Semiconductor device and manufacturing method thereof

A negative capacitance field effect transistor (NC-FET), comprising:

• a first fin structure having a first channel region and a second fin structure having a second channel region, the first and second channel regions protruding from an isolation insulating layer;
• and
• a gate structure disposed over the first and second channel regions and extending in a second direction crossing the first direction, wherein:
• the gate structure includes:
• a first dielectric layer continuously disposed over the first and second channel regions;
• a first gate electrode layer disposed over the first dielectric layer;
• a ferroelectric dielectric layer disposed over the first gate electrode layer;
• and
• a second gate electrode layer disposed over the ferroelectric dielectric layer;
• and
• in a cross section along the first direction, the ferroelectric dielectric layer has a U-shape, and
• in a cross section along the second direction, the first gate electrode layer fully fills a space between the first channel region and the second channel region.

A negative capacitance field effect transistor (NC-FET), comprising:

• a fin structure having a channel region, the channel region protruding from an isolation insulating layer;
• and
• a gate structure disposed over the channel region and extending in a second direction crossing the first direction, wherein:
• the gate structure includes:
• a first dielectric layer disposed over the channel region;
• a first gate electrode layer disposed over the first dielectric layer;
• a ferroelectric dielectric layer disposed over the first gate electrode layer;
• and
• a second gate electrode layer disposed over the ferroelectric dielectric layer;
• and
• in a cross section along the first direction, each of the first dielectric layer and the ferroelectric dielectric layer has a U-shape,
• the ferroelectric dielectric layer includes an orthorhombic crystal phase and at least one of a monolithic phase or a tetragonal phase,
• the orthorhombic crystal phase is at least 80% of the ferroelectric layer.