Effect of Multilayer versus Monolayer Dodecanethiol on Selectivity and Pattern Integrity in Area-Selective Atomic Layer Deposition.

Monolayer and multilayer dodecanethiols (DDT) can be assembled onto a copper surface from the vapor phase depending on the initial oxidation state of the copper. The ability of the copper-bound dodecanethiolates to block atomic layer deposition (ALD) and the resulting behavior at the interfaces of Cu/SiO patterns during area-selective ALD (AS-ALD) are compared between mono- and multilayers. We show that multilayer DDT is ∼7 times more effective at blocking ZnO ALD from diethylzinc and water than is monolayer DDT. Conversely, monolayer DDT exhibits better performance than does multilayer DDT in blocking of AlO ALD from trimethylaluminum and water. Investigation into interfacial effects at the interface between Cu and SiO on Cu/SiO patterns reveals both a gap at the SiO edges and a pitch size-dependent nucleation delay of ZnO ALD on SiO regions of multilayer DDT-coated patterns. In contrast, no impact on ZnO ALD is observed on the SiO regions of monolayer DDT-coated patterns. We also show that these interfacial effects depend on the ALD chemistry. Whereas an AlO film grows on the TaN diffusion barrier of a DDT-treated Cu/SiO pattern, the ZnO film does not. These results indicate that the structure of the DDT layer and the ALD precursor chemistry both play an important role in achieving AS-ALD.