Growth Of TiN Films Research Articles

Preferred orientation of TiN films studied by a real time synchrotron x-ray scattering

The orientational crossover phenomena in a radio frequency (rf) sputtering growth of TiN films were studied in in situ, real time synchrotron x-ray scattering experiments. For the films grown with pure Ar sputtering gas, the crossover from the (002)-oriented grains to the (111)-oriented grains occurred as the film thickness was increased. As the sputtering power was increased, the crossover thickness, at which the growth orientation changes from the 〈002〉 to the 〈111〉 direction, seemed to decrease. The addition of N2 besides Ar as sputtering gas suppressed the crossover, and consequently resulted in the (002) preferred orientation without exhibiting the crossover. We attribute the observed crossover phenomena to the competition between the surface and the strain energy. The x-ray powder diffraction, the x-ray reflectivity, and the ex situ atomic force microscopy surface topology studies consistently suggest that the microscopic growth front was in fact always the (002) planes. In the initial stage of growth, the (002) planes were aligned to the substrate surface to minimize the surface energy. At later stages, however, the (002) growth front tilted away from the surface by about 60° to relax the strain, which caused the crossover of the preferred growth direction to the 〈111〉 direction.

Linear arc discharge source for large area plasma processing

A linearly scalable plasma source based on the radio frequency generated hot hollow cathode discharge between two parallel plates with a magnetic field perpendicular to the plates near the outlet of the cathode is introduced. The magnetic field facilitates and confines the hollow cathode discharge which leads to a high power density and a high cathode wall temperature. The geometry and location of hot zones is directly controlled by magnetic field. The linear arc discharge (LAD) source exhibits similar features as the cylindrical radio frequency hollow cathode plasma jet. Experiments indicate a metastable assisted growth of TiN films. LAD source extends abilities of the radio frequency hollow cathode plasma jet to the large area processing.

Overall energy model for preferred growth of TiN films during filtered arc deposition

TiN films with different preferred crystalline orientations have been prepared by a new cathodic arc evaporation technique - filtered arc deposition (FAD). The evolution of the preferred orientation in the TiN films was investigated systematically. Three kinds of preferred orientation, i.e. the (200), (111), and (220) preferred orientation, were achieved continuously in one deposition procedure by varying the film thickness and substrate bias which determines the bombarding energy of the deposited energetic particles. At the initial stage of film growth, the (200) orientation is dominant at a lower substrate bias. When the film becomes thicker and/or substrate bias increases, the preferred orientation will be (111) instead of (200). If the substrate bias increases further, then the preferred (220) growth occurs at any film thickness. The evolution of the preferred orientation from (200) to (111) and then to (220) is discussed on the basis of a new concept, the so-called overall energy which consists of the surface energy, the strain energy, and the stopping energy. The preferred orientation of TiN films is determined by the competition between the surface energy, the strain energy and the stopping energy.

The crossover of preferred orientation in TiN film growth: A real time x-ray scattering study

The orientational crossover phenomena in a radio-frequency (rf) sputtering growth of TiN films were studied in a real-time synchrotron x-ray scattering experiment. Following the initial random nucleation and growth stage, the growth was dominated by the grains with the (002) planes aligned with the substrate surface. Surprisingly, at later stages, the grains with the (002) growth front tilted away from the surface by about 60° became dominant. The tilting of the growth front resulted in a faceted surface topology that was confirmed by an ex situ AFM study. Our x-ray results suggest that the crossover was driven by the competition between the surface and the strain energy

Effect of film thickness on preferred growth of TiN films during filtered arc deposition

Effect of film thickness on preferred growth of TiN films during filtered arc deposition

