Ionized Flux Fraction Research Articles

High power impulse magnetron sputtering of a zirconium target

High power impulse magnetron sputtering (HiPIMS) discharges with a zirconium target are studied experimentally and by applying the ionization region model (IRM). The measured ionized flux fraction lies in the range between 25% and 59% and increases with increased peak discharge current density ranging from 0.5 to 2 A/cm2 at a working gas pressure of 1 Pa. At the same time, the sputter rate-normalized deposition rate determined by the IRM decreases in accordance with the HiPIMS compromise. For a given discharge current and voltage waveform, using the measured ionized flux fraction to lock the model, the IRM provides the temporal variation of the various species and the average electron energy within the ionization region, as well as internal discharge parameters such as the ionization probability and the back-attraction probability of the sputtered species. The ionization probability is found to be in the range 73%–91%, and the back-attraction probability is in the range 67%–77%. Significant working gas rarefaction is observed in these discharges. The degree of working gas rarefaction is in the range 45%–85%, higher for low pressure and higher peak discharge current density. We find electron impact ionization to be the main contributor to working gas rarefaction, with over 80% contribution, while kick-out by zirconium atoms and argon atoms from the target has a smaller contribution. The dominating contribution of electron impact ionization to working gas rarefaction is very similar to other low sputter yield materials.

2D analysis of sputtered species transport in high-power impulse magnetron sputtering (HiPIMS) discharge

Among the numerous advantages of the high-power impulse magnetron sputtering (HiPIMS) technique, the most important is the enhanced ionization degree of sputtered species contributing to the film growth. Consequently, the quality of deposited thin films is highly improved. Still, the optimization process is challenging due to the complexity associated with the intricate transport of the sputtered species, ionized or neutrals. The scarce knowledge available on the spatial distribution of these species when operating a HiPIMS discharge makes the quantitative prediction of any deposition feature particularly difficult. In this paper, we discuss the influence of experimentally controllable quantities, such as gas pressure and target current density, on the transport of sputtered titanium in non-reactive (argon) HiPIMS, namely, on the behavior of metal atoms and metal ion fluxes intercepting the substrate. Systematic quantitative measurements were performed in a diameter normal plane on a circular planar target. Hence, the 2D spatial distribution of the ionized flux fraction (IFF) and the total flux of titanium sputtered particles (deposition rate) are evaluated by biasing a quartz crystal microbalance equipped with an electron magnetic filter. The wide range of parameters we examined allows us to predict and optimize the flux of sputtered species based on complete mapping of the IFF of sputtered particles.

Angular distribution of titanium ions and neutrals in high-power impulse magnetron sputtering discharges

The angular dependence of the deposition rates due to ions and neutrals in high-power impulse magnetron sputtering (HiPIMS) discharges with a titanium target were determined experimentally using a magnetically shielded and charge-selective quartz crystal microbalance (or ionmeter). These rates have been established as a function of the argon working gas pressure, the peak discharge current density, and the pulse length. For all explored cases, the total deposition rate exhibits a heart-shaped profile and the ionized flux fraction peaks on the discharge axis normal to the cathode target surface. This heart-shaped pattern is found to be amplified at increasing current densities and reduced at increased working gas pressures. Furthermore, it is confirmed that a low working gas pressure is beneficial for achieving high deposition rates and high ionized flux fractions in HiPIMS operation.

Particle-based simulation of atom and ion transport in HiPIMS: effect of the plasma potential distribution on the ionized flux fraction

We present a three-dimensional particle-based computer simulation of high-power impulse magnetron sputtering (HiPIMS) discharges which enables us to simulate the transport of atoms and ions in the discharge and the corresponding plasma parameters. The simulation requires a definition of the plasma potential and electron density distribution (not calculated self-consistently), for which parametric analytical formulae were devised. A numerical algorithm is used to constrain the simulation by an experimental target current waveform, which ensures that the simulation results are closely tied to the experimental discharge conditions. Simulations of a HiPIMS discharge with Ti target show the capability to calculate the spatial distributions of target material atoms and ions and also to quantify the process-gas rarefaction. We evaluated, among others, the ion return probability and the ionized fraction of the target material flux onto the substrate for various values of the potential difference across the magnetic presheath in front of the target racetrack, which is responsible for attracting most of the plasma ions towards the target. It is shown that this parameter of the plasma potential distribution strongly affects the ion return probability and, thus, it must be known quite precisely to reliably predict the ionized flux fraction on the substrate. Other parameters, such as the composition of the ion flux onto the target are less sensitive. The simulation can be run in a reasonably short time and can easily be extended by adding more plasma species (excited states or doubly ionized species) and their interactions.

