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Single crystal sapphire substrates with high quality surface finish and integrity significantly enhance performance and reliability of various microelectronics and LED devices. Traditional Chemical Mechanical Polishing necessitates highly alkaline slurries or ultra-hard abrasives owing to sapphire's ultra-high hardness and chemical inertness. Such trade-off is obviated by utilizing an atmospheric pressure plasma (in He–H 2 O mixture) for chemical action, facilitating higher material removal rate at neutral pH by buffing alone, without abrasives. Plasma induced surface modification is studied by nanoindentation. A 2× improvement in MRR is achieved, and 40× projected. Effects of plasma parameters and polishing conditions on planarization effectiveness are discussed.

A multi-scale model encompassing pad response and slurry behavior is developed to predict scratch propensity in a chemical mechanical planarization (CMP) process. The pad response delineates the interplay between the local particle level deformation and the cell level bending of the pad. The slurry agglomerates in the diffusion limited agglomeration (DLA) or reaction limited agglomeration (RLA) regime. Various nano-scale slurry properties significantly influence the spatial and temporal modulation of the material removal rate (MRR) and scratch generation characteristics. The model predictions are first validated against experimental observations. A parametric study is then undertaken. Such physically based models can be utilized to optimize slurry and pad designs to control the depth of generated scratches and their frequency of occurrence per unit area.