ALUMINUM FILM DEPOSITION USING AN ULTRAHIGH-VACUUM SPUTTERING SYSTEM

Deposition of pure aluminum films on (100)Si and analysis of impurities during the sputtering process were carried out using an ultrahigh-vacuum sputtering system. A large amount of impurities desorbed from the surfaces of vacuum components in the process chamber which were exposed to discharge by rf-excited plasma was measured just after rf discharge, although the process chamber was evacuated to ultimate pressure after bake-out. This discharge desorption occurring concurrently with bake-out was found to be very effective as a means of chamber cleaning. As a result, high-quality aluminum films with impurity levels as low as that of the sputtering target were obtained. Furthermore, the aluminum films grown by rf-dc sputtering showed higher crystallinity than those grown by conventional dc sputtering.