High-rate Magnetron Sputtering Research Articles

The properties of Cu films deposited by high rate magnetron sputtering from a liquid target

The focus of the paper is Cu films obtained by magnetron sputtering a liquid target at an average power density not exceeding 45 W/cm2. The deposition rates reached 140 nm/s. In the film formation, the pulsed power supplies of two types have been used. The discharge has functioned in an Ar atmosphere and in self-sustained mode. Structural and electrically conductive properties of the films have been analyzed. A comparison was made with those deposited by sputtering a cooled target with similar power.It has revealed that the evaporation of the magnetron target plays a dominant role in the formation of the structural and conductive properties of Cu films. The Cu films deposited by sputtering evaporative liquid targets have a lower electrical resistance than the films of similar thickness obtained by sputtering cooled targets. The mode of self-sustained sputtering does not significantly affect the structural properties of the films as compared with sputtering in the Ar atmosphere, but the electrical resistivity is approximately 20% lower. Due to high deposition rate in the case with evaporative targets the heating of the substrate when producing films of equal thickness turns out to be less than when using a magnetron with a cooled target.

High-rate magnetron sputtering with hot target

Chromium films were deposited by cooled and hot target magnetron sputtering techniques with unbalanced magnetic field configuration at equal target power density. The dependence of deposition rates of Cr films by the hot target magnetron sputtering on the power density was a non-linear at 27.5–31.5W/cm2. The optical emission studies indicated the enhancement of deposition rates due to the evaporation of the hot Cr target. The chromium film structure was strongly depended on the factor of «hot target» and the target power density. Cr films were structured to (110) direction in the case of the hot target sputtering, for cooled target configuration – the preferred orientation was changed from (110) to (200) with the power density. Cr+ to Cr ratio and heat flow from the cathode to the substrate influenced on the coating hardness and adhesion. The Cr films with 9.84–12.79GPa and the non-cracking behavior (up to 15N) were obtained.

Structure and properties of the ceramics based on quasicrystal powders processed by plasma coating method

Homogeneous incorporation of a small amount of binding material or modifying agent in the batch consisting of micron size particles is a problem of a composite material production process. In this work the problem is solved by deposition of a thin coating consisting of binding material on the initial powder particles by means of high-rate magnetron sputtering. The confinement of dusty particles in plasma was used in fine powder processing procedure. Composite powders based on the Al-Cu-Fe quasicrystalline particles with nickel coating were obtained. Their investigation showed that the method provides uniform incorporation of small quantities of additives (at concentration of about 3 wt. %) to fine powders. The powders were pressed at room temperature under quasi-hydrostatic conditions at high pressures. After pressing the samples were sintered in hydrogen at normal pressure. Structure and mechanical properties of the sintered samples were studied. The conditions of sintering the composite powder, which provide producing compacts with improved performance data, were established.

Microstructure evolution of Ti–Si–C–Ag nanocomposite coatings deposited by DC magnetron sputtering

Nanocomposite coatings consisting of Ag and TiC x ( x < 1) crystallites in a matrix of amorphous SiC were deposited by high-rate magnetron sputtering from Ti–Si–C–Ag compound targets. Different target compositions were used to achieve coatings with a Si content of ∼13 at.%, while varying the C/Ti ratio and Ag content. Electron microscopy, helium ion microscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed to trace Ag segregation during deposition and possible decomposition of amorphous SiC. Eutectic interaction between Ag and Si is observed, and the Ag forms threading grains which coarsen with increased coating thickness. The coatings can be tailored for conductivity horizontally or vertically by controlling the shape and distribution of the Ag precipitates. Coatings were fabricated with hardness in the range 10–18 GPa and resistivity in the range 77–142 μΩ cm.

