Cathodic Magnetron Sputtering Research Articles

Texture and microstructure evolution in single-phase TixTa1−xN alloys of rocksalt structure

The mechanisms controlling the structural and morphological features (texture and microstructure) of ternary transition metal nitride thin films of the TixTa1−xN system, grown by various physical vapor deposition techniques, are reported. Films deposited by pulsed laser deposition, dual cathode magnetron sputtering, and dual ion beam sputtering have been investigated by means of x-ray diffraction in various geometries and scanning electron microscopy. We studied the effects of composition, energetic, and kinetics in the evolution of the microstructure and texture of the films. We obtain films with single and mixed texture as well as films with columnar “zone-T” and globular type morphology. The results have shown that the texture evolution of ternary transition metal nitrides as well as the microstructural features of such films can be well understood in the framework of the kinetic mechanisms proposed for their binary counterparts, thus giving these mechanisms a global application.

Comparison between conventional and hollow cathode magnetron sputtering systems on the growing of titanium dioxide thin films: a correlation between the gas discharge and film formation

This paper reports the deposition of titanium dioxide thin films on p -type Si(100) substrates using two techniques called conventional magnetron sputtering (CMS) and hollow cathode magnetron sputtering (HCMS). The influence of the plasma parameters on the film characteristics (topography, morphology and crystallinity) was investigated. Films were deposited at different oxygen concentrations (in the Ar + O 2 gas mixture) and axial distances for fixed values of working pressure (5.0 mTorr) and DC power (55 W). They were analyzed by profilometry, AFM and XRD. The gas discharge was diagnosed by single Langmuir probe and OES. Under experimental conditions used in this work, results show that HCMS favors the growing of rutile phase due to the increase of the energy on the film surface caused by the hollow cathode effect. On the other hand, films deposited by CMS present preferentially anatase phase due to the low energy transferred to the growing film. Further studies regarding the influence of plasma properties on the films formation were done in order to understand the plasma-surface correlation.

Comparison of tribological properties of CrN, TiCN and TiAlN coatings sliding against SiC balls in water

CrN, TiCN and TiAlN coatings were deposited on WC cemented carbide disks using enhanced cathodic arc magnetron sputtering and their topographies and structures were observed and analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The friction and wear properties of CrN, TiCN and TiAlN coatings sliding against SiC balls in water were investigated and compared synthetically using ball-on-disk tribometer. The results showed that the CrN/SiC tribopairs showed the lowest friction coefficient of 0.076, while the TiCN/SiC tribopairs displayed the highest friction coefficient of 0.264. For the CrN/SiC tribopairs the specific wear rate of CrN coatings was lowest while that of SiC balls became highest. But for the TiAlN(TiCN)/SiC tribopairs, the specific wear rate of TiAlN coatings was highest while that of SiC balls for the TiCN/SiC tribopairs became lowest. This indicated that the friction and wear behaviors of nitride coatings/SiC balls tribo-systems in water were more strongly influenced by the anti-oxidative ability of tribomaterials in water than by their mechanical properties.

Development of high density plasma assisted sputtering source for high growth rate deposition process

High speed deposition method was investigated by a high density plasma assisted sputtering source (HiPASS). The HiPASS used a hollow cathode discharge (HCD) gun (maximum current: 60 A) as a high density plasma source. The extracted high density plasma from the HCD gun was transported to the magnetron sputtering region by a magnetic field. In the magnetron sputtering discharge, the transported plasma reduced a breakdown voltage and increased a discharge current about 20%. Also the transported plasma excited the sputtered particles effectively. The additional excitation of the sputtered particles increased Mg deposition rate from 70 nm/min to 130 nm/min and from 32 nm/min to 118 nm/min when a distance between the sputtering target and substrate was 250 mm and 350 mm, respectively. Abroad plasma transport near the magnetron sputtering cathode was important to enhance the deposition rate.

Effect of oxygen concentration and system geometry on the current–voltage relations during reactive sputter deposition of titanium dioxide thin films

Current–voltage relations at different magnetron sputtering systems and gas mixtures were studied during reactive sputter deposition of titanium dioxide thin films. The main goal of this work was to investigate the influence of reactive gas mixture (Ar + O 2) and system geometry on the electrical characteristics of the discharge. The geometries utilized were the conventional magnetron sputtering, hollow cathode magnetron sputtering and triode magnetron sputtering. A change in the system geometry leads to a change in the electric field distribution, which alters the working range of the discharge voltage and magnetron efficiency. It is noticed that the discharge voltage at constant current can be reduced when the geometry is altered from conventional magnetron to hollow cathode magnetron or triode magnetron, at the same time the magnetron efficiency is increased when hollow cathode magnetron or triode magnetron are used instead of conventional magnetron sputtering.

