Stress in trigate devices using complimentary gate fill materials
View Patent ↗Embodiments relate to an improved tri-gate device having gate metal fills, providing compressive or tensile stress upon at least a portion of the tri-gate transistor, thereby increasing the carrier mobility and operating frequency. Embodiments also contemplate method for use of the improved tri-gate device.
1. A semiconductor device, comprising:
a first fin comprising an N-type material raised above a substrate, the first fin having a first top surface, a first pair of sidewalls and a first current flow direction along a first major axis of the first fin;
a second fin comprising a P-type material raised above the substrate, the second fin having a second top surface, a second pair of sidewalls and a second current flow direction along a second major axis of the second fin generally parallel to the first major axis;
a first gate dielectric layer wrapped around the first top surface and the first pair of sidewalls;
a first gate comprising an intrinsically compressively stressed copper metal fill, the first gate in direct contact with the first gate dielectric layer on the first top surface and on the first pair of sidewalls, the first gate aligned substantially perpendicular to the first major axis, wherein the intrinsic compressive stress of the first copper metal fill exerts a tensile stress upon the first top surface and the first pair of sidewalls in the first current flow direction along the first major axis;
a second gate dielectric layer wrapped around the second top surface and the second pair of sidewalls; and
a second gate comprising an intrinsically tensilely stressed tungsten metal fill, the second gate in direct contact with the second gate dielectric layer on the second top surface and on the second pair of sidewalls, the second gate aligned substantially perpendicular to the second major axis, wherein the intrinsic tensile stress of the tungsten metal fill exerts a compressive stress upon the second top surface and the second pair of sidewalls in the second current flow direction along the second major axis.
2. The semiconductor device of claim 1 , wherein the first gate has a depth of 10-100 nm.
3. The semiconductor device of claim 1 , wherein the second gate has a depth of 10-100 nm.
4. The semiconductor device of claim 1 , wherein the tensile stress exerted upon the first channel is substantially unequal to the compressive stress exerted upon the second channel.
5. The semiconductor device of claim 1 , wherein the copper metal fill is intrinsically 1% stressed compared to a relaxed state.