The evolution of the surface topography of thin amorphous Cu-Ti films during the film growth is investigated by scanning tunneling microscopy. The films begin to grow with smooth surfaces until the film thickness reaches a critical value. Then, within a small thickness interval, a grainy microstructure of the film develops which looks very similar to the microstructure of polycrystalline films. Measurements of the intrinsic macroscopic stress in these films during the film growth show compressive stresses in the early growth stages. Then a change to tensile stresses accompanies the change in the surface topography within the same thickness interval. Both, the surface topography and the intrinsic stresses, are always correlated and depend on the deposition temperature and on the film composition. We discuss implications of these observations on the origin of macroscopic intrinsic tensile stresses in amorphous transition metal films.

The Schottky barrier heights (ΦB) for W/Si Schottky diodes have been determined from I–V measurements. The effects of the sputter deposition conditions of the W-films were studied. X-ray diffraction was used to examine the structure and the lattice parameters of the W-films while the stress was determined by using a profilometer from the measurement of the curvature of the substrate after metallization. The resistivity is determined by using a four-point probe. A compressive-to-tensile stress transition is associated with the transformation of the ±—W-phase into the (β—W-phase as the working gas pressure is increased. These effects, which are frequently observed, coïncide with a significant increase of the W-film resistivity and a change (△ΦB≈50 meV) in the Schottky barrier height on n-type. On the other hand, the barrier height on the p-type remains constant under all the experimental conditions investigated. These results are discussed in terms of effects of strain and structure of W-films on the work function of the W, as well as in terms of modification of the pinning position of the Fermi level or else change in the value of the Richardson constant.

Optically thin films of Ti1-xAlxN were sputter deposited using dual rotatable cathodes in nitrogen and argon-nitrogen environments. The sputtering parameters and film properties were analyzed to develop predictive techniques for possible feedback control during deposition. Also, it was found that feedback control during deposition was suitable for controlling film composition in some magnet configurations.

Laser ablation has been used to deposit a:SiC-N films from a CVD SiC target. Depositions were carried out either in vacuum or in a nitrogen ambient ranging from 10 to 100 mT. The mechanical properties of the films versus nitrogen background pressure were assessed using nanoindentation and surface acoustic wave measurements. Deflected optical beam testing, pull testing and atomic force microscopy were used to determine film stress, film-substrate adhesion and film roughness, respectively. The optical properties were also characterized as a function of nitrogen back pressure using spectroscopic ellipsometry which determined refractive indices and predicted film compositions. Fourier transform infrared spectroscopy determined the bonding structures in the films, and finally Rutherford backscattering spectroscopy measurements were also performed. Based on the best mechanical and optical properties, the optimum film deposition conditions were obtained. It was observed that with an increase in nitrogen background pressure, oxygen content in the film, in the form of SiOx, increased significantly affecting the overall properties of the a:SiC-N films.

The evolution of stress vs. temperature was measured during the formation of TiSi2 in the reaction of Ti with (100) Si and with polycrystalline Si, and during the phase transformation from C49 to C54 TiSi2. The formation of C49 TiSi2 causes an increase in compressive stress, followed by relaxation before the transformation to C54 TiSi2, which causes no significant stress change. C54 TiSi2 is shown to be elastic in the temperature range of 750–860 °C. This difference in the deformation mechanisms of C49 and C54 TiSi2 affects the morphological stability of TiSi2 in fine line structures.

The growth stress of titanium films was measured in situ with a cantilever beam technique under UHV conditions at Ts ≥ 130°C. The substrate used in these experiments was a double layer consisting of a base layer of A12O3 or of MgF2 and as a second layer a titanium film evaporated at different H2O-partiaI pressures (Ti/TiOx). With both base layers the growth stress of the substrate Ti/TiOx layer is similar.

