Towards high-rate magnetron sputter deposition: Influence of the discharge power on deposition process and coating properties

Christian Saringer

Research output: ThesisDoctoral Thesis

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Abstract

Magnetron sputtering is a very versatile technique that can be used for the deposition of high-quality functional coatings. Although it has significant advantages compared to many other deposition processes, its application often suffers from comparatively low deposition rate and hence low productivity and consequently high costs. Therefore, the present work explores the possibility of raising the efficiency of magnetron sputtering by increasing the power applied to the sputtering target. The influence of the power on several process aspects was systematically assessed: Langmuir probe measurements were performed in an argon discharge with a titanium target to determine the dependence of the plasma properties on the discharge power. The measurements showed that below a minimum power value of 800 W the plasma is not homogeneously established. A further increase, however, does not affect the distribution of the plasma properties. In addition, a systematic series of coating depositions revealed that increasing the target power indeed raises the deposition rate. The higher target power and changed growth rate of the coatings, however, influence the resulting coating properties to a great extent. In the case of amorphous carbon coatings a power increase from 530 to 3400 W results in a more pronounced thermal load, which in turn leads to a larger size of the graphitic clusters. This provokes a drop of the hardness from more than 30 down to 20 GPa for a deposition with neon, for instance. On the other hand, reactively deposited titanium nitride coatings showed a considerable increase of the hardness at higher deposition rate due to smaller grain sizes promoted by a shorter time for atom diffusion and increased compressive stresses. Furthermore it was found, that by raising the target power it is possible to increase the amount of reactive gas in the coatings and overcome the detrimental effect of target poisoning on the deposition rate. This was possible by allowing the coating deposition in the transition region between metallic and reactive sputtering mode, which is otherwise inaccessible without substantial effort. In conclusion it can be said, that raising the deposition power can be used to obtain a higher deposition rate and is a practicable way of increasing the productivity of magnetron sputtering, especially for reactive processes. However, the coating properties are concurrently affected and both, beneficial and disadvantageous consequences were observed, depending on the coating system.
Translated title of the contributionAuf dem Weg zum Hochratemagnetronsputtern: Einfluss der Leistung auf Beschichtungsprozess und Schichteigenschaften
Original languageEnglish
QualificationDr.mont.
Supervisors/Advisors
  • Mitterer, Christian, Assessor A (internal)
  • Eisenmenger-Sittner, Christoph, Assessor B (external), External person
Publication statusPublished - 2017

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