Structure of a fin field effect transistor (finfet)

A fin field effect transistor (FinFET) comprising:

• a fin extending from a substrate, the fin comprising a channel region interposed between source/drain regions, each of the source/drain regions including:
• a lower region;
• a mid region over the lower region, the mid region having a first interface with the lower region;
• and
• an upper region over the mid region, the upper region having a second interface with the mid region, the upper region having sidewalls that extend laterally beyond sidewalls of the mid region;
• a gate stack disposed over the channel region of the fin, the gate stack comprising a gate dielectric and a gate electrode;
• a gate spacer on either side of the gate stack;
• a dielectric material that surrounds the lower region and the first interface;
• and
• a fin spacer disposed on the sidewalls of the mid region, the fin spacer tapering from a top surface of the dielectric material to the second interface.

A fin field effect transistor (FinFET) comprising:

• a lower fin portion of a fin extending from a top surface of a substrate in a source/drain region of the fin;
• a middle fin portion of the fin extending from the lower fin portion, the middle fin portion having an isolation structure defining lower sidewalls thereof and a spacer structure defining upper sidewalls thereof, the spacer structure extending above an upper surface of the isolation structure;
• an upper fin portion of the fin extending from the middle fin portion, the upper fin portion expanding laterally beyond the upper sidewalls of the middle fin portion;
• and
• a gate spacer disposed on either side of a gate stack, the gate stack disposed over a channel region of the fin.

A fin field effect transistor (FinFET) comprising:

• an isolation region disposed over a substrate;
• a fin structure extending from a major surface of the substrate, the fin structure interposed by the isolation region;
• an epitaxial lower fin region extending from the fin structure, wherein a first interface of the fin structure and the epitaxial lower fin region is surrounded by the isolation region;
• a fin spacer disposed over a top surface of the isolation region and laterally surrounding a portion of the epitaxial lower fin region;
• an epitaxial upper fin region extending from the epitaxial lower fin region, the epitaxial upper fin region extending laterally beyond sidewalls of the epitaxial lower fin region;
• a gate structure disposed over the fin structure, the gate structure disposed adjacent to the epitaxial upper fin region;
• and
• a gate spacer interposed between the epitaxial upper fin region and the gate structure.