Indium Oxide Sputtering Target for Stable Semiconductor Films
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Solution Overview
Problem
Current oxide semiconductor films, particularly those based on zinc oxide and indium oxide, face challenges such as instability, high oxygen deficiency, low field effect mobility, and limited control over electron carrier concentration, making them unsuitable for practical use in semiconductor devices like TFTs for displays due to poor stability, reproducibility, and heat resistance.
Innovation Solution
A sputtering target composed of indium oxide with additional elements like gadolinium, dysprosium, holmium, or ytterbium, combined with positive divalent or trivalent elements like zinc, magnesium, or lanthanoids, is used to form a crystalline oxide semiconductor film with controlled electron carrier concentration, enabling stable semiconductor properties and improved conductivity for use in TFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indium oxide is used to improve conductivity, then electrical conductivity is enhanced, but oxygen deficiency increases making stable semiconductor properties difficult to achieve
Solution Approach 1:
The patent extracts and removes oxygen deficiencies from the indium oxide crystal structure through controlled oxidation processes during sputtering. By adjusting oxygen partial pressure and introducing oxygen-containing species, the method selectively removes harmful oxygen deficiencies while preserving the desired electrical conductivity, thus resolving the contradiction between stability and conductivity.
Solution Approach 2:
The patent changes multiple parameters including oxygen partial pressure, sputtering power, and introduction of oxygen-containing gases during the sputtering process. These parameter adjustments allow precise control over the oxidation state of indium oxide, enabling simultaneous achievement of low oxygen deficiency and stable semiconductor properties while maintaining conductivity.
2Speed
If conventional oxide semiconductor films are used, then transparency is maintained, but field effect mobility is low (8 cm2/V·sec or less)
Solution Approach 1:
The patent creates a composite oxide semiconductor film by combining indium oxide with small amounts of other metal oxides (such as zinc oxide, gallium oxide, or tin oxide). This composite structure enhances field effect mobility while maintaining transparency and stability, as the additional metal oxides modify the crystal structure and charge carrier transport properties without compromising the overall semiconductor characteristics.
3Productivity
If DC sputtering method is used for industrial production, then productivity is improved, but poor target conductivity prevents its use
Solution Approach 1:
The patent changes the compositional parameters of the sputtering target by incorporating conductive metal oxides (such as zinc oxide or gallium oxide) into the indium oxide matrix. This modification increases the bulk conductivity of the target material, enabling the use of DC sputtering mode which provides higher productivity and is more suitable for industrial production, while maintaining the desired film properties.
4Illumination intensity
If amorphous transparent semiconductor film is used, then transparency is improved, but stability is poor
Solution Approach 1:
The patent utilizes phase transition from amorphous to crystalline state by controlling the sputtering conditions and post-deposition heat treatment. The resulting microcrystalline or nanocrystalline structure maintains high transparency similar to amorphous films while providing the structural order and stability of crystalline materials, thus resolving the contradiction between transparency and 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
The approach results in a semiconductor device with enhanced stability, uniformity, reproducibility, heat resistance, and durability, allowing for improved transparency, electrical properties, and a higher on-off ratio, suitable for use in display applications.
Implementation Method 1
a sputtering target formed of an oxide sintered body, the oxide sintered body comprising indium (In) and at least one element selected from gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er) and ytterbium (Yb)
Data Source
AI summary
A sputtering target including an oxide sintered body, the oxide sintered body containing indium (In) and at least one element selected from gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er) and ytterbium (Yb), and the oxide sintered body substantially being of a bixbyite structure.