Sputter Coater Research Articles

Deposition of Al/Cu Multilayer By Double Targets Cylindrical DC Magnetron Sputtering System

A cylindrical direct current magnetron sputtering coater with two targets for deposition of multilayer thin films and cermet solar selective surfaces has been constructed. The substrate holder was able to rotate around the target for obtaining the uniform layer and separated multilayer phases. The Al/ Cu multilayer film was deposited on the glass substrate at the following conditions: Working gas = Pure argon, Working pressure = 1 Pa, Cathode current = 8 A and cathode voltage = -600 V .Microstructure of the film was investigated by X-Ray Diffraction and the scanning electron microscopy analyses. The elements profile was determined by glow discharge–optical emission spectroscopy analysis. During deposition, both targets with magnetron configuration were sputtered simultaneously by argon ions. A Plasma column on the targets surface was generated by a 290 G permanent magnet unit. Two DC power supply units with three phases input and maximum output of 12 A/1000V were used to deposit the multilayer thin films. A control phase system was used to adjust output voltage.

Numerical optimization of baffles for sputtering optical precision filters

The optimization of the coating uniformity of precision optical filters generally is a critical and time consuming procedure. The present paper demonstrates this optimization procedure on a new optical precision sputter coater “Enhanced Optical Sputtering System (EOSS)” at Fraunhofer IST. The coater concept is based on dual cylindrical sputtering sources and a rotating turn-table as sample-holder. For compensating non-uniformity introduced by the particle flux profile and the radially dependent track speed on the turntable, baffle elements have to be designed and inserted beneath the substrates.For that purpose the distribution of the particle flow from the cylindrical magnetron as well as the resulting thickness profile for different shaper designs is simulated using Direct Simulation Monte Carlo (DSMC) transport simulation. For comparison, experimentally obtained film thickness profiles are evaluated by spectrophotometry and ellipsometry. The simulation model is used for optimization of the baffle geometry as well as investigation on the role of long term drifts caused by target erosion and mechanical tolerances.

Model based investigation of Ar+ ion damage in DC magnetron sputtering

Magnetron discharges in a sputter coater for Ag backside mirrors on LED devices have been simulated via Particle-in-Cell Monte Carlo (PIC-MC). The primary goal was the investigation of experimentally observed device damage apparently due to high energy Ar+ ion bombardment in the subsequent sputtering process. The PIC-MC simulation provided, among others, time integrated ion energy distribution function (IEDF) associated with the surfaces in the simulation domain. A high energy tail in the substrate's IEDF could be related to the measured degree of damage at corresponding process conditions.Further investigation revealed that the IEDFs' high energy tail correlates with the extent of plasma fluctuations seen at certain process conditions. Several experimental studies in recent years have broached the issue of such plasma fluctuations in magnetron discharges. However, PIC-MC simulation data could provide more detailed insights into cause and effect of this inherent discharge anomaly. Thus, it could be instructively revealed how electric field enhancements accompanying these fluctuations affect the IEDF and generation of high energy ions, respectively.

Swelling of U(Mo) dispersion fuel under irradiation – Non-destructive analyses of the SELENIUM plates

Extensive fuel-matrix interactions leading to plate pillowing have caused a severe impediment on the development of a suitable high density low-enriched uranium dispersion fuel for high power applications in research reactors. Surface engineering of the U(Mo) kernel surfaces, where the interaction occurs, is put forward by SCK⋅CEN as a possible solution in the Surface Engineering of Low ENrIched Uranium Molybdenum fuel (SELENIUM) program. The project involved the construction of a sputter coater, the coating of U(Mo) kernels, the production of fuel plates, the irradiation and post-irradiation examination of 2 plates. The irradiation of 2 distinct (600nm Si and 1000nm ZrN coated) full size, flat fuel plates was performed in the BR2 reactor in 2012. The irradiation conditions were: 470W/cm2 peak Beginning Of Life (BOL) power, with a ∼70% 235U peak burnup. The plates were successfully irradiated and did not show any pillowing at the end of the irradiation.This paper reports the results and interpretation of the non-destructive post-irradiation examinations that were performed on these fuel plates and derives a law for the fuel swelling evolution with burnup for this fuel type. It further reports additional PIE results obtained on fuel plates irradiated in campaigns in the past in order to allow a complete comparison with all results obtained under similar conditions. The fuel swelling is shown to evolve linearly with the fission density, with an increase in swelling rate around 2.5×1021f/cm3, which is associated with the restructuring of the fuel. A further increase in swelling rate is observed at the highest burnups, which is discussed in this article.

