| AVS 54th International Symposium | |
| Electronic Materials and Processing | Friday Sessions |
| Session EM-FrM |
| Session: | Hf-based Dielectrics and Their Interfaces |
| Presenter: | A. Herrera-Gomez, The University of Texas at Dallas and Cinvestav-Queretaro, Mexico |
| Authors: | M.I. Medina-Montes, The University of Texas at Dallas and Cinvestav-Queretaro, Mexico M.V. Selvidge, The University of Texas at Dallas F.S. Aguirre-Tostado, The University of Texas at Dallas A. Herrera-Gomez, The University of Texas at Dallas and Cinvestav-Queretaro, Mexico R.M. Wallace, The University of Texas at Dallas |
| Correspondent: | Click to Email |
Although there is a consensus regarding the use of Hf-based dielectrics as an alternative to SiO2 in MOS structures, the search for a suitable metal for n-MOS is still open. The addition of a La-based layer to HfxSi1-xO2/SiO2/Si dielectric stacks has proven to allow for the engineering of the work function to appropriate levels when TaN or TiN is employed as the metal gate. It has been suggested that the La diffuses into the Hf layer with thermal treatment. We performed high resolution Angle Resolved X-Ray Photoelectron Spectroscopy experiments to study the chemical depth profile distribution of La2O3/HfO2/SiO2/Si dielectric stacks exposed to a nitridation treatment by NH3 at 700°C. The expected stoichiometry and distribution of the HfO2 and SiO2 layers was reproduced from self consistent analysis of the ARXPS data. Regarding La, this study clearly shows that it diffuses to the top of the SiO2 layer, and that subsequent Rapid Thermal Annealing at 1000°C for 5s does not change significantly that distribution. A similar conclusion was derived by Sivasubramani et al. from FTIR analysis.1 In addition, back-side Secondary Ion Mass Spectroscopy results presented by Alshareef et al. are consistent with a location for La close to the HfO2/SiO2 interface.2 The quantitative results for the location and amount of La, together with the associated uncertainties, will be discussed in extent in the presentation.
1 P. Sivasubramani, T. S. Boscke, J. Huang, C. D. Young, P. D. Kirsch, S.A. Krishnan, M.A. Quevedo-Lopez, S. Govindarajan, B.S. Ju, H.R. Harris, D.J. Lichtenwalner, J.S. Jur, A.I. Kingon, J. Kim, B.E. Gnade, R.M. Wallace, G. Bersuker, B.H. Lee, and R. Jammy. VLSI (2007).
2 H.N. Alshareef, M. Quevedo-Lopez, H.C. Wen, R. Harris, P. Kirsch, P. Majhi, B.H. Lee, R. Jammy, D.J. Lichtenwalner, J.S. Jur, and A.I. Kingon. Applied Physics Letters 89, p. 232103 (2006).