SEMICONDUCTOR DEVICES AND METHODS OF FABRICATING THE SAME

摘要

A MOS transistor includes a pair of impurity regions formed in a substrate as spaced apart from each other, and a gate electrode formed on a region of the substrate located between the pair of impurity regions. Each of the impurity regions is formed of a first epitaxial layer, a second epitaxial layer on the first epitaxial layer, and a third epitaxial layer on the second epitaxial layer. The first epitaxial layer is formed of at least one first sub-epitaxial layer and a respective second sub-epitaxial layer stacked on each first sub-epitaxial layer. An impurity concentration of the first sub-epitaxial layer is less than that of the second sub-epitaxial layer.

主权项

1. A semiconductor device comprising:
a substrate, and a pair of impurity regions spaced apart from each other in the substrate; and a gate electrode disposed on the substrate at a location between the pair of impurity regions in a first direction, wherein each of the impurity regions includes a first epitaxial layer, a second epitaxial layer on the first epitaxial layer, and a third epitaxial layer on the second epitaxial layer, the first epitaxial layer is a stack of at least one first sub-epitaxial layer and at least one second sub-epitaxial layer, each said second sub-epitaxial layer being disposed on a respective said first sub-epitaxial layer such that the first and second sub-epitaxial layers are alternately disposed in the stack, and a concentration of an impurity in material constituting the at least one first sub-epitaxial layer is less than a concentration of an impurity in material constituting the at least one second sub-epitaxial layer.