Thin HfO2 films grown on Si(100) by atomic oxygen assisted molecular beam epitaxy

Abstract

Thin high-k dielectric HfO2 films are deposited on Si(100) substrate by molecular beam epitaxy using Hf and atomic oxygen source. The composition of the film is determined to be stoichiometric HfO2. The very flat surface of the deposited film with a root mean square roughness less than 0.16nm without any visible pin holes down to the nanometer size can be reached. The film maintains good thermal stability after annealing at 900°C for 15min in N2 ambient. The refractive index of the film is 1.89 with a negligible extinction coefficient in the visible wavelength region and the dielectric constant is around 19. A low leakage current of 1.61×10−3A∕cm2 at −2V bias is achieved for a film with the equivalent oxide thickness of 2.4nm after annealing.