The stress formation during N/Ar ion assisted deposition of boron nitride films on Si(001) substrates was measured in-situ by a very sensitive capacity technique in dependence on the ion energy, temperature during deposition and the ion to atom arrival rate.

The stress evolution in dependence on the layer thickness is characterized by a high tensile stress in the initial stage of the film growth, followed by a transition from the tensile to the compressive stress state, a strong increase of the compressive stress with the film thickness. A simultaneous UV-light irradiation during the deposition process leads to a reduction of the compressive stress.

In this work we address the studies of enhancement in diamond growth on Ti-6AI-4V metal alloy by modifying the surface using the excimer laser ablation technique, prior to deposition of diamond. Ti-6Al-4V is chosen for its technological importance in aerospace industry, dental and bio-implant applications. Analysis of the structures of the film is done using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Ablation of the alloy by excimer laser pulses produces periodically hill/valley structures on the surface, thus increasing the density of diamond nucleation and film adhesion. The roughness of the alloy surface was measured to be in the 0.5μm – 1μm range with an average distance between peaks of the hill/valley structure measuring 1.5μm.

SiC thin films were formed on Si (111) at growth temperatures of 750–1000 °C using the molecular ion beam technique, with a precursor of methylsilicenium ions (SiCH3+). The chemical bindings and surface structures of SiC thin films were analyzed by Raman spectroscopy and reflection high-energy electron diffraction. As a result, 3C-SiC (111) was grown on Si (111) substrates without carbonized treatments.

Effects of ion-irradiation on oxidation of silicon at low temperatures (130°C) in an argon and oxygen mixed plasma excited by electron cyclotron resonance (ECR) interaction are investigated. First, dependence of energy and flux of incident ions on the flow rate and the microwave power is evaluated. It is shown that the flow rate and the microwave power are key parameters for controlling the energy and the flux of incident ions, respectively. Second, growth kinetics of the oxide films are studied. The growth rate depends on the energy and the flux of argon ions irradiated to the substrate, and the growth thickness increases proportionally to the root square of the oxidation time. Thus, the growth rate is limited by diffusion of oxidants enhanced by irradiation with argon ions. The effect of substrate bias on oxidation characteristics is also discussed. The electrical properties of the oxide films are improved by increasing the bias. The improvement is due to the reduction of damage at the surface of the substrate induced by the irradiation.

The Smart-Cut™ process and its variants involve H and/or He ion implantation and annealing to neatly exfoliate a layer of material as thin as the ion range. At low ion energy, as required for further miniaturisation, several effects may inhibit the process. We implanted undoped Si (100), (110) and (111) with 5 keV H or D ions at doses below (3–4×1016/cm2) or above (5.5×1016/cm2) the critical dose for blistering. The samples were either isochronally annealed for 1h or 2h in three steps at 500, 550 and 600°C, or subjected to thermal desorption spectroscopy (TDS) with linear ramps of 7.5 K/min up to 500, 550 or 600°C. The surface morphology was observed at each step by scanning electron or atomic force microscopy. Below the critical blistering dose, TDS only shows a broad high temperature (∼525°C) peak, while above that dose, a low temperature peak (∼360°C) also appears, though weakly in the case of (110) samples. The exfoliated area (as % of total surface) increases with temperature, and also varies with wafer orientation, being minimum for (110) samples and maximum for (111) samples. This orientation effect is much more pronounced for H-implants than for D-implants. All these trends indicate that ion channelling leads to an inhibition of exfoliation.

Strain relaxation in epitaxial Si-Ge structures induced by ion beam bombardment has been studied using a He+ channeling technique. It is shown that hot ion beam bombardment (230°C, Si+ ions with energy 200 keV and fluence 6·1013 ion/cm2) of thin strained Si-Ge layers results in partial strain relaxation. A model of the strain relaxation induced by radiation damage is proposed.

