Dc Triode Sputtering Research Articles

Magnetic Properties of Nd-Fe-B Sputtered Films (II)

As trends continue toward lighter and more compact equipment, the preparation in thin film form of rare earth magnets with high energy products, by liquid quenching, sputtering and other methods, is being studied. In a previous report, the authors described the effect of the substrate temperature and film deposition rate on the magnetic properties of Nd-Fe-B films prepared by dc diode sputtering and reported that by choosing the film fabrication conditions appropriately, it was possible to obtain films with an anisotropy in the thickness direction. However, the films thus prepared had a small coercivity, and also suffered from poor reproducibility of magnetic characteristics. In the study reported, in consideration of the reproducibility of film properties, the authors used a dc triode sputtering method to prepare films, and investigated the effect of the annealing conditions on the film coercivity.

Preparation, patterning, and properties of thin YBa2Cu3O7−δ films

High TC superconducting thin films were prepared on (100) SrTiO3 substrates by dc triode sputtering and subsequent annealing. In these films Hall-bar structures having a width down to 5 μm were patterned using a reactive ion etching technique. Superconductivity above 77 K was observed. When compared with the original film there is only a small reduction in TC. The critical current density determined by electrical measurements is substantially reduced. On the other hand, the critical current density in the bulk of the grains as measured by the torque on a film is not reduced by the patterning process. It is suggested that superconductor-normal metal-superconductor junctions between the grains account for this difference.

Magnetic properties of Ni-Fe films prepared by a DC triode sputtering method

The magnetic properties of Ni-Fe films with 81-wt.% Ni prepared by a DC triode sputtering method are studied as functions of sputtering parameters. Two kinds of substrates are used: one is flat and the other is patterned. In the former case sufficiently low coercive forces are obtained when both the target voltage and the Ar pressure are kept below the critical values. In the latter case, a negative substrate bias voltage is necessary to improve the magnetic properties in addition to the previous conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Partial structure of Ni-Ni correlation in Ni-42 at.%V amorphous alloy by neutron diffraction

The plate-like Ni-42 at.%V amorphous alloy was prepared by a DC triode sputtering method. The structure factors were obtained by TOF pulsed-neutron scattering and normal X-ray diffraction. The partial structure factor of the Ni-Ni correlation was directly observed by neutron diffraction, because the neutron coherent scattering length of a vanadium atom is very small. It is interesting to note that the prepeak located at Q approximately 1.9 AA-1 in SNiNi(Q) and observed in Ni-42 at.%V amorphous alloy was the same in Ni-M(Ti or Zr) amorphous alloys. This prepeak is related to the second-neighbour ordering of the Ni-Ni correlation, which is enhanced by decreasing the Ni atom content.

Superconducting and structural properties of sputtered thin films of YBa2Cu3O7−x

We have fabricated thin films of YBa2Cu3Ox by dc triode sputtering from two metallic targets. Post-annealing in pure O2 after sputtering resulted in superconducting films with a Tc onset as high as 89 K and a midpoint Tc of 75 K. We report preliminary results of films deposited on sapphire, MgO and sol-gel coatings of ZrO2 on sapphire, with and without buffer layers of Ag. The chemical and physical structures of these films were analyzed by using several x-ray diffraction techniques and Rutherford backscattering spectroscopy.

Magnetic properties of Fe-Al-Si films prepared by a DC triode sputtering method

The magnetic properties of FeAlSi films prepared using a DC triode sputtering method are studied. The FeAlSi film must be annealed above 500°C in order to improve the magnetic properties. The thermal expansion coefficient of substrates has less influence on the magnetic properties as the film thickness increases. The dependence of the magnetic properties on the film thickness is related to the film structure.

Magnetic studies in multilayer Ni-C films

Multilayer Ni-C films have been prepared using dc triode sputtering with a fixed C layer of 2 nm thick and with a Ni layer varying from 3 to 10 nm thick. The C layer is amorphous and the structure of the Ni layer is hexagonal for 3 nm thick but becomes fcc when the thickness is above 6 nm. The magnetization is strongly reduced which is attributed to the presence of nonmagnetic layers at each interface. These layers could be Ni3C. FMR indicates an easy perpendicular axis for t(Ni)&amp;gt;20 nm, but for t(Ni)&amp;lt;7 nm, the films develop an easy plane anisotropy. The Hc and the linewidth increases for t(Ni)&amp;lt;7 nm. Annealing at 473 K in vacuum leads to an increase in 4πM, indicating that C atoms are segregating out of the Ni layer and that the Ni film crystallizes better. The perpendicular anisotropy also develops strongly after annealing. The results are discussed.

Deposition of zirconium boride thin films by direct current triode sputtering

Specular, crack-free thin films of the refractory conductor zirconium boride have been deposited for possible applications in combined contact/diffusion barrier metallization schemes. Films were deposited by dc triode sputtering, which allowed the independent study of the effects of sputtering pressure, target voltage, and current on the film properties. The mole ratio of boron in the films increased (composition tending to ZrB2) and the resistivity decreased with increasing deposition rates which at a fixed target voltage and sputtering pressure increased almost linearly with target current. Decrease in sputtering pressure, with only a minor change in deposition rate, dramatically decreased resistivity and caused stress in the films to change from tensile to compressive. X-ray photoelectron spectroscopy correlated reduced oxygen content to reduced resistivity. Triode sputtering permitted deposition of films at 2 mTorr with a resistivity of 162 μΩ cm which is the lowest reported value for as-deposited films.