Growth of zinc oxide nanostructures

Zinc oxide (ZnO) nanowhiskers have been prepared using a multilayer ZnO(50 nm)/Zn(20 nm)/ZnO(2μm) structure on a polished stainless steel (SS) substrate by high rate magnetron sputtering. The formation of uniformly distributed ZnO nanowhiskers with about 20 nm dia. and 2 to 5 μm length was observed after a postdeposition annealing of the prepared structure at 300–400° C. An array of highlyc-axis oriented ZnO columns (70–300 nm in dia. and up to 10 μm long) were grown on Si substrates by pulsed laser deposition (PLD) at a high pressure (1 Torr), and Raman studies showed the activation of surface phonon modes. The nanosized powder (15–20 nm) and nanoparticle ZnO films on glass substrate were also prepared by a chemical route. Nanowhiskers showed enhanced UV light detection characteristics, and the chemically prepared ZnO nanoparticle films exhibited good sensing properties for alcohol

Study of the microwave electrodynamic response of MgB 2 thin films

We present a study on the power dependence of the microwave surface impedance in thin films of the novel superconductor MgB 2. 500 nm thick samples exhibiting critical temperatures ranging between 26 and 38 K are synthesized by an ex situ post-anneal of e-beam evaporated boron in the presence of an Mg vapor at 900 °C. Preliminary results on films grown in situ by a high rate magnetron sputtering technique from stoichiometric MgB 2 and Mg targets are also reported. Microwave measurements have been carried out employing a dielectrically loaded niobium superconducting cavity operating at 19.8 GHz and 4 K. The study shows that the electrodynamic response of MgB 2 films is presently dominated by extrinsic sources of dissipation, appearing already at low microwave power, likely to be ascribed to the presence of grain boundaries and normal inclusions in the samples.

Structural properties of AlSn thin films deposited by magnetron sputtering

The application of physical vapor deposition (PVD) processes and specially the development of high rate magnetron sputtering opened up possibilities for the deposition of a wide variety of new materials and material combinations of considerable attraction in the field of tribology [1–4]. This paper focuses on the deposition of a soft coating for the solid lubrication of plain bearings in high performance diesel engines [5]. The material, known in metallurgy as AlSn20 (Al with 20 wt% Sn), has been used since 1940, when rolled aluminum-tin bearings were introduced for heavy machinery. The system AlSn is an immiscible binary alloy with a solid solubility of Sn in Al below 0.02% [6]. Consequently, the material shows an heterogeneous structure which is characterized by a continuous aluminum matrix with embedded tin grains [7, 8]; the tough matrix takes mechanical loads, while the soft Sn inclusions act as a solid lubricant. Therefore, the size, shape and distribution of the inclusions determine the tribological behavior of the coating. During the last decade, aluminum-tin coatings prepared by PVD have gained considerable attention. The deposition of the two component coatings has been carried out either by co-evaporation from tungsten spiral and boat sources [9, 10], or by magnetron sputtering as codeposition from two targets [11, 12], from cast planar targets [13–15], or from cylindrical post magnetron alloy targets [5, 16, 17]. Most of the works have studied the influence of oxygen contamination on the microstructure of the films [9, 10, 13–15, 17], and the distribution and percolation threshold of the Sn in the Al matrix [11, 12, 16]. In this work, a study on the microstructural evolution of the film as a function of the film thickness is presented. Preliminary results on the tribological properties of AlSn20 films are also reported. Deposition of AlSn20 films on Si(001) and NaCl substrates was carried out in a dc magnetron sputtering system (Leybold Univex 450) with a base pressure of ∼1 × 10−6 Torr. A cast (99.999% purity) target, 5 cm diameter, with a nominal composition of Al with 20 wt% Sn was mounted at a distance of 3.5 cm from the substrate, and Ar (99.99% pure) was used as sputtering gas. The magnetron was operated in a constant-current mode of IT = 300 mA, with a target voltage of VT ∼ 300 V at an Ar pressure of 5 mTorr; as a result, the deposition rate for the AlSn20 films was 0.7–1.0 nm/s. Although no intentional substrate heating was used, the film growth temperature was recorded to be approximately 100 ◦C at steady state. The film thickness was varied between 0.1 and 4 μm. Structural characterization was made by transmission electron microscopy (TEM) using a Phillips CM 200 microscope operated at 160 kV and a Phillips 515 scanning electron microscope (SEM) operated at 18 kV. Plain-view TEM samples were obtained by floating-off in de-ionized water the films deposited on freshly cleaved NaCl substrates. Cross-sectional SEM views were prepared by mechanical cleaving of the Si substrates in N2-liquid in order to avoid plastic deformation of the film during fracture. Film composition was determined by energydispersive X-ray spectroscopy (EDX) operated at 20 keV and a beam diameter of 100 nm. Small amounts (<5 at.%) of oxygen were detected on the surface of all the samples, probably due to their exposure to air before analysis. Fig. 1 shows a plain-view TEM image of a 150 nm thick AlSn20 film. The bright background corresponds to the Al matrix which continuously covers the substrate. The dark features are extremely elongated and well separated Sn islands of 0.3 × 2 μm size. Abis et al. [7] have shown that the commercial AlSn20 rolled material adopted in current engine applications consists of isolated intergranular Sn-based islands surrounded by a continuous three-dimensional Al network. The Sn based regions exhibit an elongated shape with dimensions of ∼5 × 20 μm, one order of magnitude higher than in our films. Fig. 2, corresponding to a SEM micrograph of a film deposited on a Si substrate under the same conditions of the film of Fig. 1, shows a similar structure. Figs 1 and 2 suggest a high mobility of the Sn on the Al-surface, a high diffusion length, and a low stability of the small grains.

