Photomask Design for Column Spacer Patterning

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Solution Overview

Problem

Current photomask technologies for manufacturing column spacers in color filters require multiple transmissivity regions to achieve complex patterns, leading to increased production costs and inefficiencies due to the need for multiple exposure steps and high-cost photomasks with limited transmissivity differences.

Innovation Solution

A photomask design featuring a central region with a specific transmittance, surrounded by perimeter regions with varying transmittances, utilizing diffraction and interference phenomena to pattern column spacers with multiple heights using a photomask with only three transmissivity regions, and a method involving coating a negative photoresist on a substrate and exposing it using this photomask.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple transmissivity regions are used in the photomask to achieve complex column spacer patterns, then the patterning capability is improved, but the production cost increases

Engineering Contradiction:

Improvepatterning capabilityVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by utilizing diffraction and interference phenomena through specific photomask pattern arrangements to achieve multiple exposure effects. Instead of using multiple transmissivity regions, the invention changes the optical parameters by creating constructive and destructive interference patterns that generate the desired multi-height column spacer structures with a simpler photomask design, thereby reducing manufacturing cost while maintaining patterning capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/optical system of multiple transmissivity regions with a wave optics-based system utilizing diffraction and interference. By substituting the direct transmissivity control approach with wave interference mechanisms, the invention achieves complex patterning effects without requiring complex photomask structures, thus reducing production cost while preserving manufacturing precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If four tones are used in the photomask to create four-step patterns, then the pattern complexity is improved, but the production cost increases

Engineering Contradiction:

Improvepattern complexityVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the optical parameters by utilizing diffraction and interference phenomena to generate multiple exposure tones. Instead of directly encoding four tones in the photomask transmissivity, the invention uses wave interference to create the equivalent effect, achieving four-step column spacer patterns with a photomask that has fewer transmissivity regions, thereby reducing production cost while maintaining pattern complexity

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the difference in transmittances of the photomask for each area is not large, then the photomask complexity is reduced, but no PR pattern is made according to the pattern shape of the photomask

Engineering Contradiction:

Improvephotomask complexityVSAvoidPR pattern accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent converts the potential harm of insufficient transmittance difference into a benefit by utilizing diffraction and interference phenomena. The wave optics effects amplify the contrast and enhance the pattern formation capability, allowing the photomask to produce accurate PR patterns even with smaller transmittance differences between regions, thus reducing photomask complexity while maintaining PR pattern accuracy

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

The solution reduces manufacturing costs by utilizing diffraction and interference phenomena to achieve four height patterns with a three-transmissivity region photomask, improving the shape of photoresist patterns and reducing the number of required transmissivity regions.

Implementation Method 1

The photomask has a pattern arrangement capable of utilizing diffraction and interference phenomena at the time of exposure

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

The photomask has a pattern arrangement capable of utilizing diffraction and interference phenomena at the time of exposure

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS10642150B2Photomask and method for manufacturing column spacer for color filter using the same

Publication Date: 2020.05.05 LG CHEM LTD

AI summary

The present invention relates to a photomask and a method for manufacturing a column spacer for a color filter using the same, and according to one aspect of the present invention, a photomask is provided, which comprises a central region having a first transmittance, a first perimeter region surrounding the central region and having a second transmittance lower than the first transmittance, and a second perimeter region surrounding the first perimeter region and having the first transmittance.