The set of acoustic mode frequencies associated with elastic constants has been determined from Brillouin light scattering measurements on carbon films of different crystallographic phases, i.e. on chemical vapour deposited (CVD) polycrystalline diamond, polycrystalline graphite, and amorphous carbon films (a-C:H). From the measured sound velocities of the acoustic phonons Young's moduli, shear moduli, and bulk moduli of the films were calculated. On a-C:H films depth-sensing indentation tests were performed. The values of ultramicrohardness of these films are, therefore, also reported.

A three-step process for producing a composite diamond film is presented. Plasma deposited diamonds are reinforced by an electroplated metal binder and the diamonds regrown to produce a continuous, strongly adhered diamond film on molybdenum and tungsten substrates. Microscratching and pin-on-disk testing indicate that the composite films are more adherent than plasma deposited diamonds alone.

A novel method for the measurement of the mechanical properties of integrated circuit interconnection and packaging materials using a conventional acoustic microscope lens, is presented in this paper. This technique allows the simultaneous generation and detection of longitudinal (LW) and shear (SH) acoustic waves in a material system based upon acoustic mode conversion principles at a water-solid interface. Experimental results obtained using a 50 MHz acoustic lens are presented for a range of ceramic materials and compared with published data. Acoustic ray propagation theory is employed to analyse the experimental results.

A series of mechanical tests have been conducted on bonded silicon to silicon (native oxide present only) and oxide to oxide wafers at several times and temperatures. Tensile tests have been designed to evaluate the strength of the bond. Tensile tests have been conducted over the full range of bond strengths ranging from the weak van der Waals forces to the full silicon bonds.

A recently developed geometrically nonlinear stress-curvature relation based on a minimization of the total strain energy, which predicts a bifurcation in shape as the magnitude of intrinsic film stress increases, is discussed in this paper. It is compared with the linear theories of Stoney and Brenner & Senderoff for a thin molybdenum film on silicon substrates with various thicknesses. Although the ratio of film to substrate elastic modulus is only 2, Stoney's equation generates significant error for this film/substrate system and the Brenner & Senderoff relation should be used for calculating initial film stress when plate deflections are small. When deflections exceed approximately half the substrate thickness the Brenner & Senderoff equation produces over 10% error and consequently, the nonlinear stress-deflection relation should be used to relate plate curvatures to initial film stress.

Two separate phenomena occur during the low-load indentation of silicon which make its behavior distinctly different from that of most materials. First, silicon is one of only a very few materials whose hardness exceeds the pressure needed to transform it to a denser crystalline (or amorphous) form, and because of this, a reversible, pressure-induced phase transformation occurs during indentation. The transformation enhances the electrical conductivity of the material and creates a region around the indenter which flows like a soft metal. Second, silicon cracks when indented by a Berkovich or Vickers indenter at loads of less than 100 mN, i.e., loads typically used in nanoindentation experiments. These two phenomena, which account for a number of unusual features in the indentation load-displacement behavior, are documented and discussed.

We employ constant temperature molecular dynamics simulations to study, at the atomistic level, the interactions of an Ir tip with a Pb substrate. We have considered the complete cycle of approach.contact, indentation and retraction of the tip from the substrate. We have observed the wetting of the tip by the substrate atoms, and the formation of atomic necking between the tip and the substrate.

We have carried out further simulations to study the interactions of an Ir tip with an Ir substrate covered with an adsorbate monolayer of Pb film. We show that the introduction of the adsorbate considerably reduces the work of adhesion and the extent of plastic flow, in agreement with experimental results.

Three-dimensional geometries have been generated on computer and used for the animation of the simulation runs.

Time-dependent deformation in room-temperature indentation is a well known phenomenon which is frequently overlooked in depth-sensing indentation experiments. In this study, the time-dependent displacements which occur during depth-sensing indentation experiments using a Nanoindenter were investigated. Time-dependent displacements were found to result both from plastic deformation of the sample and experimental drift. A simple correction for experimental drift was applied in experiments on sputtered copper thin films and reasonable strain rate sensitivities were obtained. The sources of experimental drift were identified and measured. It appears to be possible to measure the rate-dependence of plastic deformation in a variety of materials using this instrument.

Time-dependent deformation (TDD) in small volumes was monitored using an alternating (AC) force technique and a Nanoindenter. The AC technique provides a continuous measure of contact stiffness during an indentation. By holding the force constant and monitoring the stiffness, the applied pressure and an effective strain rate were measured. Reasonable strain rate sensitivities were obtained for permanent indentations involving significant plastic strains. Time-dependent recovery due to residual strain energy is also reported. For reversible, elastic indentations, TDD was seen when the applied force was held constant. The deformation is attributed to atomic diffusion.

The stress—strain behaviour of metallic and polymer thin films are measured using a spherical indenter. A modification of the Hertzian analysis enables the elastic to plastic transition to be analyzed so that the variation of mean pressure versus depth can be calculated. The stress—strain behaviour is then calculated from the mean indentation strain using a relationship proposed by Tabor[l]. Observations of high precision load displacement data generated with a UMIS—2000 instrument are analyzed on the basis of the simple analysis developed. The measured values are compared with simulated data for the same materials.