High rate deposition of poly-Si thin films at low temperature using a new designed magnetron sputtering source

We have deposited poly-Si thin films on Si(100) and glass substrates at growth temperature of below 400°C using a newly developed high rate magnetron sputtering method. To improve the sputtering yield and the growth rate, a high power (10–30 W/cm 2) magnetron sputtering system was designed and constructed. Based on the results of computer simulation, we built up the magnetron sputter source with unbalanced magnetron and Si ion extraction grid. The maximum deposition rate reached was 0.35 μm/min due to a high ion bombardment. This is five times higher than that of conventional sputtering methods, and the sputtering yield was also increased up to 80%. The best film was obtained on Si(100) surface using Si ion extraction grid under 9.0×10 −3 torr of working pressure and 11 W/cm 2 of the target power density. The electron mobility of the poly-Si film grown on Si(100) at 400°C with ion extraction grid was 96 cm 2/Vs. In this study, however, we found that the target power density is a more important factor than working pressure to influence the growth rate, mobility, and the film quality. During sputtering, moreover, the characteristics of Si sputter source were also analyzed with an in situ Langmuir probe method and optical emission spectroscopy.

A perspective of magnetron sputtering in surface engineering

Abstract Magnetron sputtering is a very powerful process which is now currently and successfully used in many applications, particularly in microelectronics and surface engineering, for the production of films and coatings. Magnetron technology is, however, continuously developing because new advanced films with prescribed physical and functional properties are needed. This paper reports on duplex coatings, nanocomposite coatings, high-rate magnetron sputtering and self-sputtering, i.e. new advances in magnetron sputtering technology which are of great importance for the future development of surface engineering. A great deal of attention is devoted to (i) the coating/substrate interface, (ii) the magnetron sputtering of nanostructured coatings with new properties due to small grains of about 10 nm and smaller and (iii) the replacement of ecologically damaging galvanic coating processes by high-rate magnetron sputtering and self-sputtering.

Low emissivity coatings on architectural glass

New energy conservation regulations became effective in Germany by the beginning of 1995. These regulations contain stringent instructions on the thermal insulation of buildings, and thus imply the use of so-called “low emissivity” coatings for nearly any kind of architectural glazing. As a consequence, the new law has significant impact on the market for vacuum coating equipment, which nowadays plays a key role in manufacturing low emissivity thin film systems. Modern vacuum coaters handling panes of glass with dimensions of up to 3.21 m × 6.00 m operate at cycle times less than 1 min and provide uptimes that exceed 90% Novel solutions for high rate magnetron sputtering, the key process for large area coating, are presently under laboratory investigation or already successfully implemented into industrial coaters. AC powered magnetron systems permit the deposition of optical thin films with high rates and an outstanding process stability. Current development work on the design of low-e film stacks is aiming in highly transparent and chemically stable coatings permitting a heat transfer coefficient k of 1.0 W/m 2K and less. The present paper tries to give an overview on the state-of-the-art related to vacuum coating of glass as well as low-e film designs and their properties.

