Wafer level monolithic three-dimensional (3D) integration is an emerging technology to realize enhanced performance and functionality with reduced form-factor and manufacturing cost. The cornerstone for this 3D processing technology is full-wafer bonding under back-end-of-the-line (BEOL) compatible process conditions. For the first time to our knowledge, we demonstrate nearly void-free 200 mm wafer-to-wafer bonding with an ultra-thin Ti adhesive coating, annealed at BEOL-compatible temperature (400 °C) in vacuum with external pressure applied. Mechanical integrity test showed that bonded wafer pair survived after a stringent three-step thinning process (grinding/polishing/wet-etching) with complete removal of top Si wafer, while allowing optical inspection of bonding interface. Mechanisms contributing to the strong bonding at Ti/Si interface are briefly discussed.

Biological solutions to enhance strength and stability often use lateral and hierarchical composite structures from nano- to micro-scale. The effect does not consist of a large chemical variety but it is realized by structural composites (namely phase changes and orientations). A new developed bio-mimetic laser interference metallurgical technique uses this biological approach to optimize mechanical properties of surfaces and thin films. A hierarchical nano-composite is realized by both a vertical nm-scaled period of PVD-processed multi-films and a lateral μm-scaled period of laser interference metallurgy.

In past, laser interference irradiated Ni/Al multi-films showed periodical properties in the range of interference period. The hardness and modulus could be varied periodically and the texture and stress situation could be significantly changed.

In this work, the micro-structural evolution of irradiated Ni/Al multi-films is analyzed by TEM measurements to justify the properties change. The grain size can be obtained to be laterally oscillating between 5 to 10 nm and up to 100 nm and the layer interface to be semicoherent. Up to a certain depth, intermetallic compounds are found in the layer interface.

Physical properties, and the friction and wear are important issues in small-scale applications, it is therefore essential that the materials used have good micromechanical and tribological properties. The adhesion, fracture toughness and wear properties of AlN-TiN thin composite films is being investigated in this study. The multilayered structures are generated using Pulsed Laser Deposition (PLD). The durability and functionality of thin films is subject to the adhesion between the coating and the underlying substrate in addition to it's resistance to cracking. The magnitude of the critical load during a scratch test is related to the adhesion of the substrate to the coating. In this test a Berkovich indenter is used for measurements and is drawn across the surface of a coating under an increasing load. The magnitude of the critical load will be studied for various films from a monolayer TiN film to different AlN-TiN films and those relative results compared to their facture toughness and their wear properties. Despite the adhesion, the critical load depends on several other parameters including the friction coefficient. The critical characteristic load is shown to depend on the number of layers and the relative AlN-TiN thickness. The fracture toughness showed a weak dependence on the layer characteristics.

Poly-tetrafluoroethylene [PTFE] presents few rejections in a living body but has low tissue affinity. Then, the soft tissue implant material that has not only high biocompatibility but also superb bondability has been developed by photo-chemically substituting the hydrophilic of –OH or –NH2 groups on the PTFE surface with V-UV photon irradiation. The protein adsorption of the sample before and after treatment was also evaluated by scanning electron microscope [SEM] and attenuated total reflection Fourier-transform infrared [ATR FT-IR], using bovine serum albumin [ALB] and fibrin [FIB] solution as a protein index in biocompatibility test. From the results, it has been confirmed that the protein adsorption increased with the increase in the hydrophilic group's substitution density. The -OH incorporated sample adsorbed the ALB and FIB more than the -NH2 incorporated sample; the amount of the ALB and FIB sticking became 2.3 times larger than that of the non-treatment sample.

We provide an overview of our recent studies on novel tribological applications of shape memory and superelastic effects: (i) the use of shape memory NiTi alloys as self- healing surfaces, and (ii) the use of the superelastic NiTi as an interlayer between a hard coating and a soft substrate to improve interfacial adhesion, decrease friction coefficient, and improve wear resistance.

Diamond is known as the material that has excellent mechanical, electrical and chemical properties. Diamond is also an ideal interface that is compatible with microelectronics process and biological environments to work as a biosensor platform with excellent selectivity and stability. In our study, nanocrystalline diamond (NCD) films were grown on Si substrates by the microwave plasma enhanced chemical vapor deposition (MPECVD) method. Parameters such as gas composition, temperature and pressure are investigated to get the best film quality. Scanning electron microscopy (SEM) and Raman spectroscopy were used to characterize the NCD films. Then the NCD films were treated by hydrogen plasma in the CVD chamber to obtain the hydrogen terminated surface. This hydrogenated NCD film is ready for bio-modification and can work as the platform of the biosensors. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) were employed to confirm the surface hydrogenation.

The erosion of material surfaces produced by electrical discharges plays an important role on the degradation of many electrical devices, such as electrical contacts, switches or spark plugs. A discharge produces an extreme and concentrated flow of energy into the material that heats it and can even cause melting or vaporization. The plasma pressure may cause an even greater removal of material by the emission of droplets of molten material, producing craters in the surface of the material. In this contribution the microscopic erosion mechanisms on RuAl basis intermetallic compounds are compared with those for pure metals. Single discharge experiments at high pressure were done and the erosion structures were characterized with white light interferometry and scanning electron microscopy. The effects of microstructure on the surface erosion are discussed on the basis of different samples of RuAl. In certain high temperature applications, formation of oxide scales is an important process that may influence the discharge characteristics and erosion mechanisms. These effects are discussed on results in pre-oxidized samples. It was shown, that the surface can be additionally stabilized by controlling the protecting oxide coatings.

