We studied the effect of compressive stress on the wear resistance of polycrystalline diamond films synthesized by hot-filament chemical vapor deposition (CVD) method using ethanol as the precursor. Samples were (a) a film coated onto a tungsten carbide substrate to give the highest compressive stress to the film, (b)∼(d) films brazed onto tungsten carbide substrates, and (e) a film glued onto a tungsten carbide substrate to make the film almost stress-free. Compressive stress in the film sample was measured by X-ray diffraction and found to range from -300 to -1500MPa depend on the sample. Films then were subjected to a wear test involving application of a rotating diamond wheel to the film surface. Results showed that the higher the compressive stress in the film, the greater the wear resistance. Film having an absolute compressive stress of ≥1000MPa, for example, showed wear resistance about three times higher than that of a stress-free diamond film or sintered diamond.
Average internal strain was measured in situ for thin nickel-phosphorus alloy deposits electroplated from nickel-phosphorus baths containing 0.2 to 10mM ZnSO4 as impurity additives using a resistance wire strain gauge placed on the reverse side of the copper substrate. With increasing ZnSO4 concentration, total zinc oxide and zinc hydroxide included in deposits increased monotonously and average internal tensile strain in deposits also rose. Internal tensile stress rose markedly at 1mM ZnSO4, causing numerous cracks on the surface of deposits at 1.5 to 10mM ZnSO4. At phosphorus content exceeding 12mol%, the development of average internal tensile strain in deposits was independent of phosphorus content, but clearly related to increasing total zinc oxide and zinc hydroxide included in deposits during electroplating.
The effect of boron and carbon on NiB films deposited from electroless NiB plating bath was studied by differential scanning calorimetry, X-ray diffraction and transmission electron microscope observation. As-deposited NiB films containing boron below ca. 2.5wt%, showed a crystal structure. The structure was not affected by carbon content. As-deposited NiB films with above 2.5wt% B showed a mixed phase with small amounts of fine crystal, an amorphous rich phase at carbon content below 0.25wt%, and a mixed phase with small amounts of amorphous and fine crystal (crystalline-rich phase) at carbon content above 0.3wt%. In films with a boron content above ca. 2.5wt%, codeposited carbon may affect the structure. In crystallization of NiB films containing above ca. 2.5wt% B, the amorphous-rich phase changed to Ni and Ni3B crystals, and a very small amount of Ni3B was generated into the crystalline-rich phase by heat treatment up to 300°C.
Aluminum specimens were covered with zirconium oxide film by a sol-gel coating and galvanostatically anodized in a neutral borate solution. The time variation in anode potential during anodizing was monitored, and the structure and dielectric properties of the anodic oxide film were studied by TEM, EDX, RBS, and impedance measurement. We found that the anode potential increases with time, and that the slope of the potential-time curve increases with increasing the numbers of sol-gel dip coatings. During anodizing, an anodic oxide film, which consisted of an inner Al2O3 layer and an outer Al-Zr composite oxide layer, formed at the interface between Zr-oxide and the substrate. The thickness of the inner layer increased with anodizing time, and the thickness of the outer layer peaked before decreasing with time. The capacitance of the specimen after sol-gel coating and anodizing was 20% higher than that without sol-gel coating. The dielectric property of anodic oxide films was correlated with film structure. The mechanism of anodic oxide films growth on the spceimen covered with Zr-oxide is discussed in terms of the porosity distribution in the Zr-oxide layer and the outward transport of Zr4+ ions across the composite oxide layer during anodizing.
Electrodeposition of CdTe film from ammonia-alkaline aqueous solutions with different ammonia concentrations, [NH3]total=2.0-5.0mol dm-3, was studied and deposition behavior at -0.70V vs SHE is discussed using a potential-pH diagram of the Cd-Te-NH3-H2O system in terms of underpotential deposition, where the deposition of Te atoms is followed by a rapid adsorption and reduction of Cd (II) species to form CdTe We found that the composition of the resulting film is controlled by ammonia concentration as well as by the pH and Cd (II)/Te (IV) concentration ratio, as previously been studied. The cadmium content of the resulting film increases with decreasing ammonia concentration of solutions An electrolyte with a Cd (II)/Te (IV) concentration ratio of 1, for example, gave a tellurium-rich deposit with low crystallinity under [NH3]total of 5.0mol dm-3, while that with the same Cd(II)/Te(IV) ratio gave almost stoichiometric CdTe under [NH3]total of 3.0mol dm-3
Copper promises to replace aluminum in ULSI metallization thanks to its better conductivity and reliability. ULSI metallization is formed by electroless neutral copper plating using cobalt (II) compound as a reducing agent. Results show good storage stability, and trenches/holes on silicon wafers are filled by copper deposits. Hydrogen gas did not evolved in the plating reaction, and not effect from alkaline metal ions was seen. This process may thus be applied to ULSI matallization, using electroless neutral plating with cobalt (II) compound as a reducing agent.