High-rate magnetron sputtering

This article reports on the process of high-rate magnetron sputtering of solid materials using an unbalanced magnetron with extremely high target power densities of up to 150 W cm−2. Particular attention is devoted to a comparison of sputtering in the 10−1 Pa range, low pressure sputtering (&amp;lt;10−1 Pa), and self-sputtering. The advantages and drawbacks of the sputtering process at different pressures are critically analyzed. The extinction pressure measured as a function of the magnetron discharge current for the magnetron discharge of Cu, Ag, and Ti targets is given. Deposition rates and selected properties of Ti and Cu films are also reported.

The role of ion implantation in industrial sputtering processes for tribological applications

Since the early 1970s ion implantation into metal has been used successfully in the field of tribology. Because of the availability of high-current ion sources for gas ions, the most widely applied process is the implantation of nitrogen ions into various kinds of steel. Apart from direct implantation, ion-beam-assisted processes (IBAD) and ion beam mixing processes (IBM) are becoming increasingly important. In most cases the IBM process is performed with high energy implanters whereas the IBAD processes are performed with low energy ion sources in combination with electron beam evaporators within one process chamber. In addition to these established processes, the present paper presents the combination of high current medium energy ion beams with high rate magnetron sputtering. The ion beam is used for the pretreatment of the substrates, for assisting the growing film, for mixing of thin film layers and for post-treatment of reactively sputtered nitrides. The processes have been performed in a prototype implanter for industrial use applying a radio frequency ion source with slit-shaped ion optics which fit the demands of modern sputter sources with respect to beam size and dose rate. Evaluation of the films has been carried out using REM, SNMS, Rockwell C, Scratch test and pin on disc test. It is shown that medium-energy linear ion sources can be used sucessfully and simultaneously together with magnetron sputter sources within one process chamber. This can be done with already existing highly productive batch-type coating machines and also with in-line coaters by adapting the ion source so that it can be used in place of an additional magnetron source. The combination of magnetron sputter sources with simultaneously operating ion sources allows a highly controllable process, which fits the demands of high quality coatings for the future. This applies especially to the coating of polymers and ceramics.

Mechanical properties of an in situ synthesized Nb/Nb 3Al layered composite

A layered metal/intermetallic, consisting of Nb and Nb 3Al, has been synthesized using a high rate magnetron sputtering technique. The microstructure and various mechanical properties have been explored. It is demonstrated that the Nb phase contributes substantially to the toughness, through plastic dissipation, combined with frictional sliding at contacting surfaces. However, the toughness is suboptimal, because of the small layer thickness, which limits the width of the plastic zone. The tensile strength is also relatively low, because of growth defects. Some concepts for improving the strength and fracture resistance by tailoring the constituent and interface properties are suggested.

Properties of Microlaminated Intermetallic-Refractory Metal Composites

AbstractMicrolaminated composites of Nb3Al-Nb and Cr2Nb-Nb(Cr) were synthesized by high rate magnetron sputtering. Both composites were stable at elevated temperatures. A Cr2Nb-Nb(Cr) composite with 2 µm metal and intermetallic layers had room temperature tensile fracture strength over 725 MPa and a fracture toughness of about 20 MPa√m. Composites with 2 µm and 6 µm thick refractory metal and intermetallic laminations were compared and it was found that layer thickness did not affect fracture toughness. Microlaminates with the thicker 6 µm laminations had lower fracture strength, however. Good fracture strength and high fracture toughness indicated that microlaminated high temperature composites synthesized by vapor phase deposition exhibit the properties predicted by ductile toughening models.

