FinFET/Tri-Gate Channel Doping for Multiple Threshold Voltage Tuning

A method of controlling threshold voltages in a fin field effect transistor (FinFET), comprising:

• forming a dummy gate over a central portion of a fin, the central portion of the fin disposed between exterior portions of the fin unprotected by the dummy gate;
• removing the exterior portions of the fin and replacing the exterior portions of the fin with an epitaxially-grown silicon-containing material;
• applying a spin-on resist over the dummy gate and the epitaxially-grown silicon-containing material and then removing the spin-on resist over a hard mask of the dummy gate;
• etching away the hard mask and a portion of a polysilicon of the dummy gate to expose a gate oxide of the dummy gate and to form polysilicon spacers, the gate oxide disposed over the central portion of the fin;
• and
• implanting ions into the central portion of the fin through the gate oxide disposed over the central portion of the fin.

A method of controlling threshold voltages in a fin field effect transistor (FinFET), comprising:

• forming a dummy gate over a central portion of a fin;
• replacing exterior portions of the fin unprotected by the dummy gate with an epitaxially-grown silicon-containing material;
• applying a spin-on resist over the dummy gate and the epitaxially-grown silicon-containing material and then removing the spin-on resist over a hard mask of the dummy gate;
• etching away the hard mask and a polysilicon of the dummy gate to expose a gate oxide of the dummy gate, the gate oxide disposed over the central portion of the fin;
• implanting ions into the central portion of the fin through the gate oxide disposed over the central portion of the fin;
• and
• performing an annealing process to re-crystallize the fin.