Calorimetric Probes for Energy Flux Measurements in Process Plasmas

Abstract

This chapter gives an overview of the method of calorimetric probes which are used for characterizing the interaction between low-temperature plasmas and substrates in materials processing. Although the focus is on low-temperature nonequilibrium plasmas most of the concepts can also be transferred to thermal plasmas or are in fact adopted from fusion research. An introductory section showing the importance and complexity of plasma wall interactions is followed by a section providing an overview and comparison of various probe concepts, which have been developed in the last decades. Special focus is on the type of probes which are similar to the probes used by J.A. Thornton (In fact, Thornton was not the first, to use this type of probe. From his work from 1978 [1], one can follow the citations back to the work of Jackson in 1969, who used equation (6.7) for the determination of the power dissipated by a copper block located at substrate position in a sputtering discharge [2]) who was one of the pioneers connecting plasma characteristics with resulting surface properties. Thereafter, a short section gives a basic overview of the different contributions to the total energy influx and which are of importance for the plasma wall interaction. The last section shows different examples of applications of calorimetric probes. It demonstrates the applicability and flexibility of these types of probes for characterization of different low-temperature plasmas. The examples

On the correlation between the TiN thin film properties and the energy flux of neutral sputtered atoms in direct current magnetron discharge

“…It worth to mention herein that ours mass spectrometer measurements are not calibrated. Thus, the corresponding ion energy flux to the substrate is calculated using the following expression [31]:…”

Influence of the nozzle head geometry on the energy flux of an atmospheric pressure plasma jet

“…magnetron, ion beam and RF-plasmas [16,[22][23][24], and also to atmospheric pressure plasmas [25,26]. The geometries of the probes vary according to the probe type and the investigated plasma source [27]. The probe design used for the present experiments was adapted to the high energy flux and high gas flow emitted by the plasma jet.…”

Energy flux measurements on an atmospheric pressure surface barrier discharge

“…The measured transferred energy from the plasma to the substrate is an integral of several processes (e.g. particle impact, surface processes as recombination, radiation [16]) and influences film growths and particle formation processes [17][18][19][20] as well as surface cleaning and surface activation. With increasing application of atmospheric pressure plasmas successful attempts were made to adapt the diagnostic also to atmospheric pressure plasma jets with high energy fluxes for industrial use [21][22][23] and for non-equilibrium plasma jets which are used for biomedical applications [24,25].…”