Structure and method to modulate threshold voltage for high-K metal gate field effect transistors (FETs)
View Patent ↗A method for forming an electrical device that includes forming a high-k gate dielectric layer over a semiconductor substrate that is patterned to separate a first portion of the high-k gate dielectric layer that is present on a first conductivity device region from a second portion of the high-k gate dielectric layer that is present on a second conductivity device region. A connecting gate conductor is formed on the first portion and the second portion of the high-k gate dielectric layer. The connecting gate conductor extends from the first conductivity device region over the isolation region to the second conductivity device region. One of the first conductivity device region and the second conductivity device region may then be exposed to an oxygen containing atmosphere. Exposure with the oxygen containing atmosphere modifies a threshold voltage of the semiconductor device that is exposed.
1. An electrical device comprising:
a semiconductor substrate including a first device region and a second device region separated by an isolation region;
a first gate stack in the first device region comprised of at least a first portion of a high-k gate dielectric layer and a first portion of a metal nitride layer atop the first portion of the high-k gate dielectric layer, wherein a first source region and a first drain region are present in the first device region on opposing sides of the first gate stack, wherein the first gate stack extends from the first device region onto the isolation region;
a second gate stack in the second device region comprised of at least a second portion of the high-k gate dielectric layer and a second portion of the metal nitride layer atop the second portion of the high-k gate dielectric layer, wherein a second source region and a second drain region are present in the second device region on opposing sides of the second gate stack, and wherein the second gate stack extends from the second device region onto the isolation region, and is separated from the first gate stack by a gate stack space, the gate stack space extending through the metal nitride layer and the high-k gate dielectric layer to the upper surface of the isolation region; and
a connecting gate layer extending from the first gate stack across the gate stack space to the second gate stack, wherein the connecting gate layer is a single continuous material layer present in direct contact with upper surfaces of the first portion of the metal nitride layer and the second portion of the metal nitride layer, and the gate stack space.
2. The electrical device of claim 1 , wherein the metal nitride layer comprises TiN, TaN, TiAlN, TaAlN, W, WN or a combination thereof.
3. The electrical device of claim 1 , wherein the high-k gate dielectric layer is comprised of a hafnium containing material.
4. The electrical device of claim 1 , wherein the connecting gate layer is comprised of a semiconductor containing conductive material or a silicide.
5. The electrical device of claim 1 , wherein the gate stack space between ends of the first gate stack and the second gate stack ranges from 5 nm to 200 nm.
6. The electrical device of claim 1 , wherein the gate stack space is present around a perimeter of at least one of the first device region and the second device region.
7. The electrical device of claim 1 , wherein the second portion of the high-k gate dielectric layer interacts with oxygen so as to shift a threshold voltage of a semiconductor device formed in the second device region.
8. The electrical device of claim 7 , wherein the threshold voltage of the semiconductor device formed in the second device region is shifted at least +/−80 mV.
9. The electrical device of claim 8 , wherein the first device region is a n-type device region and the second device region is a p-type device region.
10. The electrical device of claim 8 , wherein the first device region is a p-type device region and the second device region is a n-type device region.