Patterned deposition by plasma enhanced spatial atomic layer deposition

An atmospheric pressure plasma enhanced atomic layer deposition reactor has been developed, to deposit Al₂O₃ films from trimethyl aluminum and an He/O₂ plasma. This technique can be used for 2D patterned deposition in a single in‐line process by making use of switched localized plasma sources. It was observed that the sharpness of the patterns is primarily influenced by the concentration of reactive plasma species and by the dimensions of the plasma source. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thick gold-film deposition by high-repetition visible pulsed-laser chemical vapor deposition

A highly conductive gold film, over 10 m-thick with well-controlled linewidth, has been successfully deposited from dimethyl-gold-acetylacetonate and its fluorinated derivative by pyrolytic CVD (Chemical Vapor Deposition) with a high-repetition, visible, pulsed laser. The thermal damage to the polyimide substrate has been substantially suppressed by reducing the thermal diffusion length within 0.2 m in pulsed-laser-induced transient heating, in contrast to the cw laser-CVD scheme. Reproducible and low contact resistance as low as 0.5 between the written line and the existing gold line has been obtained. Sufficiently tough adhesion to polyimide has been observed for the deposit from dimethyl-gold-acetylacetonate. Reasonable agreement has been obtained between the observed deposition characteristics and analytical results for precursor supply rate and temperature increase during short-pulse irradiation.     

Pulsed laser deposition

In this paper we discuss some fundamentals on uniform target ablation and present some new results on thin films of high-temperature superconductors, ferroelectrics, and polymers.     

Focused helium-ion-beam-induced deposition

The recent introduction of the helium ion microscope (HIM) offers new possibilities for materials modification and fabrication with spatial resolution below 10 nm. In particular, the specific interaction of He⁺ ions in the tens of keV energy range with materials—i.e., minimal deflection and mainly energy loss via electronic excitations—renders the HIM a special tool for ion-beam-induced deposition. In this work, an overview is given of all studies of helium-ion-beam-induced deposition (He-IBID) that appeared in the literature before summer 2014. Continuum models that describe the deposition processes are presented in detail, with emphasis on precursor depletion and replenishment. In addition, a Monte Carlo model is discussed. Basic experimental He-IBID studies are critically examined. They show deposition rates of up to 0.1 nm³/ion. Analysis by means of a continuum model yields the precursor diffusion constant and the cross sections for beam-induced precursor decomposition and beam-induced desorption. Moreover, it is shown that deposition takes place only in a small zone around the beam impact point. Furthermore, the characterization of deposited materials is discussed in terms of microstructure and resistivity. It is shown that He-IBID material resembles more electron-beam-induced-deposition (EBID) material than Ga-ion-beam-induced-deposition (Ga-IBID) material. Nevertheless, the spatial resolution for He-IBID is in general better than for EBID and Ga-IBID; in particular, proximity effects are minimal.     

Influence of inert gas pressure on deposition rate during pulsed laser deposition

The deposition rates of permalloy and Ag are monitored during pulsed laser deposition in different inert gas atmospheres. Under ultrahigh vacuum conditions, resputtering from the film surface occurs due to the presence of energetic particles in the plasma plume. With increasing gas pressure, a reduction of the particle energy is accompanied with a decrease of resputtering and a rise in the deposition rate for materials with high sputtering yield. In contrast, at higher gas pressures, scattering of ablated material out of the deposition path between target and substrate is observed, leading to a decrease in the deposition rate. While in the case of Xe and Ar these processes strongly overlap, they are best separated in He. A He pressure of about 0.4 mbar should be used to reduce the kinetic energy of the deposited particles, to reach the maximum deposition rate and to avoid implantation of the particles. This is helpful for the preparation of stoichiometric metallic alloy films and multilayers with sharp interfaces. Received: 27 March 2002 / Accepted: 3 April 2002 / Published online: 5 July 2002     

MAPLE deposition of biomaterial multilayers

Double layers of polyethylene glycol (PEG) and 3-(3,4-dihydroxyphenyl)-2-methyl-l-alanine (m-DOPA) thin films were obtained by matrix assisted pulsed laser evaporation (MAPLE) technique, by depositing a first layer of m-DOPA on Si substrate and a second layer of PEG on top of it. The films were characterized by low angle X-ray diffraction (LAXRD), X-ray reflectivity (XRR), atomic force microscopy (AFM), and micro-Raman spectroscopy. From these analyses it resulted that PEG was deposited without any relevant damage both in terms of chemical structure and molecular weight. Furthermore, PEG chains were mostly in the extended conformation, although PEG micelles appeared.     

