Plasma enhanced metal-organic chemical vapor deposition of aluminum oxide dielectric film for device applications

Abstract

Low temperature (≤250 °C) deposition of aluminum oxide gate dielectric film using a new plasma enhanced metal‐organic chemical vapor deposition technique is described. With this technique, the substrate was not directly exposed to the plasma which minimizes radiation damage to both the substrate and the film. A dc potential was used to generate the plasma and the deposition of the film was achieved at extremely low plasma power (≤2 W) using trimethylaluminum and nitrous oxide reactant sources. The dielectric films were found to have a resistivity of ∼10¹⁴ Ω cm, dielectric constant of 7.9±0.2, and breakdown field ≥10⁶ V/cm. A linear dependence of the film growth rate upon TMAl concentration was observed, indicating that the growth process is mass transport limited. Metal–oxide–semiconductor device structures were fabricated both on n‐Si and p‐InP substrates and the interface properties were evaluated by capacitance–voltage and Auger measurements. Both the devices show sharp interface with a minimum density of states in the range of 8×10¹⁰–10¹¹ cm⁻² eV⁻¹ for Si and 4×10¹¹ cm⁻² eV⁻¹ for p‐InP.