Friction and wear properties of TiCN coatings sliding against SiC and steel balls in air and water

The TiCN coatings were deposited on WC cemented carbides using enhanced cathodic arc magnetron sputtering. The topography of TiCN coatings were observed using scanning electron microscopy (SEM), the composition and structure of TiCN coatings were analyzed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The friction and wear properties of TiCN coatings sliding against SiC and steel balls in air and water were investigated using ball-on-disk tribometer. The results showed that the TiCN coatings had a strong (111) preferred orientation. The friction coefficient and the specific wear rates of the TiCN/SiC tribopairs in air were higher than those in water. When the TiCN coatings slid against SiC balls in water, the friction coefficient and the specific wear rates first decreased, and then increased with the normal load, but decreased linearly with the sliding velocity. The lowest friction coefficient of 0.171 was obtained at 3 N and 0.4 m/s, while the lowest specific wear rate of the TiCN coatings was 2.3 × 10 − 6 mm 3/Nm at 6 N and 0.1 m/s. The TiCN coatings were worn out when the normal loads were higher than 6 N. When the TiCN coatings slid against the SUJ2 and SUS440C balls in water, the friction coefficient increased to 0.271 and 1.026 respectively. The EDS analysis showed that Fe and O elements existed on the wear track. This indicated that the tribochemical reaction occurred at the friction contact area.

Large-Scale Deposition of Transparent Conducting Oxides by Hollow Cathode Sputtering

ABSTRACTThis paper reviews the status of hollow cathode sputtering as an evolving technology for production of thin-film transparent conducting oxides for PV applications. A large market segment for PV TCOs is represented by thin-film a-Si:H and tandem a-Si:H/nc-Si:H modules. For superstrate devices, textured SnO2:F produced on-line by APCVD is currently the market leader, although alternative off-line methods and materials are now emerging. In particular, zinc oxide can be produced by LPCVD, APCVD, magnetron sputtering, and hollow cathode sputtering (HCS). HCS is a stable process featuring low-cost metal targets and a soft deposition process. We discuss the deposition principles and the film results obtained using linear hollow cathodes 0.5 m and 1.0 m in length. We report the direct deposition of highly textured doped ZnO having an electron mobility in excess of 50 cm2/Vs. The production cost of textured ZnO is estimated for several competing techniques.

Growth and Characterization of Thermoelectric Mg2Si Thin Films

ABSTRACTIn this work, room temperature co-deposition of Mg and Si was used to successfully fabricate Mg2Si thin films on Si substrate by dual cathode magnetron sputtering (DCMS). Films were annealed at 380°C. Various Mg/Si sputtering power ratios have been examined. XRD, SEM and IR reflectivity measurements on grown and annealed films, reveal that annealing is enhancing the formation of crystalline Mg2Si.

Development and evaluation of two PVD-coated β-titanium orthodontic archwires for fluoride-induced corrosion protection

The present research was aimed at developing surface coatings on β titanium orthodontic archwires capable of protection against fluoride-induced corrosion. Cathodic arc physical vapor deposition PVD (CA-PVD) and magnetron sputtering were utilized to deposit thin films of titanium aluminium nitride (TiAlN) and tungsten carbide/carbon (WC/C) coatings on β titanium orthodontic archwires. Uncoated and coated specimens were immersed in a high fluoride ion concentration mouth rinse, following a specially designed cycle simulating daily use. All specimens thus obtained were subjected to critical evaluation of parameters such as electrochemical corrosion behaviour, surface analysis, mechanical testing, microstructure, element release, and toxicology. The results confirm previous research that β titanium archwires undergo a degradation process when in contact with fluoride mouth rinses. The study confirmed the superior nature of the TiAlN coating, evident as many fewer changes in properties after fluoride treatment when compared with the WC/C coating. Thus, coating with TiAlN is recommended in order to reduce the corrosive effects of fluorides on β titanium orthodontic archwires.

