Cu filling of 10 nm trenches by high-magnetic-field magnetron sputtering

Abstract

Ru and Cu sputterings were performed with two different high-vacuum sputtering systems. The Ru sputtering was performed by high-vacuum sputtering. On the other hand, the Cu sputtering was performed by high-magnetic-field sputtering. High-magnetic-field sputtering, which entails a Cu deposition rate of 80 nm/min (target–substrate distance: 200 mm) at a sputtering pressure of 7 × 10−2 Pa, is used for the Cu filling of 10-nm-wide Ru-lined trenches with an aspect ratio of 6.5. The complete Cu filling of trenches is accomplished within 1 min of sputtering time using a 1 at. % N2–Ar sputtering gas. The reason for the complete Cu filling is considered in terms of the capillary theory, focusing on the wettability of Cu on Ru. The improvement in Cu wettability with the use of a N2 additive is also evaluated in terms of the contact angle for Cu on Ru and surface shape.