Study of HfO_2 thin films prepared by electron beam evaporation

摘要

The purpose of this paper is to report some experiments with HfO_2 film, which was deposited onto silicon substrates at different growth rates by electron beam evaporation. The chemical states were measured by X-ray photoelectron spectroscopy (XPS). The rms roughness as low as 0.85 nm was measured by atomic force microscope (AFM). Scanning electron microscopy (SEM) was also used to determine cross-section morphology. Spectroscopic ellipsometry (SE) was applied to measure the refractive index, extinction coefficient and the thickness of the films. The results of SE presented the refractive indices varied in the range of 1.81-1.95 around 1550 nm by altering deposition rates. The transmittance and reflectance spectrum were measured to determine the effectiveness of HfO_2 thin film as a single layer anti-reflection coating on Si substrates. The results suggested that the Fresnel losses below 0.05 dB/chip are achieved by depositing HfO_2 film onto SOI rib waveguide endface.