TEMPERATURE-DEPENDENCE OF THE AL-FILL PROCESSES FOR SUBMICRON-VIA STRUCTURES

Today, numerous different PVD techniques are used for the filling of s ub micron contacts and vias in ULSI devices. One of the most promising approaches is the Al-reflow process. In this process, voids in vias w hich form during the PVD deposition of Al are eliminated by the therma l diffusion of Al. The ability of the aluminum to diffuse into the voi ds becomes increasingly dependent on the temperature of the reflow ste ps as device dimensions decrease. Therefore, it becomes necessary to d eposit the Al at high temperatures, with the risk to influence the ele ctrical properties of other underlying metal films and roughen the met al surface due to larger grain sizes. In this paper, the effect of the Al-deposition temperature on contact/sheet resistance and short yield of the deposited film and the influence of high temperature Al deposi tions on the electrical properties of underneath lying metal stacks ar e investigated. (C) 1998 Elsevier Science S.A. All rights reserved.