Semiconductor device and method of fabricating a semiconductor device

A semiconductor device comprising:

• a substrate;
• a semiconductor layer disposed on the substrate, and the semiconductor layer being made of a low dimensional material;
• a dielectric structure, disposed on the semiconductor layer;
• and
• a source/drain structure laterally surrounded by the dielectric structure and comprising a barrier layer in contact with the semiconductor layer and the dielectric structure, wherein the barrier layer comprising a plurality of sub-layers, and each of the sub-layers is made of a material of MX2, where M represents transition metals, X represents a chalcogen.

A method of fabricating a semiconductor device comprising:

• providing a substrate;
• forming a semiconductor layer on the substrate, wherein the semiconductor layer being made of a first low dimensional material;
• forming a gate on the substrate and overlapping the semiconductor layer;
• forming a dielectric structure on the semiconductor layer and the dielectric structure comprising a trench structure reaching a portion of the semiconductor layer;
• and
• forming a source/drain structure, the source/drain structure comprising a barrier layer made of a second low dimensional material continuously extending along the trench structure and a metal fill filling a volume surrounded by the barrier layer, wherein the barrier layer is formed by forming a pre-layer covering the trench structure, and performing a chalcogen treatment on the pre-layer.