Experiment and simulation of the compositional evolution of Ti-B thin films deposited by sputtering of a compound target Radio frequency magnetron sputtering deposition of calcium phosphate coatings: Monte Carlo simulations of the deposition process and depositions through an apertureThe power density at the substrate during sputter deposition was measured by a calorimetric method. In combination with measurements of the atomic deposition rate, the total amount of the energy input per incorporated atom was determined. The measured values range from 18 eV for aluminum to about 1000 eV maximum per atom for carbon. There is, for all elements investigated, a general trend for a linear increase of the energy per atom with increasing sputtering argon pressure over the range from 0.2 to 7 Pa. The energy per atom decreases with increasing power of the sputtering discharge. The application of a negative bias to the substrate reduces the total energy per atom to the values measured at low pressure of 0.4 Pa or below. The total energy flux in the low pressure range ͑0.4 Pa or less͒ can be well described by contributions due to plasma irradiation, the heat of condensation of the deposited atoms, their kinetic energy, and the kinetic energy of the reflected argon neutrals. The latter two components are a priori calculated by TRIM.SP Monte Carlo simulations. There is good agreement between the a priori calculated and the measured values. The combination of experimental and theoretical data result in empirical rules for the energies of the sputtered and reflected species, which allow an estimate of the energy input during sputter deposition for every elemental target material in the low pressure range. In a first approximation, the energy per incorporated atom is proportional to the ratio between target atomic mass and sputtering yield.

The density of the low-rate (<0.1 nm/s) sputtered molybdenum films can be controlled between 48% and 96% of the bulk material by the variation of argon pressure from 4.7 to 0.45 Pa. Small angle x-ray scattering shows the existence of columnar voids with a typical size of 10 nm, especially in the low-density films, whereas a high concentration of primary voids with a diameter of 1 nm is found independent of the density. The conductivity of the films decreases monotonically with decreasing density from 2.4×104 to 2.1×102 (Ω cm)−1, with a strong decay below a density of 55%. Films of about 30 nm thickness are amorphous or nanocrystalline with a (110) texture for high- and low-pressure sputter deposition, respectively. Upon increasing the film thickness up to 3 μm, the low-density films become nanocrystalline, too, and develop the common (110) fiber texture. In contrast, increasing the thickness of the high-density films results in a turnover of texture from a (110) type to a (211) mosaiclike texture.

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