Amorphous Mixed Metal Oxide Channels for Low-Temperature TFTs
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Solution Overview
Problem
Current materials used for the channel in thin-film transistors (TFTs) face challenges such as low electron mobility, low chemical stability, and the need for high thermal treatment temperatures, which are incompatible with the constraints of 3D memory device fabrication.
Innovation Solution
The development of mixed metal oxides comprising Mg, Al, and Sb, and another amorphous mixed metal oxide comprising Al and Zn, which can be deposited at temperatures below 400°C, providing high electron mobility, chemical stability, and compatibility with silicon technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If crystalline materials are used for the channel, then electron mobility is improved, but deposition temperature requirements increase above 400°C
Solution Approach 1:
The invention changes the material composition parameters by using specific ratios of In, Ga, Zn, and Al elements in the oxide semiconductor layer. This compositional parameter change enables the material to achieve high electron mobility in an amorphous state without requiring crystallization at high temperatures, thus resolving the contradiction between electron mobility and deposition temperature.
Solution Approach 2:
The invention uses a composite oxide material containing multiple metal elements (In, Ga, Zn, Al) in specific combinations. This composite approach allows the material to exhibit both high electron mobility and chemical stability in an amorphous state, eliminating the need for high-temperature crystallization processes while maintaining superior electrical properties.
2Temperature
If amorphous materials are used for the channel, then deposition temperature is reduced below 400°C, but electron mobility and chemical stability decrease
Solution Approach 1:
The invention optimizes the compositional parameters of the amorphous oxide semiconductor by controlling the ratios of In, Ga, Zn, and Al elements. This parameter optimization enables the amorphous material to achieve electron mobility comparable to crystalline materials while maintaining chemical stability, thus resolving the contradiction between low deposition temperature and high electron mobility.
Solution Approach 2:
The invention employs a composite amorphous oxide material containing multiple metal elements in specific proportions. The synergistic effect of these elements compensates for the typically lower mobility of amorphous materials, achieving high electron mobility and chemical stability without requiring crystallization, thereby resolving the contradiction between amorphous state and performance.
3Temperature
If amorphous materials are used for the channel, then deposition temperature is reduced below 400°C, but chemical stability decreases
Solution Approach 1:
The invention optimizes the compositional parameters by incorporating specific ratios of In, Ga, Zn, and Al elements in the amorphous oxide semiconductor. This compositional optimization enhances the chemical stability of the amorphous material against forming gas anneal while maintaining low deposition temperature requirements, thus resolving the contradiction between deposition temperature and chemical stability.
Solution Approach 2:
The invention uses a composite amorphous oxide material containing multiple metal elements that work synergistically to improve chemical stability. The presence of these specific elements in controlled amounts protects the amorphous structure from degradation during forming gas anneal, resolving the contradiction between maintaining amorphous state and achieving high chemical stability.
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
These mixed metal oxides enable high current in the on-state and low current in the off-state, while maintaining chemical stability and compatibility with standard silicon technology, facilitating their use in TFTs and 3D memory devices without damaging existing components.
Implementation Method 1
The mobility of a- InGaZnO 4 and its chemical stability are, however, not sufficiently high. a-InGaZnO 4 has rather low electron mobility (approximately 20 to 35 cm 2
Data Source
Figure 1~2
AI summary
A first mixed metal oxide (4) consisting of: a) a mixture consisting of 0.50 to 0.90 parts by mole Mg, 0.05 to 0.30 parts by mole Al, 0.01 to 0.20 parts by mole Sb, and 0.00 to 0.31 parts by mole of other elements, other than Mg, Al, and Sb, selected from metals and metalloids, wherein the sum of all parts by mole of Mg, Al, Sb, and the other elements, other than Mg, Al, and Sb, selected from metals and metalloids amounts to 1.00, b) oxygen, and c) less than 0.01 parts by mole of non-metallic and non-metalloid impurities, wherein the parts by mole are as measured by Rutherford Backscattering Spectroscopy.