Image Sensor Grid Structure for Crosstalk Reduction

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Solution Overview

Problem

Existing image sensors face challenges in forming reliable structures due to issues such as light leakage and crosstalk, which affect their quantum yield and light sensitivity, particularly with the scaling down of pixels and increasing integration.

Innovation Solution

The formation of an image sensor structure involving a semiconductor substrate with a photodiode component, a titanium-based reflective element with an anti-corrosive sidewall, and a grid structure that eliminates the need for additional dielectric films, allowing the color filter element to fill the cavity and increase its width, thereby enhancing quantum yield and light sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of stationary object

If pixels are scaled down to increase integration, then resolution becomes better, but light sensitivity and quantum yield deteriorate

Engineering Contradiction:

Improvepixel sizeVSAvoidlight sensitivity

Core Design Contradiction:

Weight of stationary objectVSReliability

Solution Approach 1:

The color filter element is nested within the cavity formed by the grid structure, allowing it to be positioned in close proximity to the photodiode component. This nested arrangement maximizes the use of vertical space and enables the color filter to be wider without increasing the horizontal pixel footprint, thereby maintaining high resolution while improving light sensitivity

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention transitions from a planar arrangement to a three-dimensional structure by forming a cavity with the grid structure and placing the color filter element within this cavity. This vertical dimensionality change allows the color filter to be positioned closer to the photodiode, increasing the effective light collection area and quantum yield without increasing the horizontal pixel size

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If additional dielectric films are added to the grid structure, then structural integrity is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvestructural integrityVSAvoidnumber of dielectric films

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The grid structure merges multiple functions into a single component: it provides structural support, defines the cavity space, and positions the color filter element. By combining these functions into one integrated structure rather than using separate dielectric films for each purpose, the invention reduces the total number of layers and simplifies manufacturing while maintaining structural integrity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The grid structure serves multiple purposes simultaneously: it acts as a structural framework, creates the cavity for the color filter, and provides positioning features. This multi-functional design eliminates the need for additional specialized dielectric films, reducing device complexity while maintaining all necessary structural functions

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If the color filter element is positioned farther from the photodiode, then manufacturing alignment is easier, but light sensitivity and quantum yield decrease

Engineering Contradiction:

Improvealignment toleranceVSAvoidquantum yield

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The color filter element is nested within the cavity formed by the grid structure, which provides precise mechanical positioning. This nested configuration ensures close proximity to the photodiode for high quantum yield while the rigid grid structure maintains alignment precision during manufacturing

Inventive Principle:

Principle #7Nested doll (Nesting)

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 approach improves the yield and light sensitivity of the image sensor by reducing light leakage and allowing the color filter element to be closer to the photodiode, increasing its width by about 10%-15% and shortening the light path, thus addressing the limitations of existing image sensors.

Implementation Method 1

Each of the pixels includes a photodiode (PD) component, which converts incident light into an electric signal

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

a reflective element over the bottom dielectric element... The reflective element has a sidewall which is anti-corrosive in a basic condition and an acidic condition

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS10164156B2Structure and formation method of image sensor structure with grid structure

Publication Date: 2018.12.25 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Structures and formation methods of an image sensor structure are provided. The image sensor structure is provided. The image sensor structure includes a substrate, a photodiode component in the substrate, and a grid structure over the substrate. The grid structure includes a bottom dielectric element over the substrate, a reflective element over the bottom dielectric element, and an upper dielectric element over the reflective element. The reflective element has a sidewall which is anti-corrosive in a basic condition and an acidic condition. The image sensor structure also includes a color filter element over the substrate and surrounded by the grid structure. The color filter element is aligned with the photodiode component.