Structure and mechanical properties of Ti–Al–N coatings deposited by combined cathodic arc middle frequency magnetron sputtering

Ti–Al–N coatings were deposited on Si (1 1 1) and WC substrates by combined cathodic arc middle-frequency magnetron (MF) sputtering under a Ti arc power of 10 kW and with different Al MF targets currents. X-ray diffraction patterns (XRD) showed that the Ti–Al–N coatings were polycrystallize with a preferred (1 1 1) orientation at 2 θ = 43.7°. The (1 1 1) diffraction showed a decrease in peak intensity but a increase in FWHM values with the increasing of Al contents. Nano-meter sized TiN crystal grains distinguished by the lattice fringe contrast were verified by plan-view transmission electron (TEM) and selected area electron diffraction (SAED) images. With the increasing of MF sputter currents from 5 to 20 A, the Al contents in the Ti–Al–N coatings monotonically increased from 4.8 to 10.8 at.%, whereas the N and O contents were nearly constant. The hardness of the Ti–Al–N coatings was in the range of 23–32 GPa, and the Young modulus values were in the range of 420–540 GPa.

Numerical analysis of geometry effects for target re-deposition during low pressure hollow cathode magnetron sputtering

During low pressure ionized metal physical vapor deposition (PVD) of Cu seed layer for microprocessor interconnects, the re-deposited Cu film on the hollow cathode magnetron (HCM) target may fall off and damage the Cu film on the wafer. An analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was used to obtain re-deposition profiles for HCM targets in low pressure (below 0.1 Pa) Cu ionized PVD. The model predictions indicate that there is an inherent non-uniformity in the re-deposition profile even for uniform sputtering over the entire HCM target. The predicted re-deposition profile agrees with experimental observations. Subsequent target redesign studies found that the non-uniformity in the re-deposition profile could be mitigated by using a conical sidewall between the top disk and the cylindrical sidewall or reducing the length of the cylindrical sidewall.

Large-Area Growth of In-Plane Oriented (1120) ZnO Films by Linear Cathode Magnetron Sputtering

(1120) textured ZnO films are good candidates for shear-mode piezoelectric devices. In the previous deposition techniques of these films, there have been two problems related to their practical application. These problems are as follows: (i) highly oriented films can be obtained only in a small area and (ii) the crystallite c-axis of in the films is radially oriented in the substrate plane. To resolve these problems, the sputtering deposition technique using a linear cathode has been proposed. The in-plane and out-of-plane orientations of the films were quantitatively determined by pole figure analysis. As a result, we have demonstrated the formation of in-plane unidirectionally oriented (1120) ZnO films over the entire area of 4-in. silicon wafers.

High-power impulse magnetron sputtering and its applications

High-power impulse magnetron sputtering (HIPIMS) was introduced in the late 1990s as a unique physical vapor deposition method. The technology utilizes magnetron sputtering cathodes and high peak power density of up to 3 kW cm–2 on the target. The plasma produces a metal flux with high degree of ionization. HIPIMS has been successfully used as a substrate pretreatment method to enhance coating adhesion by promoting local epitaxial growth. As a deposition technology, HIPIMS produces high-density microstructure films. It has been industrialized and has successful applications in hard, electronic, and optical coatings.

Cr-Doped DLC Multilayered Thin Films Deposited Using Cathodic Vacuum Arc- and DC Magnetron-Assisted Ion Beam Sputtering

A series of graded films of Cr/CrN/ CrNC/CrC/(Cr-DLC)/[(Cr-(Cr-DLC))×10] were deposited on Si(100) wafer and 4135 alloy structural steel using cathodic vacuum arc technique and direct current magnetron sputtering method combined with ion beam sputtering. The surface morphology, microstructure, nano-hardness, adhesion and wear properties of the films were investigated using 3-dimensional white-light interfering surface profiler, scanning electron microscopy, nanoindentation, scratch adhesion test, ball-on-disc test, etc. It was measured that the as-prepared Cr-doped DLC multilayered thin films have a strong adhesion to the substrates with a critical load exceeding 80 N, and the average friction coefficient during 30 min test in air was 0.23. This film will be promising in application against wear.

Titanium dioxide thin films deposition by direct current hollow cathode magnetron sputtering

Cylindrical hollow cathode magnetron sputtering (HCMS) system was used to deposit crystalline titanium dioxide thin films on p-Si (100) substrates. For a fixed pressure of 0.6 Pa total gas flow rate of 20 sccm and power of 55 W, the influence of the oxygen percentage in the Ar+O 2 gas mixture on the structural and surface properties of the films was studied by profilometry, XRD and AFM. The substrates were placed inside the hollow cathode at different positions along its symmetrical axis. Numerical simulations of cathode ion collection probability (CICP) were done in order to compare calculated data with the deposition process characteristics. The results indicate that the deposition rate and the surface roughness gradually decrease with the distance from the bottom of the cathode, due to the decrease of the CICP. The increase of the oxygen percentage in the gas discharge influences directly the deposition rate and decrease the surface roughness. The XRD analyses show that all the films are crystalline with predominant anatase (101) and rutile (110) orientations.

