Bombardment Of Substrate Research Articles

Ion beam assisted electron gun deposition of MgF2 thin films

SummaryA traditional method for increasing the density of the optical films, is heating the substrate. An alternative way to increase the density of the film, is bombardment of substrate by ions during film growth. This method is known as ion assisted deposition (IAD). In this paper, magnesium fluoride, MgF2, thin film has been produced on a glass substrate by ion assisted deposition method. The effects of ion energy have been studied on density and refractive index film. Reflection, transmission and scattering spectra of the samples were measured by a spectrophotometer. Moreover, Atomic force microscope (AFM) is prepared. Using these measurements, optical and physical properties of the films are analyzed. A sample of MgF2 film has been produced without ion bombardment so that one can compare the effect of ion bombardment.

Improvement in luminance efficiency of organic light emitting diodes by suppression of secondary electron bombardment of substrate during sputter deposition of top electrode films

In this study, we investigated the degradation mechanisms of the luminance performance of organic light-emitting diodes (OLEDs) when their top electrode films were deposited by sputter deposition process. During the sputter deposition of the top electrode films, the suppression of the incidence of high-energy electrons on the substrate was attempted using various methods. As a result, we found that during electrode deposition, the incidence of the high-energy secondary electrons, which were emitted from the target surface, on the substrate was the main cause of the significant degradation of the luminance performance. It was also found that the application of a magnetic field by setting permanent magnets near the substrate holder and the insertion of a shield plate near the target cathode were effective in suppressing the incidence of secondary electrons on the substrate.

Structural modification of TiAlN coatings by preliminary Ti Ion bombardment of a steel substrate

The TiAlN coatings deposited onto steel 12Cr18Ni9Ti substrates before and after preliminary treatment by Ti ion beams are studied by X-ray diffraction, transmission electron microscopy, atomic force microscopy, and nanoindentation. The modification of the surface layer of a substrate is shown to change the structure and the preferred orientation of the coatings. The mechanical properties of the TiAlN coatings are found to depend substantially on the ion bombardment time.

Evolution of pattern formation under ion bombardment of substrate

Abstract Processes of self-organization described by a nonlinear evolution equation of sixth order are considered on substrate surfaces after ion beam bombardment. Five families of exact solutions are found for the nonlinear evolution equation. A numerical method enabling one to solve the boundary value problem is presented. Simulation of the pattern formation and classification of their profiles are given. The influence of the third, fifth order dispersion terms and a nonlinear diffusion term on processes of the pattern formation is discussed.

Increasing of Hardness of Titanium Using Energetic Nitrogen Ions from Sahand as a Filippov Type Plasma Focus Facility

In this paper a 90 kJ plasma focus facility was used to the bombardment of the titanium substrate using nitrogen ion beams. From x-ray diffraction patterns, we investigated the structure properties of titanium nitride layer has been successfully deposited on the titanium substrate such as grain size microstrain and dislocation density. In this work we observed the growth of in grain size with increasing a number of deposition shots. Decrease in dislocation density and microstrain at higher deposition is the another results we observed in this work. The topography and morphology of TiN samples was studied by scanning electron microscopy (SEM) and optical microscopy images. From SEM micrograph, damage of surface and creation of pits and cracks was reported. The goniometric test indicate increasing in contact angle of water drop for irradiated samples in respect to the unirradiated samples. The Knoop microhardness of the samples is increased about 500%. With increasing of nitrogen ion flux, the microhardness increases.

Influence of sputtering parameters on crystalline structure of ZnO thin films

The relations between the sputtering parameters and the crystalline microstructure of ZnO thin films are presented. The energetic bombardment of substrate by neutral atoms, ions and electrons during sputtering is characterized by total energy flux density which affects the film. This parameter can be estimated by RF power, substrate bias voltage and concentration of reactive gases. Substrate temperature and total energy flux density are the major parameters which have a significant influence on ZnO thin film crystalline structure.

Diamond like carbon films deposited from graphite target by asymmetric bipolar pulsed-DC magnetron sputtering

Diamond like carbon (DLC) thin films have been deposited at room temperature from a graphite target by asymmetric bipolar pulsed-DC reactive magnetron sputtering. DC bias was applied to the substrate holder between 0 and − 300 V. Pulsed-DC power density and pressure were fixed at 4.4 W/cm 2 and 1.3 Pa. Pulse frequency was kept constant at 150 kHz. The results have been discussed in terms of the effects induced by substrate bias voltage. Pulsed-DC power increases the ionization of the plasma compared to processes using RF power. The conditions during the process can be described by a higher ion and electron density, the existence of more energetic species and an intense ion bombardment of substrate during the negative pulse. The substrate bias voltage induces considerable effects on deposition rate, intrinsic compressive stress and abrasive wear of the films, but it has no appreciable effect on the surface water contact angle of DLC films. Intrinsic compressive stress is limited by the carbon surface ion implantation, which in turn is controlled by the bias voltage applied to the substrate. The Davis model fitting indicates an increase in the averaged growth rate to ion flux ratio which could justify the decrease of compressive stress of the studied samples.