The purpose of these simulations is to study the mechanisms leading to surface damage during low-energy implants. Therefore the bombarded surface has a realistic vicinal structure and contains one step edge, SA or SB. The damaging event is produced by an atom, Ar or Si, of a low kinetic energy (≤ 30eV), moving on the surface or below it. The simulation indicates a total etching of the first two layers of silicon and the ejection of the implanted Ar. These features are independent on the step structure, on the direction of motion of the moving atom and they hold over a broad range of temperatures. However. if Ar and Si move below this critical depth, they may remain in the lattice as interstitials. The preferred location of these defects is the tetrahedral location at the center of the hexagonal rings. In addition to the formation of interstitials, also a corrugation of the atomic rows on the surface is observed. This effect has a characteristic dependence on the step structure and it is remarkably more pronounced for the SB non-rebonded steps than in the other cases.

Circuit patterned nucleation of copper or nickel atoms onto polyimide surface was demonstrated by using ArF excimer laser (λ=193nm) and copper sulfate aqueous solution (CuSO4.5H2O+nH2O), or nickel sulfate aqueous solution (NiSO4–6H2O+nH2O) in an atmospheric pressure. Photo-excited C-H bonds of the polyimide surface were effectively dehydrated with hydrogen atoms which were photodissociated from the water. The dangling bonds of the dehydrated hydrogen atoms were combined with the oxygen and the copper or nickel atoms that were photodissociated by CuSO4 solution or NiSO4 solution. Thus, C-O-Cu bonds or C-O-Ni bonds were formed on the surface. After this copper and nickel substitution, it was carried out onto the nucleated parts by usual electroless plating at 70 °C. In this process, the conductive circuit patterned copper or nickel thin film was deposited on polyimide surface.

We propose to combine layer deposition or crystal growth with an X-ray standing wave field to influence the structure of growth products in-situ on an atomic scale. By placing the periodic local density distribution of energy of these wave fields properly, photo-fragmentation of precursor gases and other relevant processes can be supported at definite atomic sites at the surface of substrates. In certain cases also a local variation of the probability of desorption can be favorable to remove atoms from unwanted adsorption sites. A large number of growth processes is conceivable, which can be affected intentionally that way. The general physical principle behind this proposal is the availability of non-thermal energy contributions on a sub-nanometer scale. The fundamentals of production and application of these wave fields are communicated as well as results of theoretical estimations.

Gallium arsenide (GaAs) is an important III-V semiconductor, due to its applicability to several high-end and consumable electronic devices. However, GaAs, unlike silicon (Si), does not have a stable native oxide that can stabilize and protect the surface from further oxidation and degradation. In this paper, we report the use of femtosecond laser-based modification of the GaAs surface, leading to its stabilization against oxidation, the use of ultrafast laser-based processing and its effectiveness compared to conventional laser treatment. One of the prominent advantages of ultrafast lasers include an almost non-existent heat affected zone (HAZ). The surface stabilizing and passivating effects were confirmed by depth-profiling x-ray photoelectron spectroscopic (XPS) measurements, atomic force microscopy (AFM) measurements, and a surface sensitive spectroscopic technique called thermally stimulated exoelectron emission (TSEE) measurements.

The performance of multilayered thin film materials often depends sensitively upon the (physical) roughness and degree of (chemical) mixing at interfaces. Irradiation of a growth surface with an assisting ion beam is often used to modify surface roughness. Molecular dynamics has been used to explore the use of low energy (less than 20 eV) Xe+ and Ar+ assisted deposition of model Ni/Cu/Ni multilayers to control both physical roughness and chemical mixing. The study indicated that under normal ion incidence condition, ion energies as low as 3 eV could effectively flatten the relatively weakly bonded copper surface (and therefore the nickel on copper interface). Higher ion energies (at least 10 eV) were required to flatten the more strongly bonded nickel surface. Chemical intermixing by an exchange mechanism between a surface atom and an underlying atom in an already deposited layer depended upon the binding energy of the already deposited layer. As a result, significant chemical mixing occurred as 9 eV (and above) ions impacted with nickel atoms on an already deposited copper surface. At a given ion incident energy, (the heavier) Xe+ ions resulted in less roughness but more mixing. A modulated ion assistance strategy in which no assisting ion beam was used while depositing the first few monolayers of each new metal layer was found to successfully reduce both interfacial roughness and interlayer mixing.