Investigation of the magnetron balancing effect on the ionized flux fraction and deposition rate of sputtered titanium species for the high-power impulse magnetron sputtering pulses of different lengths

The study is focused on the impact of different magnetic field configurations of a high-power impulse magnetron sputtering (HiPIMS) in a nonreactive mode on the film precursors. Ionized flux fraction and total flux deposited onto the substrate were measured with the magnetic quartz crystal microbalance probe placed in front of the target racetrack. Particularly, we investigated the degree of magnetron balancing and the geometry of the magnetic field above the Ti target surface (4 in. diameter), as crucial factors influencing the thin film deposition, for different HiPIMS pulse lengths. Three unbalanced (II type) magnetron configurations have been chosen for this study: two symmetric geometries—with a regular magnetic field (B parallel to the target about 80 and 35 mT) and one asymmetric (highly unbalanced) magnetron configuration with an intermediate magnetic field (B parallel to the target about 48 mT). The HiPIMS was operated keeping constant the peak current at 43 A for C0-E0 and C10-E0 B-field configurations and a lower value, 33 A, when operating in C10-E10 configuration. In addition to the peak current, the pulse frequency was kept constant at 100 Hz but the pulse length (power on-time, Ton) was varied from 50 up to 100 μs. Obviously, the pulse power and the average power continuously increase with the length of the pulse. The results reveal a significant difference in the trends of the deposition rate and ionized flux fraction reaching the substrate with respect to the degree of balancing of the magnetron. It was found that the ionized fraction of metal arriving at the substrate reaches its maximum for the pulse length between Ton ≈ 70–80 μs in both symmetric cases, with strong and weak magnetic fields. The ionized fraction of Ti atoms in the asymmetric configuration increased in all measured range with the pulse length and the growth rate has a smooth increase.

Operating modes and target erosion in high power impulse magnetron sputtering

Magnetron sputtering combines a glow discharge with sputtering from a target that simultaneously serves as a cathode for the discharge. The electrons of the discharge are confined between overarching magnetic field lines and the negatively biased cathode. As the target erodes during the sputter process, the magnetic field strengthens in the cathode vicinity, which can influence discharge parameters with the risk of impairing reproducibility of the deposition process over time. This is of particular concern for high-power impulse magnetron sputtering (HiPIMS) as the discharge current and voltage waveforms vary strongly with the magnetic field strength. We here discuss ways to limit the detrimental effect of target erosion on the film deposition process by choosing an appropriate mode of operation for the discharge. The goal is to limit variations of two principal flux parameters, the deposition rate and the ionized flux fraction. As an outcome of the discussion, we recommend operating HiPIMS discharges by maintaining the peak discharge current constant.

Ionization region model of high power impulse magnetron sputtering of copper

The ionization region model (IRM) is applied to model high power impulse magnetron sputtering (HiPIMS) discharges with a Cu target. We apply the model to three discharges that were experimentally explored in the past, or applied to deposit thin copper films, with the aim to quantify internal plasma process parameters and thereby understand how these discharges differ from each other. The temporal variation of the various neutral and ionic species, the electron density and temperature, as well as internal discharge parameters, such as the ionization probability, back attraction probability, and ionized flux fraction of the sputtered species, are determined. We demonstrate that the Cu+ ions dominate the total ion current to the target surface and that all the discharges are dominated by self-sputter recycling to reach high discharge currents. Furthermore, the ion flux into the diffusion region is dominated by Cu+ ions, which represents roughly 80% of the total ion flux onto the substrate, in agreement with experimental findings. For the discharges operated with peak discharge current densities in the range 0.9 – 1.3 A cm−2, the ion back-attraction probability of the Cu+ ion ⟨βt⟩ is low compared to previously investigated HiPIMS discharges, or in the range 44 – 50%, while the ionization probability ⟨αt⟩ is in the range 61 – 69%, and the ionized flux fraction is in the range 32 – 40%. It is, furthermore, found that operating these Cu HiPIMS discharges at lower working gas pressures (in the present case around 0.5 Pa) is beneficial in terms of optimizing ionization of the sputtered species.

