Air-Stable Low Dielectric Constant SiOx/AlOx Nanolaminate Films Deposited by Thermal Pulsed Chemical Vapor Deposition with Continuous Carbon Doping For Interlayer Dielectric

Air-stable low dielectric constant carbon-doped SiOx/AlOx nanolaminate films were deposited by a thermal water-free pulsed CVD process consisting of pulses of ATSB (tris(2-butoxy)aluminum) at 330 °C and pulses of TBS (tris(tert-butoxy)silanol) exposure at 200 °C. Continuous aniline dosing was employed during the deposition processes of ATSB and TBS. For the Si:Al (75%:25%) ratio, a dielectric constant (k) value of 2.5 was measured. For the Si:Al (86%:14%) ratio, a dielectric constant (k) value of 2 was measured. The low dielectric constant value of the deposited nanolaminate was attributed to its low density and porous structure, as indicated by X-ray reflectivity (XRR) analysis. The film's nanolaminate structures have been verified through transmission electron microscopy (TEM) images. In-situ X-ray photoelectron spectroscopy (XPS) showed that 7 to 17% carbon was doped in the SiOx/AlOx nanolaminate film by the continuous aniline deposition. The high carbon content is consistent with the hydrophobic properties of the thin film, which stabilize the k value, confirmed by the CV measurement after FGA annealing and after 1 week of retest. This is the first report of a thermal process for deposition of air-stable inorganic low-k (<2.5) films.