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Anomalous current and voltage fluctuations in high power impulse magnetron sputtering
The objective of this work was to study dc and High Power Impulse Magnetron Sputtering (HiPIMS) plasmas in order to better understand the various aspects of sputtering; such as rate, uniformity and current and voltage characteristics. The results compare known characteristics for general plasmas as applied to dc and HiPIMS plasmas. Methods are put forth to better describe these plasmas. These include dielectric constant analysis, circuit equivalent models, fluid based models and other computational models to predict current and voltage vs. time curves for HIPIMS.^ Models describing the plasma behavior are important due to the nature of HiPIMS plasmas. HiPIMS systems generate very high intensity discharges resulting in a higher degree of ionization of the sputtered flux. Consideration of ionized flux from a HiPIMS process is fundamental to understanding the scattering behavior within the plasma and electric fields within the plasma. Various models are explored for their contributions to provide a better overall understanding of the magnetron process. These models include capacitor and inductor networks, and mathematical approximations to specific behaviors such as an ion matrix sheath. This dissertation focuses on developing methods to predict the characteristic current-voltage behavior for HIPIMS. Analysis of the fluctuations providing a clearer picture of the plasma behavior has been developed. This understanding provides a groundwork for a number of expectations and improvements to the HiPIMS and related processes. This dissertation links, plasma immersion ion implantation ion matrix sheath theory (PIII), and ion sheath transit times to the fluctuations.^
Physics, Fluid and Plasma|Engineering, Materials Science
Kirkpatrick, Scott, "Anomalous current and voltage fluctuations in high power impulse magnetron sputtering" (2009). ETD collection for University of Nebraska - Lincoln. AAI3365710.