Modeling of high power impulse magnetron sputtering discharges with graphite target

The ionization region model (IRM) is applied to model a high power impulse magnetron sputtering discharge in argon with a graphite target. Using the IRM, the temporal variation of the various species and the average electron energy, as well as internal parameters such as the ionization probability, back-attraction probability, and the ionized flux fraction of the sputtered species, is determined. It is found that thedischarge develops into working gas recycling and most of the discharge current at the cathode target surface is composed of Ar+ ions, which constitute over 90% of the discharge current, while the contribution of the C+ ions is always small (%), even for peak current densities close to 3 A cm−2. For the target species, the time-averaged ionization probability ⟨α t,pulse⟩ is low, or 13–27%, the ion back-attraction probability during the pulse β t,pulse is high (%), and the ionized flux fraction is about 2%. It is concluded that in the operation range studied here it is a challenge to ionize carbon atoms, that are sputtered off of a graphite target in a magnetron sputtering discharge, when depositing amorphous carbon films.

Tailoring interface alloying and magnetic properties in (111) Permalloy/Pt multilayers

We demonstrate preparation and characterization of permalloy Ni80Fe20 at.% (Py) multilayers in which the Py layers were deposited by two different sputter deposition methods. Namely, dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS), that represent low and moderate ionized flux fraction of the film forming material, respectively. We deposited ultrathin bilayers, i.e. 15 Å thick Py and 5 Å thick Pt, with 20 repetitions. Various effects such as substrate roughness, working gas pressure and sputter power are considered. The microstructure, texture and strain were characterized by X-ray diffraction, individual thicknesses and alloying were analysed by X-ray reflectivity, and uniaxial in-plane anisotropy probed by the magneto-optical Kerr effect. It is shown that HiPIMS deposition produces multilayers with reduced surface roughness regardless of the substrate surface roughness. Both dcMS and HiPIMS deposition present multilayers with strong (111) texture normal to the substrate. Using HiPIMS for deposition of the Py layer minimizes the alloying between individual layers compared to dcMS deposition performed at same average sputter power. However, this improvement in interface sharpness leads to a higher magnetic coercivity and a poor hard axis in the film plane. On the other hand, multilayers with alloying present a linear hard axis. Furthermore, we studied Py/Cu and Py/CuPt multilayers, prepared under identical conditions using HiPIMS. The results indicate that in the Py/Pt case, deterioration of the in-plane uniaxial anisotropy, is caused by inverse magnetostriction originating from the large lattice mismatch between Py and Pt. The Py/Pt multilayers that exhibit alloying have a less strained interface and have a well defined uniaxial anisotropy.

Experimental verification of deposition rate increase, with maintained high ionized flux fraction, by shortening the HiPIMS pulse

High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition technique, providing a high flux of metal ions to the substrate. However, one of the disadvantages for industrial use of this technique is a reduced deposition rate compared to direct current magnetron sputtering (dcMS) at equal average power. This is mainly due to a high target back-attraction probability of the metal ions with typical values in the range 70%–90% during the pulse. In order to reduce this effect, we focused on the contribution of ion fluxes available immediately after each HiPIMS pulse; a time also known as afterglow. Without a negative potential on the target at this stage of the HiPIMS process, the back-attracting electric field disappears allowing remaining ions to escape the magnetic trap and travel toward the substrate. To quantify the proposed mechanism, we studied the effect of HiPIMS pulse duration on the outward flux of film-forming species in titanium discharges, which are known to exhibit more than 50% reduction in deposition rate compared to dcMS. By shortening the HiPIMS pulse length, it was found that the contribution to the outward flux of film-forming species from the afterglow increases significantly. For example, HiPIMS discharges at a constant peak current density of about 1.10 A cm−2 showed a 45% increase of the deposition rate, by shortening the pulse duration from 200 to 50 μs. Ionized flux fraction measurements, using a gridless quartz crystal micro-balance-based ion meter, showed that this increase of the deposition rate could be achieved without compromising the ionized flux fraction, which remained approximately constant. The key to the achieved optimization of HiPIMS discharges lies in maintaining a high peak discharge current also for short pulse lengths to ensure sufficient ionization of the sputtered species.