Chemical vapor deposition of diamond

In the recent decade a multitude of diamond thin film production methods has been developed, generally based on chemical vapor deposition processes from thermally or plasma activated gas phases. Diagnostic studies, growth experiments and numerical kinetic investigations have in recent years lead to an improved understanding of the prerequisites of continuous diamond growth and of the chemical processes involved. While the mechanism of carbon incorporation into the diamond surface is not yet known completely, the gas-phase species which are essential in a diamond-growth atmosphere can be narrowed to a small number, whose role in the gas-phase chemistry is quite well known.     

Selective tungsten deposition into ordered nanohole arrays of anodic porous alumina by electron-beam-induced deposition

The selective deposition of a metal (tungsten) into ordered nanohole arrays of an anodic porous alumina membrane was performed using an electron-beam-induced deposition process. After deposition, the membrane was observed and analyzed using electron microscopy and energy-dispersive X-ray spectroscopy. It is shown that the deposition was preferentially conducted in the holes in the irradiated area of the electron beam. A calculation of the electron-beam intensity explains the reason for the preferential deposition in the holes. PACS 81.07.-b; 81.16.Rf; 61.46.+w     

Inverse pulsed laser deposition

Since the advent of pulsed laser deposition (PLD), several different target-substrate arrangements have been proposed. Besides the most common on-axis PLD, several off-axis geometries were studied, mainly to protect the substrate from the agglomerated species (clusters, droplets, particulates) of the plasma plume, which are detrimental to the homogeneity of films. Recently we introduced a novel geometry, termed inverse pulsed laser deposition (IPLD), in which the substrate is placed parallel to and slightly above the target plane. In this paper we summarize our results on this new geometry, and show how it can extend the perspectives of pulsed laser deposition, e.g., by improving the surface morphology of the films. Effects of ambient pressure are presented and exemplified on metallic and compound IPLD films, including Ti, CN _x , and Ti-oxides. AFM topographic images are used to prove that under optimized conditions IPLD is capable of growing compact and smooth films that are superior to PLD ones. A special—but easy-to-implement—IPLD arrangement is also introduced that considerably improves the homogeneity of IPLD films. In this geometry, the properties (e.g., deposition rate and roughness) of the films grown in the 1–25 Pa pressure domain are examined.     

Electrospray deposition in vacuum

We have used the established technique of electrospray in developing a portable vacuum electrospray system which can deposit, in vacuo, dissolved molecules onto a sample which may then be analysed by UHV techniques. As an initial test of the system we have analysed silicon samples with an electrosprayed layer of poly(ethylene) oxide (PEO) using atomic force microscopy (AFM). The polymer forms different structures depending on the voltage applied to the emitter, and solution composition. The system is part of our ongoing effort to deposit other materials such as nanoparticles, and large dye molecules for developing molecular dye sensitised solar cells.     

XRD study on the effect of the deposition condition on pulsed laser deposition of ZnO films

Using a pulsed laser deposition (PLD) process on a ZnO target in an oxygen atmosphere, thin films of this material have been deposited on Si(111) substrates. An Nd: YAG pulsed laser with a wavelength of 1064 nm was used as the laser source. The influences of the deposition temperature, laser energy, annealing temperature and focus lens position on the crystallinity of ZnO films were analyzed by X-ray diffraction. The results show that the ZnO thin films obtained at the deposition temperature of 400°C and the laser energy of 250 mJ have the best crystalline quality in our experimental conditions. The ZnO thin films fabricated at substrate temperature 400°C were annealed at the temperatures from 400°C to 800°C in an atmosphere of N₂. The results show that crystalline quality has been improved by annealing, the optimum temperature being 600°C. The position of the focusing lens has a strong influence on pulsed laser deposition of the ZnO thin films and the optimum position is 59.5 cm from the target surface for optics with a focal length of 70 cm.      

