Tantalum Sputtering Target Boron Refinement
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Solution Overview
Problem
Existing tantalum sputtering targets struggle to achieve a uniform and fine structure while maintaining high purity, leading to instability in plasma and film uniformity, particularly due to difficulties in adjusting trace amounts of impurity elements like Ag, Au, and Cu, resulting in lower than desired purity levels and prolonged burn-in times.
Innovation Solution
Incorporating boron as an essential component within a specific concentration range (1-50 mass ppm) in high-purity tantalum sputtering targets, ensuring a purity of 99.998% or higher excluding boron and gas components, to achieve a uniform and fine structure, stabilize plasma, and reduce burn-in time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trace amounts of impurity elements (Ag, Au, Cu) are added to tantalum, then plasma discharge characteristics improve, but purity level decreases and uniformity of addition becomes difficult to achieve
Solution Approach 1:
The patent introduces an intermediary element (specifically copper at 0.003-0.03 mass%) that mediates between the tantalum matrix and plasma discharge requirements. This intermediary element facilitates plasma stability without requiring trace amounts of multiple impurity elements, thereby achieving reliable plasma discharge while maintaining manufacturing precision and uniformity.
Solution Approach 2:
The patent changes the concentration parameter of the additive element from trace amounts (0.001-20 ppm as in prior art) to a controlled low concentration range (0.003-0.03 mass%). This parameter change enables uniform addition throughout the tantalum target while still achieving the desired plasma discharge characteristics, resolving the contradiction between reliability improvement and manufacturing precision.
2Reliability
If multiple impurity elements are tolerated at low levels, then high-purity tantalum can be produced, but the total impurity content remains above 100 ppm reducing actual purity below 99.99%
Solution Approach 1:
The patent extracts and eliminates unnecessary impurity elements from the tantalum composition. By specifying that only copper at 0.003-0.03 mass% is intentionally added and all other impurities are controlled below 0.001 mass%, the patent removes extraneous elements that would contribute to total impurity content, thereby achieving high purity characteristics with minimal total impurity content.
Solution Approach 2:
The patent applies local quality by allowing a specific element (copper) at a controlled low concentration to provide localized plasma stabilization benefits, while maintaining extremely low levels of all other elements. This selective approach ensures that the total impurity content remains below 100 ppm while still achieving the desired high-purity tantalum characteristics for reliable sputtering performance.
3Ease of manufacture
If conventional sputtering targets are used, then production process is simple, but film uniformity and plasma stability are insufficient
Solution Approach 1:
The patent changes the compositional parameters by introducing a precisely controlled amount of copper (0.003-0.03 mass%) into the tantalum target. This parameter change improves plasma stability and film uniformity during sputtering while maintaining a relatively simple production process. The controlled addition of this single element achieves superior film quality without requiring complex multi-element formulations or elaborate manufacturing procedures.
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 addition of boron enables the production of high-purity tantalum sputtering targets with a uniform and fine structure, stabilizing plasma and improving film uniformity, while shortening the burn-in time and maintaining high purity levels, thus enhancing the quality of sputtered films.
Implementation Method 1
the addition of a specific element enables a uniform and fine structure to be obtained, and plasma to be stabilized
Implementation Method 2
the addition of a specific element enables a uniform and fine structure to be obtained, and plasma to be stabilized
Implementation Method 3
the sputtering method for forming films from materials such as metal or ceramics has been used in numerous fields
Data Source
AI summary
Provided is a tantalum sputtering target, in which 1 mass ppm or more and 50 mass ppm or less of boron is contained as an essential component, and of which the purity excluding boron and gas components is 99.998% or higher. Thereby obtained is a high-purity tantalum sputtering target having a uniform and fine structure and enabling plasma stabilization and achievement of superior film evenness (uniformity).