Structure of metal gate structure and manufacturing method of the same
A manufacturing method of a metal gate structure is provided. First, a substrate covered by an interlayer dielectric is provided. A gate trench is formed in the interlayer dielectric, wherein a gate dielectric layer is formed in the gate trench. A silicon-containing work function layer is formed on the gate dielectric layer in the gate trench. Finally, the gate trench is filled up with a conductive metal layer.
1. A metal gate structure, comprising:
a gate dielectric layer;
a conductive metal layer, disposed on the gate dielectric layer; and
a silicon-containing work function layer having a U-shaped profile, disposed between the gate dielectric layer and the conductive metal layer, wherein the silicon-containing work function layer comprises a vertical portion and a horizontal portion, wherein an atomic percentage of silicon in the silicon-containing work function layer is between 10% and 30%.
2. The metal gate structure according to claim 1 , further comprising a barrier layer disposed between the gate dielectric layer and the silicon-containing work function layer, wherein a composition of the barrier layer comprises titanium nitride.
3. The metal gate structure according to claim 2 , further comprising an etch stop layer disposed between the barrier layer and the silicon-containing work function layer, wherein a composition of the etch stop layer comprises tantalum nitride.
4. The metal gate structure according to claim 1 , wherein a work function of the silicon-containing work function layer is greater than 4.9 electron volts (eV).
5. The metal gate structure according to claim 1 , wherein a composition of the silicon-containing work function layer further comprises titanium and an atomic ratio of titanium to silicon in the silicon-containing work function layer is between 1.5 and 4.
6. The metal gate structure according to claim 1 , wherein a composition of the silicon-containing work function layer further comprises oxygen.
7. The metal gate structure according to claim 6 , wherein an atomic ratio among titanium, silicon, nitrogen, and oxygen in the silicon-containing work function layer is 28.9:13.2:46.8:10.