P. Adámek

System for time-resolved laser absorption spectroscopy and its application to high-power impulse magnetron sputtering

This paper deals with the development and construction of an apparatus for time-resolved tunable diode laser absorption spectroscopy (LAS) for the diagnostics of pulsed plasma. A detailed description of the extension of a progressive method of laser absorption spectroscopy in continuous regime to a direct triggering method of the time-resolved laser absorption spectroscopy (TR-LAS) is presented. The main advantage of the developed method is its capability to measure the time evolution of the whole absorption profile with a preset time resolution, which can be less than 1 μs. Therefore, the presented method of repetitive sampling applied on LAS in plasma processes is capable of simultaneous measurement of the density and kinetic temperature of selected particles. Its appropriate applications are to periodical processes in technological plasma, namely pulsed plasma discharges. The developed method of TR-LAS was applied to measurements of the temporal evolution of density and kinetic temperature of argon metastable species during high-power impulse magnetron sputtering of titanium and titanium dioxide thin films.

A modified Katsumata probe—Ion sensitive probe for measurement in non-magnetized plasmas

A modified Katsumata probe has been developed for measurement of ion velocity distribution function (IVDF) in technological non-magnetized plasmas. A simple construction of the modified Katsumata probe consists of adding a pair of permanent Sm-Co magnets in front of Katsumata probe. A comparative study regarding IVDF measurement in a high power impulse magnetron sputtering system operating in pure argon atmosphere by means of developed modified Katsumata probe and commercially available gridded retarding field analyzer (RFA) has been carried out. A time-resolved measurement of IVDF for two different pressures whilst other plasma conditions have been kept unchanged has revealed that the main advantage of the modified Katsumata probe compared to the RFA consists in significantly smaller angular aperture of entrance orifice of modified Katsumata probe being approximately 15° in comparison with a commercial RFA having angular aperture more than 160°. It leads in much better velocity resolution in measured IVDF since the transversal part of velocity vector is much more suppressed compared to RFA. Furthermore, the modified Katsumata probe less suffers from collisions of ions in the space charge sheath in front or inside of the probe compared to the RFA.

Space Resolved Optical Emission Spectroscopy During Deposition of BaxSr1-xTiO3 Thin Films by Double Hollow Cathode Plasma Jet System

Pulse modulated double hollow cathode RF plasma jet system with two separate independent nozzles made of BaTiO3 (BTO) and SrTiO3 (STO) was used for deposition of BSTO thin films on Si and on multi-layer Si/SiO2/TiO2/Pt substrates. Dielectric properties of BSTO layers strongly depend on ratio composition expressed by parameter x = Ba/(Ba+Sr) and on accuracy in presence of other elements. Space resolved optical emission spectroscopy (OES) was used mainly for monitoring of concentration of particles sputtered from the hollow cathode and for feedback correction of power supplied in both nozzles because applied power was responsible for sputtering speed of Ba and Sr particles. Main attention was focused on relation between ratio of spectral intensity of Ba, Ba+, Sr and Sr+ lines close to substrate and ratio of Ba and Sr concentration in the deposited film. 2D map of emission lines intensity distribution for Ba, Ba+, Sr, Sr+, Ti, Ar, and Ar+ for double hollow cathode plasma jet system with BTO and STO nozzles was created. OES was also used for observing of excess of Ti particles in final layer with negative effect on layer properties and for measurement of rotational temperature of OH radicals. Preliminary results of all these optical measurements are published in this paper. Deposited thin films were analyzed by X-ray diffraction, which confirmed presence of BSTO and STO perovskite phase in the films, by atomic force microscopy (AFM), by electron microprobe and by micro-Raman scattering measurement.

Measuring the Ion Flux to the Deposition Substrate in the Hollow Cathode Plasma Jet

Measurements of positive ion flux to a negatively biased substrate for deposition of TiOx thin films by the hollow cathode plasma jet system are presented. Different methods of obtaining the bias of substrate and measuring the resulting ion flux were used for different bias frequencies. Pulsed DC bias, middle frequency 500 kHz bias, and 13.56 MHz RF bias were compared. For 13.56 MHz two different methods of ion flux determination were used. These measurements were performed for different bias voltage and discharge conditions.

Imaging of unbalanced magnetron DC discharge

We present the framework used to obtain a comprehensive set of data on discharge of unbalanced magnetrons by means of Langmuir-probe diagnostics and the resulting images of the internal plasma parameters.