Interface Effects of Laser Ablated and Sputtered High Tc Superconducting Thin Films

ABSTRACTHigh Tc superconducting thin films were prepared by DC triode sputtering and laser ablation. With both deposition methods we were able to fabricate thin films on SrTiO3 which show an onset at Tcf=92 K. The superconductive transition is complete at Tcf=86 K. On other substrates like Al2O3, MgO and ZrO2 relatively poor results were obtained.

Superconducting Superlattice Structures

ABSTRACTSuperlattice superconductors exhibit behavior different from other “homogeneous” superconductors because of their layered structures. Sputtering has proved to be an excellent technique for producing such multilayered systems. Also, systems naturally having layered structures, such as the new high-Tc materials, can be fabricated by sputtering. Here we describe the preparation of superconducting superlattices by dc triode sputtering and techniques useful for characterizing them. In particular, we discuss Mo/Ta superconducting superlattices and high Tc thin films of YBa2Cu3O7-x.

Spectroscopic investigation of tantalum nitride thin film deposition by reactive sputtering in a triode system

In the present paper the change of the partial pressure of nitrogen during reactive dc triode sputtering of a Ta target in Ar+N 2 gas mixture is spectroscopically investigated by means of a quadrupole mass spectrometer. AES analysis of thin films, deposited at different N 2 partial pressures is carried out and the atomic concentration of the contaminants in the films is investigated. It is established that the change of nitrogen content in the sputtering gas and in the deposited films at different N 2 partial pressures is connected with a nitridation of the Ta target.

Intermediate range order in pure and hydrogenated thin amorphous Si films

One micrometer thick pure and hydrogenated Si films have been prepared by DC triode sputtering onto Si single crystals for coupled X ray and Infra-red characterization. Topological features of the amorphous relaxation process and transition to the microcrystalline state are described and associated with modifications of the atomic population under the peaks of the radial distribution function corresponding to intermediate range order (I.R.O.). Hydrogenated material I.R.O. lies in between that observed in unrelaxed and relaxed pure a. Si films. The indirect effect of SiH bond conformation on the Si network structure is also investigated.

An evaluation of chromium deposited by high rate sputtering

The structure, chemical composition and hardness of 0.005 cm (0.002 in.) thick sputter-deposited chromium coatings produced at deposition rates of 2 to 5 nm/s (0.3 to 0.7 mils/h), substrate temperatures of 20‡C and 60‡C, and substrate potentials of -30 V (floating) and -50 V, with respect to ground, in a dc-triode sputtering system were examined. The chromium coatings were examined by X-ray diffraction, optical metallography, and scanning electron microscopy of fracture and growth surfaces. Trace element analysis and krypton analysis of powdered target and deposit material were performed by X-ray energy spectroscopy. Diamond pyramid and Knoop microhardness measurements were made on transverse sections. The chromium structure, krypton content and properties were influenced by substrate temperature and potential with little effect of target voltage and deposition rate. Both the deposit hardness and crystal lattice parameter decreased with increasing substrate temperature. A substrate bias of -50 V during deposition altered both the growth morphology and the krypton content of the chromium, but had little effect on the lattice parameter relative to a -30 V substrate potential (floating). A hardness increase of 150 KHN, a marked grain refinement and an increase in surface reflectivity accompanied the change in growth morphology.

1300. Argon entrapment in metal films by dc triode sputtering: W W Y Lee and D Oblas, J Appl Phys, 46 (4), 1975, 1728–1732

1300. Argon entrapment in metal films by dc triode sputtering: W W Y Lee and D Oblas, J Appl Phys, 46 (4), 1975, 1728–1732

Argon entrapment in metal films by dc triode sputtering

Sputtered films of 12 elementary metals were analyzed for argon content by an rf spark−source mass−spectrographic method. All films were deposited using dc triode sputtering under similar conditions. Corrections in the data have been made to account for variations in target size and deposition rate. The experimental results are compared with sticking probabilities calculated using the Born−Mayer interatomic potentials; the agreement is fair except for elements having low atomic numbers, e.g., Cu and lower. The data confirm the role of reflected argon atoms in the entrapment mechanism at the substrate—as the atomic mass of the target material increases, the average energy of the reflected energetic argon atoms also increases, leading to the increased argon content in the film. The data also suggest that the entrapped argon content is dependent upon the atomic spacing of the film material.

Practical Techniques for Improving Sputtered Film Quality

Conventional electrode geometry in dc diode, triode, and rf sputtering systems results in an inherently nonuniform plasma density, with accompanying nonuniformity of ion current density on the target and nonuniform film thickness. Furthermore charge effects often result in film contamination caused by sputtering of surfaces other than the target. This paper will present practical suggestions for improving deposited film quality and uniformity by the use of appropriately shaped plasma confining enclosures, consideration of the effects of ground planes, relative electrode size and spacing, and the application of suitable operating techniques. In addition the merits of combining substrate motion and sputtering through a shaped aperture window, will be discussed.