The mixing of titanium overlayers with hydroxyapatite (HA) substrates via ion irradiation has been demonstrated. Analysis via secondary ion mass spectroscopy (SIMS) indicates an interfacial broadening of titanium and calcium of the implanted sample compared to that of the unimplanted sample. Attendant to the observed ion beam mixing of titanium into the HA, the oxygen signal of the titanium overlayer increases as a result of ion irradiation. It is supposed that this change is evident of diffusion through the metal layer and possibly from titania formation at the free surface and perovskite formation at the film/substrate interface. This possibility is consistent with thermodynamic predictions. Additionally, the force required to separate the film from the substrate increased as a result of ion irradiation, validating the continued study of ion beam processing of Ti/HA systems towards the improvement of long term fixation of implant devices.

We have nitrided Ti-6A1-4V alloys using excimer laser pulses at 1.2 J-cm−2 in high purity N2 at approximately one atmosphere. Substantial nitrogen and oxygen incorporation resulted from multiple pulse processing. The surface microstructure that results is of fine grained precipitates in the Ti alloy matrix. Formation of a TiN surface film was not observed. We have examined the tribological and mechanical properties of these surfaces using pin-on-disk and nanoindenter techniques respectively. Nitrogen alloying results in a period of reduced friction and torque noise in the pin-on-disk measurements. At higher N concentrations, abrasive wear of the pin is observed, but with little deterioration of the disk surface. This is consistent with the formation of a transfer film at the sliding interface. Nanoindenter measurements of the surfaces show increasing hardness proportional to nitrogen incorporation. The tribological properties can therefore be understood to result from a combination of tribochemical effects and increased surface hardness.

The effects of ion implantation on two types of electroplated chromium were studied. Both hard chromium and low contraction chromium were plated onto samples of AISI 4340 grade steel and subsequently implanted with N2+ or Ar+ at ion energies of 150 keV and 75 keV, respectively. The dose was varied from 9.4 x 1015 to 3.1 x 1018 atoms/cm2 and the implantation was conducted at both room temperature and 500 °C. The properties of the resulting surface layers were characterized using secondary ion mass spectrometry and Knoop microhardness. The dry sliding wear and friction behavior was also compared between implanted and unimplanted layers. An increase in hardness was observed for both types of electroplated chromium. The wear rate and friction coefficient were reduced in the nitrogen implanted samples. At the intermediate doses tested, the elevated temperature condition provided improved wear and friction properties compared to the room temperature condition.

Scratch testing has long been used to assess the adhesion of a film to its substrate. As film thicknesses have decreased, the need for greater precision and sensitivity in the scratch testing apparatus has increased. To this end, a nanoindenter was modified to make finely controlled, low-load scratches. Scratches at various loads and two orientations of a Berkovich scratching diamond were made in films of 100 nm of gold and 200 nm of copper, each on single crystal silicon. For each film type, samples with no interlayer, with an SiO2 interlayer, and with a TiW on SiO2 interlayer were tested. The scratch morphology was found to vary in a regular way with load, diamond orientation and interlayer material.

This paper presents the results of the mechanical characterisation, by a mechanical properties microprobe or nanoindenter, of tribochemical films produced by the sliding wear of alumina in a humid environment.

It was found that the tribochemical films were softer than the remnant alumina on the worn surfaces, and were liable to fracture and cracking under the indenter.

A new procedure for obtaining accurate work of adhesion values for stiff films as thin as 0.5 µm or less is presented in this paper. The technique is based on fabrication of a two-dimensional test structure using a photolithographic alignment sequence. With precracks of variable length at the end of a fine line, a well known stress state is imposed before delamination. The test structure allows simple analytical equations to be applied to approximate the strain energy release rate, G. Finite element method is used to obtain more accurate values of G as well as of mode mixity. For short crack lengths, no buckling occurs, and the phase angle is near mode II. Kinking into the glass substrate is observed when the measured critical strain energy release rate, Gc, is greater than glass, but not when Gc is less than glass. When the precrack is lengthened, buckling may occur before delamination. In this case the phase angle has a large mode I component, and the crack remains in the interface even in the case of the strong interface.

