Cathode Target Research Articles

Influence of the edge effect of the solenoid magnetic field on the discharge process of magnetron sputtering in long and narrow chambers

The fourth-generation light source or future particle accelerators have compact vacuum systems, resulting in a small flow conductance of the beam chamber. The development of NEG (Non-Evaporable Getters) films technology with distributed pumping is a good solution. This technology can obtain a pressure distribution with a small pressure gradient and an ultra-high vacuum of 10-8 Pa inside the vacuum chambers. In the magnetron sputtering process for NEG coating, the inhomogeneity of the magnetic field at the edge of the solenoid is a key parameter for affecting the stability of the magnetron sputtering discharge process. The influence mechanism of the edge magnetic field on the plasma discharge process and discharge uniformity was studied to optimize the coating parameters, which is very important. The Particle-In-Cell/Monte Carlo Collision (PIC/MCC) method was employed to simulate plasma discharge in a narrow vacuum chamber under various edge magnetic field conditions. The potential distribution, charged particle density distribution, and particle density distribution on the target were acquired for four sets of discharge parameters, followed by data processing and analysis. The electric field distribution during the discharge process is closely linked to the non-uniformity of the magnetic field at the solenoid's edge. The smaller Br (the radial component of the magnetic field) component of the magnetic field, the more uniform distribution of Ar+ on the target surface, and the smaller the difference along the length of the vacuum chamber. A smaller radial component (Br) of the magnetic field results in a more uniform distribution of Ar+ on the target surface and reduces variations in film thickness along the length of the vacuum chamber. This is attributed to the small distance between the inner wall of the vacuum chamber and the cathode target. The change in the edge magnetic field will result in the rapid migration of electrons to the inner wall of the vacuum chamber and insufficient collision with the discharge gas, making it challenging to sustain the discharge process. Moreover, fluctuations in the edge magnetic field of the solenoid induce gradient drift and curvature drift in charged particles, resulting in rapid electron loss and alterations in the density and potential distribution of charged particles at the ends of the vacuum chamber, ultimately leading to discharge instability. The research results show the importance of the edge magnetic field effect on the magnetron sputtering coating of the slender vacuum chambers, which provides an important reference for the segmented coating process of similar vacuum chambers in future accelerators.

Effects of pulse time offset between Cr and Zr dual cathodes in closed-magnetic-field unipolar high-power impulse magnetron sputtering

Two cathode (target) materials, Cr and Zr, were paired in a closed-field magnetron dual-cathode configuration and used in unipolar high-power impulse magnetron sputtering (HiPIMS). Two pulse widths (pulse-on durations) and various pulse-time offsets between the negative-voltage pulses of the Cr and Zr targets were investigated by setting the synchronization delay between the HiPIMS power supplies of the two targets at two different Ar pressures. Several trends were observed by analyzing the waveforms of the target discharge current, target discharge voltage, and substrate current. The closed-magnetic-field dual-cathode configuration significantly enhanced the HiPIMS discharge efficiency of the Zr target at all pressures; however, the enhancement for the Cr target was considerably lower. The ion fluxes toward the substrate were influenced by two competing mechanisms. The charged species generated from the previous pulse on one target could be attracted by the subsequent pulse of the adjacent target as a preionized medium to enhance the HiPIMS discharge. However, the fraction of the previously emitted ion flux toward the substrate could be reduced. When a shorter pulse width of 70 μs was applied, the ion flux that reached the substrate was mainly affected by the pulse power of the Zr target, and delaying the pulses of the Cr target with a relatively lower ion yield can achieve a higher ion flux toward the substrate. Increasing the pulse width significantly increased ion fluxes emitted from both the Cr and Zr targets, increasing the total ion flux toward the substrate. The study indicates that for the Cr and Zr dual cathode pair, a pulse time offset of one pulse width plus more than approximately 200 μs would be the most efficient way to obtain the highest ion fluxes toward the substrate and achieve a better film quality.