Cubic boron nitride deposition on silicon substrates at room temperature by KrF excimer laser ablation of h-BN

A hexagonal-BN target was ablated by high-fluence (6 and 12 J/cm2) KrF excimer laser pulses in low-pressure (5 Pa) N2 atmosphere, without any aid of ion bombardment and heating of the Si substrate. Investigations of the deposited films show that the cubic-BN phase was deposited. The film deposited at 6 J/cm2 appears to contain a higher cubic phase content with respect to the one deposited at 12 J/cm2.

AlN thin films prepared by ion beam induced chemical vapour deposition

AlN thin films have been prepared by bombardment of a suitable substrate with a beam of accelerated N 2 + ions (400 eV) while a flow of an organometallic precursor is directed onto its surface. This procedure has resulted in very compact and dense films of AlN obtained at room temperature. Since the films were amorphous by XRD, the formation of an AlN phase has been confirmed by different spectroscopies, while the morphology and optical properties of the films have been characterized by electron microscopy and ultraviolet-visible absorption.

Evaluation of adhesion strength of Ti films on Si(100) by the internal stress method

Titanium films were sputter deposited onto Si(100) surface. Adhesion strength of the Ti film was evaluated by the internal stress method. The Ti film was overcoated by a Ni coating in the state of a high internal stress, the value of which was about 0.5 GPa (tensile). The internal stress induces large normal and shear stress at the interface between the Ti film and the Si(100) surface. Those stresses increase with the increase of the Ni coating thickness. The stress distribution was evaluated by the finite element method. The evaluation shows that the normal stress on the interface is extremely large at the edge of the sample. This result suggests that a peeling of the Ti film is initiated at the edge and is consistent with observed spontaneous peeling phenomena. We could determine the adhesion strength of the Ti film by measuring the thickness of the Ni coating to peel off the Ti film. The value was found to range in 0.1–1 GPa region. The effect of the Ar ion bombardment of Si substrate on the adhesion enhancement was investigated in detail by this method.

Ion‐Beam‐Induced CVD: An Alternative Method of Thin Film Preparation

AbstractThe ion‐beam‐induced chemical vapor deposition method for the preparation of thin films consists of the bombardment of a suitable substrate with O or N ions of relatively high energy while a flow of an organometallic precursor is directed onto its surface. Single and mixed oxides and nitride thin films can be prepared by this procedure. This paper describes the principles of the method, and presents some examples of thin films prepared with it (TiO2, PbTiO3, AlxTiyOz, AlN, and SnO2). Some characterization results of these thin films by different techniques are reported, with special emphasis on physical and electronic methods such as X‐ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), and X‐ray absorption spectroscopy (XAS). Other aspects, such as the preferential removal of C, H, and other impurity atoms from the precursors under the action of oxygen beams, or the possibility of performing lithographic depositions of these dielectric materials, are also considered.

Energy of an excited atomic configuration in alloys

We investigate a model relating the excitation caused by ion bombardment of a metal substrate to the formation of an additional energy minimum relative to the equilibrium state for the excited atomic configuration. We present an explanation of the effects of changing the boundaries of solid solutions during ion implantation.

X-ray photoelectron spectroscopy study of growth of thin cerium films on polypropylene

From x-ray photoelectron spectroscopy (XPS) measurements of thermally evaporated cerium films on polypropylene (PP) we conclude that an ion bombardment pretreatment of the substrate significantly improves the deposited amount of cerium. The metal–polymer interface state is dependent upon the ion bombardment of the PP substrate. For a mild bombardment (Ar+ ions of kinetic energy less than 500 eV and doses less than 1015 ions/cm2) we observed the formation of Ce–C bonds, which are not observed if we apply a more energetic ion bombardment (ions kinetic energy 3 keV, doses≳1016 ions/cm2). The effect of the ion bombardment on the cerium film formation can be summarized in an increased coverage of the polymeric substrate for the same thickness of the cerium film. We find that the cerium film grows with a Volmer–Weber mechanism and the difference between treated and untreated samples consists in an increased coverage of the substrate by cerium for the treated samples. A new kind of plot of the XPS data is used to discriminate between different surface coverages. The XPS measurements have also shown that an oxidation of the cerium films takes place during the XPS measurements. Mass spectrometry of the residual gas composition of the ultrahigh vacuum system, where the XPS measurements are performed, shows that the x-rays induce an outgas of H2, water, OH, CO, and CO2 originating from the polypropylene substrate. Water in the PP is dissociated by x-ray influence and therefore is responsible for the oxidation of the cerium film.

