Forming narrow fins for finFET devices using asymmetrically spaced mandrels

摘要

A method of forming fins for fin-shaped field effect transistor (finFET) devices includes forming a plurality of sacrificial mandrels over a semiconductor substrate. The plurality of sacrificial mandrels are spaced apart from one another by a first distance along a first direction, and by a second distance along a second direction. Spacer layers are formed on sidewalls of the sacrificial mandrels such that portions of the spacer layers between sacrificial mandrels along the first direction are merged together. Portions of the spacer layers between sacrificial mandrels along the second direction remain spaced apart. The sacrificial mandrels are removed. A pattern corresponding to the spacer layers is transferred into the semiconductor layers to form a plurality of semiconductor fins. Adjacent pairs of fins are merged with one another at locations corresponding to the merged spacer layers.