Copper target erosion during unbalanced magnetron sputtering under different electromagnetic fields

Unbalanced magnetron sputtering (UBMS) is used to deposit mechanical and optical coatings due to the advantages of high deposition rate and low pollution level, but the low utilization rate of the target material limits its applications for industrial-scale production. To improve target utilization during UBMS, a magnetron system combining a coil magnet and a permanent magnet has been developed. The effects of the operating parameters of the magnetic flux density on the magnetic field were investigated, and the erosion profiles on the target surface were examined in terms of the plasma distribution. It was found that the erosion center was located where the lines of magnetic induction were parallel to the target surface. A strategy of changing the current of the central coil was finally proposed, which improved the target utilization to 52.9 %. These results provide theoretical guidance to improve the target utilization of UBMS by optimizing the design of the cathode target and magnetic field.

Investigation of the Al-Mo-B(CN) Coatings Deposited Using Magnetron Sputtering of Al-Mo-B4C Target Produced by Detonation Spray Coating

In this work, a metal–ceramic composite target for magnetron sputtering was manufactured by a robotic complex for detonation spraying of coatings equipped with a multi-chamber detonation accelerator. The powder composition (30Mo-30Al-40B4C) was sprayed onto the copper plate base of the composite target cathode. The obtained cathode target with Al-Mo-B4C coating (thickness 280–300 μm) was used to deposit the Al-Mo-B(CN) coating (DC mode) on flat specimens of AISI 316 steel and silicon using equipment for magnetron sputtering UNICOAT 200. The Al-Mo-B4C coating has a lamella-type structure with inclusions of boron carbide particles. The structure and morphology of the coatings were studied using methods of optical analysis, scanning electron microscopy, atomic force microscopy, X-ray analysis, and X-ray photoelectron spectroscopy. Mechanical and tribological properties of the Al-Mo-B(CN) thin coatings were studied using a nanoindenter, a scratch tester, and a tribometer under a fluid-free friction regime at room temperature. The Al-Mo-B(CN) coating (thickness ~1 μm) exhibited a dense homogeneous fine-grained design without columnar elements and had an amorphous structure. The formation of the MoB2 and AlN phase with an admixture of oxygen in the form of aluminum oxide, molybdenum oxide, and boron oxide was determined using XPS analysis. The Al-Mo-B(CN) coating possessed a hardness of 13 GPa, an elasticity modulus of 114 GPa, an elastic recovery of 45%, a friction coefficient of 0.8 against a steel 100 Cr6 ball, and an adhesion strength of 11 N.

Exploring the impact of substrate placement on Cu3N thin films as a solar cell window layer: Structural and optical attributes

Copper nitride (Cu3N) thin films have garnered significant interest due to their exceptional stability, corrosion resistance, and optical qualities. In this research, Cu3N thin films were produced through reactive dc magnetron sputtering (dcMS) in a nitrogen/argon atmosphere on glass substrates without any external heat treatment. The study examined the effects of substrate positions from the cathode target, and subsequently film thicknesses, on the structure and optical properties of Cu3N thin films. Different methods were employed to examine the structural and optical characteristics of the films, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible-near infrared (UV–vis–NIR) spectrophotometry in the wavelength range of 400–2500 nm. The XRD patterns indicated a cubic crystal structure for the films with a dominant orientation along the (100) plane, while SEM images displayed uniform and smooth surface morphologies for the films. The UV–vis–NIR spectrophotometry findings demonstrated transmittance above 70% in the visible region for the films, and the optical bandgap values ranged between 2.29 and 2.49 eV. The optical conductivity (σ), electrical susceptibility (χc), and optical electronegativity (ηopt) have been calculated. Furthermore, the nonlinear optical qualities of Cu3N thin films were discussed, including the nonlinear refractive index (n2), the nonlinear optical susceptibility, and the nonlinear absorption coefficient (βc). The Cu3N thin films showed promising optical properties, suggesting their potential use as a window layer in solar cell technology.

