Multi-layer work function metal gates with similar gate thickness to achieve multi-vt for vfets
AssigneeInternational Business Machines Corporation
InventorsRuqiang Bao, Hemanth Jagannathan, Paul C. Jamison, ChoongHyun Lee
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Abstract
A method is presented for forming a device having multiple field effect transistors (FETs) with each FET having a different work function. In particular, the method includes forming multiple microchips in which each FET has a different threshold voltage (Vt) or work-function. In one embodiment, four FETs are formed over a semiconductor substrate. Each FET has a source, drain and a gate electrode. Each gate electrode is processed independently to provide a substantially different threshold voltage.
Claims20
A structure for forming a device having multiple field effect transistors (FETs) with each FET having a different work function, the structure comprising:
- first, second, third, and fourth FETs formed over a semiconductor substrate;
- an interfacial layer and a high-k dielectric layer formed over the first, second, third, and fourth FETs;
- a first work function conducting layer formed over the high-k dielectric layer, where the first work function conducting layer is subsequently removed from the third FET;
- a second work function conducting layer, where the first and second work function conducting layers are subsequently removed from the second FET;
- a third work function conducting layer, where the first, second, and third work function conducting layers are subsequently removed from the first FET;
- a fourth work function conducting layer;
- a sacrificial block layer and a sacrificial cap layer, the sacrificial block layer and the sacrificial cap layer subsequently removed from the first and second FETs;
- a fifth work function conducting layer and a patterning cap layer, where the patterning cap layer, the fifth work function conducting layer, the sacrificial cap, and the sacrificial block layer are subsequently removed from the third and fourth FETs;
- and
- first and second conducting layers formed over the first, second, third, and fourth FETs.
A structure for forming a device having a plurality of field effect transistors (FETs) with each FET having a different work function, the structure comprising:
- at least one dielectric layer formed over the plurality of FETs;
- a first work function conducting layer formed over the at least one dielectric layer, where the first work function conducting layer is subsequently removed from a first FET;
- a second work function conducting layer, where the first and second work function conducting layers are subsequently removed from a second FET;
- a third work function conducting layer, where the first, second, and third work function conducting layers are subsequently removed from a third FET;
- a fourth work function conducting layer;
- at least one sacrificial layer, where the at least one sacrificial layer is subsequently removed from the second and third FETs;
- a fifth work function conducting layer, where the fifth work function conducting layer and the at least one sacrificial layer are subsequently removed from at least the first FET;
- and
- at least one conducting layer formed over the plurality of FETs;
- wherein multi-layer work function metal gates of each of the plurality of FETs have a similar gate thickness.
Dependencies are inferred from the claim text.