Semiconductor device with multiple threshold voltage and method of fabricating the same

A vertical semiconductor field effect transistor (FET), comprising:

• a source;
• a channel over the source;
• a drain over the channel;
• a gate dielectric layer adjacent to a lateral surface of the channel;
• a conductive layer adjacent to the gate dielectric layer;
• and
• a gate metal layer adjacent to the conductive layer,
• wherein the conductive layer includes TiN, TiAl, or TaN, which further comprises Mn, or Sn.

A semiconductor device, comprising a first vertical device, a second vertical device, a third vertical device, a fourth vertical device, a fifth vertical device and a sixth vertical device, wherein:

• each of the first, second, third, fourth, fifth and sixth vertical devices includes:
• a source;
• a channel over the source;
• a drain over the channel;
• a gate dielectric layer adjacent to a lateral surface of the channel;
• a work function adjustment layer adjacent to the gate dielectric layer;
• and
• a gate metal layer adjacent to the work function adjustment layer,
• the work function adjustment layer of the first vertical device includes one conductive layer,
• the work function adjustment layer of the second vertical device includes two conductive layers,
• the work function adjustment layer of the third vertical device includes three conductive layers,
• the work function adjustment layer of the first vertical device includes four conductive layers,
• the work function adjustment layer of the first vertical device includes five conductive layers, and
• the work function adjustment layer of the first vertical device includes six conductive layers.