UBC Theses and Dissertations
Unbalanced magnetrons Clarke, Glenn A.
In recent years the ‵unbalanced′ magnetron sputter source has been shown to be an important advancement for applications requiring ion-assisted, thin film deposition. Diamondlike coatings and optical multilayers are examples of coatings which can be significantly improved by ion bombardment of the growing film. The purpose of this thesis is to develop a better understanding of the main engineering factors which determine the ultimate performance of the unbalanced magnetron. Two pieces of experimental apparatus were designed for this study. A scanning magnetometer system was constructed to measure the magnetic field pattern of the magnetrons, which allowed for a detailed analysis in terms of magnetic field lines. A multiple, plasma probe assembly was developed to measure the discharge characteristics for various unbalanced magnetron configurations. The results showed that the ion flux to the substrate was highly dependant on the development of a secondary discharge away from the target surface. The secondary discharge was generated through confinement of ionizing electrons in a magnetic bottle along the magnetron axis. The ion flux to the substrate was observed to be approximately independent of the pressure and target material but highly dependant on the discharge current and target thickness. The ion/deposition flux ratio increased with decreasing target-to-substrate distance. However, the useful deposition area decreased under these conditions as the ion currents became highly focused about the axis.
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