Amorphous Oxide Transistor Channel Layer Hydrogen Control
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Solution Overview
Problem
Existing thin film transistors (TFTs) using amorphous silicon and polycrystalline silicon face challenges in high temperature process requirements, making it difficult to form on plastic substrates, and oxide materials like ZnO have instability and scattering issues, leading to hysteresis and degraded display image quality.
Innovation Solution
An amorphous oxide material with controlled hydrogen concentration is used for the channel layer, allowing for reduced hysteresis and improved reproducibility of transistor properties by forming a thin film with a desired electron carrier concentration, using methods such as sputtering in a hydrogen-containing atmosphere or ion implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous silicon or polycrystalline silicon is used as channel layer material, then transistor performance can be achieved, but high temperature processes are required making it difficult to form on plastic substrates
Solution Approach 1:
The patent changes the material composition parameters by introducing specific metal elements (Al, Ga, In, Sn, Ti, Zn, Mg, Ca, Sr, Ba, Li, Na, K) into the oxide semiconductor channel layer. This compositional modification enables the material to achieve appropriate carrier concentration and transistor performance without requiring high temperature processing, thus resolving the contradiction between performance and temperature requirements
Solution Approach 2:
The patent employs composite oxide semiconductor materials combining multiple metal elements with oxygen. These composite materials exhibit unique properties that allow low-temperature fabrication on plastic substrates while maintaining functional performance, addressing both the performance requirement and the temperature constraint simultaneously
2Temperature
If ZnO-based polycrystalline oxide thin film is used as channel layer, then low temperature formation is enabled, but electron mobility is reduced due to scattering at polycrystalline grain interfaces
Solution Approach 1:
The patent modifies the structural parameters by maintaining the amorphous phase through specific composition control and processing conditions. By adjusting the metal element ratios and adding hydrogen, the material achieves high electron mobility in the amorphous state without forming polycrystalline grains, thus eliminating grain boundary scattering while preserving low-temperature formation capability
Solution Approach 2:
The patent introduces hydrogen at specific concentrations (10^16 to 10^20 atoms/cm³) into localized regions of the oxide semiconductor structure. This localized hydrogen addition passivates defect states and improves electron mobility without inducing crystallization, resolving the contradiction between low-temperature formation and high electron mobility
3Temperature
If amorphous In-Ga-Zn-O-based oxide is used for low temperature formation, then transistor can be formed on plastic substrate, but hysteresis in transistor properties occurs
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: hydrogen concentration (10^16 to 10^20 atoms/cm³), metal element ratios (In:Ga:Zn = 1:(0.3-2.0):(0.7-3.0)), and oxygen partial pressure during deposition. This multi-parameter optimization reduces hysteresis by controlling carrier concentration and passivating defects, achieving stable transistor properties while maintaining low-temperature formation capability
Solution Approach 2:
The patent implements process control with feedback mechanisms to maintain precise hydrogen concentration and composition ratios during film formation. By monitoring and adjusting deposition parameters in real-time, the process achieves reproducible transistor characteristics with minimal hysteresis, resolving the reliability issue
4Reliability
If hydrogen concentration in amorphous oxide film is increased to control electron carrier concentration, then transistor performance improves, but hysteresis may occur if concentration is not properly controlled
Solution Approach 1:
The patent establishes a precise hydrogen concentration range (10^16 to 10^20 atoms/cm³) and correlates it with specific metal composition ratios and deposition conditions. This parameter specification enables controlled improvement of transistor performance while avoiding excessive hydrogen that would cause hysteresis, achieving the optimal balance through defined parameter windows
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
This approach enables the formation of TFTs with reduced hysteresis, controlled electron carrier concentration, and improved uniformity, leading to enhanced transistor performance and image quality in display devices, particularly suitable for flexible and transparent applications.
Implementation Method 1
a method for forming a thin film comprising: forming an amorphous oxide film containing hydrogen on a substrate in a state where gas containing hydrogen atoms and oxygen gas are supplied in a film-forming apparatus at predetermined partial pressures
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
An amorphous oxide containing hydrogen (or deuterium) is applied to a channel layer of a transistor. Accordingly, a thin film transistor having superior TFT properties can be realized, the superior TFT properties including a small hysteresis, normally OFF operation, a high ON/OFF ratio, a high saturated current, and the like. Furthermore, as a method for manufacturing a channel layer made of an amorphous oxide, film formation is performed in an atmosphere containing a hydrogen gas and an oxygen gas, so that the carrier concentration of the amorphous oxide can be controlled.