Characterization of High-k Al_2O_3 Gate Dielectrics Prepared by Oxidation of Aluminum Thin Films

摘要

This work describes the formation and characterization of aluminum oxide (Al_2O_3) prepared by oxidation of aluminum thin films in nitric acid at room temperature followed by annealing at 650°C in N_2 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 Al_2O_3 films presented equivalent thicknesses (EOT) ranging from 2.3 to 4.3nm for different cleaning procedures and annealings of the aluminum oxides. In addition, Al_2O_3 physical thickness (X_(RBS) ≈6.0-11.5nm) and Al_2O_3 permissivity (ε_(Al_2O_3) ≈ 10.5) were obtained with the aid of Rutherford Back-Scattering (RBS) Spectrometry. Also, it was shown that Al_2O_3 thin films annealed in ultrapure Argon presented better electrical characteristics (leakage current ≈ 11.5 mA/cm~2).