Atomic layer deposition and characterization of stoichiometric erbium oxide thin dielectrics on Si(100) using (CpMe)_3Er precursor and ozone

摘要

Thin stoichiometric erbium oxide films were atomic layer deposited on p-type Si(100) substrates using tris(methylcyclopentadienyl)erbium and ozone. The film growth rate was found to be 0.12±0.01 nm/cycle with an atomic layer deposition temperature window of 170-330℃. X-ray pho-toelectron spectral (XPS) analysis of the resulting Er_2O_3 films indicated the as-deposited films to be stoichiometric with no evidence of carbon contamination. Studies of post deposition annealing effects on resulting films structures, interfaces, surface morphologies, and electrical properties were done using Fourier transform infrared spectroscopy, XPS, glancing incidence X-ray diffraction, optical surface pro-filometry, and C-V/l-V measurements. As-deposited Er_2O_3 films were found to start crystallizing in the cubic structure with dominant (2 2 2) orientation; no erbium silicate was found at the interface. After annealing at 800 ℃ in N_2, a new XPS feature was found and it was assigned to the formation of erbium silicate. As the annealing temperature was increased, the interfacial erbium silicate content was found to increase in the temperature range studied. Electrical characterization of Er_2O_3 thin gate dielectrics annealed at 600 ℃ exhibited higher dielectric constant (κ = 11.8) than that of as-deposited films (9.8), and a remarkably low hysteresis voltage of less than 50 mV along with a leakage current density of 10~(-7) Acm~(-2) at 1 MVcrrr~(-1).