The main objective of this paper was the investigation of the effect of a variation in the chemical composition of the substrate Ti/TiOx layer on the growth stress and -by way of our stress model - on the growth mode of a clean titanium film always evaporated under identical vacuum conditions onto this bilayered substrate. At low water content of the substrate titanium layer (the substrate layer still consists of metallic titanium) the growth of the clean titanium film is a continuation of the growth of the second substrate layer. As soon as the substrate titanium film contains only a few percent of water the initial compressive stress is overcompensated by atensile stress contribution which increases as the water content of the substrate isincreased. We interprete this to indicate renewed nucleation for the clean titanium film on the substrate surface. A small part of the tensile stress is also due to gas interdiffusion (hydrogen) from the substrate film. This effect is rather small when the second substrate film consists of stoichiometric oxide. With a MgF2 base layer in the substrate bilayer the results indicate a diffusing species from the MgF2 base layer into the Ti/TiOx layer. This interdiffusion from the substrate significantly affects the growth stress of the clean titanium film on this substrate bilayer. However, the general trends due to the incorporation of water in the substrate Ti/TiOx film, seen in case of the A12O3 base layer, are the same.

TiB2 is a very hard refractory compound that strongly resists erosion and shows metallic luster and good electrical conductivity. It has potential applications in protective coating systems. This paper investigates the microstructure and stresses of as-deposited TiB2 thin films ranging from 2000 °A to 4000 °A thick produced by dc magnetron sputtering as a function of sputtering power and Ar pressure. Three power levels: 100, 400, 600 W, and four pressures: 3, 5, 8, and 12 mTorr were used. X-ray diffraction studies indicate that two types of crystalline structure are formed: a randomly oriented fine crystalline structure and a coarser grained (001) textured structure, depending on the sputtering power and pressure. As-deposited stresses at different powers all show a transition from compression to tension as the Ar pressure increases. The relationship between the processing parameters, microstructure and residual stresses is discussed. The effects of the deposition power and pressure on the residual stress transition of TiB2 thin films are clearly mapped out by 3-D and contour maps.

Stress, density and refractive behavior are analyzed for TiO2 layers deposited by reactive evaporation (RE), ion plating (IP), plasma impulse chemical vapour deposition (PICVD) and spin coating (SP) from bending of the substrate and by means of Rutherford Backscattering Spectroscopy (RBS), respectively. Densities between 2.7 gem-3 and 3.8 gem-3 are obtained depending on coating techniques and coating conditions. Refractive index depends linear on density. A correlation between film stress and density is observed which is independent from coating process, production parameters and crystal structure of the as-deposited films. Stress is tensile at low densities and compressive for films with densities of the order of the crystal phase of anatase (3.84 gem-3). The phase transition from amorphous to anatase due to annealing induces an increase in stress. Film density determines the transition temperature, and the magnitude of stress increase.

Silicon monoxide (SiO) formed by molecular beam deposition (MBD) has many attractive optical, electrical, mechanical, and chemical properties which make it a suitable dielectric for many semiconductor device applications. It can be thermally evaporated at a much lower temperature than Si, SiO2 or Si3 N4 and it condenses on cooler surfaces in uniform and adherent stoichiometric SiO (x = 1) films when evaporated in high vacuum. At low deposition rates and at high pressures of oxygen, SiOx (1 ≤ x ≤ 2) films result. This allows variation of refractive index, stress and other properties of SiOx with x. In general, the SiO (x = l) films are under tensile stress <100 MPa which is significantly lower than that observed in other dielectric films. Slight introduction of oxygen during deposition reduces the tensile stress; at an O2 pressure of 5 × 10−7 Torr and above, the films are in compression. This allows the tunability of stress in SiOx films and deposition of films essentially free from stress. Furthermore, both Si and SiO have similar values of the linear thermal expansion coefficient (average values between 23 °C and 350°C: 3.37 × 10−6°C−1 and 2.7 × 10−6°C−1, respectively). As a result, SiOx/Si films develop little thermal stress during thermal cycling.

The properties of sputtered films are strongly affected by the topography of the underlying substrate, due to the dependence of film growth and resputtering yield on the angle of incidence of the sputtered material and other species from the plasma. Thick r.f.-sputtered alumina films were deposited with different levels of substrate bias onto substrates into which parallel grooves had been cut. The alumina sputtered in the vicinity of the grooves forms well-defined regions with a lower incorporated argon content than the alumina sputtered onto the planar parts of the substrate. The ratio of compressive stress perpendicular to the grooves compared to the stress parallel to the grooves varies from 0.85 at zero substrate bias and 0.5 at biases of -50V and -100V. Comparing with finite element simulations, these ratios suggest that in the biased samples, the material near the steps has a lower level of compressive intrinsic stress than exists in the planar material. Nanoindentation was used to measure the modulus and hardness of the material near the steps and on the planar areas of the substrate. The alumina has an indentation modulus of 150 – 200 GPa and a hardness of 8 – 10 GPa, depending on its proximity to the grooves and on the substrate bias.

