Kunitoshi Namba

Novel PEALD-Ru formation technique using H 2 & H 2 /N 2 plasma as a seed layer for direct CVD-Cu filling

In this paper, novel Ru film formation technique by plasma enhanced atomic layer deposition (PEALD) is reported to be extremely promising as a seed layer for direct CVD-Cu full filling. PEALD-Ru film property can be controlled by H<inf>2</inf> to N<inf>2</inf> gas flow ratio in plasma step. PEALD-Ru film using H<inf>2</inf>/N<inf>2</inf> mixed gas based plasma can provide low resistivity (20µΩ-cm), sufficient Cu barrier property and 100% step-coverage. PEALD-Ru film using H<inf>2</inf> gas based plasma can provide (002) oriented Ru film, which is confirmed as good nucleation layer for CVD-Cu formation. Stacked film of Ru(H<inf>2</inf>)/ Ru(H<inf>2</inf>/N<inf>2</inf>) is demonstrated to be attractive as an underneath for direct CVD-Cu full filling without void generation in 50 nm via pattern.

Plasma-Enhanced ALD Ru Thin Films on PVD-TaN Films with Smooth Morphology at Low Temperature Using DER Ru Precursor

Introduction Ruthenium(Ru) is one of promising candidates as a seed layer material, because its resistivity is lower than the conventional Ta-based barrier materials and it realizes seedless Cu electrochemical deposition (ECD) [1]. For void-free Cu interconnects, the conformal seed layer deposition in the damascene structure is strongly required. Atomic layer deposition (ALD) method is a possible solution to overcome this issue. We have reported the plasma-enhanced (PE) ALD of Ru thin films on WNC barrier films using bis(ethylcyclopentadienyl)ruthenium [Ru(C2H5C5H4)2; Ru(EtCp)2] with NH3 plasma as reducing agent for the Ru precursor, previously [1]. In a sequential work, we examined the Ru film deposition on conventional PVD-TaN barrier films by the PE-ALD using Ru(EtCp)2. The surface morphology of the obtained Ru film was rougher than that on WNC. The temperature of 400 C is required to obtain adequate deposition rate for Ru(EtCp)2 precursor. This high temperature causes the surface roughness.