Area-Selective Atomic Layer Deposition of SiO ₂ on SiO ₂ with Alkanethiol Functionalized Cu as the Nongrowth Surface

We report on the area-selective, O 3 and O 2 -plasma-assisted atomic layer deposition (ALD) of SiO 2 on plasma-deposited SiO 2 with Cu as the nongrowth surface. Di- sec -butyl-aminosilane (DSBAS) was used as the Si precursor for SiO 2 ALD. We studied the surface functionalization of Cu and the ALD process on bare and functionalized Cu surfaces using in situ reflection–absorption infrared spectroscopy (RAIRS). The Cu surface was functionalized at 100 °C using heptanethiol (HT) supplied from the gas phase. The native oxide on Cu promoted the uptake of HT and led to the formation of a multilayer hydrocarbon passivation layer. Since O 3 and O 2 plasma degraded the organic layer, the inhibitor was redosed during every cycle in a three-step A–B–C-type ALD process (A: HT; B: DSBAS; C: O 3 or O 2 plasma) performed at a substrate temperature of 100 °C. In situ RAIRS and X-ray photoelectron spectroscopy (XPS) show that combustion of the hydrocarbon passivation layer by O 3 and O 2 plasma leads to the formation of surface carbonates, and these were more readily formed during the O 3 -based process compared to the O 2 plasma ALD process. Within the sensitivity of the RAIRS setup, for both the ALD processes, surface −SiH 3 groups were not detected after the DSBAS partial cycle. High-resolution XPS indicated some SiO 2 growth and partial oxidation of the Cu surface after theA–B–C ALD processes. Approximately 5 nm of SiO 2 was deposited on the SiO 2 growth surface for both O 3 and O 2 plasma-assisted ALD with high selectivity. However, perfect growth selectivity could not be obtained due to the formation of surface carbonates.