On how to measure the probabilities of target atom ionization and target ion back-attraction in high-power impulse magnetron sputtering

High-power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition technique that provides a high flux of ionized target species for thin film growth. Optimization of HiPIMS processes is, however, often difficult, since the influence of external process parameters, such as working gas pressure, magnetic field strength, and pulse configuration, on the deposition process characteristics is not well understood. The reason is that these external parameters are only indirectly connected to the two key flux parameters, the deposition rate and ionized flux fraction, via two internal discharge parameters: the target atom ionization probability αt and the target ion back-attraction probability βt. Until now, it has been difficult to assess αt and βt without resorting to computational modeling, which has hampered knowledge-based optimization. Here, we present a simple method to deduce αt and βt based on measured deposition rates of neutrals and ions. The core of the method is a refined analytical model, which is described in detail. This approach is furthermore validated by independent calculations of αt and βt using the considerably more complex ionization region model, which is a plasma-chemical global discharge model.

HiPIMS optimization by using mixed high-power and low-power pulsing

The possibility to optimize a high-power impulse magnetron sputtering (HiPIMS) discharge through mixing two different power levels in the pulse pattern is investigated. Standard HiPIMS pulses are used to create the ions of the film-forming material. After each HiPIMS pulse an off-time follows, during which no voltage (or, optionally, a reversed voltage) is applied, letting the remaining ions in the magnetic trap escape towards the substrate. After these off-times, a long second pulse with lower amplitude, in the dc magnetron sputtering range, is applied. During this pulse, which is continued up to the following HiPIMS pulse, mainly neutrals of the film-forming material are produced. This pulse pattern makes it possible to achieve separate optimization of the ion production, and of the neutral atom production, that constitute the film-forming flux to the substrate. The optimization process is thereby separated into two sub-problems. The first sub-problem concerns minimizing the energy cost for ion production, and the second sub-problem deals with how to best split a given allowed discharge power between ion production and neutral production. The optimum power split is decided by the lowest ionized flux fraction that gives the desired film properties for a specific application. For the first sub-problem we describe a method where optimization is achieved by the selection of five process parameters: the HiPIMS pulse amplitude, the HiPIMS pulse length, the off-time, the working gas pressure, and the magnetic field strength. For the second sub-problem, the splitting of power between ion and neutral production, optimization is achieved by the selection of the values of two remaining process parameters, the HiPIMS pulse repetition frequency and the discharge voltage of the low-power pulse.

Optimizing the deposition rate and ionized flux fraction by tuning the pulse length in high power impulse magnetron sputtering

High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapour deposition technique. While HiPIMS provides a high flux of metal ions to the substrate, the disadvantage is a reduced deposition rate compared to direct current magnetron sputtering (dcMS) at equal average power. This is mainly due to the high target back-attraction probability of the metal ions with typical values in the range 70%–90% during the pulse. In this work, we investigate how to reduce this effect by quantifying the contribution of the metal ion flux after each HiPIMS pulse, a period also known as afterglow. Without a negative potential on the target at this stage of the HiPIMS process, the back-attracting electric field disappears allowing remaining ions to escape the ionization region. In order to analyze the fate of the film-forming ions, we extend the time-dependent ionization region model (IRM) by adding consideration of an afterglow. This approach allows to distinguish between fluxes from the ionization region during the pulse and during the afterglow. We show that by shortening the pulse length of a titanium HiPIMS discharge, the contribution to the outward flux of film-forming species from the afterglow increases significantly. The IRM predicts a gain in deposition rate of 46% and 47% for two discharges with different peak discharge currents, when using 40 μs compared to 100 μs-long pulses at the same average power. This is without compromising the ionized flux fraction that remains constant for the range of pulse lengths investigated here.

Sideways deposition rate and ionized flux fraction in dc and high power impulse magnetron sputtering

The sideways (radial) deposition rate and ionized flux fraction in a high power impulse magnetron sputtering (HiPIMS) discharge are studied and compared to a dc magnetron sputtering (dcMS) discharge, while the magnetic field strength |B| and degree of balancing are varied. A significant deposition of the film forming material perpendicular to the target surface is observed for both sputter techniques. This sideways deposition decreases with increasing axial distance from the target surface. The sideways deposition rate is always the highest in dc operation, while it is lower for HiPIMS operation. The magnetic field strength has a strong influence on the sideways deposition rate in HiPIMS but not in dcMS. Furthermore, in HiPIMS operation, the radial ion deposition rate is always at least as large as the axial ion deposition rate and often around two times higher. Thus, there are a significantly higher number of ions traveling radially in the HiPIMS discharge. A comparison of the total radial as well as axial fluxes across the entire investigated plasma volume between the target and the substrate position allows for revised estimates of radial over axial flux fractions for different magnetic field configurations. It is here found that the relative radial flux of the film forming material is greater in dcMS compared to HiPIMS for almost all cases investigated. It is therefore concluded that the commonly reported reduction of the (axial) deposition rate in HiPIMS compared to dcMS does not seem to be linked with an increase in sideways material transport in HiPIMS.

