Oxide TFT Display Structure for High Aperture and Fast Driving
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Solution Overview
Problem
Display devices with increased pixel density face challenges in achieving high on-off ratios and operation speed for transistors in pixel and driver circuits, leading to decreased aperture ratios and longer writing times for display images.
Innovation Solution
A display device structure and manufacturing method that incorporates specific transistor configurations, including oxide semiconductors and insulating layers, over a single substrate, with light-transmitting properties to enhance switching characteristics and operation speed, utilizing metal oxides for gate and source/drain electrodes and oxide insulating layers formed by sputtering methods to reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel density is increased, then display resolution is improved, but aperture ratio decreases
Solution Approach 1:
The patent employs light-transmitting thin film structures for transistor components including the gate electrode layer, source electrode layer, drain electrode layer, and insulating layers. These thin films minimize the area occupied by transistor components while maintaining electrical functionality, thereby increasing the aperture ratio even at high pixel densities
Solution Approach 2:
The patent utilizes oxide semiconductor materials with specific physical and electrical parameters that enable high field-effect mobility in thin film configurations. By changing material parameters and layer thicknesses, the transistor can achieve required performance with reduced area occupation
2Loss of time
If writing time is reduced for high pixel density, then display speed is improved, but transistor operation speed requirements increase
Solution Approach 1:
The patent changes the electrical parameters of the transistor by using oxide semiconductor materials that provide high field-effect mobility. This material parameter change enables faster charge carrier transport, increasing transistor operation speed to meet the reduced writing time requirements of high pixel density displays
Solution Approach 2:
The patent transitions to thin film transistor architecture where the channel formation region is formed in a planar thin film rather than bulk semiconductor. This dimensional change enables higher field-effect mobility and faster operation speeds suitable for high-speed display applications
3Area of stationary object
If oxide semiconductor layers and light-transmitting materials are used, then aperture ratio and display characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the oxide insulating layer structure, which serves as both a gate insulator and a protective layer over the oxide semiconductor. This merging reduces the total number of separate layers and manufacturing steps, simplifying the overall manufacturing process while maintaining high aperture ratio
Solution Approach 2:
The oxide insulating layer performs multiple functions including electrical insulation, protection of the oxide semiconductor layer, and potential passivation of interface states. This multi-functionality reduces the need for additional specialized layers, simplifying manufacturing while achieving high aperture ratio
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 solution enables the production of display devices with improved aperture ratios and display characteristics, allowing for high-speed operation of transistors in driver circuits and reliable electrical performance in pixel circuits, while reducing manufacturing costs.
Implementation Method 1
oxide insulating layers formed by sputtering methods
Data Source
AI summary
An object is to provide a display device with excellent display characteristics, where a pixel circuit and a driver circuit provided over one substrate are formed using transistors which have different structures corresponding to characteristics of the respective circuits. The driver circuit portion includes a driver circuit transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using a metal film, and a channel layer is formed using an oxide semiconductor. The pixel portion includes a pixel transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using an oxide conductor, and a semiconductor layer is formed using an oxide semiconductor. The pixel transistor is formed using a light-transmitting material, and thus, a display device with higher aperture ratio can be manufactured.