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

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.