Fully dense, non-faceted 111-textured high power impulse magnetron sputtering TiN films grown in the absence of substrate heating and bias

We demonstrate the deposition of fully dense, stoichiometric TiN films on amorphous SiO2 by reactive high power impulse magnetron sputtering (HiPIMS) in the absence of both substrate heating and applied bias. Contrary to the highly underdense layers obtained by reactive dc magnetron sputtering (dcMS) under similar conditions, the film nanostructure exhibits neither intra- nor intergrain porosity, exhibiting a strong 111 preferred orientation with flat surfaces. Competitive grain growth occurs only during the early stages of deposition 100 nm). The strong differences in the kinetically-limited nanostructural evolution for HiPIMS vs. dcMS are explained by high real-time deposition rates with long relaxation times, high ionization probabilities for Ti, and broad ion energy distributions

Fully dense, non-faceted 111-textured high power impulse magnetron sputtering TiN films grown in the absence of substrate heating and bias

We demonstrate the deposition of fully dense, stoichiometric TiN films on amorphous SiO2 by reactive high power impulse magnetron sputtering (HiPIMS) in the absence of both substrate heating and applied bias. Contrary to the highly underdense layers obtained by reactive dc magnetron sputtering (dcMS) under similar conditions, the film nanostructure exhibits neither intra- nor intergrain porosity, exhibiting a strong 111 preferred orientation with flat surfaces. Competitive grain growth occurs only during the early stages of deposition 100 nm). The strong differences in the kinetically-limited nanostructural evolution for HiPIMS vs. dcMS are explained by high real-time deposition rates with long relaxation times, high ionization probabilities for Ti, and broad ion energy distributions

Influence of residual water on magnetron sputter deposited crystalline Al2O3 thin films

The effects of residual water on the phase formation, composition, and microstructure evolution of magnetron sputter deposited crystalline alumina thin films have been investigated. To mimic different vacuum conditions, depositions have been carried out with varying partial pressures of H2O. Films have been grown both with and without chromia nucleation layers. It is shown that films deposited onto chromia nucleation layers at relatively low temperatures (500 °C) consists of crystalline alpha-alumina if deposited at a low enough total pressure under ultra high vacuum (UHV) conditions. However, as water was introduced a gradual increase of the gamma phase content in the film with increasing film thickness was observed. At the same time, the microstructure changed drastically from a dense columnar structure to a structure with small, equiaxed grains. Based on mass spectrometry measurements and previous ab initio calculations, we suggest that either bombardment of energetic negative (or later neutralized) species being accelerated over the target sheath voltage, adsorbed hydrogen on growth surfaces, or a combination of these effects, is responsible for the change in structure. For films containing the metastable gamma phase under UHV conditions, no influence of residual water on the phase content was observed. The amounts of hydrogen incorporated into the films, as determined by elastic recoil detection analysis, were shown to be low. Overall, the results demonstrate that residual water present during film growth drastically affects film properties, also in cases where the hydrogen incorporation is found to be low.Original publication: E. Wallin, J.M. Andersson, M. Lattemann, and U. Helmersson, Influence of residual water on magnetron sputter deposited crystalline Al2O3 thin films, 2008, Thin Solid Films, (516), 12, 3877-3883. http://dx.doi.org/10.1016/j.tsf.2007.07.135. Copyright: Elsevier B.V., http://www.elsevier.com

Guiding the deposition flux in an ionized magnetron discharge

A study of the ability to control the deposition flux in a high power impulse magnetron sputtering discharge using an external magnetic field is presented in this article. Pulses with peak power of 1.4 kWcm-2 were applied to a conventional planar magnetron equipped with an Al target. The high power creates a high degree of ionization of the sputtered material, which opens for an opportunity to control of the energy and direction of the deposition species. An external magnetic field was created with a current carrying coil placed in front of the target. To measure the distribution of deposition material samples were placed in an array surrounding the target and the depositions were made with and without the external magnetic field. The distribution is significantly changed when the magnetic field is present. An increase of 80 % in deposition rate is observed for the sample placed in the central position (right in front of the target center) and the deposition rate is strongly decreased on samples placed to the side of the target. The measurements were also performed on a conventional direct current magnetron discharge, but no major effect of the magnetic field was observed in that case.Original publication: J. Bohlmark, M. Östbye, M. Lattemann, H. Ljungcrantz, T. Rosell, and U. Helmersson, Guiding the deposition flux in an ionized magnetron discharge, 2006, Thin Solid Films, (515), 4, 1928-1931. http://dx.doi.org/10.1016/j.tsf.2006.07.183. Copyright: Elsevier B.V., http://www.elsevier.com/</p

