Planarization effect evaluation of acid and alkaline slurries in the copper interconnect process**Project supported by the Special Project Items No. 2 in National Long-Term Technology Development Plan (No. 2009ZX02308), the Doctoral Program Foundation of Xinjiang Normal University Plan (No. XJNUBS1226), the Key Laboratory of Coal Gasification, Ministry of Education, and the Inorganic Chemistry Key Disciplines of Xinjiang Normal University.

Abstract

We observed and analyzed the acid and HEBUT alkaline of Cu chemical mechanical polishing (CMP) slurry to evaluate their effects. Material analysis has shown that the planarity surfaces and the removal rate of alkaline slurry are better than the acid slurry during metal CMP processes. The global surface roughness and the small-scale surface roughness by 10 × 10 μm2 of copper film polished by the SVTC slurry are 1.127 nm and 2.49 nm. However, it is found that the surface roughnesses of copper films polished by the HEBUT slurry are 0.728 nm and 0.215 nm. All other things being equal, the remaining step heights of copper films polished by the SVTC slurry and HEBUT slurry are respectively 150 nm and 50 nm. At the end of the polishing process, the dishing heights of the HEBUT slurry and the SVTC slurry are approximately both 30 nm, the erosion heights of the HEBUT slurry and the SVTC slurry are approximately both 20 nm. The surface states of the copper film after CMP are tested, and the AFM results of two samples are obviously seen. The surface polished by SVTC slurry shows many spikes. This indicates that the HEBUT alkaline slurry is promising for inter-level dielectric (ILD) applications in ultra large-scale integrated circuits (ULSI) technology.