Fets with self-aligned bodies and backgate holes

A silicon on insulator (SOI) field effect transistor (FET) comprising:

• a substrate having a top surface;
• a gate over said top surface of said substrate;
• a channel region in said substrate below said gate;
• source and drain regions in said substrate on opposite sides of said channel, and
• a halo implant on opposite sides of said channel,
• wherein said channel region extends a further distance from said top surface into said substrate when compared to said source and drain regions and wherein said halo implant extends a further distance from said top surface into said substrate when compared to said source and drain regions.

A method of making a silicon on insulator (SOI) field effect transistor (FET) comprising:

• providing a SOI wafer;
• performing trench isolation to form a well region;
• performing anisotropic etching on opposite ends of said well to create a cavity extending from a top surface of a substrate into said substrate adjacent to the opposite sides of a channel region;
• filling a portion of said cavity with said substrate;
• and
• filling an unfilled portion of said cavity with a conductive material to create source and drain regions,
• wherein said channel region extends a further distance from said top surface into said substrate when compared to said source and drain regions.

A self-aligning method of making a silicon on insulator (SOI) field effect transistor (FET) comprising:

• forming a gate stack on a substrate;
• performing shallow trench isolation to form a well region in said substrate;
• performing anisotropic etching on opposite ends of said well to create a cavity extending from a top surface of said substrate into said substrate adjacent to the opposite sides of a channel region;
• filling a portion of said cavity;
• and
• filling an unfilled portion of said cavity with a conductive material to create source and drain regions,
• wherein said channel region extends a further distance from said top surface into said substrate when compared to said source and drain regions.