Development of gold induced surface plasmon enhanced CIGS absorption layer on polyimide substrate

Localized surface plasmon resonance (LSPR) with metal nanoparticles is the promising phenomenon to increase light absorption by trapping light in thin film solar cells. In this study we demonstrate a successful LSPR effect with gold (Au) nanoparticles onto the Cu(In,Ga)Se2 (CIGS) absorption layer. First, the CIGS absorber layers is fabricated onto the Mo coated polyimide (PI) substrate by using two stage process as DC sputtering of CIG thin film followed by the selenization at 400°C. Finally, the Au nanoparticles are deposited onto the CIGS layer with increasing particles size from 4–15nm by using sputter coater for 10–120s. The X-ray diffraction (XRD) patterns confirm the formation of CIGS/Au nanocomposite structure with prominent peak shift of CIGS reflections and increasing intensity for Au phase. The CIGS/Au nanocomposite morphologies with Au particle size distribution uniformity and surface coverage is examined under ultra-high resolution field effect scanning electron microscope (UHR-FESEM). A peak at 176cm−1 in Raman spectra, associated with the “A1” mode of lattice vibration for the attributed to the pure chalcopyrite structure. The secondary ion mass spectroscopy (SIMS) showed ∼200nm depth converge of Au nanoparticles into the CIGS absorption layer. The optical properties as transmittance, reflectance and absorbance of CIGS/Au layers were found to expand in the infrared region and the LSPR effect is the most prominent for Au particles (5–7nm) deposited for 60s. The absorption coefficient and band gap measurement also confirms that the LSPR effect for 5–7nm Au particles with band gap improvement from 1.31 to 1.52eV for CIGS/Au layer as the defect density decreases due to the deposition of Au nanoparticles onto the CIGS layer. Such LSPR effect in CIGS/Au nanocomposite absorption layer will be a key parameter to further improve performance of the solar cell.

Lysophosphatidic acid triggers mast cell-driven atherosclerotic plaque destabilization by increasing vascular inflammation

Lysophosphatidic acid (LPA), a bioactive lysophospholipid, accumulates in the atherosclerotic plaque. It has the capacity to activate mast cells, which potentially exacerbates plaque progression. In this study, we thus aimed to investigate whether LPA contributes to plaque destabilization by modulating mast cell function. We here show by an imaging mass spectrometry approach that several LPA species are present in atherosclerotic plaques. Subsequently, we demonstrate that LPA is a potent mast cell activator which, unlike other triggers, favors release of tryptase. Local perivascular administration of LPA to an atherosclerotic carotid artery segment increases the activation status of perivascular mast cells and promotes intraplaque hemorrhage and macrophage recruitment without impacting plaque cell apoptosis. The mast cell stabilizer cromolyn could prevent intraplaque hemorrhage elicited by LPA-mediated mast cell activation. Finally, the involvement of mast cells in these events was further emphasized by the lack of effect of perivascular LPA administration in mast cell deficient animals. We demonstrate that increased accumulation of LPA in plaques induces perivascular mast cell activation and in this way contributes to plaque destabilization in vivo. This study points to local LPA availability as an important factor in atherosclerotic plaque stability.

Research on Preparation Band-Pass Filter by Lon Beam Sputtering

According to the requirement of the filter for laser tracking system, we chose Ta as the target material of high refractive index and SiO2 as the target material of low refractive index, the film system was designed and optimized with the TFCalc software, adopted the double ion sputter coaters by VEECO company for plating system, using two sides of the substrate to broaden the long and short wavelength cut-off band respectively, we improved the peak transmittance and simplified the difficulty of experimental analysis, the filter to meet the demand has been deposited. The average transmittance of the filter at 532nm, 808nm, 1064nm and1550nm wavelength was less than 0.2% and the peak transmittance at 905nm wavelength was 96.3%. The filter can withstand the test of bad environment and satisfy the requirements of the laser tracking system.

