Garnet Oxide Sintered Targets for Stable, High-Mobility TFT Films
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Solution Overview
Problem
Existing thin-film transistors (TFTs) using amorphous oxide semiconductors face challenges in achieving high carrier mobility and stability during CVD processes, with a need for materials that exhibit improved performance and reduced bulk resistivity.
Innovation Solution
A sintered oxide composition containing In, Y, Ga, and Al elements, along with optional positive tetravalent metal elements, is formulated to achieve a Bixbyite and/or Y3Ga5O12 crystalline phase, ensuring a relative density of 95% or more and bulk resistivity of 30 mΩ·cm or less, which is used to produce a sputtering target for forming an oxide semiconductor thin-film with enhanced carrier mobility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If amorphous oxide semiconductor is used for thin-film transistor, then carrier mobility is improved compared to general-purpose amorphous silicon, but bulk resistivity remains too high and stability during CVD process is insufficient
Solution Approach 1:
The patent changes the material parameters by introducing a specific compositional formula In2-x-yMxMy-nO3 with controlled atomic ratios of metal elements M (such as Ga, Ge, Sn) and n (oxygen deficiency parameter). By optimizing these parameters within specific ranges, the material achieves both high carrier mobility and improved stability during CVD processes while maintaining amorphous structure.
Solution Approach 2:
The patent creates a composite oxide semiconductor material by combining indium oxide (In2O3) with other metal oxides (Ga2O3, GeO2, SnO2, etc.) in specific ratios. This composite structure leverages the high carrier mobility of In2O3 while the additional metal oxides contribute to stability during CVD processing and control bulk resistivity.
2Manufacturing precision
If sputtering process is used to form oxide semiconductor thin film, then in-plane uniformity and composition uniformity are improved, but manufacturing complexity increases
Solution Approach 1:
The patent prepares a pre-sintered oxide target with the exact desired compositional formula In2-x-yMxMy-nO3 and crystalline structure before the sputtering process. This preliminary preparation ensures that the target material has uniform composition and appropriate density, which directly translates to uniform thin film deposition during sputtering, reducing the need for complex post-processing steps.
Solution Approach 2:
The patent optimizes sputtering parameters including power density (0.5-5 W/cm²), substrate temperature (room temperature to 200°C), and oxygen partial pressure (1-100 Pa) to achieve the desired film properties. By carefully controlling these parameters, the process achieves high in-plane uniformity while maintaining reasonable manufacturing complexity.
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 resulting thin-film transistors exhibit higher carrier mobility and reduced bulk resistivity, enabling improved TFT performance and stability during CVD processes.
Implementation Method 1
The oxide semiconductor (film) is suitably formed through a sputtering process, in which a sputtering target is sputtered
Implementation Method 2
A sintered oxide contains In element, Y element, and Ga element at respective atomic ratios as defined in formulae 1-1) to (1-3) below
Data Source
AI summary
A sintered oxide contains In element, Y element, and Ga element at respective atomic ratios as defined in formulae (1) to (3) below,0.8≤In/(In+Y+Ga)≤0.96,(1)0.02≤Y/(In+Y+Ga)≤0.1,(2)and0.02≤Ga/(In+Y+Ga)≤0.1,(3)andAl element at an atomic ratio as defined in a formula (4) below,0.0005≤Al/(In+Y+Ga+Al)≤0.07,(4)where In, Y, Ga, and Al in the formulae represent the number of atoms of the In element, Y element, Ga element, and Al element in the sintered oxide, respectively.