Enhancing energy flux to insulating surfaces using unipolar and bipolar HiPIMS pulse configurations

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23520%2F25%3A43976502" target="_blank" >RIV/49777513:23520/25:43976502 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Enhancing energy flux to insulating surfaces using unipolar and bipolar HiPIMS pulse configurations

Original language description

High-power impulse magnetron sputtering (HiPIMS) is an advanced thin film deposition technique, delivering high target power in short pulses, increasing ionization compared to conventional DC sputtering. However, many ions still have low energy, so substrate biasing is often used to enhance energy transfer to the growing film. For insulating surfaces where direct biasing is impossible, bipolar HiPIMS (alternating negative and positive pulses with floating substrate) offers a partial solution. However, rapid charging of insulated surfaces limits energy transfer. This study aims to optimize bipolar HiPIMS pulse configurations to explore the potential enhancement of energy transfer even for insulating surfaces.Experiments were conducted using a magnetron with a Ti target powered by a DC source and a bipolar HiPIMS pulsing unit. Various pulse configurations (unipolar, bipolar, chopped unipolar, and chopped bipolar HiPIMS) were applied under unbalanced magnetic fields with the same average power. In-situ ion mass and energy spectrometry (MS) analyses were employed, and total energy flux to a substrate was measured using a passive thermal probe at a floating and ground potential. Moreover, the depositions on insulating substrates or films with various capacitances were simulated by connecting a defined external capacitor between the probe and the ground. Finally, Ti films were deposited on a floating substrate holder for structural analysis.Thermal probe measurements confirm that chopped unipolar pulses enhance the energy flux to the substrate compared to standard HiPIMS. Bipolar HiPIMS introduces a high-energy peak in the IEDF; for chopped bipolar configurations, this peak broadens, and the high-energy tail is enhanced. For chopped bipolar configurations, the energy flux increase varies with substrate capacitance. For low capacitance, ion acceleration occurs only at the start of each positive pulse before the substrate surface is fully charged, providing a slight increase in energy flux. For medium capacitance, chopping the positive pulse amplifies the increase of energy flux due to longer charging time and substrate neutralization during pulse off times. Finally, with high capacitance, ion acceleration is sustained throughout the positive pulse regardless of its length, as for a grounded substrate. These effects were also verified by analyzing the deposited film properties.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

10305 - Fluids and plasma physics (including surface physics)

Project

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Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů