Effect of argon and hydrogen on deposition of silicon from tetrochlrosilane in cold plasmas

The roles of Ar and H2 on the decomposition of SiCl4 in cold plasma were investigated by Langmuir probes and mass spectrometry. Decomposition of the reactant by Ar only has been found to be very slow. In presence of H2 in the plasma SiCl4 is decomposed by fast radical-molecule reactions which are further enhanced by Ar due to additional ion-molecule reactions in which more H radicals are produced. A model for the plasma-surface interactions during deposition of mu-Si in the Ar + H2 + SiCl4 system is presented

Protective coatings of metal surfaces by cold plasma treatment

The cold plasma techniques for deposition of various types of protective coatings are reviewed. The main advantage of these techniques for deposition of ceramic films is the lower process temperature, which enables heat treating of the metal prior to deposition. In the field of surface hardening of steel, significant reduction of treatment time and energy consumption were obtained. A simple model for the plasma - surface reactions in a cold plasma system is presented, and the plasma deposition techniques are discussed in view of this model

Correlations between plasma variables and the deposition process of Si films from chlorosilanes in low pressure RF plasma of argon and hydrogen

The dissociation of chlorosilanes to silicon and its deposition on a solid substrate in a RF plasma of mixtures of argon and hydrogen were investigated as a function of the macrovariables of the plasma. The dissociation mechanism of chlorosilanes and HCl as well as the formation of Si in the plasma state were studied by sampling the plasma with a quadrupole mass spectrometer. Macrovariables such as pressure, net RF power input and locations in the plasma reactor strongly influence the kinetics of dissociation. The deposition process of microcrystalline silicon films and its chlorine contamination were correlated to the dissociation mechanism of chlorosilanes and HCl

Proposal for a hardness measurement technique without indentor by gas-cluster-beam bombardment

Large gas-cluster-ion bombardment has been shown to be a unique tool for generating a variety of bombarding effects over a broad range of acceleration energies. A hardness measurement technique is proposed in this paper based on the use of the effect of crater formation by large gas-cluster beams. The cluster impact leaves a hemispherical crater on a surface, the size of which varies with surface hardness and cluster parameters ~which can be predetermined!. As shown in this paper, the crater depth h ~or diameter d! and Brinell hardness B are correlated through the formula h;(E/B)1/3, where E is the cluster acceleration energy. The material hardness, binding energy, and the crater size have also been correlated with the sputtering yield Y, and hence this correlation can also be experimentally applied for measuring hardness. The proposed method is based entirely on surface effects which depend only on the surface material and not on the substrate and therefore should be particularly suitable for measuring hardness of thin deposited films. This technique also eliminates the need for indentors that are harder than the material measured

Studies on the surface modification of TiN coatings using MEVVA ion implantation with selected metallic species

Improvement in the performance of TiN coatings can be achieved using surface modification techniques such as ion implantation. In the present study, physical vapor deposited (PVD) TiN coatings were implanted with Cr, Zr, Nb, Mo and W using the metal evaporation vacuum arc (MEVVA) technique at a constant nominal dose of 4 1016 ions cm2 for all species. The samples were characterized before and after implantation, using Rutherford backscattering (RBS), glancing incident angle X-ray diffraction (GIXRD), atomic force microscopy (AFM) and optical microscopy. Friction and wear studies were performed under dry sliding conditions using a pin-on-disc CSEM Tribometer at 1 N load and 450 m sliding distance. A reduction in the grain size and surface roughness was observed after implantation with all five species. Little variation was observed in the residual stress values for all implanted TiN coatings, except for Wimplanted TiN which showed a pronounced increase in compressive residual stress. Mo-implanted samples showed a lower coefficient of friction and higher resistance to breakdown during the initial stages of testing than as-received samples. Significant reduction in wear rate was observed after implanting with Zr and Mo ions compared with unimplanted TiN. The presence of the Ti2N phase was observed with Cr implantation

Proposal for a hardness measurement technique without indentor by gas-cluster-beam bombardment

Large gas-cluster-ion bombardment has been shown to be a unique tool for generating a variety of bombarding effects over a broad range of acceleration energies. A hardness measurement technique is proposed in this paper based on the use of the effect of crater formation by large gas-cluster beams. The cluster impact leaves a hemispherical crater on a surface, the size of which varies with surface hardness and cluster parameters ~which can be predetermined!. As shown in this paper, the crater depth h ~or diameter d! and Brinell hardness B are correlated through the formula h;(E/B)1/3, where E is the cluster acceleration energy. The material hardness, binding energy, and the crater size have also been correlated with the sputtering yield Y, and hence this correlation can also be experimentally applied for measuring hardness. The proposed method is based entirely on surface effects which depend only on the surface material and not on the substrate and therefore should be particularly suitable for measuring hardness of thin deposited films. This technique also eliminates the need for indentors that are harder than the material measured

MEVVA ion implantation of TiCN coatings; structural and tribological properties

The application of wear resistant metal nitride coatings, typically 25 μm thick, is a well-established strategy, employed for prolonging service life of cutting tools, twist drills, taps, dies. Although TiN is an established coating for such applications, in recent years attention has focused on a more diverse range of metal nitride coatings. Specifically, modifications to the TiN structure through the addition of C to produce TiCN are well established for improvement in properties such as friction coefficient and wear rates. Further improvements in tribological performance are expected by modifying the surface using ion implantation. In this exploratory study, TiCN coatings were deposited onto polished AISI 316 stainless steel substrates using commercially available physical vapor deposition technology. Coated samples were ion implanted with a range of metal ions to include Mo, Nb, W, Zr and Cr using the metal vapor vacuum arc (MEVVA) technique. Ions were implanted at a constant dose of 4 × 10 16 ions/cm 2 . The range of techniques used to characterize the implanted layers included x-ray diffraction, Rutherford backscattering, and optical and atomic force microscopy. Dry sliding friction and wear behavior of implanted coatings was assessed using pin on disc equipment. The results showed that, with some exceptions, ion implantation generally improved friction and wear; in particular, implantation with Nb reduced stress levels, grain size, surface roughness, friction and wear rates