Pore-sealing process initiated by self-assembled layer for extreme low-k SiOCH (k=2.0)

Abstract

A pore sealing process by Plasma-enhanced ALD (PEALD) with an amino-silane precursor has been developed, which enabled simultaneous restoration and pore-sealing film formation on damaged low-k film with k = 2.0. The precursor adsorbed preferentially at OR termination on the low-k surface to form self-assembled (SA) SiOC layer, which simultaneously recovered low-k damage. It is suggested that the SA-SiOC layer narrowed the pore opening at the low-k surface, and was followed by hermetic SiCN layer formation by PEALD. Sealing of pores against wet chemical was confirmed by forming 1.3 nm SiCN. Leakage current after pore-sealing formation was reduced by more than one magnitude compared to the pristine low-k. The current process will pave the way for enabling extremely thin diffusion barrier <;2nm at IX nm node Cu interconnect.