Method of manufacturing a semiconductor device for recessed fin structure having rounded corners

A method of manufacturing a semiconductor device including a Fin FET, the method comprising:

• forming a plurality of fin structures over a substrate, the plurality of fin structures extending in a first direction and arranged in a second direction crossing the first direction in plan view,
• forming an isolation insulating layer over the substrate so that lower portions of the plurality of fin structures are embedded in the isolation insulating layer and upper portions of the plurality of fin structures are exposed from the isolation insulating layer;
• forming a fin mask layer on sidewalls of source/drain regions of the plurality of fin structures protruding from the isolation insulating layer;
• recessing the source/drain regions of the plurality of fin structures;
• and
• forming an epitaxial source/drain structure over each of the recessed fin structures to form a merged source/drain epitaxial layer,
• wherein in the recessing the source/drain regions, a plasma process combining etching and deposition processes is used to form recesses having a rounded corner shape both in a cross section along the first direction and in a cross section along the second direction.

A method of manufacturing a semiconductor device including a Fin FET, the method comprising:

• forming a first fin structure and a second fin structure over a substrate, the first and second fin structures extending in a first direction in plan view,
• forming an isolation insulating layer over the substrate so that lower portions of the first and second fin structures are embedded in the isolation insulating layer and upper portions of the first and second fin structures are exposed from the isolation insulating layer;
• forming a gate structure over parts of the first and second fin structures, the gate structure extending in a second direction crossing the first direction in plan view;
• forming a fin mask layer on sidewalls of the first and second fin structures protruding from the isolation insulating layer and not covered by the gate structure, and on an upper surface of the isolation insulating layer;
• recessing the upper portions of the first and second fin structures, thereby forming a recessed first fin structure and a recessed second fin structure;
• and
• forming a first epitaxial source/drain structure over the recessed first fin structure and a second epitaxial source/drain structure over the recessed second fin structure, such that the first and second epitaxial source/drain structures are merged to form a void between the merged first and second epitaxial source/drain structures and the remaining fin mask layer on the upper surface of the isolation insulating layer,
• wherein in the recessing the first and second fin structure, a plasma process combining etching and deposition processes is used to form a recess having a rounded corner shape both in a cross section along the first direction and in a cross section along the second direction.