Sputtering Target Grain Control for Arcing Prevention
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Solution Overview
Problem
High-power film-deposition processes in sputtering often result in abnormal discharge and target cracking due to abnormal grain growth of the Zn2TiO4 crystal phase in sintered composite oxides, which affects the refractive index and electrical conductivity of the target material.
Innovation Solution
A sintered oxide with specific atomic ratios of zinc, aluminum, and titanium, controlled grain size of the Zn2TiO4 phase, and absence of aluminum oxide diffraction peaks, ensuring stable DC discharge and high refractive index while preventing arcing and cracking, is produced by mixing zinc oxide, titanium oxide, and aluminum oxide powders and firing at controlled temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power is applied to a sputtering target containing Zn2TiO4 crystal phase with large grain size, then film deposition rate increases, but abnormal discharge (arcing) and target cracking occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling the grain size of the Zn2TiO4 crystal phase to be 7 μm or less, and controlling the atomic ratios of Zn, Al, and Ti within specific ranges. These parameter changes prevent abnormal grain growth that would lead to arcing and cracking, while still allowing high-power sputtering to achieve high film deposition rates.
Solution Approach 2:
The patent uses a composite oxide material system consisting of ZnO, TiO2, and Al2O3 that forms a specific microstructure with controlled Zn2TiO4 grain size. This composite material approach creates a target composition that balances electrical conductivity (for high deposition rate) with structural stability (to prevent arcing and cracking under high power).
2Stability of the object's composition
If Zn2TiO4 crystal phase undergoes abnormal grain growth, then refractive index improves, but charge accumulation increases causing vigorous abnormal discharge
Solution Approach 1:
The patent controls the grain size parameter of Zn2TiO4 to be 7 μm or less, preventing the abnormal grain growth that would cause excessive charge accumulation and arcing. Simultaneously, the controlled grain structure maintains the desired refractive index properties through proper phase composition and microstructure.
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 solution provides a sputtering target with improved electrical conductivity, high refractive index, and resistance to abnormal discharge and cracking, even under high-power conditions, enabling efficient and stable film deposition with reduced arcing and increased target durability.
Implementation Method 1
mixing zinc oxide powder, titanium oxide powder and aluminum oxide powder having a BET specific surface area of at least 10 m2/g, as raw material powders, so that when the contents of zinc, aluminum and titanium are represented by Zn, Al, and Ti, respectively, the atomic ratios of the elements would be Al/(Zn+Al+Ti)=0.035 to 0.050 and Ti/(Zn+Al+Ti)=0.05 to 0.20, followed by molding, and then, firing the obtained molded product
Implementation Method 2
a high refractive index target is a titanium oxide target, but its resistance value is extremely high, and it has a problem that DC sputtering with high mass productivity is thereby difficult
Data Source
AI summary
The purpose of the present invention is to provide a sintered oxide to be used for a sputtering target, whereby little abnormal discharge occurs even during high-power film-deposition and no cracking occurs in the target. A sintered oxide having zinc, aluminum, titanium and oxygen, as constituent elements, characterized in that when the contents of zinc, aluminum and titanium are represented by Zn, Al, and Ti, respectively, the atomic ratios of the elements constituting the sintered oxide areAl/(Zn+Al+Ti)=0.035 to 0.050 andTi/(Zn+Al+Ti)=0.05 to 0.20,and the average grain size of crystal grains having a Zn2TiO4 crystal phase as the matrix phase in the sintered oxide, is at most 5 μm.