Residual stress in hydrogenated amorphous silicon (a-Si:H) film has been studied. Deposition on square island pattern reduced the stress when the lateral dimension of the islands became comparable to the film thickness. The overall stress was reduced by approximately 40% when the lateral dimension was decreased to 40 μm, but the adhesion was not improved much. However, substrates having a 2-dimensional array of inversed pyramids of 200 μm in lateral dimension produced overall stress 3∼4 times lower than that on the normal substrates. The inversed pyramid structure also had other advantages including minimized delamination and increased effective thickness. Computer simulation confirmed that the overall stress can be reduced by deposition on the pyramidal structure.

The elastic properties of dielectric films used in microelectronics, such as undoped, phosphorous doped and boron-phosphorous doped silicate glass, as well as spin-on glass, have been studied by means of the Brillouin light scattering technique. The phase velocity of both the surface Rayleigh wave and of the longitudinal wave in the film material have been measured and the two independent elastic constants c11 and c44 evaluated. This permitted us to derive the values of the Young’s modulus and of the Poisson’s ratio which are useful quantities for the modelling of the elastic properties of multilevel structures used in electronics. Moreover, the biaxial stress in the films has been measured by the substrate curvature method. This enabled us to study the evolution of the intrinsic stress with time, caused by water adsorption into the films. The evolution of the stress during thermal cycles has been also analyzed and the thermal expansion coefficient of the films estimated.

The intrinsic stress and biaxial modulus of thin films of amorphous silicon nitride (0.5μm) and silicon oxynitride (1.5 to 2.5 μm) were measured following deposition (Ts=260 to 610°C), and then at discrete intervals throughout an annealing cycle. The biaxial modulus and intrinsic stress of the silicon nitride films increased from 110 GPa and 130 MPa, respectively, to 180 GPa and 680 MPa as the deposition temperature increased from Ts=340°C to Ts=610°C. The elemental composition was unaffected by the deposition temperature. Annealing at 1100°C increased the intrinsic stress to ≃ 1.8 GPa, as nitrogen and hydrogen were lost. Films with “near-stoichiometric” compositions (SiN1.1; H = 12 at.%) did not crack.

Adding oxygen to form silicon oxynitride lowered both the biaxial modulus (20–30 GPa) and the intrinsic stress (−50 to 100 MPa). All the silicon oxynitride compositions (SiO0.3N1.0 to SiO1.7N0.5) were unstable when annealed above the deposition temperature (260°C). Films grown using mostly nitrous oxide (R = N2O/(N20+NH3) < 0.5) oxidized at 350°C to form silica. Simultaneously, the biaxial modulus and intrinsic stress increased to 100 GPa and 170 MPa, respectively. Films grown from mostly ammonia (R <0.5) lost nitrogen and hydrogen and cracked when the temperature exceeded the deposition temperature by 40 to 90°C. The stress induced by the elemental loss was ≃ 600 MPa.

The preparation and properties of relatively thick films of DC magnetron sputtered SiC films is described. The films were prepared using a new ceramic sputter target material. The new target material is called Hexoloy® SG–90. It is an electrically conductive, dense ceramic material which can be used as a sputter target to yield insulating amorphous SiC thin films on room temperature substrates.

Nitrogen incorporated diamond-like carbon (DLC) films were deposited by r.f. plasma assisted chemical vapor deposition (r.f.-PACVD) method. Mixtures of benzene and ammonia or nitrogen were used as the reaction gases for the deposition. Composition, atomic bond structure and mechanical properties of the film were investigated when the fraction of nitrogen source increases from 0 to 0.79. All films were deposited at fixed negative bias voltage of the cathode (-500 V) and the deposition pressure (10 mTorr). While ammonia addition reduces both residual stress and hardness of the film from 1.7 to 1 GPa and from 2750 to 1700 Kgf/mm2 respectively, the mechanical properties are not significantly varied by nitrogen addition. Deposition rate, composition and atomic bond structure are also dependent on the nitrogen source gases. Observed behavior of mechanical properties is discussed in terms of the content of inter-links of sp2 clusters. In addition to hydrogen, C≡N bonds in the film are also terminated sites of three dimensional atomic bond network. By considering the hydrogen concentration and the C≡N bonds, it can be shown that the mechanical properties of nitrogen incorporated DLC films are determined by the content of inter-links of sp2 clusters.

