| 1. |
- Böhlmark, Johan, et al.
(författare)
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Ionization of sputtered metals in high power pulsed magnetron sputtering
- 2005
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 23:1, s. 18-22
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Tidskriftsartikel (refereegranskat)abstract
- The ion to neutral ratio of the sputtered material have been studied for high power pulsed magnetron sputtering and compared with a continuous direct current (dc) discharge using the same experimental setup except for the power source. Optical emission spectroscopy (OES) was used to study the optical emission from the plasma through a side window. The emission was shown to be dominated by emission from metal ions. The distribution of metal ionized states clearly differed from the distribution of excited states, and we suggest the presence of a hot dense plasma surrounded by a cooler plasma. Sputtered material was ionized close to the target and transported into a cooler plasma region where the emission was also recorded. Assuming a Maxwell–Boltzmann distribution of excited states the emission from the plasma was quantified. This showed that the ionic contribution to the recorded spectrum was over 90% for high pulse powers. Even at relatively low applied pulse powers, the recorded spectra were dominated by emission from ions. OES analysis of the discharge in a continuous dc magnetron discharge was also made, which demonstrated much lower ionization.
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| 2. |
- Ehiasarian, Arutiun P., et al.
(författare)
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Distance-dependent plasma composition and ion energy in high power impulse magnetron sputtering
- 2010
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 43:27, s. 275204-
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Tidskriftsartikel (refereegranskat)abstract
- The plasma composition of high power impulse magnetron sputtering (HIPIMS) has been studied for titanium and chromium targets using a combined energy analyser and quadrupole mass spectrometer. Measurements were done at distances from 50 to 300 mm from the sputtering target. Ti and Cr are similar in atomic mass but have significantly different sputter yields, which gives interesting clues on the effect of the target on plasma generation and transport of atoms. The Ti and Cr HIPIMS plasmas operated at a peak target current density of similar to 0.5 A cm(-2). The measurements of the argon and metal ion content as well as the ion energy distribution functions showed that (1) singly and doubly charged ions were found for argon as well as for the target metal, (2) the majority of ions were singly charged argon for both metals at all distances investigated, (3) the Cr ion density was maintained to distances further from the target than Ti. Gas rarefaction was identified as a main factor promoting transport of metal ions, with the stronger effect observed for Cr, the material with higher sputter yield. Cr ions were found to displace a significant portion of the gas ions, whereas this was less evident in the Ti case. The observations indicate that the presence of metal vapour promotes charge exchange and reduces the electron temperature and thereby practically prevents the production of Ar2+ ions near the target. The content of higher charge states of metal ions depends on the probability of charge exchange with argon.
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| 3. |
- Helmersson, Ulf, et al.
(författare)
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Ionized physical vapor deposition (IPVD): A review of technology and applications
- 2006
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 513:1-2, s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- In plasma-based deposition processing, the importance of low-energy ion bombardment during thin film growth can hardly be exaggerated. Ion bombardment is an important physical tool available to materials scientists in the design of new materials and new structures. Glow discharges and in particular the magnetron sputtering discharge have the advantage that the ions of the discharge are abundantly available to the deposition process. However, the ion chemistry is usually dominated by the ions of the inert sputtering gas while ions of the sputtered material are rare. Over the past few years, various ionized sputtering techniques have appeared that can achieve a high degree of ionization of the sputtered atoms, often up to 50 % but in some cases as much as approximately 90%. This opens a complete new perspective in the engineering and design of new thin film materials. The development and application of magnetron sputtering systems for ionized physical vapor deposition (IPVD) is reviewed. The application of a secondary discharge, inductively coupled plasma magnetron sputtering (ICP-MS) and microwave amplified magnetron sputtering, is discussed as well as the high power impulse magnetron sputtering (HIPIMS), the self-sustained sputtering (SSS) magnetron, and the hollow cathode magnetron (HCM) sputtering discharges. Furthermore, filtered arc-deposition is discussed due to its importance as an IPVD technique. Examples of the importance of the IPVD-techniques for growth of thin films with improved adhesion, improved microstructures, improved coverage of complex shaped substrates, and increased reactivity with higher deposition rate in reactive processes are reviewed.