Laser-reactive ablation deposition of silicon-nitride films

Silicon-nitride films were deposited on silicon waters by XeCl (308 nm) excimer-laser ablation of silicon in low-pressure (0.05–5 mbar) ammonia atmospheres. Series of 10 000 pulses at the repetition rate of 8 Hz were directed to the target surface. The fluence was set at about 5 J/cm². Pulse duration was about 30 ns. The deposited films were characterized by different techniques (X-ray diffraction, X-ray photoelectron spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectrometry, scanning electron microscopy, profilometry). Silicon-nitride films with thickness close to 1 m were obtained under specific experimental conditions.     

Studies of deposition in hill cloud

Summary The occurrence of cloud at ground level over hills is particularly difficult to categorise and quantify in complex mountainous terrain, and has constituted a major part of our studies as described below. For routine calculations, concentrations in hill cloud have to be estimated from daily observations at the limited national network of air and precipitation monitoring stations, coupled with meteorological data, leading to additional complications. Further approximations have to be made to calculate deposition rates, and the preliminary estimates of bulk annual deposition given in this paper. However the observed pattern of forest damage raises questions about the large variations in exposure of individual trees, and the relevance of bulk annual deposition estimates averaged over large areas. A tentative approach to identifying particularly damaging episodic conditions for tree foliage is also outlined. Paper presented at the GNFAO/EURASAP Meeting, Turin, September 1989. To speed up publication, proofs were not sent to the authors and were supervised by the Scientific Committee.     

Reaction and deposition of laser-evaporated iron

Reaction of laser-evaporated iron atom was investigated by Mössbauer spectroscopy and was applied for the production of films. Iron oxide films were produced by laser-deposition of Fe metal and hematite solid onto Al substrates, and the compositions of the films changed depending on the pressure of the O₂ atmosphere and the temperature of the substrates. The spin orientations of α-Fe films deposited by three types of deposition methods were compared. The nuclear spin of iron films produced by deposition of Fe atoms vaporized by resistive heating was perpendicular to the substrate surface, while that of films produced by laser-deposition of Fe was parallel to the substrate surface. The nuclear spins of iron films produced using an arc-plasma-gun were linear orientations along nanometer-sized grooves on the Al substrate surface.     

氧化物薄膜的离子束溅射沉积

用离子束溅射沉积的方法制备的TiO_2、ZrO_2薄膜的光吸收损耗明显降低,对其折射率、光吸收和抗激光损伤阈值等特性进行了分析.     

Pulsed laser deposition of polymer-metal nanocomposites

Different polymer-metal nanocomposites, metal clusters on a polymer surface and for the first time also polymer/metal multilayers, were pulsed laser deposited at a wavelength of 248 nm. Poly(methyl methacrylate) (PMMA) and Bisphenol A dimeth-acrylate (BisDMA), which strongly differ in their hardness of 3 and 180 N/mm², respectively, were taken as polymer components. Metals Ag and Cu were chosen because of their different reactivity to polymers. When depositing Ag on PMMA, spherical clusters are formed due to high diffusion and total coalescence. For Cu, much smaller grains with partially elongated shapes occur because of lower diffusivity and incomplete coalescence. Compared to the results on the soft PMMA, the clusters formed on the harder BisDMA are much larger due to higher diffusivity on this underlayer. In PMMA/Cu multilayers, wavy layered structures and buckling is observed due to relaxation of compressive stress in the Cu layers. Smooth Cu layers with higher thicknesses can only be obtained, when the hardness of the polymer is sufficiently high, as in the case of BisDMA/Cu multilayers.