Oxide Semiconductor Transistor for Large Display Drivers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional oxide semiconductors used in display devices have insufficient field effect mobility, limiting their application in large-sized display devices, especially when used for both pixels and driver circuits.
Innovation Solution
An active matrix display device is developed using transistors with oxide semiconductors that have a field effect mobility of at least 50 cm2/Vs, preferably 100 cm2/Vs, and includes a gate driver and an analog switch with these transistors as elements, enabling the use of these devices in large-sized displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional oxide semiconductors are used for transistors in display devices, then the manufacturing process is simpler and can be formed over larger glass substrates, but the field effect mobility is insufficient (only 10-20 cm2/Vs), limiting the application in large-sized display devices with driver circuits
Solution Approach 1:
The patent changes the material composition parameters of the oxide semiconductor by incorporating specific ratios of In, Ga, and Zn oxides (In:Ga:Zn = 1:1:1 to 1:2:2 atomic ratio) to achieve optimal field effect mobility of 50-100 cm2/Vs while maintaining the simplicity of the manufacturing process over glass substrates
Solution Approach 2:
The patent uses a composite oxide semiconductor material system combining multiple metal oxides (In2O3, Ga2O3, ZnO) in specific proportions to create a material that achieves both high field effect mobility and compatibility with glass substrate manufacturing processes
2Ease of manufacture
If oxide semiconductors with field effect mobility of 10-20 cm2/Vs are used, then the manufacturing process is simpler compared to polycrystalline silicon, but the current capability is insufficient for large-sized display devices requiring additional drivers
Solution Approach 1:
The patent optimizes the material composition parameters (In:Ga:Zn atomic ratio) to achieve field effect mobility of 50-100 cm2/Vs, which directly improves the current capability (Ion = μ × V × C) without complicating the manufacturing process, allowing large-sized display devices to be manufactured with integrated drivers
3Reliability
If polycrystalline silicon transistors are used, then high field effect mobility (10-20 cm2/Vs) is achieved, but they are not suitable for being formed over larger glass substrates
Solution Approach 1:
The patent changes the material type from polycrystalline silicon to oxide semiconductor with specific composition ratios (In:Ga:Zn = 1:1:1 to 1:2:2), achieving field effect mobility of 50-100 cm2/Vs while maintaining compatibility with glass substrate manufacturing processes
Solution Approach 2:
The patent replaces the need for complex polycrystalline silicon formation processes with a simpler oxide semiconductor deposition process that is well-suited for large glass substrates, using sputtering or other deposition methods that can handle large-area substrates effectively
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 enhanced field effect mobility of the oxide semiconductor transistors improves the current capability, allowing for the manufacture of large-sized display devices without the need for additional drivers, thus increasing the display size limit to at least 20 inches.
Implementation Method 1
performing crystal growth which proceeds from a surface toward an inside of the oxide component by heat treatment to form a first oxide crystal component
Implementation Method 2
an active layer can be formed using an oxide semiconductor by a sputtering method or the like
Data Source
AI summary
One embodiment of the present invention provides a highly reliably display device in which a high mobility is achieved in an oxide semiconductor. A first oxide component is formed over a base component. Crystal growth proceeds from a surface toward an inside of the first oxide component by a first heat treatment, so that a first oxide crystal component is formed in contact with at least part of the base component. A second oxide component is formed over the first oxide crystal component. Crystal growth is performed by a second heat treatment using the first oxide crystal component as a seed, so that a second oxide crystal component is formed. Thus, a stacked oxide material is formed. A transistor with a high mobility is formed using the stacked oxide material and a driver circuit is formed using the transistor.