Conductive capping for work function layer and method forming same

A device comprising:

• a semiconductor region;
• gate spacers on the semiconductor region;
• a gate stack over the semiconductor region and between the gate spacers, wherein the gate stack comprises a plurality of layers;
• a conductive capping layer over and contacting the plurality of layers of the gate stack, wherein the conductive capping layer is electrically conductive;
• a dielectric hard mask over the conductive capping layer and between the gate spacers;
• and
• a gate contact plug penetrating through the dielectric hard mask to land on the conductive capping layer.

A device comprising:

• an inter-layer dielectric comprising a first top surface;
• a source region and a drain region lower than the inter-layer dielectric;
• a gate stack between the source region and the drain region, wherein the gate stack is in the inter-layer dielectric, wherein the gate stack comprises a plurality of layers, and each of the layers has a basin shape with a bottom portion and sidewall portions over and joined to the bottom portion;
• gate spacers on opposite sidewalls of the gate stack;
• and
• a conductive layer over and contacting top surfaces of the sidewall portions of the plurality of layers, wherein a second top surface of the conductive layer is lower than the first top surface of the inter-layer dielectric and top ends of the gate spacers.