Growth effects in carbon coatings deposited by magnetron sputtering (original) (raw)
Related papers
Characteristics of Carbon Films Deposited by Magnetron Sputtering
Acta Physica Polonica A, 2009
Carbon thin films are often called in the literature, "diamond-like carbon" films. They consist of two basic allotropic forms of carbon, which are graphite and diamond. Carbon atoms with sp 2 bonds form after deposition of a graphite-like phase. Atoms with sp 3 bonds form a diamond-like phase. Diamond-like crystallites are built into a graphite-like phase matrix. In this paper there are presented experimental results of deposition of carbon films by the magnetron sputtering method and the results of analysis of the surface and phase structures of the deposited films. The amorphous carbon films were deposited from graphite targets on 316L steel substrates. The films were deposited at room temperature, in vacuum. The deposition time was 3 h; the depositions were conducted at two different distances between the substrate and the magnetron target.
Magnetron sputtered hard a-C coatings of very high toughness
Surface and Coatings Technology, 2003
Hydrogen-free amorphous carbon coatings of high hardness (f30 GPa) and toughness (plasticity from 50 to 60%) were deposited on 440C steel substrates by DC magnetron sputtering at target power density of 10.5 Wycm in the bias range from y 2 20 to y150 V. The surface topography, hardness and tribological behavior of the coatings were investigated. With the increase of bias voltage, coating hardness and surface smoothness increased at expense of some adhesion strength and an increase of coefficient of friction. All coatings showed low friction in humid air and graphitization was observed after a high number of rotation cycles. The graphitization adds more benefit aside from reducing friction: the graphite layer can considerably reduce the adhesive wear since it prevents the asperities of the two surfaces to be adhered to each other.
Thin Solid Films
Structure evolution of amorphous carbon (a-C) films deposited by dc magnetron sputtering of graphite in argon was investigated as a function of substrate temperature Ts (20–800°C) and dc substrate bias voltage Ub (floating — −175 V). Film structure was studied by transmission electron microscopy, selected area electron diffraction, reflective high energy electron diffraction and Raman spectroscopy. Film resistivity in two directions — parallel and perpendicular to the substrate — was also measured. The results obtained allow for the assumption that the film structure is based on coexistence of D- and G-phases formed of sp2 bonded carbon atoms. G-phase consists of small graphite-like ordered areas embedded in continuous uniform amorphous D-phase. The evolution of a-C film structure in 20−450°C interval occurs by temperature induced graphite-like ordering of small areas within D-phase (G-phase nucleation). In the 500–800°C range the change of C-film growth mechanism takes place. Inste...
Diamond and Related Materials, 2000
This work investigates the evolution of the structural, mechanical and tribological properties of amorphous carbon films (a-C) undergoing thermal annealing. Two different types of a-C film were studied: hard, stressed and dense films, henceforth called 'diamond-like', and soft, more relaxed and less dense films, called 'polymer-like'. The two sets of films were deposited by dc magnetron sputtering at 0.36 and 1.4 Pa argon plasma pressures, respectively, and both were annealed in vacuum for 1 h at temperatures between 300 and 700°C. Raman results provided indications of a remarkable increase of the sp2 hybridized domains, that occurs mainly at temperatures higher than 400°C for the diamond-like films and in a continuous way for the polymer-like films. The friction coefficient of both types of film approaches the same value with increasing temperature, whereas the surface roughness is nearly constant. For diamond-like films, the hardness and compressive internal stress are nearly constant up to 500°C, and then undergo a fast decrease. In contrast, the hardness of the polymer-like film continuously decreases with temperature, whereas the compressive stress remains constant.
Insights on the deposition mechanism of sputtered amorphous carbon films
Carbon, 1999
Low energy Ar ion bombardment (LEIB) during growth of amorphous carbon (a-C) films deposited with magnetron 3 sputtering (MS), results to dense films, rich in sp C-C bonds, and exhibit high hardness and compressive stress. We present here a preliminary study of the growth mechanism of a-C films deposited with negative bias voltage (LEIB) in terms of their composition, density and mechanical properties. The experimental results showed that stress and hardness are directly related 3 with the sp C-C bonding in the film and described well with the so far proposed models on the formation mechanism of 2 3 tetrahedral carbon. However, the film density, that is a composite property, was found to depend not only on the sp and sp 1 content but also on a new, denser than graphite, carbon phase when the Ar ion energy is above |130 eV.
