Imaging Device Wall Portions Guide Carriers

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Solution Overview

Problem

Conventional imaging devices suffer from dark current components generated in substrates, leading to noise in captured images due to accumulated carriers, which existing technologies fail to effectively suppress.

Innovation Solution

The imaging device incorporates first and second wall portions with higher impurity concentrations than the substrate, strategically positioned to guide carriers generated in the substrate to carrier absorbing portions, preventing accumulation in light receiving elements and enhancing dark current suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional imaging devices are used, then manufacturing is simpler, but dark current components are accumulated in photodiodes causing noise

Engineering Contradiction:

Improvedark current suppressionVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The device is segmented into multiple functional regions: light receiving elements, carrier absorbing portions, first wall portions, and second wall portions. This segmentation allows carriers to be directed to specific absorption regions, effectively suppressing dark current while maintaining manageable structural complexity through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

First and second wall portions act as intermediary structures with higher impurity concentrations that serve as carrier guides. These intermediary regions channel carriers generated in the substrate toward carrier absorbing portions, preventing direct accumulation in light receiving elements while reducing overall device complexity compared to complete redesign

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If wall portions with higher impurity concentrations are added, then carrier guidance improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecarrier absorption efficiencyVSAvoidimpurity concentration control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Different regions of the semiconductor substrate are assigned different impurity concentrations tailored to their specific functions: the substrate has base concentration, while first and second wall portions have locally increased concentrations to guide carriers. This local quality differentiation improves carrier absorption efficiency while allowing standard manufacturing tolerances to be maintained in each region

Inventive Principle:

Principle #3Local quality

3Device complexity

If simple potential barrier suppression is used, then device complexity is lower, but dark current noise is not effectively reduced

Engineering Contradiction:

Improvestructure simplicityVSAvoiddark current noise

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the potentially harmful effect of substrate-generated carriers into a beneficial process by using first wall portions to guide these carriers toward carrier absorbing portions. Instead of simply blocking carriers with potential barriers, the structure channels them through wall portions to absorption regions, effectively reducing dark current noise while maintaining reasonable structural simplicity

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

This configuration effectively reduces dark current noise, improving image quality by ensuring carriers are absorbed rather than accumulating in photodiodes, offering superior performance compared to simple potential barrier suppression methods.

Implementation Method 1

first wall portions 41...provided to overlap at least part of light receiving elements 32 in array directions of the plurality of pixel portions 30

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

carrier absorbing portions 80...absorb carriers generated in the substrate

Methodology Applied

Scientific EffectCarrier absorption: Absorption (physical)

Implementation Method 3

imaging device having photodiodes

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3576150B1Image-capture element and method for manufacturing image-capture element

Publication Date: 2021.11.03 NIKON CORP

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Figure 1C

AI summary

An imaging device is provided, the imaging device including: a first-conductivity-type substrate; a first-conductivity-type element forming portion provided on the substrate, and having a concentration lower than the substrate; and a plurality of pixel portions provided in the element forming portion, and arrayed two-dimensionally, each pixel portion having a light receiving element, and a second-conductivity-type carrier absorbing portion provided in an area different from an area where the light receiving element is provided. At least one pixel portion of the pixel portions has: a first-conductivity-type first wall portion provided on a substrate side relative to the light receiving element, the first wall portion overlapping at least part of the light receiving element in an array direction of the pixel portions, and having a concentration higher than the substrate, and a carrier passage area not provided with the first wall portion in the array direction of the pixel portions.