In vacuo studies on reaction mechanisms in ALD processes of ruthenium and platinum films

Abstract

Noble metal ALD processes with organometallic precursors together with oxygen have been developed extensively. Reaction mechanisms in this family of processes involve combustion of the ligands of the metal precursor by the O2 counter reactant. The ligands are oxidized and form gaseous CO2 and H2O as byproducts. Simultaneously the metallic center is reduced and a noble metal film is deposited. The overall reaction mechanism is fairly well-known, however details regarding the carbonaceous intermediates on the surface at different states of an ALD cycle and the nature of the active surface oxygen are still lacking. In this work, these details are studied mainly with in vacuo X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) for platinum and ruthenium processes. Trimethyl(methylcyclopentadienyl) platinum(IV) (MeCpPtMe3) and bis(cyclopentadienyl) ruthenium(II) RuCp2 are used as precursors together with O2.