Investigation of self-assembled monolayer resists for hafnium dioxide atomic layer deposition

In this paper, a series of self-assembled monolayers (SAMs) has been investigated as deactivating agents for the atomic layer deposition (ALD) of HfO₂. Three important factors that determine the capacity of self-assembled monolayers to prevent ALD of HfO₂, chain length, tailgroup structure, and reactive headgroup, have been investigated. We show that to achieve satisfactory deactivation toward atomic layer deposition, it is crucial to form densely packed, highly hydrophobic monolayers. This in turn requires deactivating agents with high reactivity and nonbulky tailgroups comprised of a minimum chain length. A mechanism for the blocking process is proposed in which the role of the SAMs is both to remove reactive Si-OH/Si-O-Si groups at the SiO₂ surface and to prevent ALD precursors from reaching the SiO₂-SAMs interface.