Diamond and Related Materials, 2007
The relationship between metal-induced (W, Mo, Nb and Ti) structures and the surface properties of Me-DLC thin films is discussed. Nanocomposite films were deposited on c-Si wafers by pulsed-DC reactive magnetron sputtering controlling the gas ratio CH 4 /Ar. The sputtering process of metals such as Ti, Nb and Mo (unlike the tungsten) in the presence of methane shows a low reactivity at low methane concentration. The deposition rate and the spatial distribution of sputtered material depend of Z-ratio of each metal. The surface contamination of metal targets by carbon, owing to methane dilution, limits the incorporation of metals into DLC films according to an exponential decay. Results of electron probe microanalysis and X-ray photoelectron spectroscopy indicate a C rich Me/C composition ratio for low relative methane flows. According to the depth profile by secondary ion mass spectrometry, the films are systematically homogeneous in depth, whereas at high carbon contents they exhibit a metal-rich interfacial layer on the substrate. Moreover, high resolution transmission electron microscopy has evidenced important structural modifications with respect to DLC standard films, with marked differences for each Me/C combination, providing nanodendritic, nanocrystallized or multilayered structures. These particular nanostructures favour the stress decrease and induce significant changes in the tribological characteristics of the films. This study shows the possibilities of controlling the amorphous carbon films structure and surface properties by introducing metal in the DLC matrix.
Characterization of DLC coatings deposited by rf magnetron sputtering
Journal of Materials Processing Technology, 2004
In this work diamond-like carbon (DLC) thin films have been deposited by rf magnetron sputtering in an argon gas filled chamber using graphite target under different substrate temperatures. The bonding property was characterized by micro Raman and estimated sp 3 /sp 2 in DLC films. Raman spectra showed that sp 3 -bonded carbon fraction increases from 50 to 80 • C temperatures and an increase in the substrate temperature above 80 • C results in an increase in the sp 2 -bonded carbon atoms in DLC thin films. Mechanical properties namely, hardness and Young's modulus were determined by CSM TM nanohardness tester. The hardness (H) and Young's modulus (E) were found in the range of 11-22 and 110-160 GPa, respectively, at different substrate temperatures and increased with increase of substrate temperature up to 125 • C and decreased thereafter. These results indicate that substrate temperature has a strong influence on the bonding properties of the deposited films and the changes in bonding ratio (sp 3 /sp 2 ) were correlated with changes in the mechanical properties.
DLC based coatings prepared by reactive d.c. magnetron sputtering
Thin Solid Films, 2004
Metal containing diamond-like carbon (a-C:H:MeyMe-DLC) coatings commonly will be prepared by reactive magnetron sputter deposition using targets from transition metals or transition metal carbides and acetylene as reactive gas. It is well known that Me-DLC coatings have very similar friction properties like hard hydrogenated amorphous carbon (a-C:HyDLC) coatings. However, even optimized Me-DLC nearly without exceptions exhibits clearly lower wear resistances and lower hardness values than metal free DLC. To get more insight in the effects of metal incorporation, both W-DLC using tungsten targets and metal free coatings using graphite targets were prepared. For the latter, we introduce the name C-DLC. The deposition experiments were carried out in an industrial scale d.c. magnetron sputter machine. To have a reference material metal free a-C:H was deposited by radio frequency and by mid frequency (m.f.-some 10-100 kHz) glow discharge techniques operating with acetylene. Transmission electron microscopy (TEM), secondary ion mass spectroscopy (SIMS) and Raman spectroscopy investigations as well as hardness measurements and abrasive wear tests revealed that C-DLC coatings have nearly identical composition and structure and also rather similar mechanical and tribological properties like a-C:H deposited by r.f. or m.f. processes. However, for all these features essential differences between C-DLC and W-DLC coatings were found. ᮊ
Comparative study of metal/amorphous-carbon multilayer structures produced by magnetron sputtering
Diamond and Related Materials, 2003
The present study discusses the structural and mechanical properties of metalyamorphous carbon (a-C) multilayer structures of a-CyMoya-Cy«yMoysubstrate and a-CyWya-Cy«yWysubstrate deposited by magnetron sputtering. To this end, the effects of deposition parameters on multilayered nanometric structures were examined. Samples consisted of structures with alternate metallic and a-C layers with thicknesses in the nanometric range (1-3 nm). The films were deposited on crystalline silicon and glass substrates at room temperature using two opposing magnetron sputtering heads, which allowed the alternate deposition of the metallic and a-C films on the substrates placed on a directional holder. The substrate negative bias voltage was varied between 40 and 300 V and the process was performed at Ar pressures in the range 0.2-2 Pa. The structural and morphological properties and local order of the layers and interfaces were analysed by transmission electron microscopy and X-ray diffraction. Mechanical stress, and critical load for coating failure were measured by profilometry and the microscratch technique, respectively, and the results are discussed in terms of the deposition conditions and the multilayer nanostructure. Potential applications of films based on metalya-C multilayers include the production of hard, protective, wear-resistant coatings for corrosion-resistant and high temperature-resistant applications. ᮊ