Abstract: Structures and formation methods of a semiconductor device structure are provided. The semiconductor device structure includes a gate stack over a semiconductor substrate and a spacer element over a sidewall of the gate stack. The spacer element is substantially free of oxygen. The semiconductor device structure also includes a dielectric layer over the semiconductor substrate, and the dielectric layer surrounds the gate stack and the spacer element. The semiconductor device structure further includes a conductive contact penetrating through the dielectric layer and electrically connected to a conductive feature over the semiconductor substrate. An angle between a sidewall of the conductive contact and a top surface of the spacer element is in a range from about 90 degrees to about 120 degrees, and the conductive contact covers a portion of the spacer element.

Abstract: A method of forming a gate structure includes forming an opening through an insulating layer and forming a first work function metal layer in the opening. The method also includes recessing the first work function metal layer into the opening to form a recessed first work function metal layer, and forming a second work function metal layer in the opening and over the first work function metal layer. The second work function metal layer lines and overhangs the recessed first work function metal layer.

Abstract: Structures and formation methods of a semiconductor device structure are provided. The semiconductor device structure includes a gate stack over a semiconductor substrate and a spacer element over a sidewall of the gate stack. The spacer element is substantially free of oxygen. The semiconductor device structure also includes a dielectric layer over the semiconductor substrate, and the dielectric layer surrounds the gate stack and the spacer element. The semiconductor device structure further includes a conductive contact penetrating through the dielectric layer and electrically connected to a conductive feature over the semiconductor substrate. An angle between a sidewall of the conductive contact and a top surface of the spacer element is in a range from about 90 degrees to about 120 degrees, and the conductive contact covers a portion of the spacer element.

Abstract: A method for forming a semiconductor device structure is provided. The method includes forming a spacer layer and a dielectric layer over a substrate. The spacer layer has an opening exposing the substrate, and the dielectric layer surrounds the spacer layer. The method includes forming a metal silicon nitride layer over a sidewall and a bottom surface of the opening. The method includes forming a first work function metal layer over the metal silicon nitride layer. The method includes removing a first top portion of the first work function metal layer. The method includes, after the removal of the first top portion, removing a second top portion of the metal silicon nitride layer. The method includes forming a conductive layer in the opening. The method includes removing a third top portion of the conductive layer and a fourth top portion of the metal silicon nitride layer.