Ta2O5 Polycrystalline Silicon Capacitors with CF4 Plasma Treatment

Abstract

In this research, the effects of CF4 plasma treatment with post annealing on the electrical characteristics and material properties of Ta2O5 dielectrics were determined. The dielectric performance characteristics of samples under different treatment conditions were measured using equivalent oxide thickness (EOT), current density–electric field (J–E) characteristics, gate voltage shift versus time, and Weibull plots. In addition, X-ray diffraction (XRD) analysis provided insight into the changes in crystalline structure, atomic force microscopy (AFM) measurements visualized the surface roughness, and secondary ion mass spectroscopy (SIMS) revealed the distribution of fluorine ions inside the dielectric samples. Findings indicate that dielectric performance can be significantly improved by CF4 plasma treatment for 1 min with post annealing at 800 °C. The improvements in electrical characteristics were caused by the appropriate incorporation of the fluorine atoms and the removal of the dangling bonds and traps. The Ta2O5 dielectric incorporated with appropriate CF4 plasma and annealing treatments shows great promise for future generation of nonvolatile memory applications.