A study of the parameters affecting the thickness of thin aluminum films deposited on silicon substrate by RF planar magnetron sputtering

Abstract

Aluminum is the most widely used metallization material in today's microelectronics industry for thin film interconnection or as a metallization layer on the surface of integrated circuits. Aluminum has relatively good conductivity (its resistivity ranges from 2.7 to 3.0 μΩ-cm) as well as low cost. Properties of thin aluminum films largely depend on the deposition method employed plus other factors such as type of substrate, deposition temperature, deposition rate, and base and operating pressures used in deposition. In this study, thin aluminum films were deposited on silicon substrates using the method of RF planar magnetron sputtering. The use of RF potential leads to continuous collision of ions (in other words, a sustained plasma) needed for enhanced sputtering, while application of a magnetic field leads to high plasma densities, allowing high deposition rates and good film quality to be achieved even at low substrate temperatures.
Using a commercial RF magnetron sputtering equipment (Plasma Sciences) at the U. P. Department of Mining, Metallurgical and Materials Engineering which was acquired under the DOST-ESEP Project, a study was made to investigate the effects of important deposition parameters, namely, deposition time, RF power and operating pressure on important properties of deposited aluminum films on silicon substrates such as film thickness (results in this paper will be limited to this response), crystal structure, surface morphology, surface roughness and sheet resistance/resistivity. The study is part of an ongoing project to characterize the quality of the thin films deposited by this equipment and establish the proper operating parameters in line with future wafer device fabrication.