Cross-field ion transport during high power impulse magnetron sputtering

In this study, the effect on thin film growth due to an anomalous electron transport, found in high power impulse magnetron sputtering (HiPIMS), has been investigated for the case of a planar circular magnetron. An important consequence of this type of transport is that it affects the way ions are being transported in the plasma. It was found that a significant fraction of ions are transported radially outwards in the vicinity of the cathode, across the magnetic field lines, leading to increased deposition rates directly at the side of the cathode (perpendicular to the target surface). Furthermore, this mass transport parallel to the target surface leads to that the fraction of sputtered material reaching a substrate placed directly in front of the target is substantially lower in HiPIMS compared with conventional direct current magnetron sputtering (dcMS). This would help to explain the lower deposition rates generally observed for HiPIMS compared with dcMS. Moreover, time-averaged mass spectrometry measurements of the energy distribution of the cross-field transported ions were carried out. The measured distributions show a direction-dependent high-energy tail, in agreement with predictions of the anomalous transport mechanism.Original Publication:Daniel Lundin, Petter Larsson, Erik Wallin, Martina Lattemann, Nils Brenning and Ulf Helmersson, Cross-field ion transport during high power impulse magnetron sputtering, 2008, Plasma Sources Science and Technology, (17), 035021.http://dx.doi.org/10.1088/0963-0252/17/3/035021Copyright: Iop Publishinghttp://www.iop.org

Helmersson Transition between the discharge regimes of high power impulse magnetron sputtering and conventional direct current magnetron sputtering Plasma Sources Science and Technology

Transition between the discharge regimes of high power impulse magnetron sputtering and conventional direct current magnetron sputtering, 2009, PLASMA SOURCES SCIENCE and TECHNOLOGY, (18) Abstract Current and voltage have been measured in a pulsed high power impulse magnetron sputtering (HiPIMS) system for discharge pulses longer than 100 µs. Two different current regimes could clearly be distinguished during the pulses: (1) A high-current transient followed by (2) a plateau at lower current. These results provide a link between the HiPIMS and the direct current magnetron sputtering (DCMS) discharge regimes. At high applied negative voltages the high-current transient had the characteristics of HiPIMS pulses, while at lower voltages the plateau values agreed with currents in DCMS using the same applied voltage. The current behavior was found to be strongly correlated with the chamber gas pressure, where increasing gas pressure resulted in increasing peak current and plateau current. Based on these experiments it is here suggested that the high-current transients cause a depletion of the working gas in the area in front of the target, and thereby a transition to a DCMS-like high voltage, lower current regime. Confidential: not for distribution

High resolution STEM investigation of interface layers in cemented carbides

Cemented carbides with sub-micron grain size have increased the need to restrict grain growth during sintering. Commonly used inhibitors like V, Ti, and Cr have been observed to form interface layers in the interfaces between WC grains and the Co binder. Atomistic modeling has predicted the composition and thickness of the interface layers. Earlier, the interface layers have been characterized qualitatively using high resolution transmission electron microscopy (TEM). To get more information about the structure and composition of the interface layers in a Ti containing cemented carbide in this work, Z contrast imaging and spectroscopy using scanning transmission electron microscopy (STEM) have been combined. Elemental maps revealing the structure of the interface layers will be presented

Transition between the discharge regimes of high power impulse magnetron sputtering and conventional direct current magnetron sputtering

Current and voltage have been measured in a pulsed high power impulse magnetron sputtering (HiPIMS) system for discharge pulses longer than 100 mu s. Two different current regimes could clearly be distinguished during the pulses: (1) a high-current transient followed by (2) a plateau at lower currents. These results provide a link between the HiPIMS and the direct current magnetron sputtering (DCMS) discharge regimes. At high applied negative voltages the high-current transient had the characteristics of HiPIMS pulses, while at lower voltages the plateau values agreed with currents in DCMS using the same applied voltage. The current behavior was found to be strongly correlated with the chamber gas pressure, where increasing gas pressure resulted in increasing peak current and plateau current. Based on these experiments it is suggested here that the high-current transients cause a depletion of the working gas in the area in front of the target, and thereby a transition to a DCMS-like high-voltage, lower current regime

Slavic toponyms in the territory of Greece. X (the etymologic comment)

(uk) У статті запропоновано етимологічну інтерпретацію давніх слов’янських ойконімів на території середньовічної Греції. Як і в попередніх статтях цього циклу, тут ставиться мета від­новлення первісної форми і структурної характеристики апелятивів, законсервованих в осно­вах розглянутих назв населених пунктів.(en) In the article is proposed an etymologic interpretation of ancient Slavic toponyms in the territory of medieval Greece. As in previous articles of this circle in this one the aim of reconstructing of origi­nal form and structural characteristics of appellatives that were conserved in stems of settled places names is raised