A semiconductor device may include a semiconductor layer including a two-dimensional semiconductor material and an electrode layer on the semiconductor layer. The electrode layer may include a first impurity pile-up region in which impurities are gathered.

A method of manufacturing a semiconductor device is provided. The method includes: providing a two-dimensional material layer on a substrate; and supplying an etchant to the two-dimensional material layer to remove a residue from the two-dimensional material layer. The supplying the etchant to the two-dimensional material layer includes: supplying a first process gas to a chamber in which the substrate is provided; supplying microwaves to the chamber to form a first plasma in the chamber; and supplying a second process gas, including a different material from the first process gas, to the chamber to form a second plasma including the etchant.

Provided is a semiconductor device including a plurality of active patterns spaced apart in a first direction intersecting with a surface of a substrate, a gate electrode extending in a second direction intersecting with the first direction and surrounding the plurality of active patterns, and a source/drain pattern spaced apart from the gate electrode in a third direction intersecting with the first direction and the second direction and connected to the plurality of active patterns in the third direction, and each of the plurality of active patterns includes a contact part, at least a portion of which is inserted within the source/drain pattern, and a connection part extending from the contact part away from the source/drain pattern in the third direction.