TFT-LCD Array Substrate Partition Groove Lift-Off
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Solution Overview
Problem
The 3-Mask process for manufacturing TFT-LCD array substrates faces challenges in disconnecting the transparent conductive thin film at the photoresist edges, leading to increased costs and defects due to residual adhesion, which affects the lift-off process and product quality.
Innovation Solution
The introduction of a partition groove at the periphery of the pixel electrode, combined with a dry etching process that promotes significant lateral etching of the passivation and gate insulating layers, creates a suspended undercut at the photoresist edge, ensuring the transparent conductive thin film is disconnected and facilitating a successful lift-off process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a thick photoresist layer is applied to make the photoresist edge slope as steep as possible, then the sidewalls of the photoresist pattern become vertical after photolithography, but the transparent conductive thin film cannot be appropriately disconnected at the photoresist edges
Solution Approach 1:
The invention divides the photoresist structure into two functional parts: a thick main body for providing vertical sidewalls, and a thin edge portion for enabling proper disconnection of the transparent conductive thin film. This segmentation allows each part to fulfill its specific function without compromise.
Solution Approach 2:
The photoresist layer is designed with non-uniform thickness: thick at the center to form vertical sidewalls, and thin at the edges to allow transparent conductive thin film disconnection. This local quality variation resolves the contradiction by optimizing different regions for different purposes.
2Ease of manufacture
If the sidewalls of the passivation layer have an inwardly concaved shape with over-etching during etching process, then the etching process is simplified, but the transparent conductive thin film becomes disconnected at the sidewalls of the passivation layer
Solution Approach 1:
The invention performs preliminary action by forming a protruding structure on the photoresist before depositing the transparent conductive thin film. This pre-formed structure ensures proper disconnection of the thin film, eliminating the need for over-etching that would create inwardly concaved passivation layer sidewalls.
3Reliability
If the transparent conductive thin film adheres to the photoresist edges, then the lift-off process quality cannot be ensured, but increasing process control measures increases cost
Solution Approach 1:
The invention extracts the problematic edge portion of the photoresist by designing it to be thinner than the main body. This thin edge portion is specifically removed or designed to prevent adhesion of the transparent conductive thin film, thereby ensuring lift-off quality without requiring additional complex process control measures.
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 improves the quality of the lift-off process, maintains the integrity of the pixel electrode, and reduces production time and costs by preventing adhesion of the transparent conductive thin film, thereby enhancing the overall product quality and efficiency of the 3-Mask process.
Implementation Method 1
a dry etching process that promotes significant lateral etching of the passivation and gate insulating layers
Implementation Method 2
depositing a transparent conductive thin film
Data Source
AI summary
A Thin Film Transistor-Liquid Crystal Display (TFT-LCD) array substrate is presented which includes a gate line, a data line, and a pixel electrode. The pixel electrode is disposed in a pixel region defined by the intersection between the gate line and the data line. In the pixel region, a partition groove for forming a pixel electrode pattern is provided at the periphery of the pixel electrode.