Method for fabricating a metal gate electrode

摘要

An exemplary method for fabricating a metal gate electrode includes providing a substrate having thereon a dielectric layer and a trench in the dielectric layer; depositing a work-function metal layer over the dielectric layer and into the trench; depositing a sacrificial layer over the work-function metal layer to fill the first trench; performing a chemical mechanical polishing to remove the work-function metal layer outside the trench; removing the sacrificial layer in the trench; and depositing a signal metal layer to fill the trench.

主权项

1. A method for fabricating a metal gate electrode, said method comprising:
providing a substrate having thereon a dielectric layer and a trench in the dielectric layer; depositing a work-function metal layer over the dielectric layer and into the trench, wherein depositing the work-function metal layer into the trench comprises forming a substantially flat layer across a bottom of the trench and forming a narrowing overhang protruding over the trench on a top surface of the dielectric layer, and the work-function metal layer is in direct contact with the top surface of the dielectric layer; depositing a sacrificial layer over the work-function metal layer to fill the trench; performing a chemical mechanical polishing (CMP) to remove the work-function metal layer and the sacrificial layer outside the trench such that a top surface of the sacrificial layer is co-planar with the top surface of the dielectric layer, wherein performing the CMP removes an entirety of the narrowing overhang, and the CMP stops at the top surface of the dielectric layer; removing the sacrificial layer in the trench; and depositing a signal metal layer to fill the trench.