[en] Inductively coupled impulse sputtering (ICIS) is a new development in the field of highly ionised pulsed PVD processes. For ICIS the plasma is generated by an internal inductive coil, replacing the need for a magnetron. To understand the plasma properties, measurements of the current and voltage waveforms at the cathode were conducted. The ion energy distribution functions (IEDFs) were measured by energy resolved MS and plasma chemistry was analysed by OES and then compared to a model. The target was operated in pulsed DC mode and the coil was energised by pulsed RF power, with a duty cycle of 7.5%. At a constant pressure (14 Pa) the set peak RF power was varied from 1000–4000 W. The DC voltage to the target was kept constant at 1900 V. OES measurements have shown a monotonic increase in intensity with increasing power. Excitation and ionisation processes were single step for ICIS of Ti and Ni and multi-step for Cu. The latter exhibited an unexpectedly steep rise in ionisation efficiency with power. The IEDFs measured by MS show the material- and time-dependant plasma potential in the range of 10–30 eV, ideal for increased surface mobility without inducing lattice defects. A lower intensity peak, of high energetic ions, is visible at 170 eV during the pulse. (paper)

[en] Current–voltage characteristics within the temporal pulse were recorded in high-power pulsed magnetron sputtering discharges for different target materials. These curves allowed identifying at a first glance the existence of separated plasma regimes clearly differentiated by the plasma conductivity and by the spatial arrangement of the plasma emission. We could establish that regimes of high plasma conductivity are univocally associated to the self-organization of the plasma in well-defined ionization zones. As the applied power is gradually increased, the high conductivity regime is abruptly replaced by a regime of high current and low plasma conductivity, associated to homogeneous plasma emission. (paper)

[en] HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N₂ atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current (I_d) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti¹⁺, Ti²⁺ and atomic nitrogen N¹⁺. Ti¹⁺ ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3 x 10¹⁶ m^-3. Plasma density, and ion flux ratios of N¹⁺: N₂¹⁺ and Ti¹⁺: Ti⁰ increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high I_d, N¹⁺: N₂¹⁺ > 1 and Ti¹⁺: Ti⁰ > 1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As I_d reduced and N¹⁺: N₂¹⁺ and Ti¹⁺: Ti⁰ dropped below 1, the film texture switched to strong 111 with a dense structure. At very low I_d, porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and properties are discussed.

[en] Generation of nitric oxide (NO) by a plasma needle is studied by means of mass spectrometry. The plasma needle is an atmospheric glow generated by a radio-frequency excitation in a mixture of helium and air. This source is used for the treatment of living tissues, and nitric oxide may be one of the most important active agents in plasma therapy. Efficient NO generation is of particular importance in the treatment of cardiovascular diseases. Mass spectrometric measurements have been performed under various plasma conditions; gas composition in the plasma and conversion of feed gases (nitrogen and oxygen) into other species has been studied. Up to 30% of the N₂ and O₂ input is consumed in the discharge, and NO has been identified as the main conversion product

[en] A plasma needle is a radio-frequency (rf) micro-discharge operated in a mixture of helium and air at atmospheric pressure. This source is designed for medical treatment of living tissues. Therapeutic effects of plasma treatment depend on generation of short-living active radicals: reactive oxygen and nitrogen species (ROS/RNS). In this work we determine the concentration of several ROS and RNS (atomic oxygen, nitrogen and hydroxyl radical) by means of threshold ionization mass spectrometry. It is shown that molecular oxygen and nitrogen are substantially dissociated in the plasma. Atomic nitrogen and oxygen are the most abundant radicals: the densities are on average few times 10^-4. Hydroxyl radicals are less abundant (10^-5 fraction of the total gas density). As expected, the densities of active species increase with increasing plasma power. Spatial (axial) distributions have been determined; the radical density reaches a maximum at 2.5 mm away from the rf powered electrode, and it decreases at distances larger than 3.5 mm. The amount of active radical species is reasonably high, which explains the effectiveness of plasma in bacterial inactivation and tissue treatment