Effect of rapid thermally nitrided titanium films contacting silicided and nonsilicided junctions |
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Authors: | S Chittipeddi C M Dziuba V C Kannan M J Kelly W T Cochran B Rambabu |
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Affiliation: | (1) AT&T Bell Labs., 18103 Allentown, PA;(2) Department of Physics, Southern University, 70813 Baton Rouge, LA |
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Abstract: | The effect of rapid thermally nitrided titanium films contacting silicided (titanium disilicided) and nonsilicided junctions
has been studied in the temperature range of 800 to 900°C. The rapid thermal nitridation of titanium films used as diffusion
barriers between aluminum and silicon, has a major impact on shallow junction complementary metal oxide semiconductor technologies.
During the process of rapid thermal nitridation, the dopants in the junctions undergo a redistribution and affect the electrical
properties of shallow junction structures. This work focuses on using novel contact resistance structures to measure the variation
in electrical parameters for rapid thermally nitrided titanium films annealed at different temperatures. The self-aligned
silicide (salicide) junctions in this study were formed using rapid thermally annealed titanium films. Electrical contact
resistance testers were used to measure the interface contact resistance between the salicide and silicon, as well as between
the metal and the salicide. The results show that the interface contact resistance to the p− diffused salicided junctions increases with rapid thermal nitridation of the additional titanium film, whereas the interface
contact resistance to the n− diffused salicided junction shows a decrease. Further, as a function of the rapid thermal annealing temperature (for fixed
titanium thickness), the nonsalicided diffusions show an increase in the interface contact resistance. The boron profiles
at the TiSi2/Si interface obtained using secondary ion mass spectroscopy show an excellent qualitative agreement with the electrical results
for each of the conditions discussed. The films were also characterized using Rutherford back-scattering spectrometry and
transmission electron microscopy and the results show good agreement with the measured variation in electrical parameters.
These results also show that as the anneal temperature is increased, the TiN thickness increases, further the change in the
silicide/silicon interface position with the nitridation of the additional titanium layer was verified.
This work was carried out when the author was working at AT&T Bell Labs |
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Keywords: | contact interface nonsalicided rapid thermal annealing salicide |
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