Integral Semiconductor Layer for LCD Source Line Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active matrix type LCDs face challenges in achieving high reliability, productivity, and resolution due to disconnection issues in source electrodes and lines during wet etching, particularly when using semiconductor layers with bumps, which lead to etchant penetration and photoresist residue problems.
Innovation Solution
The solution involves forming a semiconductor layer with three integral portions: a crossover portion, a TFT portion, and a connecting portion, where the crossover portion on the connecting side and the whole connecting portion are covered by the source electrode and source line, preventing etchant penetration and disconnection, and using a manufacturing method that includes sequential formation of metal films and etching to ensure accurate patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching is used to pattern source electrodes and lines, then manufacturing cost is reduced, but disconnection occurs when semiconductor layer has bumps
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the semiconductor layer before the wet etching process. This protective film prevents etchant from penetrating into gaps caused by bumps in the semiconductor layer, thereby preventing disconnection of source electrodes and lines during wet etching while maintaining the cost advantage of wet etching.
Solution Approach 2:
The patent introduces a protective film as an intermediary layer between the semiconductor layer and the source electrode/line structure. This intermediary layer acts as a barrier that prevents etchant penetration into gaps, resolving the disconnection issue while allowing wet etching to proceed.
2Area of moving object
If source lines are thinned to increase aperture ratio, then display quality improves, but resolution and accuracy decrease
Solution Approach 1:
The patent applies preliminary action by forming a protective film before etching, which enables precise patterning of thinner source lines. This protective film prevents etchant penetration and maintains pattern accuracy even when source lines are thinned to increase aperture ratio.
Solution Approach 2:
The patent changes the parameter of source line thickness to be thinner while maintaining manufacturing precision through the protective film approach. The protective film allows the etching process to accurately define thinner lines without disconnection, thus enabling higher aperture ratio while maintaining resolution.
3Reliability
If photoresist residue remains on semiconductor layer, then disconnection occurs, but complete removal affects previous process layers
Solution Approach 1:
The patent introduces a protective film as an intermediary layer that prevents etchant from interacting with photoresist residue on the semiconductor layer. This protective film acts as a barrier that eliminates the harmful effect of photoresist residue without requiring additional removal steps that would affect previous process layers.
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 enhances the reliability and productivity of active matrix type LCDs by preventing disconnection of source electrodes and lines, allowing for thinner source lines while maintaining high resolution and accuracy.
Implementation Method 1
wet etching by wet chemical etchant or dry etching by reactive gases can be used in patterning source electrodes and lines of TFTs
Data Source
AI summary
According to an aspect of the present invention, there is provided a liquid crystal display that includes a gate electrode and line formed on a transparent insulating substrate, a gate insulating film covering the gate electrode and line, a semiconductor layer formed on the gate insulating film, a source electrode, a source line, and a drain electrode formed on the semiconductor layer, and a pixel electrode connected to the drain electrode. The semiconductor layer is integrally formed of three portions which are a crossover portion of the source line and the drain line, a TFT portion, and a connecting portion connecting the crossover portion to the TFT portion. A part of the crossover portion on the connecting portion side and the whole connecting portion are covered by the source electrode and the source line.