In this study we used nanoindentation and continuous microscratch testing to determine the effect of hydrogen on the work of adhesion and fracture toughness of thin tantalum nitride films. These films were sputter-deposited on sapphire substrates to a thickness of 600 nm followed by the heating of some films in deuterium and some in vacuum at 300°C. Deuterium was used in this study because it is much easier to detect and measure than hydrogen. Ion beam spectroscopy showed that exposure to deuterium produced a uniform internal deuterium concentration of 2000 appm. Nanoindentation showed that exposure to deuterium at 300°C and vacuum annealing at 300°C had little effect on elastic modulus and hardness values of these films at room temperature. In contrast, the microscratch tests at room temperature revealed that the work of adhesion decreased from 24.5 J/m2 after vacuum annealing to 9.1 J/m2 after deuterium charging and demonstrated that tantalum nitride films have a strong susceptibility to hydrogen embrittlement.

Laser programmed connections between adjacent lines on the same level of metallization have been developed as a means to achieve high density linking for customization in programmable gate arrays and for additive redundancy in restructurable integrated circuits. The resistances of the connections were approximately 1Ω and the overlaying passivation remained in tact. Links were formed by focusing a pulsed laser between two adjacent lines of metal, one of which was connected to a lower level of metal through a contact via. The mechanism of link formation appears to be a fissure contained within planarized passivation due to the stress of thermal expansion of the metallization with molten aluminum filling the crack.

Adhesion of oxidic and metallic films with thicknesses between 40 nm and 350 nm has been investigated by means of a scratch-test method based on a vibrating diamond micro-indenter. SiO2 and TiO2 films are precipitated on fused silica substrates by sol-gel techniques (SG), reactive evaporation (RE), reactive low-voltage ion plating (IP), and plasma impulse chemical vapour deposition (PICVD), and Cr-layers are produced by rf magnetron sputtering (SP). The influence of aging effects on film adhesion is investigated in respect of several conditions, like storage under ambient surroundings with differences in relative humidity or temperature treatment. A method is presented allowing control of the long-term stability of the scratch-test conditions. Temperature treatment up to 600 °C is found to have the most significant impact on adhesion properties. Adhesion increases for some SiO2 films, whereas for TiO2 layers an opposite behavior is observed. Here, the adhesion of the originally amorphous titania films is reduced due to the phase transition to polycrystalline anatase, which correlates with a significant increase in film stress.

Thermal stress influences adhesion of many coatings applied on tool substrates. Management of thermal stresses is important for improvement of coatings and tool life. We have shown that stresses can be controlled by developing a composite layer of diamond with carbides and nitrides such as TiC or TiN. We have modeled the thermal stresses in these composite diamond coatings using finite element analysis. The composite diamond coatings consist of a discontinuous layer of diamond with an embedded layer of TiC or TiN, and a top layer of continuous diamond. For comparison, a single layer of diamond coating has also been used. The thermal stresses in these coatings on WC(Co) and Si3N4 tool substrates were calculated. Results show that the thermal stresses at the interface between the coatings and the substrate are relaxed after introducing the composite layers. This stress relaxation is responsible for the improvement of the adhesion of composite coatings.

Fracture behavior in Ni-10 wt.%P amorphous (10 µm thick) and overlay Y2O3 stabilized ZrO2 (0-1.0 µm thick) ceramic coatings on Al alloy substrates has been investigated using small punch (SP) testing and acoustic emission (AE) techniques. SP tests showed that coating cracks extensively propagate along both the radial and tangential directions under the biaxial stress condition. The formation of cracks was more profoundly found in Ni-P amorphous coatings than in amorphous/ceramic coatings. The cumulative AE events were well correlated with the severity of coating cracking independent of the type of coatings. Ceramic coatings with a thickness of 0.25 and 1.0 µm led to a decrease in the fracture toughness by 15–20%, compared with a uncoated alloy. The coating effect on the fracture toughness is discussed in light of residual stresses induced during coating processing and the presence of coating cracks.

