Nested Contact Holes in Display Devices for High Definition

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Solution Overview

Problem

In display devices, the increased depth and diameter of contact holes due to organic insulating films lead to areas with large level differences, reducing display quality and contributing to deterioration in display performance, especially as pixel size decreases and the number of wiring lines increases, affecting the display's definition and reliability.

Innovation Solution

The implementation of a display device structure where the edge of the first contact hole is located inside the second contact hole without crossing its edge, with both holes formed using dry etching with plasma gas not containing oxygen, allowing for a simplified connection structure between the switching element and pixel electrode, reducing non-display areas, and preventing damage to the relay electrode and conductive layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an organic insulating film is interposed between the source/drain electrode and the pixel electrode, then the switching element and pixel electrode can be electrically connected through contact holes, but the depth and diameter of the contact holes increase, creating areas with large level differences that do not contribute to display

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoiddisplay area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The first contact hole is positioned inside the second contact hole, creating a nested configuration where the larger second contact hole (through the organic insulating film) contains the smaller first contact hole (through the inorganic insulating film). This nesting arrangement allows both contact holes to serve their respective electrical connection functions while minimizing the overall area occupied by contact structures, thereby preserving display area.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Different insulating films (inorganic and organic) are used in different locations to achieve appropriate electrical isolation and connection properties. The inorganic insulating film provides robust isolation where needed, while the organic insulating film allows for controlled contact hole formation. This localized differentiation enables optimized electrical connections without compromising overall display quality.

Inventive Principle:

Principle #3Local quality

2Reliability

If the contact hole diameter is increased to accommodate the organic insulating film, then electrical connection is achieved, but the opening area contributing to display is reduced

Engineering Contradiction:

Improvecontact hole connection reliabilityVSAvoidopening area

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

By nesting the first contact hole within the second contact hole, the design allows the second contact hole to be sufficiently large for reliable electrical connection through the organic insulating film, while the inner first contact hole provides an additional connection path. This nested arrangement minimizes the total area occupied by contact structures, preserving maximum opening area for display purposes.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Measurement precision

If pixel size is reduced to increase definition, then higher resolution is achieved, but the number of wiring lines increases and contact hole areas become more critical

Engineering Contradiction:

Improvedisplay definitionVSAvoidwiring line complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The nested contact hole structure consolidates multiple electrical connection functions into a compact configuration. By positioning the first contact hole inside the second contact hole, the design reduces the overall footprint of contact structures, allowing for denser pixel arrangements and increased definition without proportionally increasing wiring complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 approach reduces the area not contributing to display, suppresses the reduction in opening size, and prevents deterioration in display quality, ensuring reliable connections and improved pixel definition even with smaller pixel sizes.

Implementation Method 1

both holes formed using dry etching with plasma gas not containing oxygen

Methodology Applied

Scientific EffectPlasma etching: Plasma

Implementation Method 2

preventing damage to the relay electrode and conductive layers

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Data Source

PatentUS10261373B2Display device and method of manufacturing the same

Publication Date: 2019.04.16 MAGNOLIA WHITE CORP

AI summary

According to one embodiment, a display device includes a semiconductor layer, a metal portion, and a pixel electrode, the metal portion being in contact with the semiconductor layer through a first contact hole, the pixel electrode being in contact with the metal portion through a second contact hole, the metal portion being a stacked layer body including at least a first conductive layer and a second conductive layer, an edge of the first contact hole being located inside the second contact hole without crossing an edge of the second contact hole, in planar view, the pixel electrode being in contact with the first conductive layer.