Showing papers on "Sputter deposition published in 1998"

Al-doped zinc oxide films deposited by simultaneous rf and dc excitation of a magnetron plasma: Relationships between plasma parameters and structural and electrical film properties

Abstract: A new technique of the simultaneous excitation of a magnetron sputtering discharge by rf and dc was used for the deposition of undoped ZnO- and Al-doped ZnO (ZnO:Al) films. By this technique, it was possible to change the ion-to-neutral ratio ji/jn on the substrates during the film growth by more than a factor of ten, which was revealed by plasma monitor and Langmuir probe measurements. While for a pure dc discharge the ions impinging onto a floating substrate have energies of about Ei≈17 eV, the rf discharge is characterized by Ar-ion energies of about 35 eV. Furthermore, the ion current density for the rf excitation is higher by a factor of about five, which is caused by the higher plasma density in front of the substrate. This leads to a much higher ion-to-neutral ratio ji/jn on the growing film in the case of the rf discharge, which strongly influences the structural and electrical properties of the ZnO(:Al) films. The rf-grown films exhibit about the three times lower specific resistances (ρ≈6×10−4 Ω...

Exchange-spring behavior in epitaxial hard/soft magnetic bilayers

Abstract: We present results on the magnetic reversal process in epitaxial Sm-Co(11\ifmmode\bar\else\textasciimacron\fi{}00)/TM (TM=Fe,Co) bilayer films prepared via magnetron sputtering. The magnetically hard Sm-Co films have 20-T uniaxial anisotropy and coercivities g3 T at room temperature, that double on cooling, as determined by magnetometry. The TM layers are exchange coupled to the Sm-Co layer and exhibit reversible demagnetization curves expected for an exchange-spring magnet. We also present numerical solutions of a one-dimensional model that provide the spin configuration for each atomic layer. Comparison of the experimental results with the model simulations indicates that our exchange-spring behavior can be understood from the intrinsic parameters of the hard and soft layers. The simulations are extended to realistically estimate the ultimate gain in the energy product that potentially can be realized based on the exchange hardening principle.

Improving the properties of titanium nitride by incorporation of silicon

Abstract: Thin films of Ti–Si–N have been deposited by physical vapor deposition (PVD) with the intention to improve the wear resistance of TiN coatings. The coatings are prepared by reactive unbalanced magnetron sputtering using two separate Ti and Si targets and a rotating substrate holder. The silicon concentration in the deposited films varies between 0 and 15 at.%. SEM observations and X-ray diffraction analysis (XRD) show that the addition of Si to TiN coatings transforms the [111] oriented columnar structure into a dense finely grained structure. From TEM investigations and XRD analyses, the crystallite sizes of TiN are observed to be below 20 nm. XPS analysis shows the presence of silicon nitride, while electron and X-ray diffraction results do not suggest the presence of crystalline Si3N4. This result clearly indicates that these films have a composite structure consisting of TiN nanocrystallites embedded in amorphous silicon nitride. The hardness of the nc-TiN/a-SiNx coatings reaches 3500 HV0.1. The abrasion resistance measured by ball cratering can be enhanced by a factor of 6 in comparison with TiN deposited under the same conditions.

Perpendicular magnetic anisotropy and magnetic domain structure in sputtered epitaxial FePt (001) L10 films

Abstract: The magnetic domain structure and magnetization curves of chemically ordered epitaxial FePt (001) films with perpendicular magnetic anisotropy are discussed. Films were dc magnetron sputtered from a Fe50Pt50 alloy target onto Pt seeded MgO (001) at substrate temperatures of 550 °C. The thickness of the FePt layers was varied between 18 and 170 nm. Specular and grazing incidence x-ray diffraction measurements confirm the presence of the anisotropic, face centered tetragonal (L10) crystal structure. Long range chemical order parameters of up to 0.95 and small mosaic spread, similar to results reported for FePt (001) films grown by molecular beam epitaxy. For film thicknesses ⩾50 nm in-plane and out-of-plane hysteresis measurements indicate large perpendicular magnetic anisotropies and at the same time low (about 10%) perpendicular remanence. Magnetic force microscopy reveals highly interconnected perpendicular stripe domain patterns. From their characteristic widths, which are strongly dependent on the film...

