LCD Electrode Structure Reducing Cost and Signal Delay
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Solution Overview
Problem
The manufacturing cost of liquid crystal displays (LCDs) is increased due to the need for separate photo masks for forming two electric field-generating electrodes on a single thin-film transistor (TFT) array substrate, and signal delays occur when common electrodes are electrically connected.
Innovation Solution
The design includes a substrate with gate wiring, a gate insulating layer, an electrode pattern, and auxiliary wiring that reduces electrical resistance and suppresses the generation of copper oxide (CuOx) by spacing the TFT from auxiliary wiring and using a multilayer structure for the gate and data lines, including materials like Ti and Cu, to minimize contact between copper electrodes and passivation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate photo masks are used for forming two electric field-generating electrodes on a single TFT array substrate, then the LCD can achieve wide viewing angles, but the manufacturing cost increases
Solution Approach 1:
The patent merges the pixel electrode and common electrode formation processes into a single photo mask step. The pixel electrode and common electrode are formed simultaneously using one photo mask pattern, eliminating the need for separate photo masks while maintaining the wide viewing angle characteristics achieved by having both electrodes on the same substrate
2Device complexity
If common electrodes are electrically connected to each other, then the LCD structure is simplified, but signal delays occur
Solution Approach 1:
The patent segments the common electrode into multiple electrically isolated regions corresponding to different pixel regions. Each common electrode region is separated by insulating structures, preventing electrical connection between adjacent common electrodes. This segmentation eliminates signal delays while maintaining simplified structure within each pixel region
3Ease of manufacture
If copper electrode and passivation layer are placed in contact, then the manufacturing process is simplified, but copper oxide (CuOx) generation occurs
Solution Approach 1:
The patent introduces an intermediary barrier layer between the copper electrode and passivation layer. This intermediate layer prevents direct contact between copper and the passivation layer, thereby preventing copper oxide generation while maintaining process simplicity by integrating the barrier function into the existing layer structure
4Ease of manufacture
If single-layer wiring is used for data lines, then the manufacturing process is simpler, but electrical resistance is high
Solution Approach 1:
The patent uses composite multilayer wiring structures for data lines, combining multiple conductive layers with different properties. The composite structure includes layers such as titanium and copper, where each layer contributes different characteristics (adhesion, conductivity), achieving low electrical resistance while maintaining manufacturability through established sputtering processes
Data Source
AI summary
A liquid crystal display and a method of fabricating a liquid crystal display (LCD), the LCD including a substrate; gate wiring including a gate pad, a gate electrode, and a gate line, which are formed on the substrate; a gate insulating layer disposed on the gate wiring; an electrode pattern including a connecting electrode, which is disposed on the gate insulating layer and is electrically connected to the gate pad, a source electrode and a drain electrode, which partially overlap the gate electrode; a pixel electrode, which is electrically connected to the drain electrode; a data line, which intersects the gate line; a semiconductor layer disposed on the gate electrode; first auxiliary wiring overlapping the data line and spaced from the semiconductor layer; and second auxiliary wiring overlapping the gate line.