Competing magnetic interactions in metastable Gd=Cr alloys

Gadolinium and chromium are ferromagnetic and antiferromagnetic respectively. Thus we may expect that alloys of these elements will reveal the evolution between these types of magnetic order. We have used high rate magnetron sputtering to prepare metastable Gd x Cr 1− x alloys over the entire composition range. The alloys with 0.2< x≤1 are hexagonal close-packed, as is pure Gd. By using SQUID and vibrating sample magnetometry, we have investigated both a ferromagnetic and a spin-glass like state. A magnetic phase diagram has been determined.

The Synthesis and Evaluation of Nb3Al-Nb Laminated Composites

ABSTRACTMicrolanminates of Nb3Al and Nb were synthesized in-situ by high rate magnetron sputtering. Three composites were fabricated. They had thicknesses ranging from 19 to 146 μm (5.5 mils) with 11 to 91 layers. The volume fraction of the Nb lamellae was approximately 0.4 for two and 0.5 for the third. Room temperature fracture of the composites revealed that some cleavage cracking in the Nb3Al intermetallic layers was arrested by the ductile Nb layer. The Nb layers failed by chisel point fracture and shear.

Sputtered magnetic films for rigid disk production

A description of the magnetic properties of full-sputtered rigid disks is given, such as those used in modern Winchester drives. Using a modular in-line system, and high rate magnetron sputtering, a layer stack of CrCoNiCrC was prepared on a large area, industrial scale. The influence of layer thicknesses and process parameters has been investigated. The coercivity saturates when the Cr underlayer is thick. High squareness of the hysteresis loop is achieved with thin layers. The crystalline properties have been measured as well. The epitaxial growth of the Co on top of the Cr (110) plane plays a key role in the determination of good magnetization properties.

The influence of surface topography on the adhesion of a TiN layer as a hard coating on different materials

The investigations were aimed at establishing the influence of the substrate topography (roughness) on the adhesion of TiN films deposited by high-rate magnetron sputtering and hole-cathode ion plating. The films were deposited on substrates of three grades of steel and one of aluminium alloy. The adhesion was assessed by scratch method by using a self-designed device. Plots of relation between substrate roughness measured by R a parameter and the critical force F CR representing the adhesion were drawn. It was established that for R a > 1 μm the application of TiN films is of no avail should they be exposed to wear in usage. On the other hand, for R a < 1 μm, even a slight improvement in smoothness yields a significant improvement in tribological properties of the coated element. The influence of the substrate material and deposition technology on the tribological properties of TiN films was established.

Bendable silver-based low emissivity coating on glass

A detailed investigation of a multilayer design for a temperature resistant low emissivity and highly electrical conductive coating is performed. The optical transmittance, reflectance and the heat emissivity are discussed. A good agreement with computer simulated spectra and experimental data was achieved. The layer system was prepared by high rate magnetron sputtering on large float glass sheets. By gravity bending in normal atmosphere these coated substrates were formed and then further processed to heated windshields and curved double glazed units. The performance characteristics of these final products are discussed.

Structure of Titanium Nitride coatings deposited by physical vapour deposition: A unified structure model

Although a number of studies have been published regarding the structure of physically vapour-deposited titanium nitride coatings, no unified structure model has yet been proposed which accounts for all experimental observations. The results of positron annihilation, X-ray diffraction (on both adherent and free-standing films) and scanning electron microscopy studies, performed both before and after tempering, on titanium nitride film deposited by low rate d.c. sputtering, high rate magnetron sputtering and reactive ion plating have been combined to give a unified structure model. The various contributions to both macrostrain (macrostress) and microstrain (microstress) are discussed as a function of the processing variables (substrate bias, deposition rate etc.) for each of the physical vapour deposition processes. In particular, the model can account for the high lattice parameter of physically vapour-deposited titanium nitride coatings and the variation in unit cell dimension of the nitride with deposition rate and substrate bias voltage.