The reaction of atomic oxygen with Si(100) and Si(111): II. Adsorption, passive oxidation and the effect of coincident ion bombardment

The reactions of atomic oxygen with the (100) and (111) surfaces of silicon have been investigated by employing supersonic molecular beam techniques, X-ray photoelectron spectroscopy (XPS), and low-energy ion scattering spectroscopy (ISS). Atomic oxygen adsorbs with unit probability on the clean silicon surface, independent of substrate temperature (110–800 K) and incident mean translational energy (3–16 kcal mol −1). Oxidation of clean silicon with an oxygen atom beam is characterized by wo stages: a “fast” stage that corresponds to oxygen chemisorption in the topmost 2–3 silicon layers; and a “slow” stage that corresponds to oxygen incorporation and oxide film growth. The chemisorption stage is described by first-order Langmuirian kinetics with an apparent saturation coverage of approximately 4 ML O(a), the oxide growth stage by lddirect” logarithmic kinetics, where d x/d t = α exp(− x/ L), where x is the oxide thickness. Observation of significant oxidation at substrate temperatures of 110 K suggests that oxie growth in the slow stage may occur bya field-assisted mechanism, where an internal electric field aids transport of oxygen to the underlying silicon substrate layers. XPS and ISS results support a two-dimensional layer-by-layer growth mechanism for oxidation at substrate temperatures below 900 K. At higher temperatures, T ≥ 1050 K, oxide growth is three-dimensional involving nucleation and growth of bulk-like oxide islands even for mean coverages as low as 3 ML O(a). ISS results lend support to the formation of “on-top” adsorbed oxygen atoms that cap silicon dangling bonds at the oxide/gas interface. Coincident bombardment of the silicon substrate with an Ar − ion beam leads to an enhanced rate of oxidation. The enhancement can be understood in terms of a model involving secondary implantation of adsorbed oxygen atoms, coupled with the simultaneous formation of reactive sites (e.g., dangling bonds, vacancies) for oxygen chemisorption. The effect of coincident ion bombardment is reduced at elevated substrate temperatures (∼ 800 K), since the resulting increased propensity for adlayer rearrangement leads to a decrease in the number of active sites for oxygen chemisorption.

Effect of film adhesion on tribological properties of silver-coated alumina

Soft metal films are seen as possible solid lubricants for sliding ceramics in high temperature environments. Ion bombardment of substrate and film can improve film adhesion and tribological properties of metal films deposited on ceramics. To provide a more detailed understanding of the relationship between measured adhesion strength, surface roughness, and wear performance of coatings, thin silver films were vapor deposited on smooth and roughened alumina substrates using 1 keV ion bombardment before and during deposition. A pull-type tester was used to measure the adhesion of films to the substrate. A ball-on-flat test machine was used to evaluate the wear of an uncoated alumina ball sliding on silver-coated substrates. Measurements of film adhesion and sliding wear, and a scanning electron microscopy examination of wear tracks, are reported. Ball wear on roughened surfaces was reduced by a factor of about 3 for poorly adhering coatings, but by a factor of about 130 for well-adhering coatings deposited after argon-oxygen sputter cleaning, compared with bare Al 2O 3. For films with the lowest wear, the silver coating wore off the tips of the asperities,but the film remained almost completely intact. For smooth flats, wear reductions by a factor of about 3 were obtained for well-adherent coatings.

AES analysis of sodium in a corroded bioglass using a low-temperature technique

Measurements have been made of sodium compositional profiles at a glass surface using Auger electron spectroscopy. It has been found that stable sodium signals may be obtained by lowering the temperature of the glass to 80 °K and by keeping the exciting electron beam current to less than 1 μA. Use of a low-energy electron flood gun had little effect on the AES measurement but was found to be valuable in reducing charging during ion bombardment of the low-temperature substrate. Observations on a glass designed for biological implant applications subjected to a simulated biological environment exposure showed that a region leached of alkali ions formed, and a Na-, Ca-, P-rich film built up on the surface.

Thermally stable photoresist polymer

AbstractA new photoresist stable to 500°C has been developed. The addition of potassium dichromate to a polyamic acid, believed to be the condensation product of pyromellitic dianhydride and 4,4′‐diaminodiphenylether, results in a photosensitive polymer which can be cast or spun. The resultant film after exposure, development and post‐bake is a crosslinked aromatic polyimide. An efficient developing solution consisting of a 5:1 mixture of hexamethylphosphoramide and dimethylsulfoxide has been discovered. The system has been fully characterized in terms of composition, film formation, exposure, development, hardening and removal. This material has already proven useful as an area‐controlled, thermally stable dielectric and as a sputter‐etch resist. It has been demonstrated that under the conditions of sputter‐etching (bombardment of substrate with Ar, Ar+ species with energies from 1–300 eV) commercial photoresists, of the polyisoprene variety, char to the extent of being ineffective as a masking material. Under these same conditions, the thermally stable resist retains its film integrity and uniform sputter‐etch rate. An exemplary processing sequence is included as an appendix.

Conducting Thin Films Formed by Electron Bombardment of Substrate

A new technique for depositing thin films has been investigated. The method consists in decomposing molecules on a substrate by bombarding them with electrons, leaving metal atoms on the substrate. The film is formed selectively on the area of the substrate struck by the electrons. Stannous chloride was decomposed to metallic tin by electrons of about 200 ev energy. Tetrabutyltin was also studied. With the current densities available, tetrabutyltin was only partially decomposed, to form a semiconducting polymer film. Theoretical considerations suggest that the method should be applicable to a wide variety of metals.