Image Sensor Light-Shield Layer With Porous Low-Refractive Pattern

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Solution Overview

Problem

Current image sensors face issues with image defects due to crosstalk between pixels, which are not effectively addressed by existing technologies.

Innovation Solution

The image sensor design incorporates a light-shield layer with a porous low-refractive pattern and a protection layer, where the porous low-refractive pattern has a refractive index of 1 to 1.46 and pores with diameters of 0.2 nm to 1 nm, along with a micro-lens array and color filters, to prevent crosstalk and improve image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional light-shield layer is used, then the structure is simple and manufacturing is easy, but crosstalk between pixels occurs and image defects are not effectively prevented

Engineering Contradiction:

Improvecrosstalk preventionVSAvoidlight-shield layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The light-shield layer incorporates a porous low-refractive pattern where pores are formed within the low-refractive material layer. This porous structure reduces the refractive index further and enhances light scattering, effectively preventing crosstalk between adjacent pixels while maintaining the overall grid structure for light shielding.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The light-shield layer is constructed as a composite structure combining a light-shield pattern (metallic or dielectric material) with a porous low-refractive pattern layer. This composite design integrates both the light-blocking function of the light-shield pattern and the refractive index control of the porous low-refractive material, achieving superior crosstalk prevention.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the refractive index is reduced to minimize crosstalk, then light transmittance decreases and image quality improves, but material diffusion may occur during fabrication

Engineering Contradiction:

Improveimage qualityVSAvoidmaterial diffusion resistance

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The pores in the low-refractive pattern are designed with specific size characteristics (smaller than the low-refractive material layer thickness) to create local quality variations. This local pore structure reduces the refractive index in specific regions where crosstalk occurs, while maintaining material stability in other regions during fabrication processes.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The refractive index of the low-refractive pattern is controlled by adjusting pore density and size parameters. By optimizing these parameters, the refractive index is reduced to minimize crosstalk while maintaining sufficient material integrity to prevent diffusion during subsequent fabrication steps.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a protection layer is added to prevent material diffusion, then manufacturing precision improves, but the device structure becomes more complex

Engineering Contradiction:

Improvepattern definition accuracyVSAvoidlayer structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The protection layer is formed preliminarily before subsequent fabrication steps that may cause material diffusion. This preliminary protective measure prevents contamination and material mixing during manufacturing, ensuring high manufacturing precision for the light-shield and low-refractive patterns without requiring additional complex structures.

Inventive Principle:

Principle #10Preliminary action

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 reduces light transmittance and absorptivity, minimizing crosstalk and enhancing image sensor performance by preventing the diffusion of materials into the low-refractive pattern, thereby improving image defects and overall image quality.

Implementation Method 1

This configuration reduces light transmittance and absorptivity, minimizing crosstalk

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

the porous low-refractive pattern has a refractive index of 1 to 1.46

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

Pores in the low-refractive pattern may have a diameter of about 0.2 nm to about 1 nm... preventing the diffusion of materials into the low-refractive pattern

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentUS20230121884A1Image sensor and method of fabricating the same

Publication Date: 2023.04.20 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor includes a substrate, a plurality of unit pixels provided on a pixel area of the substrate, a plurality of device isolation patterns defining the plurality of unit pixels on the pixel area, a light-shield layer provided on a top surface of the substrate and comprising a grid structure defining a plurality of optical transmission regions, a plurality of color filters provided on the plurality of optical transmission regions of the light-shield layer, and a plurality of micro-lenses provided on the plurality color filters. The light-shield layer includes a light-shield pattern, a low-refractive pattern provided on the light-shield pattern, and a protection layer configured to cover the light-shield pattern and the low-refractive pattern on the substrate. The low-refractive pattern includes a porous silicon compound. Pores in the low-refractive pattern have a diameter of about 0.2 nm to about 1 nm.