Novel Hardmask for Sub-20nm Copper/Low K Backend Dual Damascene Integration

Abstract

A new boron-based hardmask material was developed using a conventional CVD approach to address the integration challenges associated with the use of metal hardmask for low k dielectric patterning. Its low and tunable stress eliminates any patterning concerns due to line bending for device nodes below 20nm. Defectivity is also reduced because by-products from its F-based etch (BFx) are volatile unlike TiFx based defects, which dramatically widens the manufacturing process window. Extensive study concludes that boron content can be optimized to achieve good etch selectivity to the porous low k oxide. Preliminary electrical test using 45nm node 2-metal level structure showed good yield and 9% RC reduction compared to the conventional tri-layer integration scheme