In-Zn-Sn Oxide Semiconductor Precursor for Flexible TFTs
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Solution Overview
Problem
Current thin film transistors used in liquid crystal displays face challenges with low electron mobility and high energy consumption due to the use of amorphous silicon, requiring costly vacuum processes and high-temperature heat treatment, while also needing a low-temperature process for flexible display applications without costly additives.
Innovation Solution
A precursor composition of an oxide semiconductor using a metal compound with a molar ratio of indium to zinc and tin between 5% to 13%, applied to a substrate and heat-treated at 100° C to 300° C to form a thin film transistor substrate without costly additives, enabling a low-temperature process for flexible displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous silicon is used as the active layer, then the thin film transistor can be formed with conventional processes, but the electron mobility is low and costly vacuum process-based deposition equipments are required
Solution Approach 1:
The patent changes the material composition parameters by using oxide semiconductor (In-Zn-Sn) with specific molar ratios instead of amorphous silicon, enabling solution processability and higher electron mobility while eliminating vacuum deposition requirements
Solution Approach 2:
The patent replaces the mechanical vacuum-based deposition system with a solution-based coating process, using liquid precursors that can be applied through simple coating methods rather than complex vacuum equipment
2Reliability
If heat treatment is performed at high temperature of 400° C. or more to form oxide semiconductor by solution process, then the oxide semiconductor can be formed, but energy consumption is large
Solution Approach 1:
The patent changes the thermal processing parameters by reducing the heat treatment temperature from 400°C or higher to 100-300°C, achieving oxide semiconductor formation with lower energy consumption through optimized precursor composition and controlled thermal treatment
Solution Approach 2:
The patent performs preliminary preparation by formulating the precursor composition with specific metal ratios and organic ligands before heat treatment, enabling the formation of oxide semiconductor at lower temperatures through pre-organized molecular structures
3Adaptability or versatility
If a low temperature process is used for flexible display applications, then the substrate can be flexible, but costly additives are required in the precursor
Solution Approach 1:
The patent changes the compositional parameters by optimizing the metal ratio (In:Zn:Sn = 100:(5-13):(5-13)) and selecting appropriate organic ligands (acetate, halide, nitrate, perchlorate), achieving low-temperature processability and flexibility without requiring costly additives
Solution Approach 2:
The patent uses inexpensive metal salts and common organic ligands as precursors that can be easily decomposed during low-temperature heat treatment, replacing costly additives with economical, readily available materials
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 allows for the formation of thin film transistors with high electron mobility and reduced energy consumption, achieving thin film transistor characteristics without costly additives and enabling flexible display applications.
Implementation Method 1
heat-treated at 100° C to 300° C to form a thin film transistor substrate
Implementation Method 2
heat treatment is required at a high temperature of 400° C. or more in order to form the oxide semiconductor by the solution process
Data Source
AI summary
A thin film transistor substrate according to an exemplary embodiment of the present invention includes a semiconductor layer including metal disposed on an insulating substrate, a gate electrode overlapping the semiconductor layer, and a source electrode and a drain electrode overlapping the semiconductor layer, wherein the metal in the semiconductor layer comprises indium (In), zinc (Zn), and tin (Sn), and a molar ratio(R,R[mol%]=[In][In+Zn+Sn]×100)of indium (In) to the metals in the semiconductor layer is less than about 20%, and more specifically, the molar ratio(R,R[mol%]=[In][In+Zn+Sn]×100)of indium (In) of the metals in the semiconductor layer is about 5% to about 13%.