Remote plasma ALD of SrTiO3 using cyclopentadienlyl-based Ti and Sr precursors

Remote plasma atomic layer deposition (ALD) of SrTiO3 films with different [Sr]/[Ti] ratios is reported, employing Star-Ti [(pentamethylcyclopentadienyl)trimethoxy-titanium, (CpMe5)Ti(OMe)3] and Hyper-Sr [bis(trisisopropylcyclopentadienyl)-strontium with 1,2-dimethoxyethane adduct, Sr(iPr3Cp)2DME] precursors and O2 plasma. The as-deposited films were amorphous, but crystallized after post-deposition anneal above 500°C. For annealed SrTiO3 films with [Sr]/[Ti]=1.3 and a thickness of 50 nm, a high dielectric constant k>80 and low leakage current of ~10-7 A/cm2 at 1 V were obtained. It is demonstrated that changes in the composition and microstructure are apparent in the optical dielectric function of the SrTiO3 films, as obtained by spectroscopic ellipsometry