Texture control of PbTiO3 and Pb(Zr,Ti)O3 thin films with TiO2 seeding

Abstract: The nature and the role of 1 to 5 nm thick TiO2 seed layers for the growth of textured PbTiO3 and Pb(Zr, Ti)O-3 thin films on textured Pt(111) thin film substrates have been studied. Under otherwise identical in situ sputter deposition process conditions, the PbTiO3 texture could be turned from (100) to (111) orientation by adding the seed layer. This is demonstrated by patterning the TiO2 film. Auger electron spectroscopy and x-ray photoemission spectroscopy showed that the seed layer was a continuous TiO2 film. X-ray photoelectron diffraction measurements revealed epitaxial ordering in the seed layer. As there is no azimutal order among the Pt grains, the reduced information of azimutally averaged polar cuts is obtained. These give strong evidence for a strained rutile (110) structure. Various deposition experiments indicated that the TiO2 is effective only when it is ordered before the PbTiO3 nucleation starts. The epitaxial relationship between PbTiO3(111) and Pt(111) is thus mediated by the intermediate, epitaxial TiO2 film, which is dissolved of transformed to PbTiO3 afterwards. The observed growth behavior is discussed in terms of surface and interface energies. (C) 1998 American Institute of Physics. [S0021-8979(98)03607-X].

Efficient ? thin-film solar cells prepared by a sequential process

Abstract: -based thin-film solar cells are presented with 11.1% total area efficiency or 12.5% active area efficiency. This is the best efficiency reported so far for this type of solar cell. The technology is based on a sequential process using d.c. magnetron sputtering of the metals and sulphurization in elemental sulphur vapour without the use of a toxic gas. Absorber layers and solar cells with precursor atomic copper to indium ratios between 1.0 and 1.8 are analysed. The best cells with fewest defects are made from the most copper-rich CuIn precursor layers. The solar cell performance, however, decreases only slowly for small deviations of the Cu/In ratio from the optimum value.

Very high aspect ratio gapfill using HDP

Abstract: A process for filling high aspect ratio gaps on substrates uses conventional high density plasma deposition processes, with an efficient sputtering inert gas, such as Ar, replaced or reduced with an He inefficient sputtering inert gas such as He. By reducing the sputtering component, sidewall deposition from the sputtered material is reduced. Consequently, gaps with aspect ratios of 6.0:1 and higher can be filled without the formation of voids and without damaging circuit elements.

Work function of transparent conducting multicomponent oxide thin films prepared by magnetron sputtering

Abstract: The work function of transparent conducting multicomponent oxide (TCO) films is reported. TCO films consisting of binary oxides, such as In 2 O 3 , SnO 2 and ZnO, and ternary oxides, such as Zn 2 In 2 O 5 , In 4 Sn 3 O 12 , GaInO 3 , ZnSnO 3 and MgIn 2 O 4 , were prepared by magnetron sputtering. In addition, transparent conducting films consisting of multicomponent oxides composed of combinations of these binary or ternary oxides were also prepared by magnetron sputtering. The work function of these TCO films was measured by ultraviolet photoelectron spectroscopy operated in air. It was found that the work function as well as the electrical, optical and chemical properties of transparent conducting multicomponent oxide films could be controlled by varying the chemical composition.

Growth of poly- and single-crystal ScN on MgO(001): Role of low-energy N2+ irradiation in determining texture, microstructure evolution, and mechanical properties

Abstract: ScN layers, 345 nm thick, were grown on MgO(001) substrates at 750 °C by ultrahigh-vacuum reactive magnetron sputter deposition in pure N2 discharges at 5 mTorr. The N2+ to Sc ratio incident at the substrate and growing film was maintained constant at 14, while the ion energy EN2+ was varied from 13 to 50 eV. All films were stoichiometric with N/Sc ratios of 1.00±0.02. However, microstructural and surface morphological evolution were found to depend strongly on EN2+. The nucleation and initial growth stages of ScN films deposited with EN2+=13 eV are dominated by the formation of 111- and 002-oriented islands, but preferred orientation rapidly evolves toward a purely 111 texture by a film thickness of ≃50 nm as 002 grains grow out of existence in a kinetically limited competitive growth mode. In distinct contrast, films deposited with EN2+=20 eV grow in a cube-on-cube epitaxial relationship with the substrate and exhibit no indication of 111-oriented grains, even in the earliest stages. Increasing EN2+ to ...

An atomistic simulator for thin film deposition in three dimensions

Abstract: We describe an atomistic simulator for thin film deposition in three dimensions (ADEPT). The simulator is designed to bridge the atomic and mesoscopic length scales by using efficient algorithms, including an option to speed up surface diffusion using events with multiple diffusion hops. Sputtered particles are inserted and assigned ballistic trajectories with angular distributions appropriate for magnetron sputtering. Atoms on the surface of the film execute surface diffusion hops with rates that depend on the local configuration, and are consistent with microscopic reversibility. The potential energies are chosen to match information obtained from a database of first principles and molecular dynamics (MD) calculations. Efficient computation is accomplished by selecting atoms with probabilities that are proportional to their hop rates. A first implementation of grain boundary effects is accomplished by including an orientation variable with each occupied site. Energies and mobilities are assigned to atom...