Conventional photomasks consisting of chromium films on fused silica or glass substrates are widely used. However, it is becoming apparent that interfacial stress between the chromium and the transparent substrate, as well as the need for wet chemical processing for pattern production, will ultimately limit a photomask’s ability to be patterned reproducibly. An alternative approach is to chose an opaque layer which exhibits minimum interfacial stress with respect to the substrate while having the ability of being patterned by fluorocarbon gas plasma processing.

This work describes the use of silicon/germanium as an alternative opaque layer, which can be deposited uniformly by co-sputtering and patterned by fluorocarbon reactive ion etching. The suitability of the material in terms of interfacial stress is demonstrated by the use of microfabricated silicon dioxide cantilever structures. In addition, the influence of Si/Ge ratio on optical properties, the plasma processing performance, and chemical compatibility with the rest of the photomask making process is described.

Multilayers of vanadium and MgO with different layer thicknesses were grown by molecular beam epitaxy (MBE) and the V/MgO and MgO/V interfaces were investigated by cross-sectional high resolution electron microscopy (HREM). For the smallest layer thickness of 5 nm, the vanadium and MgO films were coherent with each other and no misfit dislocations were observed. For the larger layer thicknesses of 10 nm and 50 nm, the vanadium surface exhibited undulations, and for the largest thickness, interdiffusion had occurred between the MgO film and the underlying V substrate and an interfacial spinel phase had formed. These observations are discussed in terms of the morphological instabilities of the strained vanadium film as it grows on the MgO substrate.

We report the observation of stacking fault tetrahedra (SFT) in strained Si1-xGex layers grown via rapid thermal CVD on (111) Si substrates. It is shown that these defects provide a mechanism for strain relief in films strained in compression due the presence of bounding edge-type stair rod partials whose Burgers vectors lie parallel to the strained layer interface. Cross section and plan view TEM were used to characterize this defect structure in epilayers (30 to 650nm thick) of Si1-xGex (0 < xGe < 0.27) grown on 〈111〉 oriented Si wafers. Stacking fault tetrahedra were observed only in alloys in the compositional range xGe ≥ 0.13 and only when growth proceeded on the 〈111〉 surface. A critical strain energy model that identifies conditions for the stable growth of stacking fault tetrahedra in a strained layer is presented. The model was based on conventional strain energy considerations where the energy of the stacking fault area plus the bounding dislocation network (including dislocation interactions but neglecting the free surface) was balanced against the strain energy released by the introduction of the defect. In addition, a formation mechanism consistent with these observations is described that involves the dissociation of Frank partial dislocation loops bounding stacking faults lying in the growth plane.

Epitaxial misfit has been characterized in Ni/Cu/Si (100) as a function of Ni film thickness using wafer curvature measurements. This strain can be related to measurements of magnetic anisotropy made in the deposition system using the magneto-optic Kerr effect. Films were deposited using molecular beam epitaxy (MBE) with varying Ni epilayer thickness between 10 and 1000Å. The change in wafer curvature due to misfit strain was measured using optical interferometry and the strain was calculated using Stoney’s equation. Transmission electron microscopy was used to characterize misfit dislocations at the Ni/Cu interface. It has been determined that misfit strain can have a very strong effect on magnetic anisotropy, particularly in the regime between the critical thickness and complete misfit accommodation, where strain has been found to decrease significantly as a function of film thickness. A critical strain has been determined at which a transition in the direction of magnetization easy axis from perpendicular to the film to in the film plane occurs. This discovery allows the use of Kerr effect measurements to characterize misfit strain in situ.

Discontinuities in nanoindentation loading curves are frequently observed in ceramic materials. These normally occur at fairly random loads and displacements, probably due to the random distance of pre-existing defects from the indent location. Here we report the observation of reproducible, sudden indent-depth changes which occur over a very narrow distribution of depths and loads, for GaAs and a range of related epitaxial layer systems. The surface preparation and material defect density have a significant influence. Different tip geometries have been used to gain insights into the deformation processes which cause these discontinuities.