The use of copper for interconnect metallization on advanced submicron integrated circuits is attractive because of its inherent low resistivity. To date, chemical vapor deposition (CVD) processes which produce copper films with nearly bulk resistivity and good uniformity have been produced. However, adhesion of the copper deposit to underlying barrier materials, in particular to titanium nitride (TiN), has been problematic. In this work, adhesion has been measured using both a qualitative and a semi-quantitative method and has been correlated with process conditions and precursor formulation.

Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low pressure (0.17 kPa (1.25 torr)).

The effect of deposition temperature (200 − 380 °C), growth rate, film thickness, and post-deposition thermal treatment on the mechanical properties was studied. The experiments were performed with a scanning-scratch tester. The experiments are based on the estimation of the film adhesion to the substrate by determining a critical load, Lc: the load where the film starts to spall or to delaminate.

The best mechanical properties were obtained with unannealed samples. After thermal annealing the critical load decreases. Regarding the unannealed samples, the critical load increased with increasing film thickness. The deposition temperature and the growth rate had no effect on the critical load.

A model is constructed to consider the stresses (analytically and with Finite Element Analysis (MiA)) which result from the thermal mismatch between the die and the substrate. FHA is used to simulate thermal stresses induced from temperature cycling with voids and without voids in the die-attach at the die-substrate interface. Local stress concentration caused by voids is found to be dependent on the location of the voids. The presence of an edge void at the die-attach interface changes the local stress and creates a longitudinal stress field. It is also observed that for die-attachment without voids or some center voids there will be no cracking whereas specimens with voids near the edge of the die are likely to have vertical die cracks. Using the void growth, stress relaxation equations, the void growth is simulated yielding an exponential relationship to void grow th and a saturation of void volume w ith time. Stress relaxation and void growth during cool down are simulated, once the material parameters and cooling rates are known. It yields a time dependence of the relative void volume (exponential decay).

Nanocrytslline composite films of Ag-Mo and Ag-Ni have been made by a co-deposition technique in UHV. The structure and composition have been studied by x-ray diffraction (XRD), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA). For practical applications, the friction coefficient and wear rate were measured using a pin-on-plate machine for Ag-Mo composites deposited on steel. For fundamental studies, the hardness of the Ag-Ni composites deposited on oxidized Si wafers was measured using a nanoindenter. Experiments show that (1) reduction of friction and wear rate can be achieved using these nanocomposite coatings and (2) the hardness of the nanocomposites depends on the grain size. As the grain size of the Ag decreases from 100 to 10 nm, the hardness increases about 4 times.

Bonding strength is commonly measured by various kinds of single cycle tests such as scratch tests or indentation tests. These tests all reflect complex composite properties - both plastic and elastic properties of the film and the substrate - as well as the bonding strength. In many cases experimental critical value of these single cycle tests is controlled by film or substrate strength or ductility rather than bonding strength. In these cases, the single cycle test should be evaluated in terms of the specific property which controls failure and should not be taken as a measure of “bonding strength.” However, the interfacial fatigue strength measured at 5X106 cycles is shown to be measurable over a large range of bonding strengths and composite properties. And further, this interface fatigue strength is insensitive to the composite properties. The complementary nature of these two types of tests is demonstrated for various TiN-based hard coatings on various steel and cemented carbide substrates.

Diamond-like carbon (DLC), a hard, optically transparent, and chemically inert material, is becoming increasingly important for many applications. With the development of low-temperature deposition techniques, DLC can now be applied to many heat-sensitive polymers. This paper will discuss the application of a DLC coating as an abrasion and moisture barrier for three different laser-protective holographic filters. The objective of this investigation is to study the influence of the coating process on the holographic filters, and to determine the effectiveness of the DLC coating as the environmental seal for these filters. The DLC coated filters were characterized by UV/visible spectroscopy, scanning electron microscopy, before and after exposure in an environmental chamber set at 71°C, and 90% humidity. The structure and hardness of the DLC coating were evaluated respectively by Raman spectroscopy and nanoindentation method.