AVS 51st International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThM

Paper AS-ThM11
Nitridation of Hf Silicate Layers for Advanced CMOS Gate Oxides : A Core Level and Valence Band Study by Photoelectron Spectroscopy

Thursday, November 18, 2004, 11:40 am, Room 210A

Session: High-k Dielectrics
Presenter: O. Renault, CEA-DRT-LETI, France
Authors: O. Renault, CEA-DRT-LETI, France
N. Barrett, CEA-DSM-DRECAM, France
F. Calvat, CEA-DSM-DRECAM, France
Y. Le Tiec, CEA-DRT-LETI, France
P. Besson, ST-Microelectronics, France
F. Martin, CEA-DRT-LETI, France
Correspondent: Click to Email
The nitridation of high-k materials is widely investigated for sub-65nm CMOS technology nodes@footnote 1@.In this contribution, we will present recent results of a core-level and valence band study by photoelectron spectroscopy, using both synchrotron and AlKa radiation, of nitrided Hf-silicate films for advanced gate oxides. Hf-silicate layers (3.5 nm-thick) were grown onto thin oxidized Si surfaces and then nitrided in an NH3 ambient. The valence band study at 80 eV photon energy reveals the introduction, upon nitridation, of localized N2p electronic states in the band gap of the silicate, thus confirming recent theoretical predictions@footnote 2@. The core-level analysis (Hf4f, N1s, Si2p) of as-grown, partially and totally etched silicate layers indicates that nitridation creates Hf-N bonds with a gradient from the surface to the interface depending on the nitridation temperature. Spectra recorded using synchrotron radiation with enhanced surface sensitivity and photon energy tunability will be presented and highlighted emphasizing the possibility to isolate the Si bonding states from the silicate layer itself. @FootnoteText@ @footnote 1@ M. Koike et al., extended abstracts, IEDM, 107 (2003).@footnote 2@ G. Shang, P. W. Peacock, J. Robertson, Appl. Phys. Lett. 84, 106 (2004).