Low- k SiO x /AlO x Nanolaminate Dielectric on Dielectric Achieved by Hybrid Pulsed Chemical Vapor Deposition.

Selective and smooth low- k SiO x /AlO x nanolaminate dielectric on dielectric (DOD) was achieved by a hybrid water-free pulsed CVD process consisting of 50 pulses of ATSB (tris(2-butoxy)aluminum) at 330 °C and a 60 s TBS (tris( tert -butoxy)silanol) exposure at 200 °C. Aniline selective passivation was demonstrated on W surfaces in preference to Si 3 N 4 and SiO 2 at 300 °C. At 200 °C, TBS pulsed CVD exhibited no growth on W or SiO 2 , but its growth was catalyzed by AlO x . Using a two-temperature pulsed CVD process, ∼2.7 nm selective SiO x /AlO x nanolaminate was deposited on Si 3 N 4 in preference to aniline passivated W. Nanoselectivity was confirmed and demonstrated on nanoscale W/SiO 2 patterned samples by TEM analysis. For a 1:1 Si:Al ratio, a dielectric constant ( k ) value of 3.3 was measured. For a 2:1 Si:Al ratio, a dielectric constant ( k ) value of 2.5 was measured. The k value well below that of Al 2 O 3 and SiO 2 is consistent with the formation of a low-density, low- k SiO 2 /Al 2 O 3 nanolaminate in a purely thermal process. This is the first report of a further thermal CVD process for deposition of a low- k dielectric and the first report for a selective low- k process on the nanoscale.