Etch Profile Control of W/TiN/HfSiON and W/TaSiN/HfSiON Full-Metal Gates

W/TiN/HfSiON and W/TaSiN/HfSiON, equivalent oxide thickness (EOT) 1 nm, full-metal gate stacks were etched using CF4 and SF6 based gas chemistries. Vertical profiles were achieved for both TiN and TaSiN metal gates with gate lengths of 20 nm by controlling gas chemistry and pressure. The etch condition was changed from the high-pressure region to the low-pressure region immediately before the appearance of the underlying TaSiN surface by monitoring the thickness of the W layer to take advantage of both high- and low-pressure plasma characteristics.