Image Sensor Charge Release Layer for Dielectric Grid Traps

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Solution Overview

Problem

Trapped charge carriers in the dielectric grid structure of image sensors reduce the reliability and accuracy of images produced, causing issues with dark and black images, and increasing dark current and white pixels.

Innovation Solution

Incorporating a charge release layer between the dielectric grid structure and the etch stop layer, which is electrically coupled to ground to release trapped charge carriers, thereby improving image reliability and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dielectric grid structure is used in image sensors, then structural support and isolation are provided, but trapped charge carriers accumulate causing image reliability and accuracy degradation

Engineering Contradiction:

Improveimage reliabilityVSAvoidtrapped charge carriers

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful trapped charge carriers from the dielectric grid structure by introducing a charge release layer that provides a dedicated extraction path to ground, removing the harmful accumulation without eliminating the dielectric grid structure itself

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The charge release layer acts as an intermediary component between the dielectric grid structure and ground, facilitating the removal of trapped charge carriers through this intermediate extraction path without requiring changes to the primary dielectric structure

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a dielectric grid structure is used in image sensors, then structural support and isolation are provided, but dark current increases

Engineering Contradiction:

Improveimage qualityVSAvoiddark current

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The charge release layer extracts accumulated charge carriers that would otherwise contribute to dark current generation, providing a controlled extraction path that prevents harmful current accumulation while maintaining the beneficial dielectric structure

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If a dielectric grid structure is used in image sensors, then structural support and isolation are provided, but white pixel issues occur

Engineering Contradiction:

Improveimage accuracyVSAvoidwhite pixels

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of trapped charge carriers (which cause white pixel artifacts) into a beneficial outcome by providing a controlled release mechanism that directs these carriers to ground, transforming the problem into a solution that maintains image accuracy

Inventive Principle:

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

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 charge release layer effectively removes trapped charge carriers, enhancing image sensor reliability, accuracy, and reducing dark current and white pixel issues.

Implementation Method 1

a charge release layer between the dielectric grid structure and the etch stop layer, wherein the charge release layer is electrically coupled to ground and configured to remove trapped charge carriers from the dielectric grid structure

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11948962B2Charge release layer to remove charge carriers from dielectric grid structures in image sensors

Publication Date: 2024.04.02 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Various embodiments of the present disclosure are directed towards a semiconductor structure including a photodetector disposed within a substrate. A grid structure is disposed over the substrate and the photodetector. A conductive layer is disposed between the grid structure and the substrate. A conductive contact extends into an upper surface of the substrate. The conductive layer is directly electrically coupled to the conductive contact.