Metal Gate Structure

A method comprising:

• forming a trench over a substrate, wherein the trench is surrounded by gate spacers and an inter-layer dielectric layer;
• depositing a dielectric layer on a bottom and along sidewalls of the trench;
• depositing a metal layer over the dielectric layer;
• depositing a protection layer over the metal layer, wherein a surface of a portion of the protection layer in the trench and along the sidewalls is of a gradual slope;
• applying an etching process to the protection layer and a portion of the metal layer adjacent to the portion of the protection layer, wherein after applying the etching process, a bottom portion of the protection layer remains at the bottom of the trench;
• and
• removing the bottom portion of the protection layer from the trench.

A method comprising:

• depositing a dielectric layer on a bottom and along sidewalls of a trench;
• depositing a metal layer over the dielectric layer;
• depositing a protection layer over the metal layer;
• applying an etch-back process to the protection layer and the metal layer, wherein as a result of applying the etch-back process, a portion of the metal layer has been removed and at least a portion of the protection layer remains at the bottom of the trench;
• and
• removing the protection layer from the trench, wherein after removing the protection layer from the trench, the metal layer comprises a metal sidewall, a metal bottom, a corner portion between the metal sidewall and the metal bottom, wherein the corner portion comprises a step and a non-vertical slope.