Liquid Crystal Display Microcavity Formation via Sacrificial Layer Etching

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Solution Overview

Problem

Liquid crystal displays with microcavities face issues due to residual sacrificial layers affecting uniform cell gaps and potential short circuits between electrodes, leading to display quality deterioration.

Innovation Solution

A manufacturing method involving a sacrificial layer removal process without heat treatment, using a photoresist layer and etching techniques to ensure uniform microcavity formation and maintain a predetermined distance between common and pixel electrodes, preventing short circuits and ensuring uniform cell gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heat treatment is applied to remove the sacrificial layer, then the sacrificial layer can be removed, but the common electrode may curve and the cell gap becomes non-uniform

Engineering Contradiction:

Improvesacrificial layer removal completenessVSAvoidcell gap uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent extracts the harmful heat treatment step from the sacrificial layer removal process. Instead of using heat treatment to remove the sacrificial layer, the patent uses a chemical etching method with a specific etchant that selectively removes the sacrificial layer without affecting the common electrode structure, thereby avoiding curvature and maintaining uniform cell gap.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the removal method parameter from thermal (heat treatment) to chemical (etching). By using a specific etching solution with controlled composition and applying it under controlled conditions, the sacrificial layer is removed completely while the common electrode maintains its planar structure and the cell gap remains uniform.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If the common electrode is positioned close to the pixel electrode to reduce distance, then device size is reduced, but short circuits may occur between electrodes

Engineering Contradiction:

Improvedevice sizeVSAvoidelectrode insulation

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent introduces an intermediary insulating layer between the common electrode and the pixel electrode. This insulating layer acts as a mediator that maintains electrical insulation even when the electrodes are positioned close together, preventing short circuits while allowing for reduced device size.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies beforehand cushioning by pre-forming the insulating layer and precisely controlling the sacrificial layer thickness and removal process. This ensures that even after the common electrode is positioned close to the pixel electrode, adequate insulation is maintained to prevent short circuits.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the sacrificial layer is not completely removed, then manufacturing is simpler, but residual sacrificial layer causes display quality deterioration

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidmicrocavity uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical/thermal removal method with a chemical etching method. The etching process provides more precise and complete removal of the sacrificial layer, ensuring uniform microcavity formation without requiring complex mechanical or thermal processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent applies preliminary action by pre-patterning the photoresist mask before etching the sacrificial layer. This ensures that the sacrificial layer is removed precisely where needed to form uniform microcavities, and the etching process is optimized to remove the sacrificial layer completely without leaving residues that would affect display quality.

Inventive Principle:

Principle #10Preliminary action

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 method effectively removes the sacrificial layer entirely, maintaining uniform cell gaps and preventing short circuits, thereby enhancing the display quality by ensuring a consistent distance between electrodes.

Implementation Method 1

exposing a portion of the photoresist layer, common electrode and the sacrificial layer with light

Methodology Applied

Scientific EffectPhotoexposure: Photopolymerisation

Data Source

PatentUS9268164B2Liquid crystal display and manufacturing method thereof

Publication Date: 2016.02.23 SAMSUNG DISPLAY CO LTD

AI summary

A manufacturing method of a liquid crystal display includes: providing a pixel electrode on an insulation substrate; providing a sacrificial layer on the pixel electrode; providing a common electrode on the sacrificial layer; providing a photoresist layer on the common electrode; exposing a portion of the photoresist layer, common electrode and the sacrificial layer with light; developing the portion of the photoresist layer exposed with the light; etching a layer between the photoresist layer and the sacrificial layer using the developed photoresist layer as a mask to expose the portion of the sacrificial layer exposed with the light; removing the portion of the sacrificial layer exposed with the light; providing a roof layer on the insulation substrate and etching the roof layer to form a liquid crystal injection hole therein; and removing the sacrificial layer exposed through the liquid crystal injection hole to form a microcavity.