Growth and characterization of Al2O3 gate dielectric films by low-pressure metalorganic chemical vapor deposition

Ultrathin Al2O3 films have been deposited on n-Si substrates by low-pressure metalorganic chemical vapor deposition (MOCVD) as gate dielectrics for next generation MOSFET applications. Al(acac)(3) was used as metalorganic precursor. Impacts of substrate temperature and post-annealing in O-2 or N-2 on equivalent oxide thickness (EOT), leakage current density (J,) and carbon residue of Al2O3 films have been studied. It is found that post-annealing is necessary for ultrathin Al2O3 films to obtain good electrical properties. The EOT shows slight deposition temperature dependence and the lowest EOT value with similar to 0.8 nm is obtained at 600 degreesC. Typical Al2O3 ultrathin films have larger frequency dependence and EOT of similar to 1.2 nm with J(A) of 36 mA /cm(2) at V-g = + 1 V. AES depth profiles demonstrate that post-annealing in an O-2 atmosphere could effectively eliminate the carbon contamination of Al2O3 films. Meanwhile, further post-annealing in N2 could decrease the J, of Al2O3 films to 8 mA/cm(2). (C) 2002 Elsevier Science B.V. All rights reserved.