Lsi Barrier-Film Formation by Ionized Cluster Beam

Abstract

A simple deposition model of evaporated species into quarter-micron contacts on an 8-inch diameter wafer, considering the scattering by gas molecules, predicted that the narrow angular distribution of evaporated species and deposition under low vacuum pressure are essential conditions for sufficient coverage of the contacts. An ionized cluster-beam (ICB) technique satisfies these essential conditions. The bottom coverage of TiN barrier film deposited by ICB under a nitrogen pressure of less than 10−2 Pa into contacts with an aspect ratio of 4 was improved to about 30% and the bottom coverage uniformity was about ±5% within the wafer. The crystal structure of the film was confirmed to be (111) orientation, which is necessary to form a preferentially oriented aluminum layer with a high durability against electromigration on TiN barrier film.