Characteristics of titanium nitride films grown by pulsed laser deposition

Laser physical vapor deposition (LPVD) has been used to grow titanium nitride films on hydrogen-terminated silicon(100) substrates at deposition temperatures ranging from room temperature to 600 °C. A pulsed KrF excimer laser (λ = 248 nm, τ = 25 ns) was used with the deposition chamber maintained at a base pressure of 10−7 Torr prior to deposition. Different properties of the films were investigated by x-ray diffraction, Auger electron spectroscopy, Raman spectroscopy, optical, scanning, and high resolution transmission electron microscopy, and measurement of electrical resistivity. When the substrate temperature was low (at and below 500 °C), oxygen atoms from the residual gases were incorporated in the films. The microstructures and resistivities of TiN films were found to be strongly dependent on the temperature of the silicon substrates. The TiN films deposited at 600 °C were oxygen-free, as observed from Auger analysis, and the room temperature resistivity was found to be 14–15 μΩ-cm. Raman spectroscopy of the films showed that the nitrogen-related optical phonon peak increased with deposition temperature in comparison with the titanium-related acoustic peak. Transmission electron microscopy and x-ray diffraction analyses showed that the films were polycrystalline at low temperature with grain size ranging from 300–600 Å, depending on the temperature of the substrate. At 600 °C, the films were found to be single crystals with occasional presence of dislocation loops. The spacing of Moiré fringes in TiN/Si samples deposited at 600 °C established the nearly periodic elastic strain field extending into the TiN and Si at the interface. Although there exists a large misfit between TiN and Si (24.6%), the epitaxial growth of TiN films on Si(100) substrates was explained by means of domain-matched epitaxy with a 4-to-3 match in unit cells for TiN/Si structure, giving rise to a residual lattice misfit of only 4%.

The Effects of Collimator Life Time on the Ti and Tin Film Growth Rates and Conformalities in Sputter Deposition Processes: Experiments and Simulations

AbstractExperimental and simulation studies were conducted in an attempt to understand the effects of collimator life time on the Ti and TiN film growth rates and conformalities in sputter deposition processes. The Ti and TiN films were deposited with and without collimation. The hexagonal cells of the collimator used in this study have a 1:1 aspect ratio. A Monte Carlo based simulator was used to calculate the angular distributions of species exiting from a collimator cell and the percentage decrease in the rate of film growth as a function of the collimator life time. Then, a low pressure deposition process simulator, EVOLVE, was used to predict the conformalities of deposited films in contacts or vias, assuming that the films were uniformly deposited on the side-walls of collimator cells. We conclude that the loss in growth rate is largely due to the shrinkage in the cross sectional area of the collimator cell inlets. We arrive at this conclusion after comparing an estimated film thickness on the collimator side-walls with experimental measurements. With extended collimator usage, the predicted and experimental film profiles in contacts or vias show increasing bottom coverage and decreasing side-wall coverages.

The Effects of Collimator Life Time on the Ti and Tin Film Growth Rates and Conformalities in Sputter Deposition Processes: Experiments and Simulations

ABSTRACTExperimental and simulation studies were conducted in an attempt to understand the effects of collimator life time on the Ti and TiN film growth rates and conformalities in sputter deposition processes. The Ti and TiN films were deposited with and without collimation. The hexagonal cells of the collimator used in this study have a 1:1 aspect ratio. A Monte Carlo based simulator was used to calculate the angular distributions of species exiting from a collimator cell and the percentage decrease in the rate of film growth as a function of the collimator life time. Then, a low pressure deposition process simulator, EVOLVE, was used to predict the conformalities of deposited films in contacts or vias, assuming that the films were uniformly deposited on the side-walls of collimator cells. We conclude that the loss in growth rate is largely due to the shrinkage in the cross sectional area of the collimator cell inlets. We arrive at this conclusion after comparing an estimated film thickness on the collimator side-walls with experimental measurements. With extended collimator usage, the predicted and experimental film profiles in contacts or vias show increasing bottom coverage and decreasing side-wall coverages.

