Dislocations were created near the center of the surface (110) of copper small crystals whose surfaces are (111), (111), (110), (110), (112), and (112) by use of n-body atom potentials and molecular dynamics. At first, a Heidenreich-Shockley partial dislocation was created. As the partial dislocation proceeds, the partial dislocation and the surface was connected with a stacking fault until the next Heidenreich-Shockley partial dislocation was created at the surface.Just before the creation of a partial dislocation the stress was the highest. For larger crystals, forming a step on (110) plane was not enough and a shear was necessary to move dislocations.

A new tensile tester for thin films was developed to evaluate the reliability of the microelectro- mechanical devices. This tester uses the grip that fixes a thin film specimen to a probe by electrostatic force. We applied this tester for polycrystalline silicon (poly-Si) thin films prepared under various conditions. The microstructure of the film is controlled by the crystallizing temperature. The process conditions and the microstructures that contribute to the strength of poly-Si film are identified by the tensile strength and the fracture toughness. The mean tensile strength of each specimen size ranges from 1.8 to 3.7 GPa, and the fracture toughness calculated from the strength of the notched specimen ranges from 1.9 to 4.5 MN/m3/2. The 1000°C annealed film has higher strength and toughness than the other films because of the high annealing temperature and the small grain size. The contributions to the strength are evaluated by the additional annealing at 1000°C for the low temperature annealed films.

This paper focuses on in-situ transmission electron microscopy observations of surface roughening and defect formation in heteroepitaxial Sil−xGex thin films. Annealing experiments have been carried out in-situ in the microscope under a high vacuum environment. We comment on the sample preparation procedure for in-situ TEM experiments and explain the importance of having a sufficiently thick sample to have the stress state in the film unaltered. Experimental results of in-situ surface roughening are presented for suberitically and supercritically thick Sil−xGex films. We found that, in a vacuum environment, the kinetics of surface roughening and the resulting surface morphology are much different than in a hydrogen environment.

Influence of internal mechanical stresses (IMS) and dislocations on conductivity mechanisms and reliability of light emitting diode (LED) and laser InAsPSb/InAs double heterostructures has been investigated. It was shown that the presence of lattice mismatch of layers at p-n-heteroboundaries changes LED conductivity mechanisms the same way as longterm working challenges by current. It was determined that LED degradation has barrier character and is followed by appearance and growth of tunnel current components with power dependence of current from voltage. Reliability and external quantum efficiency decrease with growth of lattice mismatch.

The presence of thin surface films and adsorbate layers on both metals and ceramics can cause dramatic changes in the mechanical response of the material. A similar, related, variation in tribological properties has also been observed. Though the importance of surface effects is well known and widely documented, the exact physical and chemical mechanisms that are operating remain poorly understood. The development of point probe techniques now permits the examination of mechanical and tribological properties on the same length scale as the surface films. Recently, the utilization of these testing techniques has provided a clear insight into the mechanical processes which are operating on the atomic scale. The nanoindentation results presented here show that the mechanical deformation of an individual nano-contact is a highly dynamic phenomena in which the tip-momentum on contact, as well as the loading rate during the indentation, dictate the observed mechanical properties of the material. These results indicate that the initiation of plastic deformation is dependent on the stability of atomic-size surface asperities which can be deformed irreversibly by the high stresses generated during the initial contact. Additionally, the generation of dislocations and the presence of discontinuities in the loading curve are shown to depend upon the loading rate. More significantly, it has been found that modifying the surface chemistry can cause dramatic changes in both the mode of deformation and the time-dependence of nano-scale mechanical properties. The principal conclusion that can be drawn is that the high stresses which operate over short distances make time and temperature dependent phenomena, such as diffusion and the dissipation of energy via phonons, of vital importance in determining the near-surface mechanical properties of a material. Such effects are further magnified in tribological processes where normal and tangential loading of the surface leads to the repeated making and breaking of nano-asperity contacts.

