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

Abstract

Highly selective and smooth TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates were deposited by water-free pulsed chemical vapor deposition (CVD) at 300 °C using titanium isopropoxide (Ti(O i Pr) 4 ) and hafnium tertbutoxide (Hf(O t Bu) 4 ) with trimethylaluminum (TMA). TMA was found to be the key factor for enhancing nucleation selectivity on SiO 2 or Si versus SiCOH (hydrophobic, nonporous low k dielectric). With precise dosing of TMA, selective nucleation of TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates was achieved and smoother films were formed with higher selectivity compared to single precursor TiO 2 and HfO 2 CVD. The selectivity of TiO 2 /Al 2 O 3 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 HfO 2 /Al 2 O 3 deposition increased from 14 to 73, while the RMS roughness of HfO 2 /Al 2 O 3 on Si was maintained at a similar value of 0.78 nm. Deposition of water-free pulsed CVD TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 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 TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates can be formed on a nanoscale pattern.

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

“…Left: TEM image of a selective 300 °C TiAlO x CVD deposition (previously reported) on the W region in preference to SiO 2 . Right: selective 300 °C HfO 2 CVD process on the SiO 2 region of the W/SiO 2 patterned sample with the help of 300 °C aniline passivation.…”

Process temperature-dependent interface quality and Maxwell–Wagner interfacial polarization in atomic layer deposited Al2O3/TiO2 nanolaminates for energy storage applications

“…19 The growth of such high-quality multilayer nanolaminate structures requires a deposition method that can precisely control the factors contributing to multilayer quality, such as interfacial roughness, sublayer interdiffusion, layer-to-layer conformality, and consistency. Although the synthesis of ATA NLs has been attempted using many growth techniques such as electron beam evaporation, 20 sputtering, 21 pulsed laser deposition, 6 chemical vapour deposition, 22 and so on, fabrication of such sub-nanometric laminates using ALD has been the preferred choice, owing to its ability to provide precise control over the thickness and composition down to the atomic scale, the facility of sequential self-limiting surface reactions, and exceptionally conformal and pin-hole free coatings even at low deposition temperatures. 23 In general, the properties and performance of ALD grown thin films strongly depend on growth parameters, viz., growth rate per cycle (GPC), pulsing/purging time, deposition temperature, etc.…”

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

“…7 There are previous reports of 5 nm selective deposition of AlO 2 , TiO 2 , and HfO 2 on SiO 2 in preference to W with 300 °C aniline passivation. 8 These AlO 2 , TiO 2 , and HfO 2 DOD depositions were achieved by water-free pulsed CVD using tris(2-butoxy)aluminum (ATSB), hafnium tert-butoxide, and titanium isopropoxide, respectively. 9−11 In the present study, a "water-free process" denotes the absence of water as a coreactant; however, a minute quantity of water might be formed by dehydration reactions of the alkoxy precursor With a dielectric constant of 3.9, SiO 2 has an acceptable lowk value widely used in the semiconductor industry.…”

“…In a previous study, pulsed CVD AlO x DOD was successfully deposited on SiO 2 and not on the W surface. 8 By utilizing aniline passivation, ATSB alone proved capable of depositing up to 4 nm of selective DOD on SiO 2 surface at 330 °C. 8 This present report documents the benefits of merging the area-selective ATSB process with the low-k catalytic-based SiO 2 /Al 2 O 3 nanolaminate process.…”

“…8 By utilizing aniline passivation, ATSB alone proved capable of depositing up to 4 nm of selective DOD on SiO 2 surface at 330 °C. 8 This present report documents the benefits of merging the area-selective ATSB process with the low-k catalytic-based SiO 2 /Al 2 O 3 nanolaminate process. Through this combination, a selective low-k dielectric on dielectric can be achieved by using the novel hybrid two-temperature pulsed CVD leveraging the advantages of both techniques.…”