Simple and Portable Self-Powered Sensor Using Ultrasonically Dispersed Graphene as an Electron Transfer Promoter for Ultra-Trace Atrazine Monitoring

Atrazine (ATZ) is a typical environmental endocrine disruptor that is persistent, highly residual, and widely present in various environmental media. Thus, it is of great significance to establish a sensitive and portable detection method for ATZ. In this work, a simple and portable enzymatic biofuel cell-based self-powered sensor (EBFC-SPS) for ATZ is proposed with the ultrasonically dispersed graphene (US-G) serving as the electron transfer promoter for both the enzymatic bioanode and molecularly imprinted cathode. US-G acts as a molecular bridge to stabilize the glucose dehydrogenase (GDH) immobilization and accelerate the electron transfer between GDH and anode, promoting the spontaneous electricity generation by the bioanode and sustainable power supply to the EBFC-SPS while ensuring cathode recognition and electron transfer. The portable detection of ultra-trace ATZ is achieved using a digital multimeter with a wide linear range of 0.5 pM to 100 nM, a low detection limit of 0.37 pM, excellent selectivity and stability in complex actual water samples based on the separation strategy of the bioanode power supply, and molecularly imprinted cathode target recognition. A promising platform for the design of portable sensing strategies with the EBFC-SPS has therefore been provided, which can also be extended to a wider range of environmental pollutants.

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.

Microstructure evolution and mechanical performance of tetrahedral amorphous carbon coatings with dense droplets during annealing

Tetrahedral amorphous carbon (ta-C) coatings with approximately 50% sp3C were deposited onto cemented carbide alloy YG6 and Si wafers via direct vacuum cathode arc (DVCA) evaporation at different substrates temperatures. Coated specimens were annealed in a 5 Pa argon atmosphere. The micromorphology and chemical bonding structure of these coatings with different treatments were characterized using field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The mechanical performance was tested using a nanoindenter and film stress instrument. The obtained ta-C coatings contained dense droplets of various sizes (“abnormal particles” (An-Ps)). The densities of the An-Ps were controlled by the graphite cathode target arc rather than the substrate temperature, and their ID/IG ratios were close to their counterpart coating matrix. Increasing the substrate temperature was beneficial for increasing the sp2C fraction and the number of aromatic ring sp2C sites. Growth, coalescence, and leveling-diffusion of aggregates in the coating matrix and An-Ps occurred during annealing, which was related to the existing state of the sp2C sites, including the olefinic chain and aromatic ring. The residual stress variation with annealing temperature also depended on the sp2C state. The residual stress in the coating increased during annealing when the number of aromatic ring sp2C sites exceeded a certain critical value.

High power impulse magnetron sputtering of tungsten: a comparison of experimental and modelling results

Here, we compare the ionization region model (IRM) against experimental measurements of particle densities and electron temperature in a high power impulse magnetron sputtering discharge with a tungsten target. The semi-empirical model provides volume-averaged temporal variations of the various species densities as well as the electron energy for a particular cathode target material, when given the measured discharge current and voltage waveforms. The model results are compared to the temporal evolution of the electron density and the electron temperature determined by Thomson scattering measurements and the temporal evolution of the relative neutral and ion densities determined by optical emission spectrometry. While the model underestimates the electron density and overestimates the electron temperature, the temporal trends of the species densities and the electron temperature are well captured by the IRM.

Target ion and neutral spread in high power impulse magnetron sputtering

In magnetron sputtering, only a fraction of the sputtered target material leaving the ionization region is directed toward the substrate. This fraction may be different for ions and neutrals of the target material as the neutrals and ions can exhibit a different spread as they travel from the target surface toward the substrate. This difference can be significant in high power impulse magnetron sputtering (HiPIMS) where a substantial fraction of the sputtered material is known to be ionized. Geometrical factors or transport parameters that account for the loss of produced film-forming species to the chamber walls are needed for experimental characterization and modeling of the magnetron sputtering discharge. Here, we experimentally determine transport parameters for ions and neutral atoms in a HiPIMS discharge with a titanium target for various magnet configurations. Transport parameters are determined to a typical substrate, with the same diameter (100 mm) as the cathode target, and located at a distance 70 mm from the target surface. As the magnet configuration and/or the discharge current are changed, the transport parameter for neutral atoms ξtn remains roughly the same, while transport parameters for ions ξti vary greatly. Furthermore, the relative ion-to-neutral transport factors, ξti/ξtn, that describe the relative deposited fractions of target material ions and neutrals onto the substrate, are determined to be in the range from 0.4 to 1.1.

