R. P. Netterfield

Modification of the optical and structural properties of dielectric ZrO2 films by ion‐assisted deposition

Low‐energy bombardment by argon and oxygen ions has been used in the deposition of thin dielectric films of ZrO2. The film packing density has been improved from 0.83 to unity with a corresponding increase in the refractive index from 1.84 to 2.19. The highest stable refractive index measured was 2.23 for oxygen ion‐assisted deposition of ZrO2 on a substrate heated to 300u2009°C. Ion bombardment during condensation of evaporated ZrO2 on a room temperature substrate results in crystallization into the cubic phase which is consistent with previous studies of ion impact crystallization by thermal‐spike processes. At elevated substrate temperatures the monoclinic phase is also present.

Deposition of TiN, TiC, and TiO2 films by filtered arc evaporation

Abstract A filtered arc deposition process was used in the reactive deposition of macroparticle-free TiO 2 , TiN, and TiC films. The TiO 2 films were reactively deposited by arc evaporation of titanium in an oxygen atmosphere. The films deposited onto glass substrates heated to 350 °C had a rutile structure and a refractive index n 6.33 of 2.735 and extinction coefficient k 6.33 of 0.07. Films of TiN and TiC were prepared by reactive evaporation in nitrogen and methane respectively. The lattice parameters and preferred orientations of the deposited films were measured as a function of negative substrate bias. The films were characterized by microhardness measurements, X-ray photoelectron spectroscopy and X-ray diffraction.

The properties of TiN films deposited by filtered arc evaporation

Abstract Titanium nitride films were deposited on steel and silicon substrates using a filtered arc evaporation process. The microhardness, crystallite size, residual stress, adhesion, surface roughness and crystallographic orientation of the films were studied as a function of substrate bias over the range 0 to -400 V. The mechanical and structural properties were found to depend upon the degree of substrate bias. The spectral reflectance in the region between 250 and 2500 nm was measured and compared with Kr + ion-assisted deposited TiN films. In addition, the electrical resistivity and the superconducting transition temperature of the filtered arc deposited TiN films were measured to be 20 μΩ cm and 4.3 K respectively.

Ion-beam-deposited films produced by filtered arcevaporation

Abstract A filtered arc evaporation source has been used to deposit films of carbon, aluminium, Al2O3, AIN, vanadium, VN, VO2, titanium, TiN, copper, zirconium, ZrO2, ZrN and steel. The films are of high optical quality and free of macroparticles. The microhardness of the deposited films has been measured and found to range from 1040 HV 5 for ZrO2 to 3600 HV 5 for carbon. The optical properties of deposited ZrO2 and Al2O3 have been measured and found to be equivalent to the values reported for evaporated and ion-plated films. The deposition rates have been estimated at 40 μm h−1 for titanium and 35 μm h −1 for Al2O3. The process is found to be a practical high rate deposition technique suitable for the deposition of a wide range of technologically important materials.

Protective dielectric coatings produced by ion-assisted deposition

Optically transparent dielectric films, when prepared by thermal evaporation or sputtering, have had limited use for many applications due to their permeability and lack of stability. We report on protective dielectric films produced by ion-beam-assisted deposition which demonstrate significant improvements over films produced by conventional deposition techniques. This result can be explained in terms of the increased packing density of ion-assisted films over the porous columnar microstructure usually associated with evaporated films. In addition, ion bombardment of the metal films produced the most stable structures and also substantially improved the adhesion of the films. The endurance under chemical attack of these films was found to be limited by the surface finish of the substrates.

Characterization of growing thin films by insitu ellipsometry, spectral reflectance and transmittance measurements, and ion‐scattering spectroscopy

A versatile ultrahigh‐vacuum thin‐film deposition and analysis system is described. Films are deposited by electron beam evaporation with the possibility of ion beam bombardment of the growing film. Measurements of the reflectance and/or transmittance of the coating surface can be made simultaneously at 16 wavelengths across the visible or infrared spectrum. Ellipsometric measurements can also be made in situ, at a single wavelength and single angle of incidence, by an ellipsometer which can operate in either an automatic rotating analyzer mode or a manual nulling mode. The system is also equipped with an ion gun producing a submillimeter spot, and with a hemispherical sector, ion energy analyzer for ion scattering spectroscopy studies of the film surface. Results obtained during the deposition of a gold film are presented to demonstrate the capability of the system.

Growth dynamics of aluminum nitride and aluminum oxide thin films synthesized by ion‐assisted deposition

Some aspects of the dynamics of thin‐film synthesis of aluminum nitride and aluminum oxide produced by ion‐assisted deposition have been deduced from in situ measurements by ellipsometry, photometry, and ion scattering spectroscopy. Measurements obtained during the etching of aluminum films by nitrogen and oxygen ion beams have established the thickness of the synthesized layer and the rate of compound formation. Some of these measurements have been compared with a theoretical model which predicts the time evolution of the synthesized surface layer as well as the steady‐state layer thickness. The breakdown voltage and variation of capacitance with applied voltage of aluminum oxide films prepared by ion‐assisted deposition are also presented. Furthermore, the optical properties of ion‐assisted AlN and Al2O3 in the visible region are given.

The structure and properties of ion‐beam‐synthesized boron nitride films

Films containing boron and nitrogen were prepared by electron‐beam evaporation of boron and bombardment of the growing film with nitrogen ions of energy up to 1500 eV. Hard films of high transparency (extinction coefficient <0.01) were prepared with nitrogen‐to‐boron atomic arrival ratios greater than one. The optical constants in the visible part of the spectrum were determined as a function of B‐to‐N atomic ratio in the film and substrate temperature using optical photometry. Measurements of the optical constants were extended to 40 eV using a Kramers–Kronig analysis of electron‐energy‐loss spectra. Boron‐to‐nitrogen atomic arrival rates were determined and show that as ion energy and substrate temperature are increased ion flux must be increased to achieve the same stoichiometry. Film structure was imaged using high‐resolution electron microscopy, and the radial distribution function (RDF) was determined. The RDF of stoichiometric films showed that high substrate temperatures increased the size of the ...

Characterization of the Optical Properties and Composition of TiNx Thin Films by Spectroscopic Ellipsometry and X-ray Photoelectron Spectroscopy

Thin films of TiN x with 0.34 < x < 1.19 were deposited on silicon substrates by a filtered arc deposition process. Spectroscopic ellipsometry (SE) in the energy region 1.5-3.5 eV was used to measure the optical properties of the films. X-ray photoelectron spectroscopy (XPS) was used to determine the relative atomic concentration and the chemical states of the elements. The dielectric function e(ω) measured by ellipsometry gives the optical response of TiN x films and valuable information on their chemical composition, which is also verified by XPS. The plasma energy ω p of TiN x films was found to depend strongly on the N/Ti ratio and this is correlated with the value of x as determined by XPS and Rutherford backscattering spectroscopy (RBS). The results show that, via the calibration, spectroscopic ellipsometry may be used to estimate the stoichiometry of deposited TiN x films.

Properties of ZrNx prepared by ion-assisted deposition

Preparation de couches minces caracteristiques de ZrN et Zr 3 N 4 , et caracterisation de ces couches par ellipsometrie, reflectance et transmittance spectrales, emission photoelectronique, diffraction electronique, spectrometrie de perte denergie delectrons et retrodiffusion de Rutherford