Mr. Frost et Cw. Magee, CHARACTERIZATION OF NITRIDED SIO2 THIN-FILMS USING SECONDARY-ION MASS-SPECTROMETRY, Applied surface science, 104, 1996, pp. 379-384
Citations number
8
Categorie Soggetti
Physics, Condensed Matter","Chemistry Physical","Materials Science, Coatings & Films
For the fabrication of MOS devices, the incorporation of nitrogen into
thin SiO2 dielectric films has been shown to improve the electrical a
nd structural integrity of the films. For example, nitrogen present at
the SiO2/Si interface acts to enhance the charge-trapping properties
of the oxide. Furthermore, nitrided oxides are more resistant to impur
ity and dopant diffusion and further oxidation than non-nitrided films
. The understanding of the nitriding process has progressed to the poi
nt where the distribution and concentration of the nitrogen (the N dep
th profile) can be controlled, to some extent. The final N depth profi
le in these films is a critical piece of information to the process en
gineer. By using different nitriding agents and growing the films usin
g varying temperatures and times, the nitrogen can be 'concentrated' a
t virtually any depth in a very thin oxide (< 100 Angstrom). We have s
uccessfully employed secondary ion mass spectrometry (SIMS) for determ
ining the nitrogen distributions in such films. Using an SiO2 standard
, calibrated both in terms of concentration and film thickness, accura
te quantification of unknown samples has become straightforward. Throu
gh the extensive development of the instrumental protocol, the long-te
rm reproducibility of this measurement has been shown to be better tha
n 9%. The N detection limit using this protocol is approximately 0.001
% atomic. We will present recent examples of results using SIMS on die
lectric films processed using a variety of oxidation and nitridation c
onditions.