The properties of aluminum thin films sputter deposited at elevated temperatures

Abstract

We have developed a new planarization technique by sputter deposition of Al–Si thin films at elevated temperatures, and have also studied their properties. The films were deposited by conventional dc magnetron sputtering apparatus without any substrate bias voltage, and during the depositions the substrates were heated on a gas-assisted stage. The step coverage was gradually improved at higher substrate temperatures. However, when the substrate temperature was above 500 °C, the surface topography was very smooth and planarized. In this temperature region, the structure of Al–Si thin films seemed to be different from that of films deposited at the lower temperatures. In addition, the effect of the underlying layer on the step coverage was investigated, and the presence of the TiN undercoat was shown to be effective to the enhancement of the surface migration of Al atoms. Furthermore, significant improvement was obtained in electromigration lifetimes with the TiN undercoat.