Method to form transistors with multiple threshold voltages (VT) using a combination of different work function gate materials

A method of forming a gate electrode, comprising the steps of:

• a) providing a semiconductor substrate having an overlying patterned layer exposing a portion of said substrate within active area and patterned layer opening;
• said patterned layer having exposed sidewalls;
• b) forming a gate oxide layer upon said substrate exposed portion;
• c) forming internal spacers over a portion of said gate oxide layer within said patterned layer opening on said patterned layer exposed sidewalls;
• said internal spacers being comprised of a WF1 material having a first work function;
• and
• d) forming a planarized gate electrode body within the remaining portion of said patterned layer opening upon said gate oxide layer and adjacent to said internal spacers;
• said gate electrode body being comprised of a WF2 material having a second work function;
• said internal spacers and said gate electrode body forming said gate electrode.

A method of forming a gate electrode, comprising the steps of:

• a) providing a semiconductor substrate having an overlying patterned layer exposing a portion of said substrate within active area and patterned layer opening said patterned layer having exposed sidewalls;
• said substrate includes STIs defining said active area;
• b) forming a gate oxide layer upon said substrate exposed portion;
• c) forming internal spacers over a portion of said gate oxide layer within said patterned layer opening on said patterned layer exposed sidewalls;
• said internal spacers being comprised of a WF1 material having a first work function;
• and
• d) forming a planarized gate electrode body within the remaining portion of said patterned layer opening upon said gate oxide layer and adjacent to said internal spacers;
• said gate electrode body being comprised of a WF2 material having a second work function;
• said internal spacers and said gate electrode body forming said gate electrode.