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Correlation between composition and stress for high density plasma CVD silicon nitride films

: Sah, R.E.; Baumann, H.; Driad, R.; Wagner, J.


Journal of the Electrochemical Society 157 (2010), Nr.2, S.G33-G38
ISSN: 0013-4651
Fraunhofer IAF ()
Plasma-CVD; Rutherford backscattering; silicon compound; stress analysis; thermal expansion; thin film

Intrinsic film stress is an important issue for the fabrication, performance, and application of a device. In the present study, a correlation between stress in high density plasma chemical vapor deposited silicon nitride films and their composition has been established. This has led to the low temperature deposition of low stressed films. The films exhibit a relatively negligible amount of chemically nonbonded hydrogen atoms. The density of the films calculated from the results of Rutherford backscattering spectroscopy and nuclear reaction analysis techniques is high, around 2.4 g/cm3, indicating a dense network. The films exhibit a relatively high coefficient of thermal expansion of around 3.2 ppm/°C, indicating a fairly short-range order in the film. Furthermore, a reversible thermally induced stress, i.e., a negligible stress hysteresis upon thermal cycling between room temperature and 400°C, has been observed in the film. From the stress response to the thermal cycling experiments, contributions from the thermal and athermal components to the net room temperature stress have been deconvoluted.