Titania nanotube porosity controls dissolution rate of sputter deposited calcium phosphate (CaP) thin film coatings

Calcium phosphate (CaP) coatings are of continuing significant interest due to their ability to directly promote bone cell differentiation. Whereas sputter deposited CaP coatings have much to offer in this regard, in the as-deposited state they are inherently amorphous and readily undergo rapid dissolution. This behaviour severely limits their ability to support bone cell adhesion and the subsequent events of proliferation and/or differentiation without subsequent processing such as thermal annealing. Removal of the need for this additional processing step would significantly increase their utility. This paper reports a study of the use of nano-porous titania substrates to directly control the rate of dissolution of thin amorphous as-deposited CaP sputter coatings. Titania nanotubes with different pore sizes were prepared by electrochemical anodization of titanium foils and sputter coated with CaP. Dissolution studies were performed on the as-deposited CaP layers in cell culture media for periods of up to 21 days. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the potential of the nanotubes to prolong the rate of loss of CaP over the entire 21 day period as compared to coatings prepared on flat polished titanium surfaces, which dissolved completely in less than 48 h. The CaP coated titania nanotube surfaces showed high levels of osteoblast attachment and proliferation with no signs of cell death. Alkaline phosphatase (ALP) activity measurements at 21 days indicated that the highest levels of osteoblast differentiation occurred on CaP thin films deposited onto titania nanotubes with an average pore size of 30 ± 7.5 nm and tube length of 1.3 ± 0.2 μm. These results indicate that prolonged availability of the as-deposited sputtered CaP can be provided for by use of a substrate surface comprising titania nanotubes. Moreover, nanotube pore size and tube length affect the rate of CaP dissolution and attendant cell behaviour thereon.

Titanium oxide Films Prepared by Sputtering, Sol Gel and Dip Coating Methods for Photovoltaic Application

Dye-sensitized solar cells (DSCs) without using transparent conducting oxides (TCO) electrode can be produced at much lower cost with a flexible structure. A new type of DSCs using flexible stainless steel mesh sheets based electrode is reported in this research. The working electrode of DSCs is processed with conductive and flexible stainless mesh coated with metal oxides (TiO2) layer either by sputtering, sol gel or dip coating methods. Structures of the TCO-less DSCs sample is a stainless mesh for working electrode/dye sensitized TiO2 layer/liquid type electrolyte with polymer film/Pt doped Ti plate for counter electrode. The metal oxide coated stainless mesh sample showed higher photo-current conversion efficiency in general. The best cell performance in this experiment showed the efficiency of 3.11% (Voc = 0.58V, Jsc = 11.98mA/cm2, ff = 0.45).

Numerical shaper optimization for sputtered optical precision f ilters

A novel optimization procedure for optical precision sputter coaters with respect to the film homogeneity is demonstrated. For a coater concept based on dual cylindrical sputtering sources and a rotating turn-table as sample-holder, the inherent radial decay of the film thickness must be compensated by shaper elements. For that purpose, a simulation model of the particle flux within such a coater is set up and validated against experimental data. Subsequently, the shaper design is optimized according to the modeled metal flux profile. The resulting film thickness deviations are minimized down to ±0.35%.

Optical Characterization of Porous Sputtered Silver Thin Films

The optical properties of various porous silver films, grown with a commercial DC sputter coater, were investigated and compared for different plasma parameters. Effective Drude models were successfully used for those films whose spectra did not show particular resonance peaks. For the other films, neither an effective Drude model nor effective medium models (Maxwell Garnett, Bruggeman, and Looyenga) can describe the optical properties. It turns out that a more general approach like the Bergman representation describes the optical data of these films accurately adopting porosity values consistent with physical measurements.

Hermetic Protection of Rings by Ion Beam Sputter Coating with a Broad Beam Ion Source and a W-Shaped Hollow Sputter Target

Hermetic Protection of Rings by Ion Beam Sputter Coating with a Broad Beam Ion Source and a W-Shaped Hollow Sputter Target

Property Study on High-Speed Steel Deposited TiN Coatings by Magnetron Sputter Ion Plating

TiN coatings were deposited by Magnetron Sputter Ion Plating (MSIP) on the surface of high-speed steel W18Cr4V.The microstructure,coating thickness, micro-hardness and wear resistance of surface modification sample were investigated by the D/MAX-ⅢB X-ray diffraction tester, the coating thickness tester, the HV-1000 micro-sclerometer,the LKDM－2000 friction and wear tester,the S-3000N scaning electron microscopy.The influence of sputtering time,N2 partial pressures and sputtering current on the microstructure,coating thickness, micro-hardness and wear resistance of TiN coatings were also analysed.The best synthesis performance sputtering coatings of technologic scheme was established.

