Replacement metal gate finfet

A method for fabricating a field effect transistor device, the method comprising:

• depositing a hardmask layer over a semiconductor layer, the semiconductor layer disposed on an insulator layer;
• depositing a metallic alloy layer over the hardmask layer;
• defining a semiconductor fin by patterning and removing portions of the metallic alloy layer, the hardmask layer, and the semiconductor layer to expose portions of the insulator layer and define the semiconductor fin on the insulator layer;
• depositing a dummy gate stack material layer conformally on exposed portions of the insulator layer, the semiconductor fin, the hardmask layer and the metallic alloy layer;
• patterning a dummy gate stack by removing portions of the dummy gate stack material using an etching process that selectively removes exposed portions of the dummy gate stack without appreciably removing portions of the metallic alloy layer;
• forming spacers adjacent to the dummy gate stack;
• removing exposed portions of the metallic alloy layer;
• forming source and drain regions on exposed regions of the semiconductor fin;
• removing the dummy gate stack;
• removing exposed portions of the metallic alloy layer;
• and
• forming a gate stack conformally over exposed portions of the insulator layer and the semiconductor fin.

A field effect transistor device comprising:

• a fin including a semiconductor material arranged on an insulator layer, the fin including a channel region;
• a hardmask layer arranged partially over the channel region of the fin;
• a gate stack arranged over the hardmask layer and over the channel region of the fin;
• a metallic alloy layer arranged on a first portion of the hardmask layer, the metallic alloy layer arranged adjacent to the gate stack;
• and
• a first spacer arranged adjacent to the gate stack and over the metallic alloy layer.