Lens Capping Layer Trench Filling for Image Sensor Stability

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Solution Overview

Problem

Image sensing devices face structural failures and flare phenomena in lens capping layers during manufacturing processes like wafer back-grinding and sawing, leading to disengagement from the substrate and other structures.

Innovation Solution

The implementation of a lens capping layer with a specific edge region formed to fill trenches in the pixel-array peripheral region, increasing contact area and minimizing structural damages by extending vertically into the semiconductor substrate, and alternative shapes such as serrated edges to enhance stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the lens capping layer is formed with a conventional flat edge structure, then the manufacturing process is simple, but the lens capping layer experiences structural failure and disengagement during wafer back-grinding and sawing processes

Engineering Contradiction:

Improvestructural stability of lens capping layerVSAvoidcomplexity of lens capping layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The lens capping layer is extended vertically into the pixel-array peripheral region by filling trenches, transforming from a conventional flat two-dimensional structure to a three-dimensional structure with increased vertical dimension. This dimensional change provides additional contact area with the substrate and over-coating layer, preventing disengagement during manufacturing processes like wafer back-grinding and sawing.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The lens capping layer is divided into distinct functional regions: a pixel region portion covering the pixel array and a pixel-array peripheral region portion extending into trenches. This segmentation allows each region to serve its specific function - the pixel region portion provides optical coverage while the peripheral region portion provides mechanical anchoring and structural stability during manufacturing.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the lens capping layer contact area with over-coating layer is increased by extending vertically, then structural stability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecontact area between lens capping layer and over-coating layerVSAvoidease of forming lens capping layer structure

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Trenches are formed in the pixel-array peripheral region before depositing the lens capping layer material. This preliminary action creates pre-defined regions where the lens capping layer will extend vertically, ensuring proper structural formation and maximizing contact area with the over-coating layer while maintaining control over the manufacturing process.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the lens capping layer is made to extend deeply into trenches, then structural stability during manufacturing is improved, but the likelihood of flare phenomenon increases

Engineering Contradiction:

Improvestructural stability during manufacturingVSAvoidflare phenomenon in lens layer

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The lens capping layer is designed with different properties in different regions: in the pixel region it provides optical coverage with appropriate thickness, while in the pixel-array peripheral region it extends vertically into trenches to provide mechanical stability. This local differentiation allows the structure to achieve both optical performance and manufacturing stability without causing flare phenomena in the optical region.

Inventive Principle:

Principle #3Local quality

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 design effectively reduces the likelihood of structural failures and flare phenomena by increasing the contact area between the lens capping layer and the over-coating layer, thereby enhancing the stability and preventing disengagement during manufacturing processes.

Implementation Method 1

a lens layer disposed over the material layer in the pixel region and structured as a lens for collecting incident light into a unit pixel in the pixel region

Methodology Applied

Scientific EffectLight convergence: Lens

Data Source

PatentUS11699711B2Image sensing device

Publication Date: 2023.07.11 SK HYNIX INC

AI summary

An image sensing device includes a semiconductor substrate, a material layer, a lens layer, and a lens capping layer. The semiconductor substrate includes a pixel region, which include a plurality of unit pixels, and a pixel-array peripheral region located outside of and peripheral to the pixel region. The material layer is disposed over the semiconductor substrate in the pixel region and the pixel-array peripheral region, and includes a first trench extending to a predetermined depth in the pixel-array peripheral region. The lens layer is disposed over the material layer in the pixel region and collects incident light into a unit pixel in the pixel region. The lens capping layer is disposed over the lens layer and the material layer and includes an edge region formed to fill the first trench.