Effect of Pretreatment of TaN Substrates on Atomic Layer Deposition Growth of Ru Thin Films

The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition (ALD) using bis(cyclopentadienyl) ruthenium RuCp₂ and oxygen as ruthenium precursor and reactant respectively at a deposition temperature of 330°C. The low-energy Ar ion bombardment and Ru pre-deposition are performed to the underlying TaN substrates before ALD process in order to improve the Ru nucleation. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy are carried out to characterize the properties of ALD Ru films. The results show that the nucleation density of Ru films with Ar⁺ bombardment to the underlying TaN substrates is much higher than that of the ones without any pretreatment. The possible reasons are discussed.