NiB-CrC Coatings Prepared by Magnetron Sputtering Using Composite Ceramic NiCr-BC Target Produced by Detonation Spray Coating.

A metal–ceramic composite target for magnetron sputtering was fabricated for the first time by a robotic complex for the detonation spraying of coatings equipped with a multi-chamber detonation accelerator. A mixture of metal and ceramic NiCr/B4C powders was sprayed onto the copper base of the cylindrical composite target cathode. The study of the structure of a metal–ceramic composite coating target using scanning electron microscopy showed that the coating material is dense without visible pores; the elemental composition is evenly distributed in the material. The study of the cathode sputtering area after deposition in the DC mode showed that there are uniform traces of annular erosion on the target surface. The obtained cathode target with an NiCr-70B4C coating was used to deposit the NiB-Cr7C3 coating on flat specimens of 65G steel using equipment for magnetron sputtering UNICOAT 200. The coating was applied in the Direct Current mode. A dense NiB-Cr7C3 coating with a thickness of 2 μm was obtained. The NiB-Cr7C3 coating has a quasi-amorphous structure. The microstructures and concentration of oxygen and carbon impurities throughout the entire thickness of the coating were investigated by means of transmission electron microscopy. The results of the study show that the coatings have a nanocrystalline multi-phase structure. The microhardness of the NiB-Cr7C3 coating reached 10 GPa, and the adhesion fracture load exceeded 16 N. The results will open up new prospects for the further elaboration of technology for obtaining original composite cathodes for magnetron sputtering using detonation spraying of coatings.

Sketching novel nanostructured diamond-consisted thin films on AISI 321 stainless steel: Microstructure, mechanical and tribological properties

In a reactive direct current (DC) magnetron sputtering (MS) system, converting the cathode (target) magnetic field configuration from a balanced magnetron (BM) to an unbalanced magnetron (UBM) is an impressive strategy to enforce the energetic ion bombardment, providing sufficient activation energy for deposition of high-quality nanostructured films. In the present work, the nanostructured (grain size ˂ 100 nm) BM and UBM sputtered Niobium-doped amorphous Carbon (Nb: a-Carbon) films' microstructural, mechanical, and tribological characteristics changes were thoroughly investigated and compared. From the XRD and Raman analysis outcomes both graphite-like Carbon (GLC) and Niobium carbide (NbC) phases were detected in the BM sputtered film. However, novel cubic and hexagonal crystalline Diamond (CD) phases were successfully constructed from the UBM sputtered films besides the GLC and NbC phases. Records displayed that the change over the cathode magnetic field configuration from BM to UBM is a responsible factor for the reduction of the surface roughness (from 32 nm to 25 nm) and increment of the crystallite size (from 14 nm to 15.5 nm), hardness (from 18 GPa to 27 GPa), and elastic modulus (from 210 GPa to 425 GPa) values. On the contrary, via changing BM to UBM sputtering the films' tribological properties were negatively affected, leading to the increase of the coefficient of friction (COF) from 0.09 to 0.11 and the wear rate (WR) from 5.25 × 10−5 mm3/N.m to 9 × 10−5 mm3/N.m. The achieved results confirmed that the UBM configuration could be selected as a critical facility over the MS system that gives enough energy to arrange Carbon species in the crystalline Diamond phase at a relatively low temperature. One step further, the Ar/CH4 ratio variation was assessed as an influential factor that leaves considerable changes over the UBM sputtered film characteristics. The results indicated that by doubling the Ar/CH4 ratio, the nanocrystalline Diamond phases are still observable. However, this change led to the increase in surface roughness (from 25 nm to 28 nm) and crystallite sizes (NbC, from 15.5 nm to 18.6 nm, cubic Diamond, from 25.8 nm to 36 nm, and hexagonal Diamond from 18.9 nm to 21.6 nm). While the variations adversely affected the UBM sputtered films' hardness (from 27 GPa to 21 GPa) and modulus of elasticity (from 425 GPa to 330 GPa). Simultaneously, the COF and WR endured a slight increment, from 0.11 to 0.14 and 9 × 10−5 mm3/N.m to 9.8 × 10−5 mm3/N.m, respectively.