Ultra-thin titanium and tantalum nitride layers grown on three different dielectrics were studied to examine how low-energy ions change the chemical composition at and near their interface. Comparisons were made by growing titanium and tantalum nitride under similar conditions both with (ion-assisted) and without (reactive) nitrogen ions. Although the chemical reactions between the nitrides and the three dielectrics under both growth conditions depend on the type of dielectric used, a few general observations were seen. In comparison with the reactively grown samples, all of the ion-assisted growths show a significant increase in the amount of nitride in the nitride layer at and near the nitride/dielectric interface. Moreover, the amount of chemical binding between the titanium nitride and dielectric is increased when low-energy ions are used. Angle resolved x-ray photoemission determined that the enhancement in the deposition process from low-energy ions occurs without inducing significant intermixing between the nitride layer and dielectric. Although thicker layers of titanium nitride show a difference in the grain structure from ion deposition1, the ultra-thin layers grown in this work do not have any dependence with ion-assisted growth for the samples measured.

We present a recently developed method for modeling ionized physical vapor deposition. Using molecular dynamics techniques we examine the surface adsorption, reflection and sputter reactions taking place during ionized physical vapor deposition. We predict their relative probabilities and combine the information obtained from molecular dynamics into a transport model incorporating all effects of re-emission and re-sputtering. This provides a complete growth rate model that allows the inclusion of energy and angular dependent surface reaction rates. As an example, the method is applied to growth of an aluminum film under different deposition conditions.

The deposition of thin epitaxial hexagonal gallium nitride films on c-plane sapphire by low-energy nitrogen ion assisted deposition is shown to result in films of high crystalline quality. The quality can be further heightened by using the concept of an isothermal growth rate ramp. Characterization of film structure, defect density distribution and surface topography by XRD, RBS/C, and AFM, respectively, reveals the importance of the nitrogen ion energy and the ion to atom ratio on the film properties.

Amorphous carbon nitride films have been deposited by two different methods: (1) direct ion beam deposition from a gas mixture of CH4/N2; and (2) nitrogen ion beam sputtering of a graphite target. The chemical composition, deposition rate, chemical bond and optical properties of the as-deposited films were studied as a function of the process parameters. In the first technique, ions (CH3+, N2+, N+, NH4+, NH3+, NH2+, HCN+, CN+ and N2H2+) were directly impacted onto the substrate surface. The effects of RF power, CH4/N2 gas ratio, total gas flow, pressure, and ion energy on the film properties and deposition rates were studied. In the second technique, a flux of energetic nitrogen ions (N2+, N+), generated by N2 and N2/Ar plasmas, were used to directly sputter a graphite target. In this case, the effects of RF power, gas mixture (N2, N2/Ar), and ion energy on the film characteristics and deposition rates were determined. The properties of the films generated by the two alternative techniques were also compared.

Aluminum Nitride (AIN) is a promising material for a variety of technological applications because it has many exceptional properties, such as wide band gap (WBG) and negative electron affinity (NEA). AIN thin films were prepared by Reactive Ion Beam Coating. The properties of the AIN thin films may be a function of one of the preparation conditions: the beam energy. We used the non-Rutherford backscattering (non-RBS) and Auger Electron Spectroscopy (AES) results to analyze the composition of the AIN thin films. Atomic Force Microscopy (AFM) was applied to study the morphology of films. On the other hand, electron field emission properties were also studied to find the relationship between the compositional, morphological and electron field emission properties of the AIN thin films.

A well characterized C60 supersonic seeded beam has been used to synthesize SiC films on Si (111) 7×7. The control of beam parameters such as energy and flux distributions is shown to be important to improve quality of films in terms of morphology, defect density and structure. We demonstrate that a kinetic energy of a few eV of the C60 precursor is enough to induce carbidization at moderate substrate temperature. Kinetic energy activated SiC formation at 750°C is achieved with a strong reduction of the dimensions and density of defects. The films show a reduced roughness of about 2.5 nm (root mean square).

Silicon Carbide thin films were grown on Si(100) and (111) substrates at 1050EC using a pulsed supersonic beam of hexamethyldisilane (HMDS) in hydrogen. X-ray diffraction analysis shows that these films contain only the 3C cubic polytype, determined mainly by the SiC(111) diffraction peak at 22 = 35.6E, the SiC(200) peak at 22 = 41.4E and the SiC(220) peak at 22 = 60.OE.