Using a highly spatially resolved mechanical properties microprobe, the elastic, plastic and time dependent mechanical properties of sapphire and a 1.9 μm amorphous alumina film on a sapphire substrate have been studied. Young's modulus, hardness, and stress-exponent data are reported. The technique for characterizing time dependent properties via indentation (hardness versus displacement rate/displacement) are directly compared to standard uniaxial compressive techniques (stress vs strain rate) for a bulk Pb-In alloy to further quantify the relationships between the two techniques.

Amorphous boron coatings, ranging in thickness from 4 to 15 μm, have been synthesized via plasma-enhanced chemical vapor deposition using an rf plasma coil having serpentine rather than helical geometry for inductive coupling of the plasma. The power input to the rf coil has been established at five discrete levels ranging from 50 to 200 W during deposition from diborane onto Ti-6Al-4V substrates at 450°C. Deposition rates have been found to depend significantly on coil input power, reach in a saturation level of 15 μm/h at 100 W and higher but decreasing markedly with lower coil power levels. The amorphous nature of the coatings has been confirmed by selected area electron diffraction of extracted particles. Vickers and ultralow-load indentation experiments have been performed on boron coatings in cross-sectional and plan orientations, respectively. The ultralow-load hardnesses of the coatings deposited at all power levels exhibited relative independence from deposition power and ranged from 11.5 to 14.6 GPa. Vickers indentation in cross section produced hardnesses which were significantly greater than those using ultralow loading and an inconsistent dependence on deposition power.

The microhardness of polycrystalline and amorphous coatings on substrates of various hardness has been studied in a wide range of loads. The limits for indentation depth providing optimal conditions for microhardness testing have been found. Basing on the results of integral hardness testing of coated samples at comparatively high loads, a method has been proposed for the microhardness and thickness evaluation.

Observations are presented of the indentation of amorphous silica films of different thickness on mild steel substrates. The films were prepared by sol—gel dip coating and sintering at 500° C. Indentation of the films with a Berkovich indenter using an ultra micro—indentation hardness system (UMIS) revealed a critical load for the fracture of the thin films. The variation of the fracture load was characterised by a Weibull analysis that gave a mean fracture load and a Weibull modulus. The latter was found to be nearly independent of film thickness whereas the former varied with the square of the thickness.

When a hard tip indents a sample, cracking, delamination and plasticity can all produce acoustic signals in the form of elastic waves. This paper describes how these acoustic emissions (AE) can be monitored using piezoelectric elements and a load-controlled indentation instrument. Signals emitted from thin films and bulk materials are shown and they are correlated with distinct jumps in displacement of the indenter tip. The benefits and difficulties of different methods of monitoring the emissions are also considered.

A scanning tunneling microscopy (STM) study of low load indentations into Si, GaAs and Au is presented. Compared with standard micrographs obtained through optical microscopy and scanning electron microscopy, the STM images show greatly improved resolution in and around the indentation. The effects of relaxation and pile-up may be observed through contour plots which show inward bowing of the indentation faces in Si.

Knoop hardness and nanoindentation studies were performed on single and multilayered 80/20 mol % TiO2/SiO2 films spin-coated onto [100] silicon wafers. The Knoop microhardness results indicated that a total sol-gel thickness (h) to indentation depth (h*) ratio of >2 was sufficient to obtain reliable thin film properties independent of substrate influence. Electron microscopy techniques were used to determine the sample's absolute film thickness, to examine the morphology of the indentations, and to determine the phase of the sol-gel thin films.

The geometries, microstructures, energetics and kinetics of misfit dislocations as functions of surface orientation and the magnitude of strain/stress are investigated experimentally and theoretically. Examples are drawn from (100), (110) and (111) surfaces and from the GexSi1–x/Si and InxGa1–x/GaAs systems. It is shown that the misfit dislocation geometries and microstructures at lattice mismatch stresses < - 1GPa may in general be predicted by operation of the minimum magnitude Burgers vector slipping on the widest spaced planes. At stresses of the order several GPa, however, new dislocation systems may become operative with either modified Burgers vectors or slip systems. Dissociation of totál misfit dislocations into partial dislocations is found to play a crucial role in strain relaxation, on surfaces other than (100) under compressive stress.

Understanding die kinetics and mechanisms of strain relaxation in Si-Ge heteroepitaxial films is pertinent to several device applications. In this paper we present a method for determining the evolution of the mobile dislocation density with time during the course of strain relaxation taking place in an isothermal annealing experiment.

Wafer curvature measurements using a laser scanning technique are used to determine the elastic strain after growth in films of variable thickness and to follow the strain relaxation during isothermal annealing experiments. By coupling the strain relaxation measurements with previous TEM measurements of dislocation velocities in this system, the mobile threading dislocation density and its evolution with time are determined.

An initially pseudomorphic Sio.93Geo.07 layer is forced to relax after the deposition of 0.003 monolayers of Cu contamination and a 600°C anneal. Photoluminescence shows the dislocations have similar luminescence features (D1 to D4) to dislocations generated in bulk silicon. TEM is used to study the generation of the misfit dislocations. It is shown that the half loops form at the sample surface and a mechanism that involves the action of both the metal contaminant and the surface steps is suggested to explain the geometric arrangement of the dislocation loops that are present. The sample was found to be only 22% relaxed whereas equilibrium theory predicts 92% relaxation.