Modeling of high power impulse magnetron sputtering discharges with tungsten target

The ionization region model (IRM) is applied to model a high power impulse magnetron sputtering discharge with a tungsten target. The IRM gives the temporal variation of the various species and the average electron energy, as well as internal discharge parameters such as the ionization probability and the back-attraction probability of the sputtered species. It is shown that an initial peak in the discharge current is due to argon ions bombarding the cathode target. After the initial peak, the W+ ions become the dominating ions and remain as such to the end of the pulse. We demonstrate how the contribution of the W+ ions to the total discharge current at the target surface increases with increased discharge voltage for peak discharge current densities J D,peak in the range 0.33–0.73 A cm−2. For the sputtered tungsten the ionization probability increases, while the back-attraction probability decreases with increasing discharge voltage. Furthermore, we discuss the findings in terms of the generalized recycling model and compare to experimentally determined deposition rates and find good agreement.

Improvement of plasma uniformity and mechanical properties of Cr films deposited on the inner surface of a tube by an auxiliary anode near the tube tail

In order to improve the length of plasma in a whole tube and mechanical properties of Cr films deposited on the inner surface of the tube, a high-power impulse magnetron sputtering coating method with a planar cathode target and auxiliary anode was proposed. The auxiliary anode was placed near the tube tail to attract plasma into the inner part of the tube. Cr films were deposited on the inner wall of a 20# carbon steel tube with a diameter of 40 mm and length of 120 mm. The influence of auxiliary anode voltage on the discharge characteristics of the Cr target, and the structure and mechanical properties of Cr films deposited on the inner surface of the tube were explored. With higher auxiliary anode voltage, an increase in substrate current was observed, especially in the tube tail. The thickness uniformity, compactness, hardness and H/E ratios of the Cr films deposited on the inner surface of the tube increased with the increase in auxiliary anode voltage. The Cr films deposited with auxiliary anode voltage of 60 V exhibited the highest hardness of 9.6 GPa and the lowest friction coefficient of 0.68.

Direct synthesis of graphene on silicon by reactive magnetron sputtering deposition

In the present research, the graphene was grown directly on the Si (100) substrate by a high-power impulse reactive magnetron sputtering the copper target. The samples' structure, morphology, and composition were investigated by Raman scattering spectroscopy, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy. The synthesis temperature, time, sample position in relation to the magnetron, and grid bias effects were studied. The graphene layer number decreased with growth temperature and distance between the sample and magnetron. The defects density in graphene decreased, and graphene crystallite size increased with synthesis temperature. These parameters were changed with lateral movement of the sample's position. The graphene layer number and defects density non-monotonically depended on the grid bias voltage. We revealed that the synthesis time, the distance between the substrate and the magnetron cathode target surface, and the grid bias voltage determine the graphene surface morphology and the shape and size of the graphene flakes. It was explained by competition between the graphene growth from the CHx species, growth activation by hydrogen, etching by hydrogen and argon ions, radiative defects creation, hydrogen atoms adsorption. The changes of the electrons, argon ions and copper atoms concentration and energy, and methane dissociation products density were taken into account. The temperature gradient and ion bombardment induced stress and their release were considered.

Highly Sensitive Direct‐Conversion Vacuum Flat‐Panel X‐Ray Detectors Formed by Ga2O3‐ZnO Heterojunction Cold Cathode and ZnS Target and their Photoelectron Multiplication Mechanism

AbstractX‐ray detectors are significantly applied in medical diagnoses, industrial inspections, and scientific researches, but the detection sensitivity is limited by the material, device structure, and detection mechanism. This article proposes a direct‐conversion flat‐panel X‐ray detector formed by Ga2O3‐ZnO heterojunction cold cathode and ZnS target to achieve highly sensitive X‐ray detection. The field emission efficiency of Ga2O3‐ZnO heterojunction cold cathode is improved by optimizing the spacing between the adjacent circular pattern in patterned ZnO nanowire arrays. The electron–hole pairs generated by X‐ray photons are multiplied in ZnS target by the electron bombardment induced photoconductivity effect, resulting in a high internal gain (1 × 104%) and a high X‐ray detection sensitivity (7.1 × 102 μCGyair−1 cm−2) for 6 keV X‐ray at 9.2 V μm−1 electric field. In addition, the proposed detector has low dark current density (50 pA mm−2 at 9.2 V μm–1 electric field), good stability (0.2% fluctuation for 60 s), and fast response speed (rise time: 5.3 ms) owing to a built‐in electric field in Ga2O3‐ZnO heterojunction, a ballistic electron transportation in vacuum gap, and a high resistance in ZnS thin film.