Thermal cycling was performed in Al-lmo%Si thin films deposited on Si wafers. After a given number of cycling between room temperature and 723 K, residual stress was measured at room temperure. Residual stress was found to increase with increasing the cycling number up to the 4th cycle, followed by further a continuous decrease by further cycling. The intial increase was found to be related to the increase of lattice dislcocations and their tangling. The following decrease was caused by crack formation along grain boundaties or by film delamination in some cases.

Two series of five diamond-like carbon (DLC) coatings were sputtered under nominally identical conditions, but to different film thicknesses of 20 nm and 105 nm. First, the hardness of each sample was determined by depth-sensing indentation. Hardness measurements were substrate-affected to some extent for all samples but especially so for the 20 nm coatings. Two types of scratch tests were performed in an attempt to isolate and characterize the top coatings. The first was a wear test, which consisted of moving the sample back and forth repeatedly under a small constant load. The residual damage was inconsistent, but appeared to be a function of the composite, or substrate-affected hardness. The second test was a single-pass scratch in which the normal load was ramped linearly. For all samples, the friction coefficient was approximately constant as a function of load. Furthermore, samples with the same top coats yielded similar friction coefficients, regardless of the coating thicknesses. Friction coefficient decreased with hydrogen content and to some extent, increased with hardness, as measured on the 105 nm samples. The friction coefficient measured during a ramp-load scratch offers an alternative for characterizing ultra-thin films, when indentation alone yields measurements that are significantly affected by the substrate.

We have investigated the microstructure and tribological properties (wear resistance) of diamondlike carbon (DLC), DLC doped with Cu and DLC doped with Ti deposited by a sequential pulsed laser ablation of two targets onto Si(100) substrates. The composition of these films was determined by Rutherford backscattering spectroscopy and X-ray photoelectron spectroscopy(XPS). Raman spectroscopy and detailed analysis of the electron diffraction pattern of the films showed typical features of DLC with a structure dominated by sp3 bonded carbon. Wear resistance measurements made on these samples by means of the “crater grinding method” showed that DLC + 2.75%Ti has the highest wear resistance, while that of undoped DLC has the lowest among the samples. The improvement of wear behavior of the doped films was attributed to the reduction of internal compressive stress due to the presence of more compliant atoms, as indicated by the G-peak position shift to smaller Raman shift. The XPS studies showed the evidence for the formation of Ti- C bonding in the Ti doped films. Thus we expect metal-doped DLC coatings can have better tribological properties than the undoped, highly stressed DLC coatings.

Ferro-electric (BSTO) films of 1 μm nominal thickness were deposited on single crystals of sapphire at substrate temperatures varying from 30 °C to 700 °C. Optical analysis showed that the thin films were amorphous up to 500 °C, while at 700 °C they were polycrystalline. The microstructure of the thin films was columnar at all substrate temperatures. The film microhardness increased with increasing substrate temperature. While the cohesion failure load of the films remained fairly constant, the adhesion failure load increased with increasing substrate temperature.

Previous research has compared the mechanical properties of Ti6A14V implanted with nitrogen using the plasma source ion immersion process and Ti6A14V implanted with boron using the beamline process [1]. Although the nitrogen implanted Ti6A14V had superior wear resistance it was concluded that the wear resistance of boron implanted Ti6AI4V might be improved to comparable levels if boron were implanted at lower energies to increase the concentration of boron at the surface. Boron implantation of Ti6A14V has been conducted at combinations of 32 and 40 keV to supplement that done previously at 75 keV. Shallower boron depth profiles with higher B-concentrations in the Ti64 surface have been obtained by tailoring the combinations of ion energy and dose. This work used three different ion energy and dose combinations of 4×1017 B-at/cm2 at 40 keV plus 2×1017 B-at/ cm2 at 32 keV, 4×1017 B-at/cm2 at 40 keV, and 4×1017 B-at/cm2 at 32 keV plus 2×1017 B-at/ cm2 at 40 keV. Comparisons are made between Ti6A14V with a shallow implanted boron depth profile, Ti6AI4V with a deeper boron depth profile and nitrogen implanted using a plasma source ion implantation process. It has been previously shown that while boron implanted Ti64 has a ~30% higher surface hardness than nitrogen implanted Ti64, the N-implantation reduced the wear coefficient of Ti64 by 25–120x, while B-implantation reduced the wear coefficient by 6.5x or less. The results show that no significant improvement is made in the wear resistance of boron implanted Ti6A14V by increasing the concentration of boron at the surface from approximately 10%to 43%. Transmission electron microscopy (TEM) and selected area diffraction (SAD) indicated the formation of crystalline TiB in the implanted surface layer. Shallower depth profiles result in reductions of the Ti6AI4V wear coefficient by 6.5x or less which is the same result obtained earlier with the deeper boron depth profile. Surface hardness of Ti6A14V with shallower boron depth profiles was improved approximately 10%compared to the results previously acquired with deeper boron depth profiles.

