MOSFET including asymmetric source and drain regions

A semiconductor structure comprising a field effect transistor, said field effect transistor including:

• a gate stack including a gate dielectric and a gate electrode and located on a substrate;
• a raised source region having a top surface at a first distance from a bottom surface of said gate dielectric and a bottom surface;
• a raised drain region having a top surface at a second distance from said bottom surface of said gate dielectric, wherein said first distance is greater than said second distance, wherein said raised source region and raised drain region have a composition including a semiconductor material and at least one electrical dopant;
• an upper buried drain region having another composition, said another composition including said at least one electrical dopant and an additional dopant;
• and
• a buried source region having yet another composition that differs from said another composition by absence of said additional dopant.

A semiconductor structure comprising a field effect transistor, said field effect transistor including:

• a gate stack including a gate dielectric and a gate electrode and located on a substrate;
• a raised source region having a top surface at a first distance from a bottom surface of said gate dielectric and a bottom surface;
• a raised drain region having a top surface at a second distance from said bottom surface of said gate dielectric, wherein said first distance is greater than said second distance;
• a buried drain region having a topmost surface that is coplanar with a bottom surface of said gate dielectric;
• and
• a buried source region having a topmost surface that is coplanar with said bottom surface of said gate dielectric, wherein said raised source region and raised drain region have a same composition throughout, said same composition including a semiconductor material and at least one electrical dopant, and said buried drain region further comprises an upper buried drain region having another composition, said another composition including said at least one electrical dopant and an additional dopant at an additional dopant concentration.