Thin-Film Transistor Substrate Light-Shielding Metal Layer
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Solution Overview
Problem
Conventional thin-film transistor substrates using oxide semiconductors face challenges in minimizing non-display-pixel areas to maintain a high aperture ratio while preventing light-induced deterioration and electrical resistance issues.
Innovation Solution
The thin-film transistor substrate design includes a metal layer with a light-shield part that overlaps the channel layer, reducing electrical path length and resistance, and forms a laminated structure with the common electrode to minimize non-display-pixel areas and prevent channel layer deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductive material is used for the pixel electrode and common electrode, then light transmission is improved, but electrical resistance increases
Solution Approach 1:
The patent uses a composite structure combining transparent conductive material (ITO) with a light-shielding conductive material (Aluminum) in a laminated configuration. The ITO layer provides light transmission while the Aluminum layer provides low electrical resistance, creating a composite electrode system that achieves both optical and electrical performance requirements.
2Length of moving object
If the common electrode is placed between the TFT and pixel electrode, then electrical path length is reduced, but light shielding is compromised
Solution Approach 1:
The patent repositions the common electrode from a vertical arrangement (between TFT and pixel electrode) to a horizontal arrangement (above the pixel electrode in the same plane). This dimensional change allows the common electrode to be placed where it can form a laminated structure with the light-shielding layer, achieving both short electrical paths and light shielding without interference.
Solution Approach 2:
The common electrode is formed as a composite structure with a light-shielding conductive material layer laminated on the transparent conductive material layer. This composite configuration allows the common electrode to maintain short electrical path length while simultaneously providing light shielding to protect the oxide semiconductor channel layer.
3Speed
If oxide semiconductor is used for the channel layer, then mobility is improved, but light-induced deterioration occurs
Solution Approach 1:
The patent converts the harmful effect of light on oxide semiconductor by introducing a light-shielding conductive material layer that absorbs or blocks light before it reaches the channel layer. The light-shielding layer, which would otherwise be considered an obstruction, actually protects the oxide semiconductor from light-induced deterioration while maintaining the high mobility benefits.
Solution Approach 2:
The light-shielding conductive material layer acts as an intermediary between the light source and the oxide semiconductor channel layer. This intermediate layer blocks harmful light from reaching the channel layer, protecting it from deterioration while allowing the oxide semiconductor to maintain its high carrier mobility characteristics.
4Area of stationary object
If non-display-pixel areas are minimized, then aperture ratio is improved, but manufacturing complexity increases
Solution Approach 1:
The light-shielding conductive material layer serves multiple functions simultaneously: it provides light shielding to protect the oxide semiconductor, reduces electrical resistance in the electrode, and helps define pixel boundaries. This multi-functionality allows minimization of non-display-pixel areas without proportionally increasing manufacturing complexity, as the same layer performs multiple protective and conductive roles.
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 design effectively suppresses defective displaying caused by light-induced deterioration and maintains a high aperture ratio by reducing electrical resistance and non-display-pixel areas, ensuring improved display quality.
Implementation Method 1
a light-shield part which overlaps the channel layer at least partially in plan view
Implementation Method 2
forms a laminated structure with the common electrode to minimize non-display-pixel areas and prevent channel layer deterioration
Data Source
AI summary
A channel layer is formed of an oxide semiconductor. A first insulating film is provided on the channel layer, a source line, and a drain electrode, and includes a drain contact hole which reaches the drain electrode. A pixel electrode is provided on the first insulating film, includes a connection conductive layer which is connected to the drain electrode by the drain contact hole, and is formed of a transparent conductive material. The pixel electrode is covered with a second insulating film. A common electrode is provided on the second insulating film, includes an opening which faces the pixel electrode in a thickness direction, and is formed of a transparent conductive material. A metal layer, in conjunction with a part of the common electrode, forms a laminated structure, and includes a light-shield part which overlaps the channel layer at least partially in plan view.