Oxide TFT Grain Boundary Prevention via Solution Process
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Solution Overview
Problem
The development of thin film transistors for larger displays requires high electron mobility and cost-effective manufacturing processes, but existing amorphous silicon-based solutions suffer from low mobility and expensive vacuum deposition methods, and solution processes can deteriorate interface properties.
Innovation Solution
A thin film transistor is formed using an oxide semiconductor layer with a gate insulating layer and source/drain electrodes, where the materials diffuse and combine through a solution process to prevent grain boundary formation at interfaces, simplifying the manufacturing process and enhancing interface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amorphous silicon is used for the active channel layer with vacuum process-based deposition (CVD or sputtering), then manufacturing precision and material quality are improved, but device complexity and manufacturing cost increase due to expensive vacuum equipment
Solution Approach 1:
The patent replaces vacuum process-based deposition (mechanical/physical system) with a solution process (chemical system). The oxide semiconductor layer is formed by coating a solution containing precursor materials onto the substrate, followed by thermal treatment to convert the precursors into the desired oxide semiconductor material. This substitution eliminates the need for expensive vacuum deposition equipment while maintaining material quality.
Solution Approach 2:
The patent changes the deposition method from vacuum-based physical deposition to solution-based chemical deposition. By altering the fundamental parameter of how the semiconductor layer is deposited (from physical vapor deposition to solution coating and thermal conversion), the invention achieves cost reduction while preserving manufacturing precision through controlled solution processing parameters.
2Ease of manufacture
If solution process is used to form the active channel layer, then manufacturing cost and process simplicity are improved, but interface properties deteriorate due to grain boundary formation
Solution Approach 1:
The patent employs a composite structure consisting of multiple oxide semiconductor layers with different compositions. The first oxide semiconductor layer has a first composition, the second oxide semiconductor layer has a second composition, and they form a gradient interface. This composite approach prevents grain boundary formation at the interface while maintaining the benefits of solution processing, thereby improving interface properties without increasing manufacturing complexity.
Solution Approach 2:
The patent applies local quality by creating distinct regions with different oxide compositions. The first oxide semiconductor layer and second oxide semiconductor layer have different local compositions that are optimized for their respective positions. This local compositional variation ensures good interface properties at the junction between layers while maintaining overall device performance and avoiding grain boundary issues.
3Speed
If oxide semiconductor materials are used with solution process, then electron mobility is improved and manufacturing cost is reduced, but interface properties worsen due to grain boundary formation
Solution Approach 1:
The patent uses a composite of multiple oxide semiconductor layers with different compositions to achieve high electron mobility while preventing grain boundary formation. The first oxide semiconductor layer and second oxide semiconductor layer create a gradient structure that maintains the high mobility benefits of oxide semiconductors while eliminating interface defects through compositional grading.
Solution Approach 2:
The patent changes the compositional parameters of the oxide semiconductor layers to optimize both electron mobility and interface properties. By adjusting the oxidation states and elemental compositions of the different oxide layers, the invention achieves high electron mobility through the oxide semiconductor material while the gradual compositional transition prevents grain boundary formation at interfaces.
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 process simplifies the formation of thin film transistors by preventing grain boundary formation, thereby improving interface properties and enabling high electron mobility without the need for expensive vacuum deposition methods.
Implementation Method 1
the materials diffuse and combine through a solution process to prevent grain boundary formation at interfaces
Implementation Method 2
enabling high electron mobility without the need for expensive vacuum deposition methods
Data Source
AI summary
A thin film transistor includes a substrate, an oxide semiconductor layer that is disposed on the substrate, a gate electrode that overlaps with the oxide semiconductor layer, a gate insulating layer that is disposed between the oxide semiconductor layer and the gate electrode, and a source electrode and a drain electrode that at least partially overlap with the oxide semiconductor layer and are spaced from each other. The gate insulating layer includes an oxide including a first material. The oxide semiconductor layer includes an oxide which includes a same material as the first material and a second material, and the source electrode and the drain electrode include an oxide that includes a same material as the second material and a third material, and a grain boundary is not formed on an interface between at least one of the gate insulating layer and the oxide semiconductor layer or between the oxide semiconductor layer, and the source electrode and the drain electrode.