Influence of the oxygen/argon ratio on the properties of sputtered hafnium oxide

✍ Scribed by L. Pereira; P. Barquinha; E. Fortunato; R. Martins

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 239 KB
• Volume: 118
• Category: Article
• ISSN: 0921-5107
• DOI: 10.1016/j.mseb.2004.12.030

✦ Synopsis

In this work we have focused our attention on the role of the gas mixture (O 2 /Ar) used during HfO 2 thin film processing by r.f. magnetron sputtering, to produce dielectrics with suitable characteristics to be used as gate dielectric. Increasing the O 2 /Ar ratio from 0 to 0.2, the films properties (optical gap, permittivity, resistivity and compactness) are improved. At these conditions, films with a band gap around 5 eV were produced, indicating a good stoichiometry. Also the flat band voltage has a reduction of almost three times indicating also a reduction of the same order on the fixed charge density at the semiconductor-insulator interface. The dielectric constant is around 16 which is very good, since the surface of the silicon where the HfO 2 films were deposited contains a SiO 2 layer of about 3 nm that gives an effective dielectric constant above 20, close to the HfO 2 stoichiometric value (∼25). Further increase on the O 2 /Ar ratio does not produce significant improvements.