I. Hashim et al., VACUUM REQUIREMENTS FOR NEXT WAFER SIZE PHYSICAL VAPOR-DEPOSITION SYSTEM, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 15(3), 1997, pp. 1305-1311
Citations number
12
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
The major sources of impurities in sputtered Al alloy films for interc
onnects prepared by physical vapor deposition (PVD) include those orig
inating from the target material, residual gases present in the vacuum
system, and those introduced through the gas delivery system. In this
study, we report the effect of impurities incorporated from residual
gases present in vacuum systems on the properties of Al-Cu interconnec
ts, in particular, electromigration performance of 0.6-mu m-wide Al-1%
Cu Lines. Controlled leaks of isotope gases H2O18, N-2(15), O-2(18),
and (CH4)-H-13, in the 10(-6)-10(-9) Ton range, were introduced into a
PVD tool during the sputtering process. Using these isotope gases, th
e impurities originating from residual gases were distinguished from t
hose originating from other sources of impurities. The sputtering targ
et was found to be the major source of H and O impurities in the film,
whereas N atoms are introduced in the film mainly through the gas pha
se. The microstructural properties of blanket Al-Cu films deposited wi
th intentionally introduced residual gas phase contaminants were also
investigated using transmission electron microscopy, x-ray diffraction
, and secondary ion mass spectroscopy. Controlled leaks of N-2 during
the sputtering process were found to affect the distribution of Cu in
the blanket AI-Cu films as;well as the electromigration behavior of th
e patterned structures to a larger extent than O-2, CH4, and H2O. On t
he other hand, upon controlled exposures of the above mentioned residu
al gases to blanket Al-Cu films, N-2 was found to have the lowest stic
king coefficient to a clean AI-Cu surface. (C) 1997 American Vacuum So
ciety.