TY - JOUR
T1 - Nanoscale topography, surface charge variation and defect correlation in 2–8 nm thick functional alumina films
AU - Guinane, Luke
AU - Gautam, Devendraprakash
AU - Kubik, Jan
AU - Stenson, Bernard
AU - Geary, Shane
AU - Lebedev, Vasily
AU - Laffir, Fathima
AU - Beloshapkin, Sergey
AU - Ul-Haq, Ehtsham
AU - Tofail, Syed A.M.
N1 - Publisher Copyright:
© 2020 The Authors
PY - 2020/10/30
Y1 - 2020/10/30
N2 - In the nanometric regime, alumina films are often deposited by ALD methods yet in industrial applications, sputtered films thinner than 40 nm are used and research into those is sparse. Here, we investigated the nanoscale topography and the electrical properties of films less than 10 nm thick deposited by direct RF magnetron sputtering. Alumina films deposited on Si appeared to be uniform and topographically defect free as evaluated by TEM and AFM. However, their composition varied as a function of thickness as measured by XPS. The films were non-stoichiometric as Al content increased with film thickness. While SSRM measured current profiles did not highlight leakage sites or voids in the films, KPFM measured local charge fluctuations across the films deposited on Si and Au surfaces. The density of fluctuation sites decreased with an increase of alumina thickness. An electrodeposition method identified insulation weak spots in the alumina where Cu growths formed on the alumina surface. The growth mechanisms were investigated by TEM and EDX. The density of growths decreased with increased alumina thickness. Defects in the deposited alumina film are expected to be due to its non-stoichiometric nature causing charge variations, which weaken the films electrical insulating capability.
AB - In the nanometric regime, alumina films are often deposited by ALD methods yet in industrial applications, sputtered films thinner than 40 nm are used and research into those is sparse. Here, we investigated the nanoscale topography and the electrical properties of films less than 10 nm thick deposited by direct RF magnetron sputtering. Alumina films deposited on Si appeared to be uniform and topographically defect free as evaluated by TEM and AFM. However, their composition varied as a function of thickness as measured by XPS. The films were non-stoichiometric as Al content increased with film thickness. While SSRM measured current profiles did not highlight leakage sites or voids in the films, KPFM measured local charge fluctuations across the films deposited on Si and Au surfaces. The density of fluctuation sites decreased with an increase of alumina thickness. An electrodeposition method identified insulation weak spots in the alumina where Cu growths formed on the alumina surface. The growth mechanisms were investigated by TEM and EDX. The density of growths decreased with increased alumina thickness. Defects in the deposited alumina film are expected to be due to its non-stoichiometric nature causing charge variations, which weaken the films electrical insulating capability.
KW - AlO
KW - Defects
KW - KPFM
KW - Nanoscale
KW - RF magnetron sputtering
UR - http://www.scopus.com/inward/record.url?scp=85086729564&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2020.146950
DO - 10.1016/j.apsusc.2020.146950
M3 - Article
AN - SCOPUS:85086729564
SN - 0169-4332
VL - 528
JO - Applied Surface Science
JF - Applied Surface Science
M1 - 146950
ER -