Band-gap widening of CdO thin films

Abstract: CdO thin films were deposited on silica glass substrates by rf sputtering. The orientation of the crystal axis in the films was changed by varying the sputtering conditions. The (100)-oriented films were annealed under various conditions to change the carrier concentration. A blueshift of the optical absorption edge was observed as the carrier concentration increased, and band-gap widening was analyzed using the Burstein–Moss formula. We found that the intrinsic direct-band-gap Eg0 (Γ15–Γ1 gap) and the reduced effective mass mvc* are 2.22±0.01 eV and (0.274±0.013)m0, respectively, at room temperature. The results are discussed in relation to the band structure of CdO.

Method for deposition of a conformal layer on a substrate

Abstract: A method and apparatus for depositing a conformal dielectric layer employing a dep-etch technique features selectively reducing the flow of deposition gases into a process chamber where a substrate having a stepped surface to be covered by the conformal dielectric layer is disposed. By selectively reducing the flow of deposition gases into the process chamber, the concentration of a sputtering gas, from which a plasma is formed, in the process chamber is increased without increasing the pressure therein. It is preferred that the flow of deposition gases be periodically terminated so as to provide a sputtering gas concentration approaching 100%. In this fashion, the etch rate of a conformal dielectric layer having adequate gap-filling characteristics may be greatly increased, while allowing an increase in the deposition rate of the same.

Directional and ionized physical vapor deposition for microelectronics applications

Abstract: The manufacturing of interconnect features on semiconductor wafers has evolved from lift-off-based evaporation to reactive ion etching metallization and now to Damascene technology Physical sputter deposition has been widely used for blanket metal film deposition, but is impractical for high aspect topographies Filtered, or directional sputter techniques, such as long throw or collimation, have been used for some high aspect ratio applications, but suffer from poor efficiency, high cost, and/or poor scaling Ionized sputter deposition, which uses in-flight ionization of sputtered metal atoms and subsequent film deposition by means of a substrate potential, has been developed as a technique to extend physical vapor deposition into higher aspect ratios

Handbook of physical vapor deposition (PVD) processing : film formation, adhesion, surface preparation and contamination control

Abstract: Introduction * Substrate ("Real") Surfaces and Surface Modification * The Low-Pressure Gas and Vacuum Processing Environment * The Low-Pressure Plasma Processing Environment * Vacuum Evaporation and Vacuum Deposition * Physical Sputtering and Sputter Deposition (Sputtering) * Arc Vapor Deposition * Ion Plating and Ion Beam Assisted Deposition * Atomistic Film Growth and Some Growth-Related Film Properties * Film Characterization and some Basic Film Properties * Adhesion and Deadhesion * Cleaning * External Processing Environment. Appendix 1: Reference Material. Appendix 2: Transfer of Technology for R&D to Manufacturing. Glossary of Terms and Acronyms used in Surface Engineering. Index.

Comparison of transparent conductive oxide thin films prepared by a.c. and d.c. reactive magnetron sputtering

Abstract: Antimony-doped tin oxide and aluminum-doped zinc oxide films have been prepared by reactive a.c. and d.c. magnetron sputtering (a.c. excitation at frequency of 40 kHz; twin-cathode arrangement) from metallic targets at substrate temperature of about 573 K. The optical, electrical and structural properties of the sputtered SnO2:Sb and ZnO:Al thin films of different dopant concentrations have been investigated by means of optical spectroscopy (UV-IR), X-ray diffraction. Hall mobility and conductivity measurements. For antimony-doped SnO2 films a minimum resistivity of 1.5 × 10−3 Ω cm at high transparency (larger than 88% at film thickness of 250 nm) has been observed at dopant concentrations of about 1.2 at.% Sb in the layers. Low resistivity of 4.0 × 10−4 Ω cm and transmission in the visible spectral range of about 89% at film thickness of 550 nm has been obtained for as prepared aluminum-doped ZnO thin films. Furthermore, the investigations on a.c. plasma discharges using a planar plasma probe analyzer have revealed higher ion energies (up to some tenths of eV) and about 10 times higher ion current densities as in the case of d.c. magnetron sputtering at nearly the same deposition conditions.

