Solid State Imaging Device Transparent Layer Structure

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Solution Overview

Problem

Conventional solid state imaging devices face challenges with high reflection at the air layer interface and dust contamination, leading to reduced sensitivity and manufacturing issues during the dicing process.

Innovation Solution

A solid state imaging device structure featuring a first transparent layer made of a fluorine-containing resin and a second transparent layer, harder than the first, which is bonded to a transparent component with an adhesive layer, eliminating the air layer and reducing refractive index differences to minimize reflection and dust contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a transparent component is placed directly on the microlens without an air layer, then dust contamination is eliminated and manufacturing reliability is improved, but light reflection at the interface increases due to refractive index differences

Engineering Contradiction:

Improvemanufacturing reliabilityVSAvoidlight reflection

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A transparent resin layer is introduced as an intermediary between the microlens and the transparent component. This intermediate layer has a refractive index that is intermediate between the microlens and the transparent component, reducing the refractive index difference at interfaces and minimizing light reflection while maintaining direct bonding without an air layer

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses a composite structure consisting of the microlens, transparent resin layer, and transparent component bonded together. The transparent resin layer is specifically selected with refractive index properties that optimize the optical performance of the composite structure by reducing reflection at the interfaces

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If a fluorine-containing resin with low refractive index is used to reduce light reflection, then optical sensitivity is improved, but the resin becomes softer and more susceptible to scratches during the dicing process

Engineering Contradiction:

Improveoptical sensitivityVSAvoidresin hardness

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The protective structure is segmented into two distinct layers: a first transparent layer made of fluorine-containing resin for optimal optical sensitivity, and a second transparent layer made of harder resin for mechanical protection during dicing. Each layer performs its specific function without compromising the other

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the transparent protective structure have different properties: the first layer (in contact with microlens) has low refractive index for optical optimization, while the second layer (exposed to dicing process) has high hardness for mechanical protection. Each local region is optimized for its specific functional requirement

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the refractive index difference between transparent component and resin layer is reduced, then light reflection is minimized and sensitivity is improved, but manufacturing complexity increases due to precise refractive index matching requirements

Engineering Contradiction:

Improvelight sensitivityVSAvoidmanufacturing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent optimizes the refractive index parameter of the transparent resin layer to be an intermediate value between the microlens and transparent component. This parameter optimization reduces light reflection at interfaces while maintaining manufacturability through standard material selection

Inventive Principle:

Principle #35Parameter changes

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

The solution enhances light collection on the photodiodes, reduces damage during the dicing process, and improves manufacturing yield by minimizing scratches and dust interference, resulting in a high-sensitivity, small-sized imaging device with improved manufacturing efficiency.

Implementation Method 1

the refractive index of the transparent resin layer can be set to an intermediate value between the refractive index of the transparent component 109 and that of the microlenses 106. Therefore, the difference between the refractive indices of the transparent component 109 and the transparent resin layer is reduced, and so is the difference between the refractive indices of the microlenses 106 and the transparent resin layer. Thus, reflection of light at the interfaces between them is reduced.

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS7619678B2Solid state imaging device and method for manufacturing the same

Publication Date: 2009.11.17 CONVERSANT INTELLECTUAL PROPERTY MANAGEMENT INC

AI summary

A solid state imaging device includes: a solid state imaging element including a light receiving element, a microlens formed above the light receiving element, a first transparent layer formed on the microlens and a second transparent layer formed on or above the microlens and harder than the first transparent layer; a transparent component formed above the second transparent layer; and an adhesive layer for bonding the second transparent layer and the transparent component. The hard second transparent layer prevents the occurrence of scratches during a dicing step.