Source and drain formation technique for fin-like field effect transistor

Abstract

Source and drain formation techniques are disclosed herein for fin-like field effect transistors (FinFETs). An exemplary method for forming epitaxial source/drain features for a FinFET includes epitaxially growing a semiconductor material on a plurality of fins using a silicon-containing precursor and a chlorine-containing precursor. The semiconductor material merges to form an epitaxial feature spanning the plurality of fins, where the plurality of fins has a fin spacing that is less than about 25 nm. A ratio of a flow rate of the silicon-containing precursor to a flow rate of the chlorine-containing precursor is less than about 5. The method further includes etching back the semiconductor material using the chlorine-containing precursor, thereby modifying a profile of the epitaxial feature. The epitaxially growing and the etching back may be performed only once. In some implementations, where the FinFET is an n-type FinFET, the epitaxially growing also uses a phosphorous-containing precursor.