One-Piece ZnSn Oxide Sputtering Target for Large-Area Coatings
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Solution Overview
Problem
Current sputtering targets for producing Indium-free oxide semiconductor films, such as Zn Sn and Zn Sn Ga oxides, face challenges in achieving high strength, low resistivity, and large area coatings due to complex and labor-intensive sintering processes, which limit their performance and scalability in display technologies.
Innovation Solution
The development of one-piece Zn Sn oxide sputtering targets with a top coat comprising a mixture of zinc, tin, and optionally gallium oxides, produced through a thermal spray method, which allows for longer lengths, lower resistivity, and improved homogeneity, enabling high power density sputtering without excessive arcing, and facilitating the formation of a predominantly zinc stannate phase for enhanced mechanical and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional sintering processes are used to manufacture Zn Sn oxide targets, then the targets can be produced, but the manufacturing process becomes complex and labor-intensive with limited productivity
Solution Approach 1:
The patent replaces the conventional mechanical sintering process with a chemical solution-based infiltration method. The porous green body is infiltrated with metal salt solutions (ZnCl2 and SnCl4) that chemically deposit zinc and tin oxides within the porous structure, eliminating the need for complex multi-step sintering while maintaining target quality and enabling simplified, scalable manufacturing.
Solution Approach 2:
The patent creates a porous green body structure in advance through uniaxial pressing of mixed metal oxides, which then serves as a template for subsequent solution infiltration. This preliminary porous structure formation enables the chemical deposition method to proceed efficiently, simplifying the overall manufacturing process while improving productivity.
2Reliability
If In Ga Zn oxides are used to achieve high charge mobility, then device performance improves, but the targets become toxic and resource-limited
Solution Approach 1:
The patent changes the chemical composition parameters by completely eliminating indium and gallium from the target material, using only zinc and tin oxides. Despite this compositional change, the patent achieves comparable device performance through optimized porous structure infiltration and controlled solution chemistry, providing a non-toxic, resource-abundant alternative to In Ga Zn oxides.
3Area of stationary object
If long targets are produced for large area coatings, then coating area increases, but conventional methods require assembling multiple pieces which creates heterogeneity
Solution Approach 1:
The patent segments the infiltration process into multiple sequential steps, applying different metal salt solutions (ZnCl2 first, then SnCl4) to the porous green body in sequence. This segmented chemical deposition enables precise control over element distribution throughout the entire long target structure, ensuring homogeneous composition even in targets 50 cm or longer that are produced as single pieces.
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 results in sputtering targets that can produce homogeneous, high-quality thin films with low resistivity, enabling efficient and stable DC or AC sputtering at high power densities, overcoming the limitations of previous methods by simplifying the manufacturing process and improving the performance and scalability of Indium-free oxide semiconductor films.
Implementation Method 1
The development of one-piece Zn Sn oxide sputtering targets with a top coat comprising a mixture of zinc, tin, and optionally gallium oxides, produced through a thermal spray method
Implementation Method 2
enabling efficient and stable DC or AC sputtering at high power densities
Data Source
AI summary
A sputtering target having a one-piece top coat comprising a mixture of oxides of zinc, tin, and optionally gallium, characterized in that said one-piece top coat has a length of at least 80 cm; a method for forming such a sputtering target and the use of such a target for forming films.