Design Optimization of SS-AlN Cermet Solar Selective Coatings

In this work, effect of the number of stainless steel-aluminum nitride (SS-AlN) cermet layers and stainless steel (SS) volume fraction in each of cermets on the optical properties of SS-AlN solar selective coatings was theoretically investigated based on the effective medium theory and optical properties of SS and ceramic AlN. Results shows that increasing the number of cermets does not improve the optical performance of solar selective coatings in terms of solar absorptance and thermal emittance at 80 oC, and the two-cermet-layer structure, one having a high metal volume fraction (HMVF) and other having a low metal volume fraction (LMVF), is the most suitable due to better optical performance and easier preparation. Theoretical results also shows that, for double SS-AlN cermets structure selective coatings, optimized LMVF and HMVF are 0.35 and 0.6, respectively, optimized thickness of cermets with LMVF and HMVF are 50 and 60 nm, respectively, and optimized thickness of AlN anti-reflection film is about 60 nm. Comparisons of reflectance of a sample deposited by a pulse magnetron sputtering coater between measured and calculated showed that theoretically predicted reflectance were highly agreed with those experimentally measured, indicating that the theoretical method used in this work can pretty predict the optical properties of SS-AlN cermet solar selective coatings.

유도결합 플라즈마를 이용한 마그네트론 스퍼터링으로 증착된 나노결정질 CrN 코팅막의 성장

Nanocrystalline CrN coatings were deposited by DC and ICP-assisted magnetron sputtering on Si (100) substrates. The influences of the ICP power on the microstructural and crystallographic properties of the coatings were investigated. For the generation of the ICP, radio frequency was applied using a dielectric-encapsulated coil antenna installed inside the deposition chamber. As the ICP power increased from 0 to 500W, the crystalline grain size decreased. It is believed that the decrease in the crystal grain size at higher ICP powers is due to resputtering of the coatings as a result of ion bombardment as well as film densification. The preferential orientation of CrN coatings changed from (111) to (200) with an increase in the ICP power. The ICP magnetron sputtering CrN coatings showed excellent surface roughness compared to the DC magnetron sputtering coatings.

In vivo evaluation of bioactive glass‐based coatings on dental implants in a dog implantation model

Although titanium is commonly used as a favorable bone implant material due to its mechanical properties, its bioactive and osteoconductive capacity is relatively low. Calcium phosphate ceramics, predominantly hydroxyapatite (HA), have been frequently used for coating purposes to improve the bioactive properties. In view of the suggested osteopromotive capacity of bioactive glasses (BGs), this study aimed to evaluate the effect of BG incorporation into HA coatings on implant performance in terms of bone contact and bone area. A total of 48 screw-type titanium implants with magnetron sputter coatings containing different ratios of HA and BG (HA, HABGLow, and HABGHigh; n = 8) were placed into the mandible of 16 Beagle dogs. After 4 and 12 weeks, their performance was evaluated histologically and histomorphometrically. Peri-implant bone area percentage (BA%) was determined in three zones (inner, 0-500 μm; middle, 500-1000 μm; and outer, 1000-1500 μm). Additionally, bone-to-implant contact (BIC%) and first bone-implant contact (1st BIC) were assessed for each sample. After 4 weeks, bone-to-implant contact for the HA- and HABGLow-coated groups was significantly higher (P < 0.05) than for the HABGHigh coatings. Mean values for overall BA% showed comparable values for both the HABGLow (58.3%)- and HABGHigh (56.3%)-coated groups. Data suggest that the relative BA around the HA-coated implants (67.8%) was higher, although this was only significant compared to the HABGHigh group. After 12 weeks, all three groups showed similar bone-to-implant contact and no differences in BA were found. The incorporation of BG into HA sputter coatings did not enhance the performance of a dental implant in implantations sites with good bone quality and quantity. On the contrary, coatings containing high concentrations of BG resulted in inferior performance during the early postimplantation healing phase.

