Pixel Separation Structure for Infrared Sensitivity and Crosstalk

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Solution Overview

Problem

Photoelectric conversion devices face challenges in simultaneously improving sensitivity to near-infrared light and suppressing optical crosstalk, as metal-filled Deep Trench Isolation (DTI) reduces sensitivity due to light absorption, while dielectric-filled DTI lacks effective light shielding.

Innovation Solution

A photoelectric conversion device with a semiconductor layer and pixels separated by a pixel separation portion that includes a metal filling portion, such as copper, tungsten, cobalt, or aluminum, and a dielectric film of silicon oxide on the side portion, optimizing the thickness of the dielectric film to achieve high light shielding and low light absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the DTI is filled with a metal material, then optical crosstalk is suppressed and light shielding is improved, but sensitivity to near-infrared light decreases due to light absorption

Engineering Contradiction:

Improveoptical crosstalkVSAvoidsensitivity to near-infrared light

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The pixel separation portion uses a composite structure combining metal filling material (for light shielding) and dielectric material (for reduced absorption), achieving both optical crosstalk suppression and sensitivity improvement through material composition

Inventive Principle:

Principle #40Composite materials

2Reliability

If the DTI is filled with a dielectric material, then sensitivity to near-infrared light is improved due to reduced light absorption, but optical crosstalk increases due to inferior light shielding property

Engineering Contradiction:

Improvesensitivity to near-infrared lightVSAvoidoptical crosstalk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

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 enhances the sensitivity to near-infrared light while effectively suppressing optical crosstalk by maximizing reflectance and minimizing transmittance, achieving a balance between light shielding and sensitivity.

Implementation Method 1

Light incident on the photoelectric conversion device is diffracted by the periodic uneven structure portion

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

The diffracted light is reflected by a pixel separation portion having a trenched structure to be confined to the inside of one pixel

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

under the influence of light absorption by the metal material, a sensitivity of a photoelectric conversion device to light may decrease

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20230011124A1Photoelectric conversion device, photoelectric conversion system, and moving body

Publication Date: 2023.01.12 CANON KK

AI summary

A photoelectric conversion device includes a semiconductor layer formed of silicon, a plurality of pixels formed in the semiconductor layer, and a pixel separation portion is formed to separate each of the plurality of pixels, wherein the pixel separation portion includes a metal filling portion and a dielectric film provided on a side portion of the metal filling portion, a material of the metal filling portion is copper, a material of the dielectric film is a silicon oxide, and a thickness of the dielectric film is not less than 50 nm and not more than 270 nm.