Magnetron Cathode Research Articles

The effect of addition of Al in ZrO2 thin film on its resistance to cracking

The paper reports on the structure, mechanical and optical properties of sputtered Zr–Al–O films. The Zr–Al–O films with Zr/Al>1 and Zr/Al<1 were prepared by a reactive sputtering using ac pulse dual magnetrons. The magnetrons were equipped with a target composed of Al plate (∅=50mm) fixed to the magnetron cathode by a Zr fixing ring with inner diameter ∅in. The content of Al in the Zr–Al–O film was controlled by ∅in. It makes possible to control effectively the structure of the Zr–Al–O film determined by a mixture of the crystalline ZrO2 phase and the amorphous Al2O3 phase. The effect of Al content on the structure, mechanical and optical properties of the Zr–Al–O film is investigated in detail. It was found that (i) the Zr–Al–O films with Zr/Al<1 are X-ray amorphous and exhibit low hardness (H≤13GPa), an effective Young's modulus E⁎ resulting in a low H/E⁎<0.1 ratio and low elastic recovery We≤60 and (ii) the Zr–Al–O films with Zr/Al>1 are crystalline and exhibit high hardness (H=18 to 19GPa), an E⁎ satisfying a high H/E⁎≥0.1 ratio, high We up to 78% and strongly enhanced resistance to cracking during bending even for thick films up to 5μm.

Si&lt;sub&gt;x&lt;/sub&gt;C&lt;sub&gt;y&lt;/sub&gt; Thin Films Deposited at Low Temperature by DC Dual Magnetron Sputtering: Effect of Power Supplied to Si and C Cathode Targets on Film Physicochemical Properties

A DC dual magnetron sputtering system with graphite (C) and silicon (Si) targets was used to grow stoichiometric and non-stoichiometric silicon carbide (SixCy) thin films at low temperature. Two independently DC power sources were used to enable the total discharge power be shared, under certain proportions, between the Si and C magnetron cathodes. The motivation was to control the sputtering rate of each target so as to vary the stoichiometric ratio x/y of the deposited films. The species content, thickness and chemical bonds of as-deposited SixCy films were studied by Rutherford backscattering spectroscopy (RBS), profilometry analysis and Fourier transform infrared absorption (FTIR), respectively. Overall, the present work reveals a new reliable plasma sputtering technique for low temperature growth of amorphous SixCy thin films with the capability of tuning the degree of formation of a-SiC, a-Si and a-C bonds in the film bulk.

The effect of Ti(CN)/TiNb(CN) coating on erosion-corrosion resistance

The goal of this work was to study electrochemical behaviour in corrosion-erosion conditions for Ti(CN)/TiNb(CN) multilayer coatings having 1, 50, 100, 150 and 200 bilayer periods on AISI 4140 steel substrates by using a multi-target magnetron reactive sputtering device, with an r.f. source (13.56 MHz), two cylindrical magnetron cathodes and two stoichiometric TiC and Nb targets. The multilayers were evaluated by comparing them to corrosion, erosion and erosion corrosion for a 30º impact angle in a solution of 0.5 M NaCl and silica, analysing the effect of impact angle and the number of bilayers on these coatings' corrosion resistance. The electrochemical characterisation was performed using electrochemical impedance spectroscopy for analysing corrosion surface; surface morphology was characterised by using a high-resolution scanning electron microscope (SEM). The results showed a decreased corrosion rate for multilayer systems tested at 30°.

Formation of Mg&lt;sub&gt;2&lt;/sub&gt;Si/MgO Nano-Composites Prepared by Dual Cathode Magnetron Sputtering

In this Work, Mg2si/MgO Nano-Composites Were Prepared by Co-Sputtering of Mg and Si Targets on Si {100} Substrates Using Dual Cathode Magnetron Sputtering. Films Were, Subsequently, Annealed at 380°C and 500°C for 4 Hours in Ar Gas Atmosphere. Various Mg/Si Sputtering Power Ratios Have Been Examined. Grown Films Were Characterized by XRD, SEM/EDS, and IR Reflectivity Measurements.

Dual frequency capacitive plasmas in Fe and Ni sputter applications: correlation of discharge properties on thin film properties

Dual frequency capacitively coupled plasmas (CCPs) are widely used in (large area) etching and plasma enhanced chemical vapor deposition processes. However, applications in physical vapor deposition (PVD) are still sparse due to the well-established dc magnetron cathode discharges. Nevertheless, there exist critical applications such as ferromagnetic or ceramic thin film deposition which are difficult to handle even for dc magnetron systems. For these materials systems dual frequency CCPs pose a good alternative, because for insulators charging can be avoided and for ferromagnetic materials the target thickness becomes independent of the magnetron configuration at comparable deposition rates.In this work we investigate two separate subjects. First, in dual frequency capacitive discharges a complex coupling of the applied excitation frequencies can be observed, which from a plasma parameter point of view limits the separability of ion flux (usually controlled by frequencies >60 MHz) and ion bombarding energy (usually controlled by frequency <15 MHz) onto the sputter target. By performing deposition experiments it was found that by following simple tuning guidelines a very good degree of separability is achievable. Additionally, the deposition homogeneity is not affected.Second, we correlate the growth conditions with crystalline and magnetic properties as well as the degree of O content for Fe and Ni films. Therefore, we applied different signals as a substrate bias to influence thin film growth. It was found that the crystalline and magnetic properties can be influenced for both Fe and Ni films but is more pronounced for Ni.