Pulsed laser deposited coatings can be used to enhance the corrosion resistant of materials traditionally used for industrial applications. In this paper, we describe our initial results on coating HK40 (a material used for ethylene heater tubing) with silicon carbide (a carburization resistant coating) to increase tube life. A 1 um thick film of silicon carbide was successfully deposited onto a heated HK40 substrate. An array of characterization techniques (scanning electron microscopy, atomic force microscopy, and scratch tests) demonstrated that the processing conditions were suitable for good coverage and promising adhesion behavior.

Chromium nitride (CrN) and Titanium nitride (TiN) thin films were deposited employing unbalanced magnetron sputtering (UBMS) for various values of substrate bias voltage (Vb). The structural characterization of the films in terms of phase identification and the density determination was achieved utilizing X-Ray techniques (XRD and XRR respectively), while the internal stresses were calculated by the change of the substrate's curvature using Stoney's equation. The nanomecahnical properties of the films (hardness and elastic modulus) were investigated using the Nanoindentation (NI) technique in the Continuous Stiffness Measurement (CSM) configuration. According to the NI results the hardness of the films ranges between between 15–25 GPa while the elastic modulus between 180–250 GPa. The analysis revealed that the hardness of the films is maximum when their orientation is pure (either [111] or [100]), while it is minimized under mixed orientation regime. Furthermore, the hardness of the films increases as the internal compressive stresses and the mass density increase. The latter can be validated through the comparison of the results concerning the above films to reported results for TiN films prepared by balanced magnetron sputtering (BMS)

A novel method of in-situ detection of the high pressure phase transformation of silicon during dead-load scratching is described. The method is based on the simple fact that single crystal silicon is transparent to Infrared light while metallic materials are not. Infrared heating during scratching has been performed to thermally soften and deform the transformed metallic material and some promising results were obtained. The sample material used here is silicon, but the same approach can be applied to germanium and other materials, such as ceramics (SiC), which have appropriate optical properties.

Silicone oil was photo-chemically oxidized to change into SiO2 on the crystal by using an ArF excimer laser; the protective moistureproof film has been developed for a nonlinear optical crystal that is deliquescent.

The nonlinear optical crystals such as CsLiB6O10 (CLBO) and KH2PO4 (KDP) are deliquescent, which causes their surfaces to be cloudy by absorbing moisture in the air. We, therefore, demonstrated the growth of the SiO 2 film directly on the crystal so as to be moistureproof.

Firstly, dimethylsiloxane silicone oil (-O-Si(CH3)2-O-)n was poured on the substrate and coated by a spinner for making the silicone oil thin layer. Then, the ArF excimer laser was vertically irradiated on the sample in oxygen atmosphere. The O atom on the substrate surface was photo-excited by the laser to generate a high active O atom. At the same time, the Si-CH3 bond of the silicone oil was photo-dissociated and the dangling bond of Si was linked with the active O atom to form a SiO 2 film on the crystal surface.

In short, the film formed by the new technology can be used as a protective coating, which has the moisture resistance and the UV permeability, for a nonlinear optical crystal.

Mechanical properties of alumina-copper nano-coating interfaces have been studied by the first-principles calculations. We have applied the rigid-type first-principles tensile tests for O-rich (O-terminated) and stoichiometric (Al-terminated) interfaces and for back Cu1st-Cu2nd interlayers. The O-terminated interface is twice as strong as the Cu1st-Cu2nd interlayer whereas the Al-terminated interface is twice as weak as the Cu1st-Cu2nd interlayer. We have performed the fitting of interlayer potentials by universal binding-energy relation (UBER). The interlayer potential of the Cu-Al interface is well reproduced by UBER in whole region, although those of Cu-O interface and Cu1st-Cu2nd interlayer are partially reproduced.

Carbon-based coatings exhibit many attractive properties that make them good candidates for a wide range of engineering applications. Tribological studies of the films have revealed a close correlation between the chemistry of the hydrocarbon source gases and the coefficients of friction and wear rates of the diamond-like carbon films. Those films grown in source gases with higher hydrogen-to-carbon ratios had much lower coefficients of friction and wear rates than did films derived from source gases with lower hydrogen-to-carbon ratios. The mechanism for this low friction is as yet not properly understood. Ongoing structural characterization of the films at Argonne National Laboratory is gradually revealing this mechanism. Recent studies have included x-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS) and x-ray reflectivity (XRR). XPS showed ∼10% oxygen at the surface, which was largely removed after a 1 minute sputter; NEXAFS showed a high sp2:sp3 ratio implying a highly graphitic material; and XRR has given a comprehensive depth profile, with three layers of increasing density as the substrate was approached. The paper discusses the results and correlation with previous friction measurements.

Nanoindentations were made on a (100) single crystal Si wafer at room temperature with a series of triangular pyramidal indenters having centerline-to-face angles ranging from 35° to 85°. Indentations produced at high (80 mN) and low (10 mN) loads were examined in plan-view by scanning electron microscopy and in cross-section by transmission electron microscopy. Microstructural observations were correlated with the indentation load-displacement behavior. Cracking and extrusion are more prevalent for sharp indenters with small centerline-to-face angles, regardless of the load. At low loads, the transformed material is amorphous silicon for all indenter angles. For Berkovich indentations made at high-load, the transformed material is a nanocrystalline mix of Si-I and Si-III/Si-XII, as confirmed by selected area diffraction. Extrusion of material at high loads for the cube-corner indenter reduces the volume of transformed material remaining underneath the indenter, thereby eliminating the pop-out in the unloading curve.