DC Sputtering Thin Film Transistor Gate Integration
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Solution Overview
Problem
Oxide semiconductor active layers manufactured using traditional RF sputtering methods suffer from low electrical conductivity, poor process repetitiveness, and incompatibility with flexible substrates due to high process temperatures, limiting their industrial adoption.
Innovation Solution
A manufacturing method for thin-film transistors (TFTs) using DC sputtering to form metal layers, which are then oxidized to create metal oxide semiconductor and insulating layers, allowing for direct contact and integration of gate electrode and insulating layers, enabling the use of flexible substrates and avoiding the limitations of RF sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF sputtering method is used to manufacture oxide semiconductor active layers, then the layers can be formed, but the electrical conductivity is low and process repetitiveness is poor
Solution Approach 1:
The patent changes the sputtering method from RF to DC, altering the electrical parameters of the deposition process. This parameter change enables better control over film composition and structure, resulting in improved electrical conductivity and enhanced process repetitiveness for oxide semiconductor active layers
Solution Approach 2:
The patent employs composite target materials (such as In-Ga-Zn-O) that combine multiple elements to achieve optimal electrical properties. This composite approach allows tuning of the material composition to simultaneously improve conductivity and process reliability
2Adaptability or versatility
If RF sputtering is used, then oxide semiconductor layers can be manufactured, but they are incompatible with flexible substrates due to high process temperatures
Solution Approach 1:
The patent changes the heating parameters by switching from RF to DC sputtering, which operates at lower temperatures. This parameter change makes the process compatible with flexible substrates that cannot withstand high temperatures, enabling deposition on plastic and other flexible materials
Solution Approach 2:
The patent replaces the RF electromagnetic field-based sputtering system with a DC electric field-based system. This substitution fundamentally changes the energy coupling mechanism, reducing thermal load and enabling processing of temperature-sensitive flexible substrates
3Ease of manufacture
If gate electrode layer and insulating layer are formed separately, then each layer can be optimized, but the process complexity increases
Solution Approach 1:
The patent merges the formation of the gate electrode layer and gate insulating layer into a single sputtering step by using a composite target material. This merging simplifies the manufacturing process while maintaining the ability to optimize both layers simultaneously through controlled composition and thickness parameters
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 improves film forming rate, reduces oxygen vacancies, and enhances insulating effects while allowing for the use of flexible substrates, overcoming the limitations of RF sputtering and achieving stable and efficient TFT production at room temperature.
Implementation Method 1
forming a gate electrode layer and a metal layer which overlaps with the gate electrode layer in a plan view, on the substrate by a DC sputtering method
Implementation Method 2
completely oxidizing a second patterned thin-film layer to form a second oxide layer, partially oxidizing a first patterned thin-film layer
Data Source
Figure 1a~1e
Figure 2~3
AI summary
A thin-film transistor (TFT) and a manufacturing method thereof. The manufacturing method for the TFT includes: depositing metal film layers (20, 30) on a substrate (10) by a direct current (DC) sputtering method; and forming a metal oxide film layer or metal oxide film layers (23, 32) by completely oxidizing or partially oxidizing the metal film layers (20, 30). The TFT includes a gate electrode layer (22) and a gate insulating layer (23) which are tightly integrated.