| Summary: | 碩士 === 國立臺北科技大學 === 機電整合研究所 === 104 === The purpose of this work is to study the application of supercritical CO2 electroplating, post supercritical CO2 electroplating and traditional electroplating processes to fabricate Cu metal thin films, and discuss the effects of adjusting the electroplating pressure over the grain size, preferred grain orientation, mechanical properties and sheet resistance. The second focus point of this work is electroplating of through silicon vias with an aspect ratio of 1:7.5; it was also performed by the three methods presented, and their influence over the electrical resistance of the copper pillar was observed. From the experimental data it is seen that supercritical CO2 process provides the fastest micro-hole filling speed at around 4 hours, the post supercritical CO2 process is the second fastest at around 5 hours and the slowest was the traditional process at around 36 hours. In TSV copper pillar resistance measurements, the supercritical CO2 process displays the highest resistance value at 5mΩ, the second largest was displayed by post supercritical CO2 process at 1.5mΩ and the smallest was displayed by traditional process at around 1.1mΩ. Moreover, grain size produced by the supercritical CO2 process was the smallest calculated to be around 20nm, the second smallest was by post supercritical CO2 process at around 27nm, and the largest was traditional process at around 38nm. Experiments on mechanical properties revealed that thin films produced by supercritical CO2 process have the highest hardness at around 64-67Hv, the second hardest was post supercritical CO2 process at around 58-62Hv and traditional process gives off the lowest hardness at around 57Hv. Additionally, the surface of the films deposited by supercritical CO2 process proved to be the smoothest with a surface roughness of about 0.68-0.85µm, the second smoothest were by the post supercritical CO2 process at around 0.95-1.10µm and the roughest surface was that by traditional process at around 1.15µm. Moreover, the internal stress of the films deposited by the supercritical CO2 process were the highest at around 45-54MPa, the second highest were those by post supercritical CO2 process at around 33-41MPa, and the lowest was found in the films produced by traditional process at around 30MPa. Finally, from sheet resistance measurements it is seen that the highest values were displayed by the supercritical CO2 process at around 1.3-1.5µΩ-cm, the second largest were by the post supercritical CO2 process at around 1.2-1.3 µΩ-cm, and the lowest was by traditional process at 1.1 µΩ-cm. The supercritical electroplating described in this study was performed without the aid of any additives, but could still produce a high degree of grain refinement, high hardness and excellent filling capabilities.
|
|---|
