AVS 45th International Symposium
    Electronic Materials and Processing Division Thursday Sessions
       Session EM1-ThA

Paper EM1-ThA2
Cathodoluminescence Spectroscopy of Nitrided Si-SiO@sub 2@ Interfaces

Thursday, November 5, 1998, 2:20 pm, Room 314/315

Session: Dielectrics
Presenter: R. Bandhu, The Ohio State University
Authors: R. Bandhu, The Ohio State University
J. Schäfer, The Ohio State University
A.P. Young, The Ohio State University
L.J. Brillson, The Ohio State University
H. Niimi, North Carolina State University
G. Lucovsky, North Carolina State University
Correspondent: Click to Email
We use cathodoluminescence spectroscopy (CLS) to probe the electronic states at ultrathin gate dielectrics with nitrided Si-SiO@sub 2@ interfaces, known to improve reliability in advanced CMOS devices. The 5 nm-thick oxide at plasma-processed interfaces were: i) as-deposited (at 300 °C) structures, ii) 400 °C 30 min post-metallization annealed (PMA) in H2/N2, iii) 30 s 900°C rapid thermal annealed (RTA) in argon, and iv) a combination of both anneals. CLS emission energies and relative intensities vs. excitation energy (0.6-4.5 keV) were essentially unchanged for the as-deposited interface as reported for non-nitrided plasma-processed interfaces.@footnote 1@ In the near-IR (Ge detector), peaks appear at 0.8 and 1.0 eV, with the 1.0 eV peak intensity increasing with increasing electron energy. In the visible and near-UV (S-20 photocathode), features were observed at 1.9, 2.7 and 3.4 eV. From the depth variations, the 2.7 eV peak is generated near the surface of the oxide film, the 3.4 eV peak arises from the Si substrate, and the 1.9 eV feature comes from the near-interface region. After the PMA, CLS is essentially the same as for non-nitrided interfaces, except for an increase of the relative intensity of the 1.9 eV feature; after the RTA, analogous spectral features appear. However, the combination of the RTA and PMA does not completely suppress the 1.9 eV feature as for non-nitrided interfaces. CLS for as-deposited structures parallels optical second harmonic generation (OSHG); there are no differences with and without nitridation. However, as with OSHG, after the combined RTA/PMA, CLS reveals a substantial difference between nitrided and non-nitrided interfaces. The behaviors of the CLS features clearly distinguishes between interfacial defects (0.8 and 1.0 eV) and bulk defects (2.7 eV) which are significantly reduced by the combined RTA/PMA, and features that are intrinsic to the bonding chemistry, such as the 1.9 eV nitrided interface feature and the 3.4 eV Si substrate feature. @FootnoteText@ @footnote 1@A. P. Young, J. Schäfer, G. Jessen, R. Bandu, L. J. Brillson, H. Niimi, and G. Lucovsky, J. Vac. Sci. Technol. B, submitted. @footnote 2@G. Lucovsky, A. Banerjee, B. Hinds, C. Claflin, K. Koh and H. Yang, J. Vac. Sci. Technol. B15, 1074 (1997).