Vapor-deposited octadecanethiol masking layer on copper to enable area selective Hf3N4 atomic layer deposition on dielectrics studied by <i>in situ</i> spectroscopic ellipsometry

Abstract

Area-selective atomic layer deposition (AS-ALD) has attracted a great deal of attention in recent years for self-aligned accurate pattern placement with subnanometer thickness control. The authors demonstrate a methodology to achieve AS-ALD by using undecanethiol and octadecanethiol masking layers deposited selectively in vapor phase on copper versus low-κ. Their approach has been demonstrated in combination with an in situ Hf3N4 ALD. In situ spectroscopic ellipsometer was performed to investigate the blocking ability of the thiols on the copper surface against ALD nucleation. A considerable growth inhibition up to 480 cycles for Hf3N4 deposited at 170 °C has been observed on the copper surface, while the same functionalization did not inhibit the nucleation on the dielectric surfaces.