Self-polarization effect in Pb(Zr,Ti)O3 thin films

Abstract: The self-polarization effect is investigated in Pb(Zr,Ti)O3 (PZT) thin films deposited by sol-gel and magnetron sputtering techniques. The effective piezoelectric coefficient of as-grown films, which is proportional to their initial polarization (self-polarization), is measured by a sensitive interferometric technique as a function of the annealing temperature, PZT composition, film thickness and bottom electrode material. The results indicate that the films are self-polarized by an internal bias field upon cooling through the phase transition temperature. It is suggested that a built-in field of a Schottky barrier between the PZT film and the bottom electrode is responsible for the observed effect. Self-polarization of the films is found to be very stable and in some cases to be as high as 90% of that produced by the subsequent room temperature poling. This property is very useful for piezoelectric and pyroelectric applications of PZT films since the poling procedure can be avoided. The properti...

Mechanical and tribological properties of multilayered PVD TiN/CrN, TiN/MoN, TiN/NbN and TiN/TaN coatings on cemented carbide

Abstract: Four different multilayered coatings TiN/CrN, TiN/MoN, TiN/NbN and TiN/TaN, were deposited on cemented carbide A hybrid PVD process consisting of ion plating (TiN) and magnetron sputtering (CrN, MoN, NbN and TaN) was used The chemical and phase composition, morphology and microstructure of the coatings were assessed using auger electron spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively In addition, all coatings were characterised with respect to their residual stress, hardness, cohesion/adhesion and abrasive wear resistance A PVD TiN coating was used as a reference throughout the investigation All coatings exhibited a cubic NaCl structure Furthermore, all multilayered coatings, except TiN/MoN, were found to have a strongly preferred (200) orientation TiN/MoN displayed a mixture consisting of (111), (200) and (220) orientations TiN displayed a (111)-preferred orientation It was found that the mechanical and tribological properties of the multilayered TiN/metal nitride coatings, in general, were superior to those of homogenous TiN The overall best performance was found for the TiN/CrN coating, whereas TiN/TaN showed the highest abrasive wear resistance

Yttrium oxide films prepared by pulsed laser deposition

Abstract: Yttrium oxide, Y2O3, films were prepared by pulsed laser deposition in the presence of oxygen (O2) gas. The microstructures of these films were found to be highly dependent on the deposition temperature and the amount of O2 gas used during the deposition process. X-ray diffraction (XRD) analysis showed that the Y2O3 films transformed from amorphous to polycrystalline form when the deposition temperature was increased to 350 °C at an O2 pressure of 0.01 mbar, and an extremely strong XRD peak originated from Y2O3(111) orientation was observed when the deposition temperature was increased above 400 °C. However, during the deposition at a fixed temperature (650 °C), the Y2O3 films became amorphous when the O2 pressure was successively increased. For the films deposited on either fused silica or silicon substrate between 150 and 650 °C, very smooth surface morphologies with an average surface roughness of 0.4–19 nm have been observed by an atomic force microscopy. UV/Visible spectrometer and Fourier transform ...

Synthesis of pseudobinary Cr-Al-N films with B1 structure by rf-assisted magnetron sputtering method

Abstract: Pseudobinary Cr-Al-N films were synthesized by a new inductively combined rf-plasma assisted magnetron sputtering method. It was found that phase transition from B1 (NaCl) structure to B4 (wurtzite) structure occurs at an AlN content between 70 mol% and 80mol%, and the critical composition for the phase transition showed excellent agreement with the composition (77mol% AlN) predicted by two band parameters. It was found that the aging effect is observed in the pseudobinary nitride films synthesized by the new magnetron sputtering method. No preferred orientation was observed in as-deposited pseudobinary nitride films with B1 structure, while preferred orientation appeared in these films after aging at room temperature for six months.

Dielectric stencil-defined write head for MR, GMR, and spin valve high density recording heads

Abstract: A thin film head apparatus and method for forming such a thin film head. In one approach, the present invention recites forming a cavity in a dielectric layer. Next, a layer of high magnetic field saturation (HBsat) material is sputter-deposited over the dielectric layer such that the HBsat material is deposited into the cavity formed in the dielectric layer. The cavity in the dielectric layer functions as a mold or “stencil” for the HBsat material. The HBsat material deposited into the cavity is used to form the first core of a thin film head. After the formation of the first core of the thin film head, a gap layer of material is deposited above the dielectric layer and above the first core. Next, a layer of HBsat material is sputter-deposited above the gap layer of material and above the first core of the thin film head. The layer of HBsat material disposed above the gap layer of material and above the first core is used to form the second core of the thin film head. Hence, this invention forms first and second cores of a thin film head using sputter deposition processes. As a result, selected HBsat materials which were not well suited to conventional thin film head formation methods can now be used to form the cores of thin film head structures.