Preparation and Characterizations of High-K (Ca, Sr)ZrO3 Gate Dielectric Thin Films by Sol-Gel Technology

Abstract

We have very recently prepared perovskite high-K dielectric thin films in the CaZrO3-SrZrO3 solid solution system using the sol-gel wet chemical technology for CMOS gate and nanoelectronics applications. Such sol-gel prepared (Ca, Sr)ZrO3 thin films with various compositional ratios of Ca/Sr on Pt coated (001) Si substrates are annealed in flowing O2 at different temperatures from 550 to 700°C. Based on our best knowledge, it is the first time in the literature to successfully prepare the (Ca, Sr)ZrO3 thin films using wet chemical methods, including sol-gel and metallo-organic decomposition (MOD) technique. These thin films have been systematically characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Auger spectra (AES), and electrical and dielectric measurements. Using these techniques, the different reactions in various processing steps have been clarified. The values of dielectric constant in a range of 20–30 in (Ca, Sr)ZrO3 thin films have been obtained, and these sol-gel derived (Ca, Sr)ZrO3 thin films exhibit stable dielectric properties nearly independent on the applied electrical field and frequency at room temperature. The leakage current density of a CaZrO3 thin film annealed at 650°C for 1 hour is approximately of 9.5 × 10−8 A/cm2 at a very high applied electrical field of 2.6 MV/cm. The high dielectric constant, low leakage current density and high breakdown strength suggest that the (Ca, Sr)ZrO3 thin films are promising for CMOS gate and nanoelectronics applications.