FinFET Structures and Methods of Forming the Same

A structure comprising:

• a buffer layer over a substrate;
• a first transistor comprising:
• a first source/drain region;
• a second source/drain region;
• a plurality of first semiconductor layers extending from the first source/drain region to the second source/drain region;
• a first gate dielectric over the plurality of first semiconductor layers, wherein the first gate dielectric separates the plurality of first semiconductor layers from the buffer layer;
• and
• a first gate electrode over the first gate dielectric;
• and
• a second transistor comprising:
• a third source/drain region;
• a fourth source/drain region;
• a plurality of second semiconductor layers extending from the third source/drain region to the fourth source/drain region;
• a second gate dielectric over the plurality of second semiconductor layers, wherein a lowermost second semiconductor layer of the plurality of second semiconductor layers is closer to the buffer layer than a lowermost first semiconductor layer of the plurality of first semiconductor layers;
• and
• a second gate electrode over the second gate dielectric.

A structure comprising:

• a first fin and a second fin extending upwards from a substrate, the first fin comprising a plurality of first semiconductor layers in a first channel region, the second fin comprising a plurality of second semiconductor layers in a second channel region, each of the plurality of second semiconductor layers being vertically non-overlapping and horizontally non-overlapping with every layer of the plurality of first semiconductor layers;
• a first gate dielectric over and extending continuously along sidewalls of the plurality of first semiconductor layers in the first channel region;
• a second gate dielectric over and extending continuously along sidewalls of the plurality of second semiconductor layers in the second channel region;
• a first conductive gate over the first gate dielectric;
• and
• a second conductive gate over the second gate dielectric.