Eur. Phys. J. Appl. Phys.
Volume 43, Number 3, September 2008
Topical Issue ITFPC (Innovations on Thin Films Processing and Characterisation)
|Page(s)||315 - 320|
|Section||Simulation and Thin Films Characterization|
|Published online||06 May 2008|
Modeling the stress enhancement of plasma enhanced chemical vapor deposited silicon nitride films by UV post treatment – impact of the film density
STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex, France
Corresponding author: email@example.com
Revised: 19 February 2008
Accepted: 26 March 2008
Published online: 6 May 2008
Plasma Enhanced Chemical Vapour Deposited (PECVD) tensile nitride liners have been introduced in the 90 nm CMOS technology node to generate mechanical strain within the transistor silicon channel. With strain, because of the silicon piezoresistance effect, the electron mobility is enhanced within the silicon channel, so the nMOS transistor performance. Since that time, significant work has been carried out to develop silicon nitride films with enhanced tensile stress values to increase the gain provided by these process induced stressors along the introduction of the new technologies. For the 45 nm node, an additional UV post treatment has been introduced to achieve highly tensile residual stress. This study determines the relevant as deposited PECVD nitride film properties that modulate the final stress achievable after UV cure. Thanks to a simple stress model, it is demonstrated that as deposited nitride films must present a nitrogen rich composition and an intrinsic low density to become highly tensile after post UV treatment. With these design rules, nitride films with final stress of 1.6 GPa have been synthesized.
PACS: 83.85.St – Stress relaxation / 68.60.-p – Physical properties of thin films, nonelectronic
© EDP Sciences, 2008
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