| Summary: | 博士 === 國立成功大學 === 機械工程學系碩博士班 === 94 === The growth of thin films on substrate has become a field of much current research, because of the fabrication of many modern micro/nanometer devices. The morphology of growing nanometer-scale copper film by the sputtering process is studied using molecular dynamics (MD) simulation with embedded-atom method (EAM) many-body potential. We focus on the roughness and layer coverage for diverse deposition process parameters including substrate temperature, deposition rate, incident energy, and incident angle. This paper presents the effect of different substrate sizes. The results of simulation show smaller roughness and better layer coverage at low substrate temperature of 500K and high incident energy of 10-15eV. The film-substrate system becomes rapidly stabilized at the end of deposition. Our simulation shows that thin films can also grow with two-dimensional layer-by-layer-like way for larger size of substrate at room temperature. These simulated results are consistent with both earlier MD simulations and experimental observation. In the other hand, we have investigated the interfacial intrinsic residual stresses and interfacial mixing between substrate and films in sputtered copper films of a nanometer scale. This study presents the effect of different substrate sizes. The results of simulation reveal that the amount of interfacial mixing in film-substrate system increases after enhanced temperature of substrate or energy of incident atom while the influence of incident energy is more significant than substrate temperature. The performed computer simulations show that average force of substrate surface atoms with deposition time oscillates between repulsion and attraction. Moreover, the larger the size the smaller the force of substrate surface atoms. The residual stresses of thin films can tend towards a stead-state value with increasing adatoms gradually. The residual stresses of thin films are relevant to the substrate temperature and sputtered atomic energy in the deposition process. The residual stresses of copper films change from tensile to compressive, then back to tensile with temperature or energy enhanced. The residual stress is about 1 GPa at 500 K and ranges from -3.65 GPa to 1.25 GPa at energy of 10-15 eV. Consequently, we may get a good film of better surface properties and smaller mechanical stress for sputtered deposition at constant-temperature substrate of 500-600 K, incident energy of 10-15 eV and deposition rate of about 4 atoms/ps.
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