One of the main issues of the device technology on metal-dielectric (MD) substrates is poor adhesion of thin metallic films, which are used for interconnections in electrical circuits. Films are formed by vacuum deposition on a porous dielectric layer of substrates. The presence of pores sufficiently complicates the cleaning of the substrate surface, which significantly decreases the adhesion of the film deposited on it. Technology of metal films with high adhesion, fabricated by ion-plasma method is proposed in this work. Films were deposited on MD substrates produced by electrochemical oxidation of aluminum alloys. The main operations of the technology are the following. Removal of residual electrolyte after the oxidation is carried out by rinsing of substrates initially under running hot water, and then in deionized water, followed by drying in a flow of heated nitrogen. Annealing of substrates under the pressure of 10^{-3} Pa and temperature of 550-570 K for 20 min is carried on in the vacuum chamber before the deposition of metal films. Copper is used as the main material of the interconnection films. Adhesion sublayer is fabricated on the basis of chromium or vanadium, which have high enthalpy of the oxide formation. Measurements showed that the copper films with the thickness of 1.5 μm, deposited on the vanadium sublayer with the thickness of 0.12 μm, which is comparable with the roughness of oxide layer, have adhesion of 25 N/mm^{2} at the temperature of 520 K. Investigation of adhesion was carried on by the method of direct tear off with the error of up to 10%.
Technology is developed, materials and regimes of the fabrication of ohmic contacts to the effective thermoelectric materials Bi_{2}Te_{2.8}Se_{0.2} (n-type) and Bi_{0.5}Sb_{1.5}Te_{3} (p-type) are determined. Ohmic contacts were obtained by the vacuum deposition of nickel. Factors determining adhesion strength and resistivity of fabricated contacts are determined. Process of surface preparation of the thermoelectric materials before the ohmic contact deposition is optimized during the technology development. The use of electrochemical polishing, ultrasound treatment, finish cleaning in toluene and isopropyl alcohol vapor, and annealing in vacuum allowed achieving stable results in the formation of contacts. It was shown that contacts fabricated using of electron-beam evaporation of nickel possess maximum adhesion strength of 18-19 N/mm². It was found that high adhesion is caused by the existence of transition layer in the metal-thermoelectric material contact range, formed due to the interaction of metal with the components of thermoelectric material. Proposed technology allows obtaining ohmic contacts with the resistance of the unit area not exceeding 10^{-10} Ohm m².
The dynamics of the methane, methyl, and carbon dioxide adsorption to the (001) surface of cubic magnesium oxide (periclase) has been studied within the ab initio molecular dynamics in the temperature range between 0 and 1000 K. For methane, neither chemisorption nor physisorption has been observed in the considered temperature range, whereas methyl group and carbon dioxide build chemical bond to the MgO surface at temperatures 350 K and 450 K, with adhesive energies of 0.218 and 0.935 eV, respectively.
High demands that are posed to modern materials exposed to the action of thermal, mechanical or chemical loads oblige one to seek new solutions and technologies. Compliance with these expectations requires designing the composite materials without structural notches, and the application of gradient materials. Transient zone, determining the interphase compound, is an essential element of each composite. Interaction forces creating transient structural zones determine the value of the adhesion forces. Among all forces determining the adhesion the strongest are the forces of a chemical bond. Therefore, the molecular modeling should be a valuable method to investigate and design the composites. In the presented research the conditions of coat adhesion of the Ti (C,N,O)-type to steel substrate are taken into consideration. Using a standard quantum-chemistry program, the energies of the following systems (clusters) - Fe-α- N-Ti, Fe-α-C-Ti, and Fe-α-O-Ti - are calculated. The aim of the analysis was to determine the conditions for preparation of initial substrate, which are advantageous for the process of coat formation. This analysis confirmed benefits arising from nitriding as an initial treatment of the steel.
We present the results of preliminary experiments regarding research on the contact angle measurements of various liquids on solid surfaces with different morphology. The aim was to get insight into the dependence of wetting phenomena on the nanoscale surface roughness. Flat and nanostructurized surfaces of gold and sapphire were used in the experiments. Four liquids - bromobenzene, water, mercury, and gallium - covering a broad range of surface tension values were used to check how varying roughness influences wetting in the systems with different adhesion/cohesion ratio. Structurization was anisotropic, which resulted in the very interesting behaviour of the examined liquids on the selected surfaces. Significant change of the wetting properties was observed as well as a strong dependence on the surface morphology.
The composition of Zr-based thin films on rubber was investigated by utilizing the Rutherford backscattering technique and RUMP code simulation. The level of adhesion between the coating fabricated on rubber by means of self-ion assisted deposition was measured using Pin Pull Test. The coating deposited on the rubber consists of Zr, O, C, H. The self-ion assisted deposition process may successfully control the level of adhesion of the coating to the rubber and causes strong modification of the macroscopic properties of the rubber surface.
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