Semiconductor device and method of manufacturing thereof

Abstract

According to various embodiments, a method of forming a semiconductor device includes forming a gate-all-around field-effect transistor including a plurality of stacked channel layers and a source / drain region, performing a deposition process at a first temperature to form a first epitaxial layer over the source / drain region such that ends of the plurality of stacked channel layers are in contact with the first epitaxial layer, and performing a second deposition process at a second temperature to form a second epitaxial layer that is contacting the first epitaxial layer. In various embodiments, the second temperature is 20% to 30% lower than the first temperature. The resulting contact epitaxial layer is substantially free of dopant precipitates and includes fewer than 50 dislocations that each have a length that is from 1 nm to 40 nm, and subtend an angle that is between 20 degrees and 70 degrees relative to a [110] crystallographic plane.