Low-k SiOx/AlOx Nanolaminate Dielectric on Dielectric Achieved by Hybrid Pulsed Chemical Vapor Deposition.

Selective and smooth low-k SiOx/AlOx 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 Si3N4 and SiO2 at 300 °C. At 200 °C, TBS pulsed CVD exhibited no growth on W or SiO2, but its growth was catalyzed by AlOx. Using a two-temperature pulsed CVD process, ∼2.7 nm selective SiOx/AlOx nanolaminate was deposited on Si3N4 in preference to aniline passivated W. Nanoselectivity was confirmed and demonstrated on nanoscale W/SiO2 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 Al2O3 and SiO2 is consistent with the formation of a low-density, low-k SiO2/Al2O3 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.

Dielectric-on-Dielectric Achieved on SiO2 in Preference to W by Water-free Chemical Vapor Depositions with Aniline Passivation.

Selective and smooth dielectric-on-dielectric was achieved by water-free single-precursor chemical vapor deposition (CVD) processes with the help of aniline passivation. Aniline selective passivation was demonstrated on W surfaces in preference to SiO2 at 250, 300, and 330 °C. After aniline passivation, selective HfO2, Al2O3, and TiO2 were deposited only on the HF-cleaned SiO2 surface by water-free single-precursor CVD using hafnium tert-butoxide Hf(OtBu)4, aluminum-tri-sec-butoxide (ATSB), and titanium isopropoxide Ti(OiPr)4 as the precursor reactants, respectively. Hf(OtBu)4 and Ti(OiPr)4 single-precursor CVD was carried out at 300 °C, while the ATSB CVD process was conducted at 330 °C. HfO2 and Al2O3 nanoselectivity tests were performed on W/SiO2 patterned samples. Transmission electron microscopy images of the W/SiO2 patterned samples after deposition demonstrated nanoselectivity and low surface roughness of HfO2 and Al2O3 deposition on the SiO2 regions only.

Selective Pulsed Chemical Vapor Deposition of Water-Free TiO2/Al2O3 and HfO2/Al2O3 Nanolaminates on Si and SiO2 in Preference to SiCOH.

Highly selective and smooth TiO2/Al2O3 and HfO2/Al2O3 nanolaminates were deposited by water-free pulsed chemical vapor deposition (CVD) at 300 °C using titanium isopropoxide (Ti(OiPr)4) and hafnium tertbutoxide (Hf(OtBu)4) with trimethylaluminum (TMA). TMA was found to be the key factor for enhancing nucleation selectivity on SiO2 or Si versus SiCOH (hydrophobic, nonporous low k dielectric). With precise dosing of TMA, selective nucleation of TiO2/Al2O3 and HfO2/Al2O3 nanolaminates was achieved and smoother films were formed with higher selectivity compared to single precursor TiO2 and HfO2 CVD. The selectivity of TiO2/Al2O3 nanolaminate deposition increased from 34 to 44 (deposition on Si vs SiCOH), while RMS roughness of the film of Si decreased from 2.8 to 0.38 nm. The selectivity of HfO2/Al2O3 deposition increased from 14 to 73, while the RMS roughness of HfO2/Al2O3 on Si was maintained at a similar value of 0.78 nm. Deposition of water-free pulsed CVD TiO2/Al2O3 and HfO2/Al2O3 nanolaminates was conducted on a Cu/SiCOH patterned sample to study their nanoselectivity. Transmission electron microscopy images of the Cu/SiCOH patterned sample demonstrated that highly selective and smooth TiO2/Al2O3 and HfO2/Al2O3 nanolaminates can be formed on a nanoscale pattern.