Effect of Wettability of Silicon and Poly Silicon on Polishing Performance

Abstract

Heavily doped poly silicon films have been widely used as gate electrodes and interconnection in MOS circuits. The shrinkage of devices below 100 nm requires more stringent and new CMP processes including poly silicon CMP. Poly silicon can be polished easily with similar pads and slurries as they are used for the planarization of silicon oxide. In this study, single crystal and poly silicon wafers were polished as a function of pH in fumed silica based slurry to understand and compare the polishing mechanism of silicon. The static and dynamic etch rates and polishing temperature were measured as a function of slurry pH (11 ~ 13) with friction forces. The single crystal silicon (bare silicon) showed higher removal rate than poly silicon. However, higher friction force was measured on poly silicon wafer than on bare wafer. The initial wettability of poly silicon with HF and without HF was treatment.

Mechanical and tribological properties of ice-bonded abrasive polishing tools

“…There are several methods to determine the coefficient of friction by measuring friction forces using load cell, piezoelectric sensor, tool dynamometer, and non-contact capacitive displacement sensor. [39][40][41][42][43] It is also possible to determine the coefficient of friction between the work and the tool surface by monitoring the variation in the current drawn by the motor driving the tool during polishing of the work surface. 44 As this method is much easier compared to other methods, this work considered the measurement of power drawn by the motor rotating the tool mould.…”