Display Unit Terminal Section Protection During Wet Etching

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Solution Overview

Problem

Organic EL display units face issues with display performance variability due to unevenness in TFT characteristics and increased complexity, leading to higher short-circuit faults and reduced yield, primarily caused by damage to the wiring layer during the wet etching process.

Innovation Solution

A display unit with a semiconductor layer containing a wiring layer and pixel electrode made of materials removable by the same etchant, where the terminal section is formed using a conductive layer of the same material as the wiring layer, reducing damage during the etching process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wiring layer is made thick to decrease resistance, then the electrical conductivity is improved, but the wiring layer becomes more susceptible to damage during wet etching, increasing short-circuit faults

Engineering Contradiction:

Improveelectrical conductivityVSAvoiddamage during wet etching

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A protective film is introduced as an intermediary layer between the wiring layer and the etchant. This protective film prevents direct contact between the etchant and the wiring layer during wet etching processes, thereby protecting the wiring layer from damage while allowing the etching of other layers to proceed normally.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective film is formed on the wiring layer before the wet etching process begins. This preliminary protective measure ensures that when subsequent wet etching steps are performed to remove pixel electrodes or process other layers, the wiring layer is already protected and will not be damaged by the etchant.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the number of TFTs and wiring circuits is increased to resolve display unevenness, then the display performance is improved, but the circuit complexity increases, leading to tighter layout space and more short-circuit faults

Engineering Contradiction:

Improvedisplay performanceVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The display device is divided into multiple pixel units, each with its own TFT and wiring circuit. By segmenting the display into independent pixel elements, the overall display performance is improved through better control of display unevenness, while each segment remains manageable in size and complexity.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the wiring layer is exposed as the uppermost surface before mounted member lamination, then the terminal section can be formed, but the wiring layer is vulnerable to damage in subsequent wet etching steps

Engineering Contradiction:

Improveterminal section formationVSAvoiddamage in wet etching step

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The protective film serves as a mediator that allows the wiring layer to be exposed and formed into the terminal section while simultaneously protecting it from damage during subsequent wet etching steps. The protective film can be selectively removed or patterned to create the terminal section structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective film provides beforehand cushioning or protection to the wiring layer. This prior protective measure ensures that when the wiring layer is exposed as the uppermost surface for terminal section formation, it is already cushioned against potential damage from subsequent wet etching processes.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 minimizes variations in display performance and increases manufacturing yield by preventing damage to the terminal section during etching, resulting in a more reliable electronic apparatus.

Implementation Method 1

a method with the use of wet etching has been disclosed as a processing technique of the wiring layer

Methodology Applied

Scientific EffectWet etching:

Data Source

PatentUS10341475B2Display unit, method of manufacturing the same, and electronic apparatus

Publication Date: 2019.07.02 SONY GROUP CORP

AI summary

A display unit includes: a display layer including a pixel electrode; a semiconductor layer provided in a layer below the display layer, the semiconductor layer including a wiring layer that includes a material removable by an etchant by which the pixel electrode is also removable; and a terminal section configured to electrically connect the semiconductor layer to an external circuit, the terminal section including a first electrically-conductive layer made of a material same as a material of the wiring layer.