Initial stages of ruthenium film growth in plasma-enhanced atomic layer deposition

The initial stages of ruthenium film growth in plasma-enhanced atomic layer deposition (PEALD) on titanium nitride (TiN) substrate were investigated in detail. During the initial stages of ruthenium film growth, the influence of the substrate surface was significant and controlling thickness by counting the number of deposition cycles is no longer valid. The time required for saturated adsorption of Ru(EtCp)(2) as well as the amount of deposited ruthenium atoms per cycle changed during the initial stage. The time required for saturated adsorption of Ru(EtCp)(2) on homogeneous ruthenium surfaces was 7 s. However, it increased up to 25 s during the initial stage of the ruthenium film growth where the film growth on heterogeneous TiN substrate is dominant. By considering these changes during the initial stages of ruthenium PEALD growth, the full coverage of PEALD ruthenium can be obtained at a minimum thickness of 2.7 nm. (C) 2008 The Electrochemical Society.