A structure zone diagram including plasma-based deposition and ion etching

An extended structure zone diagram is proposed that includes energetic deposition, characterized by a large flux of ions typical for deposition by filtered cathodic arcs and high power impulse magnetron sputtering. The axes are comprised of a generalized homologous temperature, the normalized kinetic energy flux, and the net film thickness, which can be negative due to ion etching. It is stressed that the number of primary physical parameters affecting growth by far exceeds the number of available axes in such a diagram and therefore it can only provide an approximate and simplified illustration of the growth condition–structure relationships.

Structure and properties of Ti-Si-N coatings synthesized by combining cathode arc and middle-frequency magnetron sputtering

Ti-Si-N composite coatings were synthesized on a novel combining cathode and middle-frequency magnetron sputtering system, designed on an industrial scale. Ti was produced from the arc target and Si from magnetron target during deposition. The influences of negative bias voltage and Si content on the hardness and microstructure of the coatings were investigated. The composite coatings prepared under optimized conditions were characterized to be nc-TiN/a-Si3N4 structure with grain sizes of TiN ranging from 8-15 nm and exhibited a high hardness of 40 GPa. The enhancement of the hardness is suggested to be caused by the nanograin-amorphous structure effects.

Influence of Electronegative Gas on the Efficiency of Conventional and Hollow Cathode Magnetron Sputtering Systems

The aim of this work is to study the influence of electronegative gas (oxygen at different concentrations) on the electrical characteristics of two configurations of magnetron sputtering systems, namely Hollow Cathode Magnetron Sputtering (HCMS) and Conventional Magnetron Sputtering (CMS). A comparison of the plasma impedances and magnetron efficiency of these systems were carried out through the current-voltage characteristics of the discharges operating at the same pressure and different oxygen concentration on O2/Ar mixtures. The results showed significant variations in the plasma impedance and magnetron efficiency, indicating that HCMS system presents better electrical characteristics than CMS system, i.e., low plasma impedance and high magnetron efficiency. The results indicate that HCMS system is a very interesting technique to be used as deposition system in micro and nanoelectronic processes.

Microstructure and mechanical properties of Cr–Si–N nanocomposite coatings deposited by combined cathodic arc middle frequency magnetron sputtering

An industrial scale cathodic arc assisted middle frequency magnetron sputtering system was introduced and Cr–Si–N nanocomposite coatings with various amounts of Si content have been synthesized. Energy dispersive spectroscope, X-ray diffraction, transmission electron microscopy, nanoindentation technique and friction measurement were employed to characterize the microstructure and mechanical properties of the coatings. The microstructure and hardness of the coatings were greatly influenced by the Si content. The nc-CrN/a-Si 3N 4 structure was formed in the coatings and exhibited a maximum hardness of 39.8 GPa. The surfaces of the samples were smooth and the adhesion between the coating and substrate was higher than 50 N. These properties make it possible for industrial applications.

RF deposition of soft hydrogenated amorphous carbon coatings for adhesive interfaces on highly elastic polymer materials

Developing soft and elastic coating materials is one of the future challenges in research on new coating materials for vacuum deposition processes. This development direction is in its infancy and fully contrary to the thin film research mainstream. Such coatings – tailor-made with gradients in hardness and elastic modulus – could work as adhesive and load-supporting layers on polymers bridging the properties from soft substrate to the stiff, wear-resistant hard top coating. In this work we used the approach of a chemical vapour deposition process with plasma assistance from an unbalanced RF (13.56 MHz) powered magnetron sputtering cathode in planar parallel plate arrangement. The characterization of the amorphous hydrogenated and polymer-like carbon films showed a high influence of the used precursor gas (acetylene, butane) on hardness and elasticity. The elastic moduli were found to be between 2 and 35 GPa for the fully amorphous films with a-C:H structure. Specific growth structures were found in HR-TEM imaging of the amorphous coatings. All coatings adhere strongly on a rubber-like polymer (thermoplastic polyurethane).