Optimization of HiPIMS discharges: The selection of pulse power, pulse length, gas pressure, and magnetic field strength

In high power impulse magnetron sputtering (HiPIMS) operation, there are basically two goals: a high ionized flux fraction of the sputtered target material and a high deposition rate. In this work, it is demonstrated that the former always comes at the cost of the latter. This makes a choice necessary, referred to as the HiPIMS compromise. It is here proposed that this compromise is most easily made by varying the discharge current amplitude, which opens up for optimization of additionally four external process parameters: the pulse length, the working gas pressure, the magnetic field strength, and the degree of magnetic unbalance to achieve the optimum combination of the ionized flux fraction and the deposition rate. As a figure of merit, useful for comparing different discharges, (1−βt) is identified, which is the fraction of ionized sputtered material that escapes back-attraction toward the cathode target. It is shown that a discharge with a higher value of (1−βt) always can be arranged to give better combinations of ionization and deposition rate than a discharge with a lower (1−βt). Maximization of (1−βt) is carried out empirically, based on data from two discharges with Ti targets in Ar working gas. These discharges were first modeled in order to convert measured plasma parameters to values of (1−βt). The combined effects of varying the different process parameters were then analyzed using a process flow chart model. The effect of varying the degree of unbalance in the studied range was small. For the remaining three parameters, it is found that optimum is achieved by minimizing the magnetic field strength, minimizing the working gas pressure, and minimizing the pulse length as far as compatible with the requirement to ignite and maintain a stable discharge.

Oblique angle deposition of nickel thin films by high-power impulse magnetron sputtering.

Background: Oblique angle deposition is known for yielding the growth of columnar grains that are tilted in the direction of the deposition flux. Using this technique combined with high-power impulse magnetron sputtering (HiPIMS) can induce unique properties in ferromagnetic thin films. Earlier we have explored the properties of polycrystalline and epitaxially deposited permalloy thin films deposited under 35° tilt using HiPIMS and compared it with films deposited by dc magnetron sputtering (dcMS). The films prepared by HiPIMS present lower anisotropy and coercivity fields than films deposited with dcMS. For the epitaxial films dcMS deposition gives biaxial anisotropy while HiPIMS deposition gives a well-defined uniaxial anisotropy.Results: We report on the deposition of 50 nm polycrystalline nickel thin films by dcMS and HiPIMS while the tilt angle with respect to the substrate normal is varied from 0° to 70°. The HiPIMS-deposited films are always denser, with a smoother surface and are magnetically softer than the dcMS-deposited films under the same deposition conditions. The obliquely deposited HiPIMS films are significantly more uniform in terms of thickness. Cross-sectional SEM images reveal that the dcMS-deposited film under 70° tilt angle consists of well-defined inclined nanocolumnar grains while grains of HiPIMS-deposited films are smaller and less tilted. Both deposition methods result in in-plane isotropic magnetic behavior at small tilt angles while larger tilt angles result in uniaxial magnetic anisotropy. The transition tilt angle varies with deposition method and is measured around 35° for dcMS and 60° for HiPIMS.Conclusion: Due to the high discharge current and high ionized flux fraction, the HiPIMS process can suppress the inclined columnar growth induced by oblique angle deposition. Thus, the ferromagnetic thin films obliquely deposited by HiPIMS deposition exhibit different magnetic properties than dcMS-deposited films. The results demonstrate the potential of the HiPIMS process to tailor the material properties for some important technological applications in addition to the ability to fill high aspect ratio trenches and coating on cutting tools with complex geometries.

