveEMR shieldingVSAvoidangular response discrimination

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The EMR shield is extracted from the PDAF pixel region and relocated to a position outside the pixel region. This allows the shield to protect against harmful EMR while leaving the PDAF pixel region open to receive NIR radiation, thereby maintaining angular response discrimination capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

An EMR diffuser is introduced as an intermediary element between the incident NIR radiation and the PDAF pixel region. The diffuser scatters the NIR radiation to reduce the impact of the EMR shield on angular response discrimination while still allowing sufficient NIR transmission to the photodetector.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If EMR shields block incident NIR radiation to protect from electromagnetic radiation, then protection is improved, but NIR sensitivity is reduced

Engineering Contradiction:

ImproveEMR shieldingVSAvoidNIR sensitivity

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The EMR shield is relocated from a position where it blocks NIR radiation to a position outside the PDAF pixel region. This extraction allows the shield to maintain its protective function against harmful EMR while eliminating its detrimental effect on NIR sensitivity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The EMR shield, which originally caused harm by blocking NIR radiation, is repositioned to provide benefit without the harmful effect. The shield continues to block harmful EMR while its placement outside the pixel region allows NIR radiation to reach the photodetector, converting the harmful blocking effect into a beneficial protective function.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If EMR shields are positioned to block harmful radiation, then protection is improved, but phase difference determination becomes more difficult

Engineering Contradiction:

ImproveEMR shieldingVSAvoidphase difference determination

Core Design Contradiction:

Object-affected harmful factorsVSDifficulty of detecting and measuring

Solution Approach 1:

The EMR shield is extracted from the PDAF pixel region and placed outside it. This removal from the pixel region eliminates the shield's interference with the phase difference measurement process, allowing accurate determination of phase differences between light rays while maintaining EMR protection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The EMR diffuser serves as an intermediary that modifies the NIR radiation path without blocking it. By scattering the radiation, the diffuser helps maintain the phase difference information between light rays while the relocated EMR shield provides protection, making phase difference determination easier and more accurate.

Inventive Principle:

Principle #24Intermediary (Mediator)

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, enabling more accurate phase difference determination and autofocus capabilities.

Implementation Method 1

EMR diffusers laterally spaced from the PDAF pixel regions, diffusing incident NIR radiation

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20240170506A1Image sensor with improved near-infrared (NIR) radiation phase-detection autofocus (PDAF) performance

Publication Date: 2024.05.23 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Various embodiments of the present disclosure are directed towards an integrated chip. The integrated chip includes a first pixel region and a second pixel region within a substrate. A first recess region is disposed along a back-side of the substrate within the first pixel region. The back-side of the substrate within the first pixel region is asymmetric about a center of the first pixel region in a cross-sectional view. A second recess region is disposed along the back-side of the substrate and within the second pixel region. The back-side of the substrate within the second pixel region is asymmetric about a center of the second pixel region in the cross-sectional view. The first recess region and the second recess region are substantially symmetric about a vertical line laterally between the first pixel region and the second pixel region.