Gate formation process

Abstract

Processes to form differently-pitched gate structures are provided. An example method includes providing a workpiece having a substrate and semiconductor fins spaced apart from one another by an isolation feature, depositing a gate material layer over the workpiece, forming a patterned hard mask over the gate material layer, the patterned hard mask including differently-pitched elongated features, performing a first etch process using the patterned hard mask as an etch mask through the gate material layer to form a trench, performing a second etch process using the patterned hard mask as an etch mask to extend the trench to a top surface of the isolation feature, and performing a third etch process using the patterned hard mask to extend the trench into the isolation feature. The first etch process includes use of carbon tetrafluoride and is free of use of oxygen gas.