A spectroscopic ellipsometry study of TiO2:ZrO2 on TiN/Si thin films prepared by Chemical Beam Vapor Deposition

Abstract

The application of variable angle spectroscopic ellipsometry (VASE) to the characterization of thin films is very important because it facilitates the understanding of their physical and optical properties. To prepare a series of film samples consisting of TiO2:ZrO2 on a TiN/Si substrate, we employed the SYBILLA P200 equipment (manufactured by ABCD Technology) through the process of Chemical Beam Vapor Deposition (CBVD). TiO2:ZrO2 on TiN/Si thin films is a composite material that has gained significant attention in various technological applications, particularly in the field of thin film coatings on semiconductor substrates like TiN/Si. TiO2:ZrO2 thin films exhibit excellent dielectric properties and good thermal stability, making them suitable for various electronic and semiconductor applications. From FESEM and EDX analysis, it is found that with increase of Ti/Zr atomic ratio, grain size increases. Ellipsometric analysis reveals increase in film thickness and refractive index with increase in Ti/Zr atomic ratio. As the film continues to grow, changes in its microstructural phase led to a transition from a monolayer physical ellipsometry model to a bilayer physical model. This transition is due to the appearance of inhomogeneity in the TiO2:ZrO2 thin film. Dynamic fits obtained using a two‐layer physical model and a Cauchy–Lorentz optical model show three distinct phases in the film growth phase: a nucleation phase, a fusion phase, and a continuous layer phase. Although our proposed model shows satisfactory performance in most cases, the determination of the refractive index can be problematic for very thin thicknesses. The developed VASE modeling process should be able to generate TiO2:ZrO2characterization on TiN/Si substrate films using comparable physical and optical modeling considerations.