The Effect of Magnetic Field Strength and Geometry on the Deposition Rate and Ionized Flux Fraction in the HiPIMS Discharge

We explored the effect of magnetic field strength | B | and geometry (degree of balancing) on the deposition rate and ionized flux fraction F flux in dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) when depositing titanium. The HiPIMS discharge was run in two different operating modes. The first one we refer to as “fixed voltage mode” where the cathode voltage was kept fixed at 625 V while the pulse repetition frequency was varied to achieve the desired time average power (300 W). The second mode we refer to as “fixed peak current mode” and was carried out by adjusting the cathode voltage to maintain a fixed peak discharge current and by varying the frequency to achieve the same average power. Our results show that the dcMS deposition rate was weakly sensitive to variations in the magnetic field while the deposition rate during HiPIMS operated in fixed voltage mode changed from 30% to 90% of the dcMS deposition rate as | B | decreased. In contrast, when operating the HiPIMS discharge in fixed peak current mode, the deposition rate increased only slightly with decreasing | B | . In fixed voltage mode, for weaker | B | , the higher was the deposition rate, the lower was the F flux . In the fixed peak current mode, both deposition rate and F flux increased with decreasing | B | . Deposition rate uniformity measurements illustrated that the dcMS deposition uniformity was rather insensitive to changes in | B | while both HiPIMS operating modes were highly sensitive. The HiPIMS deposition rate uniformity could be 10% lower or up to 10% higher than the dcMS deposition rate uniformity depending on | B | and in particular the magnetic field topology. We related the measured quantities, the deposition rate and ionized flux fraction, to the ionization probability α t and the back attraction probability of the sputtered species β t . We showed that the fraction of the ions of the sputtered material that escape back attraction increased by 30% when | B | was reduced during operation in fixed peak current mode while the ionization probability of the sputtered species increased with increasing | B | , due to increased discharge current, when operating in fixed voltage mode.

On three different ways to quantify the degree of ionization in sputtering magnetrons

Quantification and control of the fraction of ionization of the sputtered species are crucial in magnetron sputtering, and in particular in high-power impulse magnetron sputtering (HiPIMS), yet proper definitions of the various concepts of ionization are still lacking. In this contribution, we distinguish between three approaches to describe the degree (or fraction) of ionization: the ionized flux fraction the ionized density fraction and the fraction α of the sputtered metal atoms that become ionized in the plasma (sometimes referred to as probability of ionization). By studying a reference HiPIMS discharge with a Ti target, we show how to extract absolute values of these three parameters and how they vary with peak discharge current. Using a simple model, we also identify the physical mechanisms that determine and α as well as how these three concepts of ionization are related. This analysis finally explains why a high ionization probability does not necessarily lead to an equally high ionized flux fraction or ionized density fraction.

Linear magnetron HiPIMS high deposition rate magnet pack

High Power Impulse Magnetron Sputtering (HiPIMS) or High Power Pulsed Magnetron Sputtering (HPPMS) is a promising magnetron sputtering technique for ionized physical vapor deposition (iPVD), with industrial implementation hindered by low deposition rates in non-reactive HiPIMS. Because HiPIMS is currently of low interest in high volume manufacturing where deposition rates should be high, there is a demand for a solution to the low deposition rate problem, scalable to any desired length. To increase the deposition rate, a magnet pack behind a linear magnetron target is altered, and the new magnetic field is designed to allow for an increased ion flux to the substrate. The modeled magnet pack is manufactured and named the linear tripack magnet pack. Deposition rate is discussed for both DCMS and HiPIMS, using both a standard linear magnet pack and the linear tripack magnet pack in non-reactive HiPIMS. Observed deposition rates for the linear tripack magnet pack are found to be equal to or greater than the DC standard magnet pack at 1.5 kW and copper ionized flux fraction measurements were found to be as high as 35% at the substrate for the linear tripack magnet pack at 3.2 kW. Electron temperature and electron density measurements are taken and discussed.

Measurement of deposition rate and ion energy distribution in a pulsed dc magnetron sputtering system using a retarding field analyzer with embedded quartz crystal microbalance.

A compact retarding field analyzer with embedded quartz crystal microbalance has been developed to measure deposition rate, ionized flux fraction, and ion energy distribution arriving at the substrate location. The sensor can be placed on grounded, electrically floating, or radio frequency (rf) biased electrodes. A calibration method is presented to compensate for temperature effects in the quartz crystal. The metal deposition rate, metal ionization fraction, and energy distribution of the ions arriving at the substrate location are investigated in an asymmetric bipolar pulsed dc magnetron sputtering reactor under grounded, floating, and rf biased conditions. The diagnostic presented in this research work does not suffer from complications caused by water cooling arrangements to maintain constant temperature and is an attractive technique for characterizing a thin film deposition system.