Structure and method to suppress work function effect by patterning boundary proximity in replacement metal gate
A semiconductor device includes a first transistor formed on a substrate, the first transistor including a channel region positioned on the substrate; a second transistor formed on the substrate, the second transistor including a channel region positioned on the substrate; a high-k dielectric layer disposed on the channel region of the first transistor and the channel region of the second transistor; a first transistor metal gate positioned in contact with the high-k dielectric on the first transistor; a second transistor metal gate positioned in contact with the high-k dielectric on the second transistor; an oxygen absorbing barrier disposed in contact with the high-k dielectric between the first transistor and the second transistor; and a conductive electrode material disposed on the first transistor, the second transistor, and the oxygen absorbing barrier.
1. A method of making a semiconductor device, the method comprising:
forming a first transistor channel region of a first transistor and a second transistor channel region of a second transistor on a substrate;
depositing a high-k dielectric layer on the first transistor channel region and the second transistor channel region, the high-k dielectric layer extending continuously over the first transistor channel region and the second transistor channel region;
forming a first transistor metal gate stack directly on the high-k dielectric on the first transistor;
forming a second transistor metal gate stack directly on the high-k dielectric on the second transistor, with a portion of the second transistor metal gate stack arranged directly on the first transistor metal gate stack;
depositing an oxygen absorbing barrier layer directly on the high-k dielectric layer extending continuously between the first transistor metal gate stack and the second transistor metal gate stack, the oxygen absorbing barrier layer positioned in direct contact with the high-k dielectric between the first transistor metal gate stack and the second transistor metal gate stack, the oxygen absorbing barrier layer extending continuously from the high-k dielectric layer to a top surface of the portion of the second transistor metal gate stack arranged directly on the first transistor metal gate stack; and
depositing a conductive electrode material on the first transistor and the second transistor such that the conductive electrode material covers the first transistor metal gate stack and the second transistor metal gate stack.
2. The method of claim 1 , wherein the first transistor is an nFET, and the second transistor is a pFET.
3. The method of claim 1 , further comprising depositing a sacrificial material on the first transistor metal gate and the second transistor metal gate after forming the second transistor metal gate; forming an opening in the sacrificial material between the first transistor and the second transistor; and removing the first transistor metal gate and the second transistor metal gate beneath the opening to expose the high-k dielectric between the first transistor and the second transistor.
4. The method of claim 3 , further comprising removing the sacrificial material and then depositing the oxygen absorbing barrier between the first transistor and the second transistor, wherein the oxygen absorbing barrier is also disposed on the second transistor gate stack on the first transistor and the second transistor.
5. The method of claim 1 , wherein the oxygen absorbing barrier layer is TiN, TiC, TiN, TiC, TaC, Ti, Al, TiAl, W, Ni, Nb, NbAl or any combination thereof.