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.

Generation of a Metal Ion Beam Using a Vacuum Magnetron Discharge

We have designed, fabricated and characterized an ion source based on a vacuum magnetron discharge. The magnetron discharge is initiated by a vacuum arc discharge, the plasma of which flows onto the magnetron sputtering target working surface. The vacuum arc material is usually the same as that of the magnetron target. The discharges operate at a residual pressure of 3 × 10−6 Torr without working gas feed. Pulses of vacuum arc (30 μs) and magnetron discharge (up to 300 μs) are applied simultaneously. After ignition by the vacuum arc, the magnetron discharge runs in a self-sustained mode. Cu–Cu, Ag–Ag, Zn–Zn, and Pb–Pb pairs of magnetron target material and vacuum arc cathode material were tested, as well as mixed pairs; for example, Cu vacuum arc cathode and Pb magnetron target. An ion beam was extracted from the discharge plasma by applying an accelerating voltage of up to 20 kV between the plasma expander and grounded electrodes. The ion beam collector current reached 80 mA. The ion beam composition, analyzed by a time-of-flight spectrometer, shows that the beam consists mainly of singly-charged (about 90%) and doubly-charged (about 10% current fraction) magnetron target material ions. The ion beam radial current density non-uniformity was as low as ±5% over a diameter of 6.6 cm, which is the diameter of the source output aperture.

Effect of electromagnetic voltage on wear resistance of CrAlN coatings

ABSTRACT In arc-ion plating, the droplets ejected from the cathodic target inevitably contaminate the coating with macro-particles (MPs), causing defects that usually reduce the mechanical properties of the coating. Normally, MP formation is suppressed by electromagnetic filtration technology. To investigate the influence of the electromagnetic field on the structure and mechanical properties of coatings, this study applied various electromagnetic voltages (0–45 V) in the arc-ion plating preparation of CrAlN coatings. The proportion of MPs in the coatings was effectively reduced by adding the electromagnetic voltage, and was minimized at 25 V. The wear resistance of coatings was also comparatively studied. The wear of all coatings followed the same abrasive wear mechanism, but reducing the number of MPs improved the wear resistance. The enhancement of wear resistance was attributed to the improved fracture toughness of the coatings with fewer MPs.

Helium ion penetration in sputtering cathode materials: A crucial process for the helium treatment of oxide thin films

• La 0.7 Ca 0.3 MnO 3 films sputtered from He-treated target surface. • He + ion penetration in the cathode target is the crucial step for the He treatment. • He treatment increased the films’ transition temperature and c-axis lattice parameter. • Direct film exposition to He plasma was more effective than He target treatment. We previously reported that out-of-plane lattice of in-plane tensile strained (001) La 0.7 Ca 0.3 MnO 3 thin films can be stretched by He treatment of the films via adding helium gas in an Ar/O 2 mixed sputtering atmosphere. To gain more insight into the He treatment process, in this study, we carried out He plasma treatment on a target and He atom adsorption on a substrate surface respectively before/between sputtering deposition of La 0.7 Ca 0.3 MnO 3 films. The films deposited after the target pre-treatment show remarkable changes in the out-of-plane lattice and magnetotransport properties, while the films deposited through the latter method changes only slightly, suggesting that the He + ion penetration in the cathode target plays a key role in the He treatment of the manganite films. Furthermore, we placed the as-grown films at the cathode position and exposed them directly to He discharge plasma. After the He plasma post-treatment, the out-of-plane lattice parameter increases from 3.823 to 3.851Å, accompanied by an increase in the metal-insulator transition temperature from 260 to 290 K. The results demonstrate that the He plasma treatment is a simple strategy for the single-axis control of epitaxial thin films.