Light-Transmitting Capacitor for High Aperture Ratio Displays
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Solution Overview
Problem
In liquid crystal display devices, increasing the capacitance of capacitors to maintain liquid crystal molecule alignment and reduce power consumption is hindered by the need for larger light-blocking conductive films, which lowers the aperture ratio and degrades display quality, especially in high-resolution displays. Additionally, oxide semiconductor transistors face issues with electrical characteristic changes over time, leading to malfunction, increased power consumption, and decreased contrast.
Innovation Solution
A display device structure incorporating a transistor with an oxide semiconductor film, a dual-gate structure, and a capacitor with a metal oxide film and light-transmitting conductive films, along with an organic and inorganic insulating film stack, to enhance electrical characteristics and aperture ratio while maintaining low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area of light-blocking conductive film is increased to increase capacitor area, then capacitance value is improved, but aperture ratio is lowered and display quality is degraded
Solution Approach 1:
The patent applies the principle of using light-transmitting conductive films instead of traditional light-blocking conductive films for the capacitor electrodes. This material change allows the capacitor to maintain high capacitance value while being transparent or translucent, thus not blocking light and preserving high aperture ratio and display quality in high-resolution displays
Solution Approach 2:
The patent employs composite material structures including light-transmitting conductive films combined with insulating films to form the capacitor. This composite approach enables the capacitor to achieve both electrical functionality (high capacitance) and optical functionality (light transmission), resolving the contradiction between capacitance and aperture ratio
2Ease of manufacture
If oxide semiconductor transistor is used, then manufacturing flexibility is improved, but electrical characteristic stability deteriorates due to change over time and stress
Solution Approach 1:
The patent applies parameter changes by optimizing the oxide semiconductor composition (such as In-Ga-Zn-O system with specific atomic ratios), controlling film thickness, and adjusting manufacturing parameters to achieve both ease of manufacture and stable electrical characteristics. The controlled formation process with specific temperature and atmosphere parameters ensures reliability while maintaining manufacturing flexibility
Solution Approach 2:
The patent implements local quality control by creating specific regions with different oxide semiconductor compositions and structures. By controlling the local stoichiometry, defect density, and crystalline structure in the channel region, the patent achieves stable electrical characteristics while maintaining the overall manufacturing flexibility of oxide semiconductor transistors
Data Source
AI summary
Provided is a display device with high display quality. The display device includes a transistor over a substrate, an inorganic insulating film over the transistor, an organic insulating film over the inorganic insulating film, a capacitor electrically connected to the transistor, and a pixel electrode over the organic insulating film. The transistor includes a gate electrode over the substrate, an oxide semiconductor film overlapping with the gate electrode, a gate insulating film in contact with one surface of the oxide semiconductor film, and a pair of conductive films in contact with the oxide semiconductor film. The capacitor includes a metal oxide film over the gate insulating film, the inorganic insulating film, and a first light-transmitting conductive film over the inorganic insulating film. The pixel electrode is formed of a second light-transmitting conductive film and in contact with one of the pair of conductive films and the first light-transmitting conductive film.