Ion-Assisted Crystal Growth by Post Irradiation as Applied to Nitride Formation

A (100)-oriented TiN film was successfully prepared by means of the post irradiation of the 5 keV N2+ ion beam onto the predeposited titanium film ∼500 Å thick on a Si(001) substrate at room temperature. The crystal growth of TiN film was monitored by reflection high energy electron diffraction (RHEED) during the experiment in ultrahigh vacuum (UHV). The TiN film was also studied by reflection electron microscopy (REM) and cross-sectional transmission electron microscopy (XTEM). Results have clearly shown that the color and crystallographic orientation of the TiN film are substantially controlled by the ion dose; the TiN film showed polycrystallinity at a low ion dose, whereas the TiN(100)-oriented face grew mainly with high ion dose, ∼1×1017 ions ·cm-2. The color of the film also changes as ion dose increased; in particular, a golden color became conspicuous between ∼3×1016 ions · cm-2 and ∼5×1016 ions·cm-2.

Morphology modification by high energy ion beam bombardment concurrent with TiN film growth

Ion bombardment during film growth has been shown to be useful in controlling the growth kinetics and thus the physical properties of the film. One of the more spectacular aspects of how ion beams modify the growing film concerns topographical changes. There have been a number of reports in the literature concerning the development of surface morphology of films growing under concurrent low energy (<1 keV) ion bombardment [1, 2], but few works dealing with morphology modification by high energy ion beam bombardment concurrent with film growth. There are remarkable differences between low energy ion/surface interaction and high energy ion/surface interaction in terms of range and energy deposition etc. In assessing the role of low energy ion irradiation on the surface morphology, ion energy and ion flux were often considered, but the effect of ion species was usually neglected, because the mean ion ranges in the film for different ions at low energies are very similar. However, at higher energies, ions with different masses penetrate to quite different depths, and thus their influence on topography modification should be detectable. On the other hand, there are also differences between morphology modification by high energy ion bombardment concurrent with film growth and after film deposition [3-5]. The present authors have reported the fabrication of TiN films by vapour deposition of Ti in a N2 atmosphere concurrent with high energy inert Xe + ion beam bombardment [6] and studied the effect of ionic mass on the intrinsic stress of the formed TiN films [7]. In this letter, the morphologies of the synthesized TiN films were examined by atomic force microscopy (AFM), which can provide quantitative three-dimensional surface morphological information with high resolution. In order to investigate the mechanism of surface morphology modification by high energy ion beam irradiation during film growth, both Xe + ions and lighter Ne + ions were employed to prepare TiN films. A detail description of the film synthesis facility has been given elsewhere [6]. The TiN films were deposited onto optically polished silicon substrates by electron beam evaporation of Ti at a rate of 1 nms -a in a N2 atmosphere. The angle of incidence of the vapour stream to the substrate was 45 °. During deposition the substrates were water-cooled and did not reach atemperature greater than 200 °C.

A Real-time X-ray Scattering Study of Sputtering Growth of TiN Films

AbstractWe report the results of a real-time synchrotron x-ray scattering study of the growth of TiN thin films on Si(001) substrates by RF sputtering. Our experiemnts show that the morphology of the TiN films strongly depends on growth conditions. After the nucleation and growth takes place with random crystallographic orientation at the very early stage, the films grow with a preferred orientation. Such preferred orientation was found to depend on both the sputtering power and the carrier gases used in the sputtering. Generally, the final morphology assumes either (111) or (002) crystallographic orientation. Using Ar sputtering, a cross-over effect from (002) to (111) was observed at intermediate time. The nature of the observed morphological changes is discussed.