Probe and Emission Spectrometry Diagnostics in Hollow Cathode Magnetron

This paper deals with the characterization of an ionized physical vapor deposition (IPVD) by means of hollow cathode magnetron. Langmuir probe, optical emission spectroscopy measurements were used to study a mechanism for the production of excited argon and copper atoms and ions. The kinetic processes of excitation were considered and the main processes were determined using results of measurements. The pressure range is 0.5 - 10 mTorr with 1- 5 kW discharge power. Plasma parameters such as electron densities and temperatures, electron energy distribution function, plasma space and floating potentials as a function of the position, pressure and power in the growth chamber were measured. The plasma density is up to 1012 cm?3 at 20 cm from the magnetron for 10 mTorr.

Rotatable magnetron sputtering of aluminium in continuous and high power pulse modes using different strength magnetic arrays

This paper reports preliminary results of industrial size (152 mm target O.D.) rotatable magnetron sputtering of Al target in direct current (DC) and High Power Impulse Magnetron Sputtering (HIPIMS) modes using two standard commercially available magnetic arrays: standard strength array (as used for DC and AC processing) and a lower strength ‘RF’ array [i.e. as used for radio frequency (RF) magnetron sputtering]. A comparison of processes resulted in by combining the different magnetic arrays and power modes is made in terms of magnetic field distribution on the cathode surface, magnetron characteristics, process characteristics and deposition rates. Optical emission spectroscopy (OES) revealed enhanced sputtered Al flux ionisation in the HIPIMS discharge monitored 64 mm away from the target surface when using the ‘RF’ array. Importantly, the results of this work (at the processing conditions investigated) demonstrate that at the same average power the deposition rate of Al using HIPIMS in conjunction with the ‘RF’ array is substantially the same as that obtained for the ‘standard’ strength balanced array and DC power. This indicates that the magnetic field design of the ‘RF’ magnetic array affects favourably the sputtered flux transport perpendicular to the target surface by altering mass transport direction and minimising effects that reduce deposition rate (e.g. ion return effect). Arc rate is also reduced significantly (approximately ten times) if the low strength ‘RF’ array is used.

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.

Influence of Magnetron Effect on Barium Hexaferrite Thin Layers

In this paper, we study the effects of a magnet, located in the cathode, on barium hexaferrite thin films deposited by RF magnetron sputtering technique. During the process, these effects can modify thickness, roughness and stress of coatings. The characteristics of the deposited layers depend on the substrate position that is located opposite of magnetron cathode. In the "magnetron area", one can observe that the high stress can produce cracks or detachment of layers and the increasing of both depositing rate and surface roughness. After sputtering elaboration, barium hexaferrite films are in a compressive stress mode. But, after the post-deposition heat treatment these films are in a tensile stress mode. To improve the quality of BaM films, the subsrtate has to be set outside the magnetron area.

Improving the quality of barrier/seed interface by optimizing physical vapor deposition of Cu Film in hollow cathode magnetron

The quality of physical vapor deposition (PVD) grown barrier/seed interface in Cu interconnect metallization was significantly improved by enhancing Cu nucleation on the Ta barrier surface. This was accomplished through filtering of nonenergetic species from the deposition flux, increasing the fraction of Cu ions, improving metal ion flux uniformity, and minimizing gas ion bombardment of the growing film. The self-sputtering ability of Cu was combined with a magnetically confined high-density plasma in the Novellus hollow cathode magnetron (HCM®) PVD source. Spatial profiles of plasma density and temperature, as well as ion flux, metal ion fraction, and ion energy, were measured by planar Langmuir probes, quartz crystal microbalances, and gridded energy analyzers, all located at the wafer level. Multiple criteria, such as seed step coverage and roughness, the seed layer’s resistance to agglomeration, and its stability in the plating bath, have been used to evaluate interface quality. As a result, a new and improved Cu PVD process which demonstrates superior stability during subsequent process steps and ensures successful electrofill performance with a more than 50 % reduction in minimal requirement of field thickness as well as sidewall thickness has been developed.

Microstructure analysis of Ag films deposited by low-voltage sputtering

The microstructure of Ag films was investigated as a function of the cathode voltage during sputter deposition. It was found that the resistivity of the Ag films decreased when the Ag film was deposited at low cathode voltage using a magnetron cathode with high-magnetic flux density. X-ray diffraction measurement revealed that the Ag films deposited at low cathode voltages exhibited higher crystallization degree and larger crystallites. Besides, it was confirmed from glancing incident X-ray reflectivity measurement that the density of the Ag films increased with decreasing in the cathode voltage. It can be concluded from these results that the improvements in the resistivity and microstructure of Ag films result from the low-voltage sputtering. It can be concluded that the kinetic energy of the Ar gas particles decreased with decreasing the cathode voltage; as a result, the microstructure of Ag films should be improved.

