Atomic Layer Deposition and Characterization of Amorphous ErxTi1-xOyDielectric Ultra-Thin Films

Er 1-x Ti x O y dielectric thin films were deposited on Si(100) substrates by atomic layer deposition (ALD) using tris(methylcyclopentadienyl)erbium [(CpMe) 3 Er] and tetrakis(diethylamino)titanium [TDEAT] as metal precursors, and O 3 as oxidant. The deposition temperature dependence of both Er 2 O 3 and TiO 2 film growths showed the overlapping ALD window of 175–250°C. Compositional tunability of Er 1-x Ti x O y films was obtained through deposition process control. Carbon and nitrogen impurities in as-deposited films were found to be below X-ray photoelectron spectroscopy detection level. Glancing incidence X-ray diffraction and phase-shifting interferometry results showed that Er x Ti 1-x O y films with ALD cycle ratios (Er 2 O 3 /TiO 2 ) of 1:8 or higher have a good thermal stability and remain amorphous with unchanged surface roughness after post-deposition rapid thermal processing (RTP) at 700°C in O 2 . Electrical measurements showed that optimized amorphous Er 1-x Ti x O y films after RTP exhibited a dielectric constant of ∼36, a hysteresis voltage of less than 10 mV, and a leakage current density of 10 −8 A/cm 2 at −1 MV/cm; such properties compare favorably with the properties of other reported amorphous titanium-based ternary dielectrics on Si. The sizable reduction of leakage current density of Er 1-x Ti x O y found in our study suggests that amorphous Er 1-x Ti x O y thin films are promising future dielectrics in Si integrated circuit technology.