Nucleation and growth of chemical vapor deposition TiN films on Si (100) as studied by total reflection x-ray fluorescence, atomic force microscopy, and Auger electron spectroscopy

We report for the first time the characteristics of the early growth of chemical vapor deposition (CVD) TiN films on Si (100) in the surface reaction limited regime, using total reflection x-ray fluorescence (TXRF), atomic force microscopy (AFM), and Auger electron spectroscopy (AES). Small amounts of CVD TiN from TiCl4 and NH3 reactants were deposited on Si (100) at 650 °C using a rapid thermal CVD system, at a total pressure of 155 mTorr. We examined these small amounts of CVD TiN by introducing TXRF as a tool for observing the initial stages of growth, and AFM for characterizing changes in the overall surface morphology. The nucleation and growth of the resulting CVD TiN films as determined by TXRF, AFM, and AES will be discussed.

Thin film properties of low-pressure chemical vapor deposition TiN barrier for ultra-large-scale integration applications

Titanium nitride films deposited by low-pressure chemical vapor deposition (LPCVD) on Si(100) using TiCl4 and NH3 as reactants, were investigated as a function of deposition temperature between 400 and 700 °C. LPCVD TiN depositions were carried out in a rapid thermal chemical vapor deposition system with a total deposition pressure of 155 mTorr. Stoichiometric TiN films were formed regardless of the deposition temperature and composition was uniform across the entire film. Depending on deposition temperature, varying amounts of chlorine (Cl) and oxygen (O) impurities are found in the TiN films. Films deposited at lower temperatures (400 and 550 °C) contained more than 5 at. % Cl, while the films produced at 700 °C contained as little as 1 at. % Cl. For the films deposited at 650 and 700 °C, the bulk of the TiN films is oxygen-free. LPCVD TiN deposition rates of 400 Å/min with no appreciable incubation time were routinely achieved. The LPCVD TiN deposition process is surface reaction controlled with an activation energy of 35 kJ/mol. Excellent TiN film conformality was observed. Electrical resistivity of the TiN films was found to decrease with increasing deposition temperature. Resistivity in the range of 85 μΩ cm was observed. Polycrystalline ∂-TiN phase with a preferred orientation of (200) was observed at all deposition temperatures. These TiN films have columnar grain structure. The TiN/Si interface is smooth, and no voids are observed at the silicon substrate interface, a prerequisite for good adhesion. An increase in the average grain size and lattice parameter was observed with increasing deposition temperature. While increasing the deposition temperature increases the TiN film growth rate, it also produces larger TiN grains and rougher surface morphology. The reliability of the TiN films as a diffusion barrier between aluminum and silicon was evaluated by diode leakage current measurements, which remained low after being thermally stressed up to 550 °C.

Monte-Carlo study of reactive ion-beam assisted film growth

A Monte-Carlo computer program which is composed of ion implantation simulation and deposition calculation is described. It is applied to study TiN film growth by reactive ion-beam assisted deposition in a N2 gas environment. The relationship between film composition and nitrogen partial pressure in the processing chamber is established. The influence of ion energy, atomic arrival rate ratio and ion species on the thickness of the film is studied. We also investigated the intermixing at the interface region between the film and substrate. The calculated data are compared with experimental results.

Growth of epitaxial TiN films on MgO(100) by high current discharge plasma

High current discharge plasma produced by the Ta-LaB6 cathode was used for ion plating of TiN films. The dependence of the deposition rate of TiN on the substrate dc bias potential was measured using the Rutherford backscattering spectrometry (RBS) method. The results indicate that the particles impinging on the substrate, i.e., vaporized particles (Ti) and reactive gases (N2), could be ionized at high efficiency of 70%. Epitaxial TiN films were grown at temperatures between 400 and 700 °C on cleaved MgO(100) substrate supplied with negative dc anf rf potential. Structures of the epitaxial film were investigated by RBS and ion channeling, and scanning tunneling microscope (STM). The minimum channeling yields for (100) and (110) axes obtained at a substrate temperature of 550 °C with the growth rate of 40 Å/s were found to be 1.4% and 2.0%, respectively, which were almost the same as that of the MgO substrate. Atomically resolved tunneling images of (100) surface of the epitaxial TiN film were observed by STM.

