Characterization of High-k Al2O3 Gate Dielectrics Prepared by Oxidation of Aluminum Thin Films

Abstract

This work describes the formation and characterization of aluminum oxide (Al2O3) prepared by oxidation of aluminum thin films in nitric acid at room temperature followed by annealing at 650oC in N2 or Ar on previously engineered (100) silicon wafer surfaces using different cleaning procedures finished in diluted HF (dHF last) or in a sulfuric peroxide mixture (SPM last). The electrical characterization was performed by measurements of Capacitance X Voltage - CV and Current-Voltage - I-V characteristics. The Al2O3 films presented equivalent thicknesses (EOT) ranging from 2.3 to 4.3nm for different cleaning procedures and annealings of the aluminum oxides. In addition, Al2O3 physical thickness (XRBS »6.0-11.5nm) and Al2O3 permissivity (eAl2O3 » 10.5) were obtained with the aid of Rutherford Back-Scattering (RBS) Spectrometry. Also, it was shown that Al2O3 thin films annealed in ultrapure Argon presented better electrical characteristics (leakage current » 11.5 mA/cm2).