Titanium-Tungsten Target Nodule Control via Grain Size
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Solution Overview
Problem
Nodule formation on titanium-tungsten targets during sputtering leads to particle contamination and quality issues in deposited films, as material from the central target is redeposited on the peripheral edge rather than the substrate.
Innovation Solution
Controlling the grain size of titanium and tungsten powders in the target mixture, with the titanium powder grain size being less than or equal to the tungsten powder grain size, and using an inert gas plasma process to remove nodules, applying DC power to ignite and then increase plasma power for nodule removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional titanium-tungsten target material is used during sputtering, then the target can be processed, but nodules form on the target surface causing particle contamination and reduced film quality
Solution Approach 1:
The patent applies parameter changes by controlling the grain size of titanium and tungsten powders to be substantially equal before target formation. This specific parameter control prevents the formation of titanium-rich or tungsten-rich regions during sputtering, thereby eliminating nodule formation and the associated particle contamination that degrades film quality.
Solution Approach 2:
The patent applies homogeneity by ensuring that the mixed powder of titanium and tungsten has substantially equal grain sizes. This homogeneous mixture prevents segregation during target formation and sputtering processing, ensuring uniform material composition across the target surface and preventing localized nodule formation that would contaminate the deposited film.
2Productivity
If sputtering continues on conventional targets, then production can proceed, but nodules flake and generate particles that contaminate the deposited film
Solution Approach 1:
The patent applies parameter changes by controlling the grain size of titanium and tungsten powders to be substantially equal before target formation. This specific parameter control prevents the formation of titanium-rich or tungsten-rich regions during sputtering, thereby eliminating nodule formation and the associated particle contamination that degrades film quality.
Solution Approach 2:
The patent applies homogeneity by ensuring that the mixed powder of titanium and tungsten has substantially equal grain sizes. This homogeneous mixture prevents segregation during target formation and sputtering processing, ensuring uniform material composition across the target surface and preventing localized nodule formation that would contaminate the deposited film.
3Productivity
If target material is sputtered continuously, then deposition rate is maintained, but material from central target is redeposited on peripheral edge instead of substrate
Solution Approach 1:
The patent applies parameter changes by controlling the grain size of titanium and tungsten powders to be substantially equal before target formation. This specific parameter control prevents the formation of titanium-rich or tungsten-rich regions during sputtering, thereby eliminating nodule formation and the associated particle contamination that degrades film quality.
Solution Approach 2:
The patent applies homogeneity by ensuring that the mixed powder of titanium and tungsten has substantially equal grain sizes. This homogeneous mixture prevents segregation during target formation and sputtering processing, ensuring uniform material composition across the target surface and preventing localized nodule formation that would contaminate the deposited film.
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
Reduces or eliminates nodule formation, increases target lifetime by a factor of 5-7 from 70 to 350-500 kilowatt-hours, maintaining film quality by preventing particle contamination.
Implementation Method 1
applying DC power to the target at a first power to ignite the inert gas to form a plasma; and increasing the DC power to the target to a second power to remove nodules from the target
Implementation Method 2
During the sputtering process, titanium-tungsten material is sputtered from the surface of the target and deposited onto a substrate disposed opposite the surface of the target
Data Source
AI summary
Embodiments of the present disclosure include methods and apparatus for controlling titanium-tungsten (TiW) target nodule formation. In some embodiments, a target includes: a source material comprising predominantly titanium (Ti) and tungsten (W), formed from a mixture of titanium powder and tungsten powder, wherein a grain size of a predominant quantity of the titanium powder is less than or equal to a grain size of a predominant quantity of the tungsten powder.