A role of energetic ions in RF-biased PECVD of TiO₂

Process plasmas generate energetic ions that participate in film growth through sputtering, atomic mixing, densification, enhanced migration of adatoms and field-enhanced diffusion via charging. RF-biased PECVD favors the anatase phase of TiO2 due to film densification by energetic ion bombardment suppressing the rutile phase. With a given bias voltage, anatase dominates at low deposition temperatures, below 400°C, but transforms to rutile upon annealing at higher temperatures. The dielectric constant of 60 (±5) showed no variation with a film thickness in the range between 20 to 200 nm, due to a thin SiO2 diffusion barrier intentionally grown at the Si/TiO2 interface. This oxide barrier prevents TiSix formation, resulting in a low leakage current below 10-10 A/cm2. © 1998 Elsevier Science Ltd. All rights reserved.