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.

On the use of radioisotopes to study the possible synthesis by magnetron sputtering of bimetallic nanoparticles

An approach using physical vapor deposition technology to produce nanoparticles (NPs) containing radioactive atoms and the methodology to transfer them in pure water is investigated. NPs are synthesized by magnetron sputtering at high pressure and radioactive atoms are loaded on magnetron cathodes prior to sputtering. The technique was tested for gold cathode loaded with 57/58 Co and 195/196 Au. Linked to biological vector molecules, the nanoparticles can be used to enhance diagnostic sensitivity in medical imaging or to treat cancer. Sizes and morphologies of the NPs were analyzed by electron microscopy, UV-Visible spectroscopy and atomic absorption spectroscopy. Results show well dispersed NPs with sizes varying between 5 and 10 nm. Activities of these NPs were measured with a CAPINTEC well counter and a High Purity Germanium detector system. Centrifugation analyses also demonstrate that the choice of the activated metal which can be alloyed with NPs plays an important role in the synthesis. This was confirmed by the Au–Co phase diagram that shows that cobalt cannot be included efficiently in the gold NPs conversely to gold.

Investigation of the Negative Ions in Ar/O2 Plasma of Magnetron Sputtering Discharge with Al:Zn Target by Ion Mass Spectrometry

AbstractThe magnetron sputtering discharge used to deposit aluminum‐doped zinc oxide was analyzed by energy‐resolved ion mass spectrometry. The flux of negative ions was measured at three radial positions in the plane of the substrate holder. The oxygen flow $\phi _{{\rm O}_{2} } $ was varied from 0 to 17 sccm to investigate the discharge in all operation modes, i.e., metallic, transition, and oxide mode of sputtering. The existence of negative ions was determined from the energy spectra. Main attention was devoted to the investigation of O−, ${\rm O}_{2}^{{-} } $, AlO−, ${\rm AlO}_{2}^{{-} } $, ZnO−, ${\rm ZnO}_{2}^{{-} } $, and ${\rm AlO}_{3}^{{-} } $ negative ions and correlations of their intensities in the energy spectrum with discharge parameters (cathode voltage, magnetron power, and gas pressure). It was found that (i) intensities of negative ions exhibit maxima in the vicinity of transition between the metallic and transition mode of sputtering and (ii) in the oxide mode intensities of these ions are saturated. magnified image

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.

Faceted magnetron concept using field emission cathodes

A magnetron concept using field emission cathodes has been modeled with the Air Force Research Laboratory particle-in-cell code ICEPIC and the two-dimensional particle trajectory simulation Lorentz2E. In this approach, field emitters are used to provide a distributed cathode in place of a traditional thermionic cathode. The emitters are placed below the interaction space in a shielded structure. The cathode is comprised of facet plates with slits to protect the emitters. Simulation of an L-band rising sun magnetron shows that the faceted magnetron will oscillate using both five and ten facet cathodes. The startup times are very similar to that of a cylindrical cathode magnetron. The electron trajectories of the shielded slit structure have been modeled, and the results indicate that electrons can be injected through the slits and into the interaction space using lateral edge emitters and a pusher electrode design.

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.

Computer-aided development of a magnetron source with high target utilization

Target erosion in the straight section of a conventional and a novel rectangular magnetron cathode is simulated and tested. The simulation includes modeling the magnetic field, tracing electron trajectories with a fourth-order Runge-Kutta numerical method, predicting ionization distribution with a Monte-Carlo method etc. It is shown that the conventional and the novel magnetron cathodes yield a target utilization of ∼32% and 67% in the straight section, respectively. We demonstrate that the highly improved utilization is mainly due to a multi-zero-point feature of the magnetic field in the novel magnetron, i.e., the position of zero-point for the vertical component of the magnetic flux density shifts continuously from the inner side to outer side of the target with an increase in the distance from the target surface.

Flux and energy analysis of species in hollow cathode magnetron ionized physical vapor deposition of copper

To meet the stringent requirements of interconnect metallization for sub-32 nm technologies, an unprecedented level of flux and energy control of film forming species has become necessary to further advance ionized physical vapor deposition technology. Such technology development mandates improvements in methods to quantify the metal ion fraction, the gas∕metal ion ratio, and the associated ion energies in the total ion flux to the substrate. In this work, a novel method combining planar Langmuir probes, quartz crystal microbalance (QCM), and gridded energy analyzer (GEA) custom instrumentation is developed to estimate the plasma density and temperature as well as to measure the metal ion fraction and ion energy. The measurements were conducted in a Novellus Systems, Inc. Hollow Cathode Magnetron (HCM(TM)) physical vapor deposition source used for deposition of Cu seed layer for 65-130 nm technology nodes. The gridded energy analyzer was employed to measure ion flux and ion energy, which was compared to the collocated planar Langmuir probe data. The total ion-to-metal neutral ratio was determined by the QCM combined with GEA. The data collection technique and the corresponding analysis are discussed. The effect of concurrent resputtering during the deposition process on film thickness profile is also discussed.

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.