Mg-Zn Mixed Metal Oxide Channel for Low-Temperature TFTs
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Solution Overview
Problem
Current materials for thin-film transistors, such as amorphous InGaZnO4, have limitations in electron mobility and chemical stability, which are not sufficient for high-performance applications, especially when subjected to high thermal treatments during semiconductor manufacturing, and are not compatible with standard silicon technology.
Innovation Solution
A mixed metal oxide comprising 0.40 to 0.70 parts by mole of Mg, 0.30 to 0.60 parts by mole of Zn, and less than 0.30 parts by mole of other elements, with oxygen, deposited at temperatures below 400°C, providing good electron mobility, chemical stability, and compatibility with silicon technology, suitable for use as a channel material in transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If amorphous materials are deposited at low temperatures to avoid altering existing devices, then device compatibility is improved, but charge carrier mobility deteriorates
Solution Approach 1:
The patent changes the compositional parameters of the oxide material by incorporating specific ratios of Mg, Zn, and In elements, along with controlled oxygen content and vacancies. This compositional parameter change enables the amorphous material to achieve high charge carrier mobility (μ ≥ 10 cm²/Vs) while maintaining low deposition temperatures compatible with existing devices
Solution Approach 2:
The patent creates a composite amorphous oxide semiconductor material combining multiple metal elements (Mg, Zn, In) with oxygen in specific ratios. This composite structure leverages the beneficial properties of each element to achieve both low-temperature processability and high electron mobility, resolving the contradiction between temperature and mobility
2Reliability
If IGZO is used as channel material to achieve adequate electron mobility, then transistor performance is improved, but chemical stability deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating Mg and Zn elements alongside In in specific atomic ratios (In:(Mg+Zn) between 0.2-2.0). This compositional adjustment maintains high electron mobility while significantly improving chemical stability and resistance to forming gas annealing compared to conventional IGZO
3Temperature
If deposition temperature is kept below 400°C to avoid degrading silicon devices, then device compatibility is improved, but material selection is limited
Solution Approach 1:
The patent changes the material composition parameters to create an amorphous oxide semiconductor with specific Mg-Zn-In ratios and oxygen content. This compositional parameter optimization enables the material to be deposited at low temperatures (below 400°C) while maintaining excellent electrical and chemical properties, thus expanding material selection compatibility with silicon technology
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 mixed metal oxide achieves high current in the on-state and low current in the off-state, maintains stability during forming gas annealing, and is compatible with silicon technology, enabling its use in thin-film transistors without degrading silicon devices at elevated temperatures.
Implementation Method 1
a mixed metal oxide according to the disclosed technology may be deposited at or below 400° C.
Data Source
AI summary
A mixed metal oxide and methods for making the mixed metal oxide are disclosed. The mixed metal oxide includes metal and metalloid elements including 0.40 to 0.70 parts by mole Mg, 0.30 to 0.60 parts by mole Zn, and 0.00 to 0.30 parts by mole of other elements selected from metals and metalloids, wherein less than 0.01 parts by mole of the other elements is Al, and wherein less than 0.04 parts by mole of the other elements is Ga. The sum of all parts by mole of Mg, Zn, and the other elements may amount to about 1.00. The mixed metal oxide additionally includes) oxygen and less than 0.01 parts by mole of non-metallic and non-metalloid impurities.