Epitaxial growth of TiN films on (100) silicon substrates by laser physical vapor deposition

We report epitaxial growth of TiN films having low resistivity on (100) silicon substrates using pulsed laser deposition method. The TiN films were characterized using x-ray diffraction, Rutherford backscattering, four-point-probe ac resistivity, high resolution transmission electron microscopy and scanning electron microscopy techniques and epitaxial relationship was found to be 〈100〉 TiN ∥ 〈100〉 Si. TiN films showed 10%–20% channeling yield. In the plane, four unit cells of TiN match with three unit cells of silicon with less than 4.0% misfit. This domain matching epitaxy provides a new mechanism of epitaxial growth in systems with large lattice misfits. Four-point-probe measurements show characteristic metallic behavior of these films as a function of temperature with a typical resistivity of about 15 μΩ cm at room temperature. Implications of low-resistivity epitaxial TiN in silicon device fabrication are discussed.

高周波反応性スパッタリング法による(001)NaCl基板上でのTiN薄膜の成長

高周波反応性スパッタリング法による(001)NaCl基板上でのTiN薄膜の成長

Epitaxial Growth of TiN on GaAs(100) by Pulsed Laser Deposition

ABSTRACTEpitaxial growth of TiN films on GaAs(100) by pulsed laser deposition has been studied. Excimer KrF laser (λ=248 nm, τ=30 ns) has been used for deposition of TiN films in a chamber maintained at vacuum of ≤ 10−6 torr. The microstructure of TiN films has been characterized by x-ray diffraction and transmission electron microscopy (TEM). Cross-sectional high resolution TEM showed a smooth unreacted interface between the single crystalline TiN film and GaAs. The predominant epitaxial relationship was found to be [110]TiN//[010]GaAs, (220)TiN//(040)GaAs at a substrate temperature of 350°C. Modelling of epitaxial growth showed that the interfacial energy is an important term responsible for 45° rotation of the TiN unit cell with respect to that of GaAs. The high strain energy associated with the coherent epilayer is reduced by domain epitaxial growth. These films were characterized using high-resolution TEM techniques, and experimental results were rationalized by thin film growth modeling.

Epitaxial Growth of TiN Films on (100) Silicon Substrates by Laser Physical Vapor Deposition

ABSTRACTWe have synthesized epitaxial TiN films having low resistivity on (100) silicon substrates using pulsed laser deposition method. The TiN films were characterized using X-ray diffraction, Rutherford back-scattering, four-point-probe ac resistivity, high resolution transmission electron microscopy techniques and epitaxial relationship was found to be &lt;100&gt; TiN // &lt;100&gt; Si. TiN films showed 10–20% channeling yield. In the plane, four unit cells of TiN match with three unit cells of silicon with less than 4.0% misfit. This domain matching epitaxy provides a new mechanism of epitaxial growth in systems with large lattice misfits. Room-temperature resistivity of these films was found to be about 15 μΩ-cm. Implications of low-resistivity epitaxial TiN in silicon device fabrication are discussed.

Growth and characterisation of substrate-stabilised heteroepitaxial grey tin films

The authors report molecular beam epitaxy growth of grey tin films on (001)CdTe substrates. The transverse magnetoresistance and Hall effect have been studied. Films thinner than 400 AA are p-type with carrier densities of (1-2)*1019 cm-3; thicker films are n-type with carrier densities as low as 2*1017 cm-3 Shubnikov-de Haas (SDH) oscillations are observed in samples having Hall mobilities >or=104 cm2 V-1 s-1 at low temperatures. Beat patterns are observed in the SDH spectra, which they ascribe to either inhomogeneous doping, arising from the diffusion of Cd and Te from the substrate, or quantisation of the motion in the direction parallel to the film normal. For field directions at 45 degrees and 90 degrees to the film plane normal, clear SDH oscillations are also observed at fields much lower than the expected size effect cut-off field, implying that specular reflection at the film boundaries plays a significant role.