The angle of incidence of the HMDS/hydrogen beam could be varied through an angle of 0 to 90E without displacing the specimen from the focal point of the beam. On the Si(100) surface, the film growth texture was monitored by measuring the ratio of the SiC(111) to (200) diffraction peak intensity for beam incidence angles of 0, 30, 45 and 60E. On Si(111). The SiC(111)/(220) ratio was monitored. An 8-fold increase in the incident translational kinetic energy of the precursor molecules can be achieved at the highest glancing angle. In general, the effects of enhanced translational kinetic energy on SiC film growth were insignificant, in agreement with calculations of the sticking probability for SiC homoepitaxial growth with seeded beams on SiC [1]. Further examination of the films with SEM and AFM revealed the growth of epitaxial islands at low coverages, and the process of island coalescence.

The principal interests in this work are energetic-beam control of carbon-film properties and the roles of doping and surface morphology in field emission. Carbon films with variable sp3-bonding fraction were deposited on n-type Si substrates by ArF (193 nm) pulsed-laser ablation (PLA) of a pyrolytic graphite target, and by direct metal ion beam deposition (DMIBD) using a primary Cs+ beam to generate the secondary C- deposition beam. The PLA films are undoped while the DMIBD films are doped with Cs. The kinetic energy (KE) of the incident C atoms/ions was controlled and varied over the range from ∼25 eV to ∼175 eV. Earlier studies have shown that C films' sp3-bonding fraction and diamond-like properties can be maximized by using KE values near 90 eV. The films' surface morphology, sp3–bonding fraction, and Cs-content were determined as a function of KE using atomic force microscopy, TEM/EELS, Rutherford backscattering and nuclear reaction measurements, respectively. Field emission (FE) from these very smooth undoped and Cs-containing films is compared with the FE from two types of deliberately nanostructured carbon films, namely hot-filament chemical vapor deposition (HF-CVD) carbon and carbon nanotubes grown by plasma-enhanced CVD. Electron field emission (FE) characteristics were measured using ∼25-μm, ∼5-μm and ∼1-μm diameter probes that were scanned with ∼75 nm resolution in the x-, y-, and z-directions in a vacuum chamber (∼5 × 10-7 torr base pressure) equipped with a video camera for viewing. The hydrogen-free and very smooth a-D or a-C films (with high or low sp3 content, and with or without ∼1% Cs doping) produced by PLD and DMIBD are not good field emitters. Conditioning accompanied by arcing was required to obtain emission, so that their subsequent FE is characteristic of the arc-produced damage site. However, deliberate surface texturing can eliminate the need for conditioning, apparently by geometrical enhancement of the local electric field. But the most promising approach for producing macroscopically flat FE cathodes is to use materials that are highly nanostructured, either by the deposition process (e.g. HF-CVD carbon) or intrinsically (e.g. carbon nanotubes). HF-CVD films were found to combine a number of desirable properties for FE displays and vacuum microelectronics, including the absence of conditioning, low turn-on fields, high emission site density, and apparent stability and durability during limited long-term testing. Preliminary FE measurements revealed that vertically aligned carbon nanotubes are equally promising.

We studied the effects of low-energy electron bombardment during diamond growth over the film crystalline quality and morphology. The film growth was monitored via the effective extinction coefficient (k) at 1.96 eV with in situ ellipsometry, in order to determine the developmental stage of the film in real time. Taking advantage of this in situ monitoring, we triggered the electron bombardment over the growing surface at different growth stages and studied the corresponding induced changes in film morphology and crystalline quality. Ex situ Raman spectroscopy and scanning electron microscopy (SEM) were also employed to evaluate the crystalline quality and the morphology of the grown films, respectively. We found that electron bombardment can be used to control the surface morphology of the films (triangular, pyramidal, square, amorphous). The results also indicate that applying the electron bombardment over the diamond film during the whole time of growth is detrimental to its crystalline quality and favors the formation of non-sp3 carbon. However, when the electron bombardment is triggered just after high quality scattered diamond crystallites have formed, the resulting film is of similar quality as those grown without bombardment. Therefore, properly chosen and triggered electron bombardment during diamond growth by chemical vapor deposition (CVD) can be used to control the film morphology while maintaining the film crystalline quality.