Oxide Semiconductor Transistor Aperture Ratio and Mobility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current display devices face challenges in achieving low manufacturing costs, low power consumption, high aperture ratio, and reliability, particularly due to limitations in transistor technology and the difficulty of forming transistors over large substrates using polycrystalline silicon films, and the increased power consumption associated with high-resolution displays.
Innovation Solution
A display device is designed with a transistor electrically connected to a light-transmitting pixel electrode, featuring a multilayer film structure with an oxide semiconductor layer, where the channel formation region is not in contact with the gate insulating film, and a capacitor with a light-transmitting property, utilizing In—Ga—Zn-based oxide layers with specific atomic ratios and electron affinities to enhance field-effect mobility and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an amorphous silicon film is used for the transistor, then the display device can be manufactured over a large substrate, but the field-effect mobility is low and the aperture ratio decreases
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which fundamentally alters the electrical characteristics to achieve high field-effect mobility while maintaining compatibility with large substrate manufacturing processes
Solution Approach 2:
The patent employs a composite structure with multiple oxide semiconductor layers having different compositions and electron affinities, creating a layered material system that optimizes both mobility and manufacturing feasibility
2Reliability
If a polycrystalline silicon film is used for the transistor, then the field-effect mobility is high and the aperture ratio is increased, but the display device is difficult to be manufactured over a large substrate
Solution Approach 1:
The patent changes the material parameter from polycrystalline silicon to oxide semiconductor, which allows high field-effect mobility to be achieved through a low-temperature sputtering process suitable for large substrate manufacturing
Solution Approach 2:
The patent replaces the high-temperature laser light treatment or heat treatment process with a low-temperature sputtering method, eliminating the need for complex thermal processing equipment and enabling large substrate manufacturing
3Area of stationary object
If the width of wiring is reduced to increase aperture ratio, then the aperture ratio increases, but the operation of the display device is delayed
Solution Approach 1:
The patent changes the semiconductor material parameter to oxide semiconductor with high field-effect mobility, which compensates for the reduced wiring cross-sectional area and maintains operation speed despite narrower wiring width
Solution Approach 2:
The patent applies different oxide semiconductor layers with specific electron affinity values to different regions (channel formation region, source region, drain region) to optimize local electrical characteristics and maintain high-speed operation
4Area of stationary object
If the size of capacitor is reduced to increase aperture ratio, then the aperture ratio increases, but the display quality deteriorates
Solution Approach 1:
The patent changes the capacitor electrode material to light-transmitting oxide semiconductor, which reduces the effective area occupied by the capacitor and increases aperture ratio while maintaining sufficient capacitance function
Solution Approach 2:
The oxide semiconductor layer serves dual functions as both the transistor channel formation region and the capacitor electrode, eliminating the need for separate metal electrode layers and reducing overall device area
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 stable electrical characteristics, high field-effect mobility, and increased aperture ratio, reducing power consumption and manufacturing costs while allowing for large substrate manufacturing, thus improving reliability and efficiency.
Implementation Method 1
An oxide semiconductor film is known to transmit visible light because of its energy gap as wide as approximately 3 eV to 4 eV
Implementation Method 2
An oxide semiconductor film can be formed by a sputtering method
Data Source
AI summary
A display device with low manufacturing cost, with low power consumption, capable of being formed over a large substrate, with a high aperture ratio of a pixel, and with high reliability is provided. The display device includes a transistor electrically connected to a light-transmitting pixel electrode and a capacitor. The transistor includes a gate electrode, a gate insulating film over the gate electrode, and a first multilayer film including an oxide semiconductor over the gate insulating film. The capacitor includes the pixel electrode and a conductive electrode formed of a second multilayer film which overlaps with the pixel electrode with a predetermined distance therebetween, and has the same layer structure as the first multilayer film. A channel formation region of the transistor is at least one layer, which is not in contact with the gate insulating film, of the first multilayer film.