In-situ formation of metal gate modulators

A device comprising:

• a semiconductor fin;
• a high-k dielectric layer on the semiconductor fin;
• a work-function layer over the high-k dielectric layer;
• a first metal nitride layer over the work-function layer, wherein the first metal nitride layer comprises a first material selected from the group consisting of titanium nitride and tantalum nitride;
• a silicon layer over the first metal nitride layer, wherein the silicon layer comprises elemental silicon therein;
• a second metal nitride layer over the silicon layer, wherein the second metal nitride layer comprises a second material selected from the group consisting of titanium nitride and tantalum nitride;
• and
• a filling-metal region over and contacting the second metal nitride layer.

An integrated circuit device comprising:

• a semiconductor fin;
• a high-k dielectric layer on the semiconductor fin;
• a work-function layer over the high-k dielectric layer;
• a first metal nitride layer over the work-function layer;
• a silicon-containing layer over the first metal nitride layer, wherein a peak concentration of silicon is in the silicon-containing layer;
• a second metal nitride layer over the silicon layer, wherein concentrations of the silicon gradually reduce in the first metal nitride layer and the second metal nitride layer and in directions away from the silicon-containing layer;
• and
• a filling-metal region over and contacting the second metal nitride layer.