Oxide Semiconductor TFT Aperture Ratio via Reducing Insulating Layer
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Solution Overview
Problem
Current active-matrix substrates for liquid crystal display devices face challenges in achieving high aperture ratios while maintaining low manufacturing costs, as the use of oxide semiconductor TFTs alone is insufficient to meet increasing demands for higher definition and aperture ratios.
Innovation Solution
A semiconductor device structure incorporating a substrate with a gate electrode, oxide semiconductor layer, source and drain electrodes, and transparent electrodes, where a reducing insulating layer reduces the oxide semiconductor's electrical resistance, allowing for a higher aperture ratio without decreasing the pixel's luminance, and a method for fabricating this structure that simplifies the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture ratio is increased to improve display quality, then the display quality is improved, but the pixel area becomes smaller making it difficult to maintain required element sizes
Solution Approach 1:
The patent applies local quality by forming a reducing insulating layer selectively in specific regions (source region and drain region) of the oxide semiconductor layer, rather than uniformly across the entire layer. This localized treatment reduces resistance only where needed for electrical connection, while preserving the channel region's properties for transistor operation, thus enabling higher aperture ratios without compromising element functionality.
Solution Approach 2:
The oxide semiconductor layer is segmented into functionally distinct regions: a channel region for transistor operation and source/drain regions for electrical connection. The reducing insulating layer is applied selectively to the source and drain regions, creating locally optimized electrical properties that enable smaller overall pixel dimensions while maintaining required performance.
2Ease of manufacture
If oxide semiconductor TFTs are used to reduce manufacturing steps, then the manufacturing process is simplified, but the aperture ratio cannot be increased sufficiently to meet high definition demands
Solution Approach 1:
The patent merges the formation of the pixel electrode and the resistance reduction step into a single integrated process. The reducing insulating layer is formed as part of the pixel electrode structure, simultaneously achieving both the electrode function and the resistance reduction function, thereby maintaining manufacturing simplicity while enabling higher aperture ratios.
Solution Approach 2:
The reducing insulating layer serves multiple functions: it acts as part of the pixel electrode structure, provides resistance reduction in the source and drain regions, and maintains the simplified manufacturing process characteristics of oxide semiconductor TFTs. This multi-functionality allows aperture ratio enhancement without adding significant process complexity.
3Reliability
If the resistance of the oxide semiconductor layer is reduced to improve electrical connection, then the electrical connection is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The reducing insulating layer is formed using the same sputtering process and conditions as the oxide semiconductor layer itself, allowing it to be deposited simultaneously or in sequence without requiring additional specialized equipment or processes. The layer serves itself by providing both the insulating function and the resistance reduction function through its inherent properties and strategic placement.
Solution Approach 2:
The resistance reduction is achieved by changing the physical and chemical parameters of the insulating layer through selective formation conditions. By controlling the sputtering parameters, composition, and thickness of the reducing insulating layer in specific regions, the electrical resistance is reduced without requiring additional processing steps or complex manufacturing procedures.
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
The proposed solution enables the fabrication of a TFT substrate with a higher aperture ratio and improved display quality at a lower cost, enhancing the performance and efficiency of liquid crystal display devices.
Implementation Method 1
a reducing insulating layer which contacts with a lower surface of the oxide semiconductor layer and has a property of reducing an oxide semiconductor included in the oxide semiconductor layer
Data Source
AI summary
A semiconductor device (100A) includes a substrate (2), an oxide semiconductor layer (5) formed on the substrate (2), source and drain electrodes (6s, 6d) electrically connected to the oxide semiconductor layer (5), a first transparent electrode (7) electrically connected to the drain electrode (6d), a dielectric layer (8) formed on the source and drain electrodes (6s, 6d), and a second transparent electrode (9) formed on the dielectric layer (8). The upper and/or lower surface(s) of the first transparent electrode (7) contacts with a reducing insulating layer (8a) with the property of reducing an oxide semiconductor included in the oxide semiconductor layer (5). The second transparent electrode (9) overlaps at least partially with the first transparent electrode (7) via the dielectric layer (8). The oxide semiconductor layer (5) and the first transparent electrode (7) are formed out of the same oxide film.