Non-aligned Grid Patterns in Image Sensors

Solution Overview

Problem

The increasing density of pixels in image sensors due to reduced pixel size leads to increased crosstalk and reduced sensitivity, as oblique light can be incident on neighboring pixels rather than the intended one.

Innovation Solution

The grid pattern on the image sensor is not vertically aligned with the device isolation layer, allowing oblique light to be reflected and focused onto the corresponding pixel, thereby reducing crosstalk and enhancing sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pixel size is reduced to increase integration density, then the number of pixels per area increases, but crosstalk between pixels increases and sensitivity decreases

Engineering Contradiction:

Improveintegration densityVSAvoidsensitivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The grid pattern is intentionally designed with asymmetric positioning relative to the device isolation layer. The grid pattern is shifted horizontally by a predetermined distance from the vertical alignment position, creating an asymmetric configuration that redirects oblique light paths to fall within the active pixel area rather than spilling into neighboring pixels, thereby reducing crosstalk while maintaining high integration density

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent modifies the positional parameter of the grid pattern relative to the device isolation layer. By changing the horizontal offset parameter from zero (vertically aligned) to a predetermined non-zero distance, the light reflection characteristics are altered to improve light collection efficiency and reduce inter-pixel interference, thus maintaining sensitivity despite reduced pixel size

Inventive Principle:

Principle #35Parameter changes

2Productivity

If pixel size is reduced to increase integration density, then the number of pixels per area increases, but crosstalk between pixels increases

Engineering Contradiction:

Improveintegration densityVSAvoidcrosstalk

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The grid pattern is intentionally designed with asymmetric positioning relative to the device isolation layer. The grid pattern is shifted horizontally by a predetermined distance from the vertical alignment position, creating an asymmetric configuration that redirects oblique light paths to fall within the active pixel area rather than spilling into neighboring pixels, thereby reducing crosstalk while maintaining high integration density

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent converts the potentially harmful effect of oblique light that would normally cause crosstalk into a beneficial effect. By positioning the grid pattern asymmetrically, the reflected oblique light is redirected to fall within the intended pixel's active area, transforming what would be interfering light into useful signal light, thus reducing crosstalk while maintaining high integration density

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 improves the sensitivity of the image sensor by ensuring that oblique light is directed to the correct pixel, minimizing crosstalk and maintaining high integration density.

Implementation Method 1

the grid pattern on the image sensor is not vertically aligned with the device isolation layer, allowing oblique light to be reflected and focused onto the corresponding pixel

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS10229950B2Image sensors including non-aligned grid patterns

Publication Date: 2019.03.12 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor includes a substrate including a first surface and a second surface, a first device isolation layer disposed in the substrate and defining a plurality of pixels in the substrate, and having a lower surface adjacent the first surface of the substrate and an upper surface adjacent the second surface of the substrate. Each of the pixels includes a photoelectric conversion element, a floating diffusion region adjacent the first surface of the substrate, and a grid pattern on the second surface of the substrate. At least one of the grid patterns is not vertically aligned with the first device isolation layer.