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| 4. |
- Hänninen, Tuomas, 1988-
(författare)
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Silicon Nitride Based Coatings Grown by Reactive Magnetron Sputtering
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Silicon nitride and silicon nitride-based ceramics have several favorable material properties, such as high hardness and good wear resistance, which makes them important materials for the coating industry. This thesis focuses the synthesis of silicon nitride, silicon oxynitride, and silicon carbonitride thin films by reactive magnetron sputtering. The films were characterized based on their chemical composition, chemical bonding structure, and mechanical properties to link the growth conditions to the film properties. Silicon nitride films were synthesized by reactive high power impulse magnetron sputtering (HiPIMS) from a Si target in Ar/N2 atmospheres, whereas silicon oxynitride films were grown by using nitrous oxide as the reactive gas. Silicon carbonitride was synthesized by two different methods. The first method was using acetylene (C2H2) in addition to N2 in a Si HiPIMS process and the other was co-sputtering of Si and C, using HiPIMS for Si and direct current magnetron sputtering (DCMS) for graphite targets in an Ar/N2 atmosphere. Langmuir probe measurements were carried out for the silicon nitride and silicon oxynitride processes and positive ion mass spectrometry for the silicon nitride processes to gain further understanding on the plasma conditions during film growth. The target current and voltage waveforms of the reactive HiPIMS processes were evaluated.The main deposition parameter affecting the nitrogen concentration of silicon nitride films was found to be the nitrogen content in the plasma. Films with nitrogen contents of 50 at.% were deposited at N2/Ar flow ratios of 0.3 and above. These films showed Si-N as the dominating component in Si 2p X-ray photoelectron spectroscopy (XPS) core level spectra and Si–Si bonds were absent. The substrate temperature and target power were found to affect the nitrogen content to a lower extent. The residual stress and hardness of the films were found to increase with the film nitrogen content. Another factors influencing the coating stress were the process pressure, negative substrate bias, substrate temperature, and HiPIMS pulse energy. Silicon nitride coatings with good adhesion and low levels of compressive residual stress were grown by using a pressure of 600 mPa, a substrate temperature below 200 °C, pulse energies below 2.5 Ws, and negative bias voltages up to 100 V.The elemental composition of silicon oxynitride films was shown to depend on the target power settings as well as on the nitrous oxide flow rate. Silicon oxide-like films were synthesized under poisoned target surface conditions, whereas films deposited in the transition regime between poisoned and metallic conditions showed higher nitrogen concentrations. The nitrogen content of the films deposited in the transition region was controlled by the applied gas flow rate. The applied target power did not affect the nitrogen concentration in the transition regime, while the oxygen content increased at decreasing target powers. The chemical composition of the films was shown to range from silicon-rich to effectively stoichiometric silicon oxynitrides, where no Si–Si contributions were found in the XPS Si 2p core level spectra. The film optical properties, namely the refractive index and extinction coefficient, were shown to depend on the film chemical bonding, with the stoichiometric films displaying optical properties falling between those of silicon oxide and silicon nitride.The properties of silicon carbonitride films were greatly influenced by the synthesis method. The films deposited by HiPIMS using acetylene as the carbon source showed silicon nitride-like mechanical properties, such as a hardness of ~ 20 GPa and compressive residual stresses of 1.7 – 1.9 GPa, up to film carbon contents of 30 at.%. At larger film carbon contents the films had increasingly amorphous carbon-like properties, such as densities below 2 g/cm3 and hardnesses below 10 GPa. The films with more than 30 at.% carbon also showed columnar morphologies in cross-sectional scanning electron microscopy, whereas films with lower carbon content showed dense morphologies. Due to the use of acetylene the carbonitride films contained hydrogen, up to ~ 15 at.%. The co-sputtered silicon carbonitride films showed a layered SiNx/CNx structure. The hardness of these films increased with the film carbon content, reaching a maximum of 18 GPa at a film carbon content of 12 at.%. Comparatively hard and low stressed films were grown by co-sputtering using a C target power of 1200 W for a C content around 12 at.%, a negative substrate bias less than 100 V, and a substrate temperature up to 340 °C.
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| 5. |
- Lewin, Erik, et al.
(författare)
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Comparison of Al-Si-N nanocomposite coatings deposited by HIPIMS and DC magnetron sputtering
- 2013
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 232, s. 680-689
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a comparative study between DC magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS) of Al-Si-N. Coatings were synthesised through co-sputtering of Al and Si in a mixed Ar/N-2. One set of DCMS experiments and one set of hybrid HIPIMS (Al-target)/DCMS (Si-target) experiments were conducted. It was found that a higher partial pressure of N-2 was necessary to obtain fully nitrided material using the HIPIMS process. The Si content of the samples was varied between 0 and 16 at.%. All processes were characterised using optical emission spectroscopy (OES) as well as energy-resolved mass spectrometry (E-MS). The obtained coatings were characterised using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), as well as UV-Vis spectroscopy and nanoindentation. The HIPIMS processes were found to provide a highly activated growth environment, with Al+ comprising 87% of the total ion flux, compared to 0.6% for the DCMS case, where Ar+ was found to be the dominating species comprising 90% of the total ion flux. Coatings from both HIPIMS and DCMS processes were found to form nanocomposites of a solid solution phase (Al1-xSix)N and most likely a SiN, phase, as shown by XRD and XPS analyses. Compared to coatings from DCMS, samples deposited with HIPIMS had a slightly more textured AlN-phase with smaller grains, as well as smoother and, denser morphology as observed by SEM. In agreement with previous studies, the coatings had a high transparency in the visual and near IR range; an optical band gap (E-04) between 4.6 and 5.2 eV and a refractive index between 1.9 and 2.1 was observed. The ternary coatings studied here were found to be hard with the HIPIMS coatings (combined average 22 +/- 3 GPa) being harder than their DCMS counterpart (combined average 17 +/- 1 GPa). A maximum hardness of 27 GPa was observed for the sample deposited with HIPIMS and a Si-content of 7 at.%.
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