Amorphous carbon-germanium films were grown by dc-magnetron sputtering at different argon plasma pressures ranging from 0.17 and 1.4 Pa. The water-cooled sample holder was grounded. The film thickness were typically 0.5 μm. The ratio between germanium and carbon atomic concentration ranges up to 2.8, as measured by Rutherford backscattering spectrometry (RBS). Elastic recoil detection technique was used to measure hydrogen contamination. The film hardness was measured by nanoindentation techniques and the internal stress was determined by the bending of the substrate. The incorporation of Ge reduces both the film hardness and the internal stress. Hardness and internal stress increases when the films are deposited in lower pressures. Atomic Force Microscopy (AFM) was used to measure the surface roughness, which was found to be insensitive to the pressure and to the Ge content. A possible influence of the thickness on the morphology of pure carbon films is discussed. The friction coefficient measured by AFM is independent on the film composition within experimental errors.

Fracture mechanics models indicate that nonplanarity of the interface should have a significant effect on the measured fracture energy [1–5]. Previous work on a typical interconnect structure (Fig 1) has demonstrated that two thin film systems with nominally the same composition, but processed under different conditions exhibited different SiO2/TiN interface fracture energies [6,7]. pon investigation via crosssectional TEM, it was found that the stronger interface was significantly rougher than the weaker interface. These results indicate that small changes in processing conditions can significantly effect both interface morphology and adhesion. Accordingly, in this study, samples differing in the flow rate of Ar to a plasma arc during deposition of a TIN layer were chosen in order to investigate the effects on the interface morphology and the resulting interface fracture energy.

Nanoindentation at loads from 100 to 750 mN was used to measure the interfacial adhesion energy of sputtered copper thin-films, for which the release of elastic strain energy drives delamination. The as-sputtered films were of four thicknesses, nominally 225 nm, 400 rn, 600 nm and 1000 nm, and were deposited onto Si/SiO2 wafers; one wafer of each two-wafer run was annealed at 600°C for 2 hrs in a nitrogen atmosphere. Subsequently, a nominally 700 nm thick sputtered superlayer of tungsten was deposited over all wafers. The tungsten overlayer was used to promote delamination at the copper-SiO2 interface. The energies for fracture ranged from 1 to 80 J/m2, increasing with increased indentation depth, and a trend of higher adhesion energy for annealed films. The large values of adhesion energy with respect to the thermodynamic work of adhesion are attributed primarily to plasticity and/or void nucleation within the copper film, which appears to be strongly influenced by the constraint of an overlayer.

We have used picosecond ultrasonics to study the effects of ion irradiation on the interfacial bonding between gold films and a silicon substrate. Acoustic vibrations are excited in the metal film when a picosecond light pulse is absorbed. The rate at which these vibrations damp out via sound transmission across the interface into the substrate gives a measure of the adhesion of the film to the substrate. The films were irradiated with 2.5 MeV helium ions with doses between 7×1014 and 8×1016 ions cm-2. The adhesion, as measured by the rate of acoustic damping, was found to be significantly improved by the ion irradiation.

