Thin Film Transistor Metal Induction Crystallization
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Solution Overview
Problem
Low-temperature polysilicon thin film transistors (LTPS-TFTs) used in liquid crystal displays have high impurity content, leading to significant leakage current and poor switching characteristics, which hinders their application in high-definition TFT-LCDs and current-driven TFT-OLEDs.
Innovation Solution
The method involves forming an active layer in thin film transistors using atomic layer deposition (ALD) to deposit an inducing metal on an amorphous silicon layer, followed by heat treatment for metal induction crystallization and lateral crystallization, reducing impurity content and improving transistor performance at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTPS-TFT technology is used to achieve higher mobility and better stability, then drive capacity and device performance are improved, but impurity content in the active layer increases leading to greater leakage current
Solution Approach 1:
The patent extracts and removes metal impurities from the active layer through selective etching processes. The method involves treating the active layer with a first etchant to remove metal particles, then treating with a second etchant to further purify the layer, thereby reducing leakage current while maintaining the benefits of LTPS-TFT technology
Solution Approach 2:
The patent applies preliminary protective measures by forming a protective film on the active layer before metal particle removal treatment. This protective film prevents damage to the active layer during the etching process, ensuring that the purification process does not compromise the transistor's performance or structure
2Ease of manufacture
If amorphous silicon thin film field effect transistors are used, then manufacturing process is mature and easy to implement, but mobility is low and device size is large
Solution Approach 1:
The patent changes the material parameter of the active layer from amorphous silicon to LTPS (low-temperature polysilicon). This parameter change increases carrier mobility by hundreds of times compared to amorphous silicon, enabling high-definition TFT-LCDs and current-driven TFT-OLEDs while maintaining low processing temperatures
3Productivity
If LTPS-TFT is used to reduce device size and improve drive capacity, then integration of peripheral circuits is enabled, but impurity content increases affecting switching characteristics
Solution Approach 1:
The patent extracts metal impurities from the active layer through a two-stage etching process. The first etchant removes bulk metal particles, while the second etchant removes remaining metal contaminants, thereby purifying the active layer and restoring proper switching characteristics while maintaining high drive capacity
Solution Approach 2:
The patent employs a feedback mechanism by using metal particle removal treatment to eliminate impurities that degrade performance. The process continuously improves the active layer quality by removing contaminants, ensuring that switching characteristics meet required specifications for high-definition display 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
This approach effectively reduces impurity content and enhances the switching characteristics of thin film transistors, enabling their use in high-definition displays with improved mobility and stability, while maintaining low processing temperatures.
Implementation Method 1
depositing an inducing metal on an amorphous silicon layer of the source and drain regions by an atomic layer deposition (ALD) method
Implementation Method 2
conducting heat treatment on the amorphous silicon layer deposited with the inducing metal so that metal induction crystallization and metal induction lateral crystallization take place in the amorphous silicon layer
Implementation Method 3
conducting heat treatment on the amorphous silicon layer deposited with the inducing metal
Data Source
AI summary
The disclosure discloses a thin film transistor and a manufacturing method thereof, an array substrate, and a display device, which can manufacture a thin film transistor with lower contents of impurity at a low temperature. The thin film transistor comprises: a substrate, and an active layer disposed on the substrate, the active layer comprising a source region, a drain region and a channel region, wherein the active layer is formed by depositing an inducing metal on an amorphous silicon layer on the substrate by an atomic layer deposition (ALD) method and then conducting heat treatment on the amorphous silicon layer deposited with the inducing metal so that metal induction crystallization and metal induction lateral crystallization take place in the amorphous silicon layer.