Study on electrostatic and electromagnetic probes operated in ceramic and metallic depositing plasmas

Abstract

This paper discusses plasma probe diagnostics, namely the multipole resonance probe (MRP) and Langmuir probe (LP), operated in depositing plasmas. The aim of this work is to show that the combination of both probes provides stable and robust measurements and clear determination of plasma parameters for metallic and ceramic coating processes. The probes use different approaches to determine plasma parameters, e.g. electron density n e and electron temperature T e . The LP is a well-established plasma diagnostic, and its applicability in technological plasmas is well documented. The LP is a dc probe that performs a voltage sweep and analyses the measured current, which makes it insensitive against conductive metallic coating. However, once the LP is dielectrically coated with a ceramic film, its functionality is constricted. In contrast, the MRP was recently presented as a monitoring tool, which is insensitive to coating with dielectric ceramics. It is a new plasma diagnostic based on the concept of active plasma resonance spectroscopy, which uses the universal characteristic of all plasmas to resonate on or near the electron plasma frequency. The MRP emits a frequency sweep and the absorption of the signal, the |S 11 | parameter, is analysed. Since the MRP concept is based on electromagnetic waves, which are able to transmit dielectrics, it is insensitive to dielectric coatings. But once the MRP is metallized with a thin conductive film, no undisturbed RF-signal can be emitted into the plasma, which leads to falsified plasma parameter.In order to compare both systems, during metallic or dielectric coating, the probes are operated in a magnetron CCP, which is equipped with a titanium target. We present measurements in metallic and dielectric coating processes with both probes and elaborate advantages and problems of each probe operated in each coating environment.

The magnetic asymmetry effect in geometrically asymmetric capacitively coupled radio frequency discharges operated in Ar/O2

“…According to Lapke, from this resonance frequency, the electron density can be calculated as described in references [37][38][39]. Further information about the concept of the MRP can be found in references [20,57,58,69,70].…”

Kinetic Simulation of the Ideal Multipole Resonance Probe

“…The theoretical and numerical results are substantially confirmed through the simulation and experimental work [20][21][22][23]. Nevertheless, there are deviations: the fluid approach has a poor prediction in a pressure regime of a few Pa and lower.…”

The multipole resonance probe: simultaneous determination of electron density and electron temperature using spectral kinetic simulation

“…The component in the ϕ-direction vanishes as the IMRP is azimuthally symmetric. Furthermore, the theoretical and experimental results in [38][39][40] demonstrate the importance of the first resonance: one particular feature of the MRP is the dominating dipole model. Compared to the first resonance peak, the peaks in the higher modes are barely visible.…”