Color Filter Array with Inorganic Mask and Light Blocking Spacers

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Solution Overview

Problem

Current color filter arrays in solid state imagers suffer from limited resolution, shrinkage, poor planarity, and optical crosstalk due to the use of photoresist materials, which affect the accuracy of color separation and optical properties.

Innovation Solution

The implementation of a patterned mask layer to define and maintain the boundaries of color filters, combined with light blocking spacers to separate adjacent filters and reduce optical crosstalk, enhancing color separation and accuracy while minimizing manufacturing complexity and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If photoresist materials are used to form color filters, then the manufacturing process is simple, but the resolution is limited and shrinkage occurs affecting boundary definition

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidcolor filter boundary definition

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter from photoresist to inorganic material (such as silicon oxide, silicon nitride, or silicon oxynitride), which fundamentally alters the properties: inorganic materials provide better resolution, prevent shrinkage, and maintain boundary definition accuracy while being compatible with standard semiconductor fabrication processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the photochemical process (photoresist) with a physical deposition process (CVD or PECVD), substituting chemical-based pattern formation with vapor-phase deposition that offers superior precision and control over film thickness and boundary definition

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If color filters are formed in close proximity to increase pixel density, then productivity increases, but optical crosstalk occurs between adjacent pixels

Engineering Contradiction:

Improvepixel densityVSAvoidoptical crosstalk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an inorganic material layer that serves as an intermediary between adjacent color filters. This layer acts as a light-blocking barrier that prevents optical crosstalk while allowing the filters to be positioned in close proximity, thus maintaining high pixel density without sacrificing optical isolation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the space between adjacent color filters by depositing inorganic material layers that physically divide and isolate each filter region. This segmentation creates distinct optical zones that prevent light leakage between pixels while maintaining compact arrangement

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If photoresist is used for color filter formation, then fabrication cost is low, but planarity is poor affecting overlying lens array

Engineering Contradiction:

Improvefabrication costVSAvoidplanarity

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The patent changes the material state and deposition method from liquid photoresist to vapor-deposited inorganic film. This parameter change produces a inherently planar surface that provides a flat foundation for subsequent lens array fabrication, eliminating the planarity issues associated with photoresist while maintaining cost-effectiveness through standard semiconductor processes

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 effectively defines the boundaries and colors of color filters, reducing optical crosstalk and improving color separation, thereby enhancing the imaging performance of solid state imagers with minimal additional complexity or cost.

Implementation Method 1

A color filter array and imaging device are provided which more effectively and accurately defines the boundaries and colors of the various color filters to improve color separation and/or which blocks light from being transmitted between color filters to reduce optical crosstalk

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

each pixel of a color image sensor is covered with either a red, green or blue filter, according to a specific pattern

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

a resist is typically used containing a color pigment

Methodology Applied

Scientific EffectLight absorption by pigment: Absorption (EM radiation)

Data Source

PatentUS7799491B2Color filter array and imaging device containing such color filter array and method of fabrication

Publication Date: 2010.09.21 APTINA IMAGING CORP

AI summary

A method and apparatus are disclosed which provide a color filter array for an imaging device in which the filters of the array are accurately positioned through the use of a patterned mask layer used to form filters for one color of the array. Additionally or alternatively, the color filter array can have a light blocking spacer to block light from being transmitted between color filters and/or to a peripheral circuitry region.