LCD Array Substrate Active Layer Segmentation for Leakage Current Reduction
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Solution Overview
Problem
In-plane switching mode liquid crystal display (LCD) devices face issues with leakage currents and wavy noise due to the exposure of intrinsic amorphous silicon patterns and active layers during the manufacturing process, leading to incorrect transistor operation and image distortion.
Innovation Solution
The array substrate is manufactured using three mask processes, where the active layer is formed in an island shape over the gate electrode, preventing exposure to light and subsequent photocurrent generation, and a passivation layer is placed between the pixel and common electrodes to minimize leakage currents and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the active layer and source/drain electrodes are formed through the same mask process, then manufacturing cost and time are reduced, but the active layer becomes exposed to light causing photocurrent generation and wavy noise
Solution Approach 1:
The patent divides the formation process into two separate mask processes: one for forming the active layer and another for forming the source and drain electrodes. This segmentation ensures that when the active layer is formed, the electrode materials that would cause light reflection and photocurrent are not yet present, thus eliminating the wavy noise issue while maintaining manufacturing efficiency through integrated process design.
Solution Approach 2:
The active layer is formed in advance before the source and drain electrodes are deposited. This preliminary action of forming the active layer first, then subsequently forming the electrodes, prevents the active layer from being exposed to reflected light from electrode materials during the electrode formation process, thereby eliminating photocurrent generation and wavy noise.
2Ease of manufacture
If the active layer is exposed to light during manufacturing, then manufacturing process is simplified, but leakage currents occur and transistor operation becomes incorrect
Solution Approach 1:
The manufacturing process is segmented into distinct stages: first forming the active layer through a mask process, then forming the source and drain electrodes through a separate mask process. This segmentation ensures that the active layer is never exposed to light from electrode materials, preventing photocurrent generation and ensuring correct transistor operation while maintaining process simplicity through integrated design.
Solution Approach 2:
The active layer is formed preliminarily before any electrode materials are deposited. This timing arrangement ensures that the active layer is in its final position before electrode formation begins, eliminating any subsequent light exposure issues and ensuring reliable transistor operation without complicating the manufacturing process.
3Ease of manufacture
If intrinsic amorphous silicon patterns are exposed during manufacturing, then manufacturing is easier, but wavy noise occurs on displayed images
Solution Approach 1:
The patent segments the manufacturing process so that intrinsic amorphous silicon patterns are formed and positioned before electrode materials are deposited. This segmentation ensures that the silicon patterns are never exposed to light from electrode materials, eliminating wavy noise while maintaining manufacturing simplicity through the integrated process design.
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 prevents wavy noise, ensures correct transistor operation, reduces manufacturing costs and time, and enhances image quality by minimizing photocurrents and exposure of active layers, while maintaining a high aperture ratio and brightness.
Implementation Method 1
a passivation layer directly between the pixel electrode and the common electrode and directly between the source and drain electrodes
Implementation Method 2
Liquid crystal molecules have a long and thin shape, and the liquid crystal molecules are regularly arranged along in an alignment direction. Light passes through the LCD device along the long and thin shape of the liquid crystal molecules. The alignment of the liquid crystal molecules depends on the intensity or the direction of an electric field applied to the liquid crystal molecules.
Data Source
AI summary
An array substrate for a liquid crystal display device includes a substrate, a gate line on the substrate, a thin film transistor including a gate electrode of the gate line, a gate insulating layer over the gate electrode, an active layer on the gate insulating layer and ohmic contact layers on the active layer, and source and drain electrodes over the ohmic contact layers, a pixel electrode electrically connected to the drain electrode, a data line electrically connected to the source electrode and crossing the gate line, a common electrode spaced apart from the pixel electrode, and a passivation layer directly between the pixel electrode and the common electrode and directly between the source and drain electrodes.