Oxide Semiconductor Transistor Crystallinity for Large Substrates
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Solution Overview
Problem
Transistors manufactured using conventional oxide semiconductors have limitations in field-effect mobility, making them unsuitable for large-sized display devices and high-performance semiconductor applications, particularly in driving devices and driver circuits.
Innovation Solution
A method involving the formation of multi-component and single-component oxide semiconductor layers with single crystal regions, achieved through heat treatment and epitaxial growth, to enhance crystallinity and field-effect mobility, allowing for the use of larger substrates and improved performance in large-sized display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oxide semiconductor is used to manufacture transistor, then the transistor can be formed, but the field-effect mobility is limited and insufficient for large-sized display devices and high-performance applications
Solution Approach 1:
The patent changes the crystalline state parameter of the oxide semiconductor from amorphous or polycrystalline to single crystal by performing heat treatment at 500°C to 1000°C. This parameter change dramatically improves field-effect mobility from conventional limited values to 10 cm²/Vs or higher, making the transistor suitable for large-sized display devices and high-performance applications while maintaining ease of manufacture on large substrates
Solution Approach 2:
The patent uses a composite structure consisting of a first multi-component oxide semiconductor layer and a second multi-component oxide semiconductor layer, where at least one layer has a single crystal structure. This composite material approach enables high field-effect mobility while maintaining compatibility with large substrate manufacturing processes
2Area of stationary object
If amorphous silicon is used to manufacture transistor, then the transistor can be formed over larger glass substrate, but the field-effect mobility is low
Solution Approach 1:
The patent changes the crystalline state parameter from amorphous to single crystal through heat treatment at 500°C to 1000°C. This enables the oxide semiconductor transistor to achieve high field-effect mobility (10 cm²/Vs or higher) while maintaining the ability to be formed over large glass substrates, thus resolving the contradiction between substrate size and mobility
3Reliability
If polycrystalline silicon is used to manufacture transistor, then high field-effect mobility is achieved, but it is not suitable for larger glass substrate
Solution Approach 1:
The patent forms single crystal regions in the oxide semiconductor layer through heat treatment, achieving high field-effect mobility comparable to polycrystalline silicon. The oxide semiconductor-based process maintains compatibility with large substrate manufacturing, resolving the contradiction between mobility and substrate size that limits polycrystalline silicon applications
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 approach results in a high-field effect mobility transistor suitable for large-sized display devices and high-performance semiconductor applications, with reduced hydrogen concentration and increased band gap, enabling efficient operation and reliability.
Implementation Method 1
crystal growth is carried out from a surface to an inside by performing heat treatment at 500° C. to 1000° C. inclusive, preferably 550° C. to 750° C. inclusive
Implementation Method 2
crystal growth is carried out from a surface to an inside by performing heat treatment
Data Source
AI summary
A larger substrate can be used, and a transistor having a desirably high field-effect mobility can be manufactured through formation of an oxide semiconductor layer having a high degree of crystallinity, whereby a large-sized display device, a high-performance semiconductor device, or the like can be put into practical use. A first multi-component oxide semiconductor layer is formed over a substrate and a single-component oxide semiconductor layer is formed thereover; then, crystal growth is carried out from a surface to an inside by performing heat treatment at 500° C. to 1000° C. inclusive, preferably 550° C. to 750° C. inclusive so that a first multi-component oxide semiconductor layer including single crystal regions and a single-component oxide semiconductor layer including single crystal regions are formed; and a second multi-component oxide semiconductor layer including single crystal regions is stacked over the single-component oxide semiconductor layer including single crystal regions.