The ultrasonic wire bonding process is widely used for making interconnections between IC chips and package lead frames, yet the relationships between the wire/substrate materials properties and the bond formation processes are not yet well understood. In this study, we have conducted experiments to understand the mechanical response in thin film substrates subject to ultrasonic wire bonding. Atomic force microscopy (AFM) has been used to examine the morphology of thin film surfaces before and after bonding. Al wires were bonded to thin films of Cu, Cu-Ni and Ag, after which the aluminum wire was removed by etching. AFM examination of the Cu and Cu-Ni bonded surfaces revealed the extent of surface smoothing increased with bonding power level. However, at power levels typically employed in practice almost no morphological surface changes were observed, indicating surface smoothing is not required to obtain good bonds. TEM and SEM cross-sections were also used to examine Al wedge bonds and Au ball bonds to Al films on Si. A wide variety of features were observed, including surface smoothing, microcracking and void formation.

We have used transmission electron microscopy (TEM) to study the microstructure of thin gold films which were grown on 〈100〉 rock salt. The samples were annealed on the rock salt substrate or on a gold TEM specimen grid. Films annealed on rock salt had a larger mean grain size than those annealed on TEM grids. All of the annealed films have a 〈111〉 preferred orientation. Several cracks are observed in the film annealed on rock salt. Plastic yielding of the film was identified by the presence of dislocations, and is caused by tensile stress derived from grain growth. In spite of the uniform texture of the films, the observed dislocations were concentrated only in some individual grains, while their surrounding grains remained dislocation-free. Yielded grains showed no difference of orientation that would lead to higher Schmid factors, so other predictors of yielding must be considered.

Residual stresses in four types of diamond films deposited by hot filament chemical vapor deposition on molybdenum substrate, three types on tungsten carbide or silicon nitride substrate are measured. Residual stresses are determined by X-ray method and Raman spectroscopy. The results from both these techniques are compared and conclusions are made on the mechanisms of adhesion of diamond films to the different substrates.

This paper focusses on the development of biaxial stress in Cu0.57Nio. 42Mno.ol thin films during annealing in Ar and, for comparison, in vacuum. Besides stress-temperature measurements also resistance-temperature investigations as well as chemical and microstructural characterization by Auger electron spectroscopy, scanning and transmission electron microscopy, and X-ray diffraction were carried out. To explain the stress evolution, atomic rearrangement (excessvacancy annihilation, grain-boundary relaxation, and shrinkage of grain-boundary voids) and oxidation were considered. Up to 250 - 300 °C grain-boundary relaxation was found to be the dominating process. A sharp transition from compressive to tensile stress between 300 °C and 380 °C is explained by the formation of a NiO surface layer

In this work we show that stress in sputter deposited lead zirconate titanate (PZT) films can be controlled by variation of both deposition and annealing temperatures. These films were deposited via reactive rf magnetron sputtering using a Pb1.25Zr. 52Ti. 48 03 composite target and 02 as a reactive gas in an Ar ambient. Variation of stress as a function of deposition and annealing temperature was characterized. The deposited film composition was determined from x-ray fluorescence measurements. There is a strong correlation between film stress, composition, and crystallographic orientation. Stress was determined from the deflection of released SiO 2/Pt cantilever beams. We show that films with a wide range of intrinsic stress can be deposited which still exhibit good piezoelectric properties, making the fabrication of reliable thin film piezoelectric actuators possible.

We have developed a technique of X-ray diffraction in order to measure strain fields near semiconductor surface and interface. The diffraction geometry is using the extremely asymmetric Bragg-case bulk reflection of a small incident angle to the surface and a large angle exiting from the surface. The incident angle of the X-rays is set near critical angle of total reflection by tuning X-ray energy of synchrotron radiation at the Photon Factory, Japan. For thermally grown-silicon oxide/Si(100) interface, the X-ray intensity of the silicon substrate 311 reflection has been measured. From comparison of the full width at half maxima (FWHM) of X-ray rocking curves of various thickness of silicon oxides, it has been revealed that silicon substrate lattice is highly strained in the thin ( less than about 5 nm) silicon oxide/silicon system. In order to know the original silicon surface strain, we have also performed the same kind measurements in the ultra-high vacuum chamber. A clean Si(l 11) 7×7 surface gives sharper X-ray diffraction peak than that of the native oxide/Si(l 11) system. From these measurements, it is concluded that the thin silicon oxide film itself gives strong strain fields to the silicon substrates, which may be the reason of the existence of the structural transition layer at the silicon oxide/Si interface.