Heterogeneous catalysts based on polypropylene and polyamide fibers

The ability to use polypropylene and polyamide fibers modified with a cobalt phthalocyanine complex as catalysts for removing mercaptans was evaluated. Fibers were prepared by electrospinning from polymer solutions and melts. The average diameter and specific surface area were determined. The fiber surface was activated by treatment with a low-temperature plasma in air. The catalytic activity and specific capacity of the fibers before and after plasma treatment were calculated. Polymeric fibers can be produced by several methods. The traditional method is extrusion. At present, electrospinning, which is the spinning of ultrafine fibers from a liquid medium in an electrical field, is especially interesting. This method is typified by simplicity, high throughput, and low polymer consumption and can produce finished material in one step. Electrospinning is the most efficient method for preparing continuous polymeric fibers with improved mechanical properties and diameters from several nanometers to several micrometers. Fibers prepared by electrospinning are used in medicine, bioengineering, and filtration of gases and liquids; in the fabrication of composites (for reinforcing polymeric matrices); and for other applications [1, 2]. Nano-sized fibers are used in catalysis because of their large specific surface area, low polymer consumption, and cost savings in addition to the ability to produce continuous fibers. Herein we examine the possibility of using polypropylene (PP) and polyamide (PA) fibers modified by a cobalt phthalocyanine complex (CoPc) as catalysts for removing mercaptans. In the initial stage of the work, we prepared heterogeneous catalysts of PP and PA fibers modified with CoPc. PP fibers were spun from polymer melt; PA, from a 12% solution of PA-6.6 in formic acid. The modification was made by dissolving CoPc in the polymeric matrix during fiber spinning. The catalyst content in PP fibers was 5 and 10%; in PA fibers, 10, 20, and 30%. The mass of the studied fiber samples was 0.0064 g. The specific surface area of the samples was determined by low-temperature adsorption (desorption) of argon on a Tsvet 211 sorption meter. The PP fiber diameter was measured using a Hitachi S-3000N scanning electron microscope with an Edwards Sputter Coater S 150B attachment for coating samples with a layer of gold for better contact. The PA fiber diameter was measured using a Solver 47 PRO atomic force microscope. Catalyst efficiency was estimated with an accuracy of ±5% from the reduction of propylmercaptan content resulting from stirring its alkaline aqueous solution of concentration 0.92% (by mass). The experimental temperature was 25°C. The content of dissolved oxygen in the initial sodium propylmercaptide solution was determined using a portable series HQ meter with an IntelliCAL TM sensor. A blank experiment was carried out in parallel and consisted of stirring an alkaline aqueous solution of propylmercaptan without catalyst. The total duration of the experiment was 20 min. Samples were taken every 5 min. Potentiometric titration was used to determine the concentration of mercaptide sulfur remaining in the solution [3]. Samples were rinsed after performing each sequential mercaptan removal step.

Amorphous sputter coating of a multi-component Zr–Ti–Ni–Cu alloy as a filler for brazing Zircaloy-4

Amorphous sputter coatings of a Be-free multi-component Zr–Ti–Ni–Cu alloy were applied as a novel brazing filler metal for brazing Zircaloy-4. The homogeneous and amorphous-structured layers were uniformly coated by sputtering the crystalline Zr47.6Ti19.9Ni17.4Cu15.1 target. By preserving the near equivalent target composition, the coating showed an excellent compositional uniformity in spatial distribution, as well as almost the same melting characteristics as that of the parent target. By applying the amorphous sputter coatings, the highly reliable joints were obtained with the formation of predominantly grown α-Zr grains due to a complete isothermal solidification, exhibiting strengths comparable to that of Zircaloy-4. The present investigation showed that a Be-free and Zr-base multi-component amorphous sputter coating can offer great potential for brazing and manufacturing a Zr alloy nuclear fuel bundle system.

Lipid Polarity Is Maintained in Absence of Tight Junctions

The role of tight junctions (TJs) in the establishment and maintenance of lipid polarity in epithelial cells has long been a subject of controversy. We have addressed this issue using lysenin, a toxin derived from earthworms, and an influenza virus labeled with a fluorescent lipid, octadecylrhodamine B (R18). When epithelial cells are stained with lysenin, lysenin selectively binds to their apical membranes. Using an artificial liposome, we demonstrated that lysenin recognizes the membrane domains where sphingomyelins are clustered. Interestingly, lysenin selectively stained the apical membranes of epithelial cells depleted of zonula occludens proteins (ZO-deficient cells), which completely lack TJs. Furthermore, the fluorescent lipid inserted into the apical membrane by fusion with the influenza virus did not diffuse to the lateral membrane in ZO-deficient epithelial cells. This study revealed that sphingomyelin-cluster formation occurs only in the apical membrane and that lipid polarity is maintained even in the absence of TJs.

Fundamental Adsorption Properties for Low Molecular Weight Alcohols in Fluorocarbon Thin Films Deposited onto Quartz Crystal Microbalance Electrode by an R.F. Sputtering and Spin Coating

Fundamental Adsorption Properties for Low Molecular Weight Alcohols in Fluorocarbon Thin Films Deposited onto Quartz Crystal Microbalance Electrode by an R.F. Sputtering and Spin Coating