Atomic Layer Deposition of Ruthenium Using the Novel Precursor bis(2,6,6-trimethyl-cyclohexadienyl)ruthenium

A recently reported ruthenium molecule, bis(2,6,6-trimethyl-cyclohexadienyl)ruthenium, has been developed and characterized as a precursor for atomic layer deposition (ALD) of ruthenium. This molecule, which has never been reported as an ALD precursor, was developed to address low growth rates, high nucleation barriers, and undesirable precursor phases commonly associated with other Ru precursors such as RuCp and Ru(EtCp) 2 . The newly developed precursor has similar vapor pressure to both RuCp and Ru(EtCp) 2 but offers significant improvement in stability as evaluated by thermogravimetric analysis and differential scanning calorimetry. In an ALD process, it provides good self-limiting growth, with a 0.5 Å/cycle growth rate under saturated dose conditions in a temperature between 250 and 300 °C. Furthermore, the precursor exhibits considerably better nucleation characteristics on SiO 2, TiO 2, and H-terminated Si surfaces, compared to RuCp 2 and Ru(EtCp) 2 .