Method to recess cobalt for gate metal application
First Claim
1. A method of forming a semiconductor structure comprising:
- providing a structure comprising a gate cavity exposing a portion of a semiconductor material portion, wherein a gate spacer surrounds the gate cavity;
forming a material stack comprising, from bottom to top, a gate dielectric, a work function metal and a cobalt gate electrode within the gate cavity;
recessing the cobalt gate electrode, wherein the recessing the cobalt gate electrode is performed by repeating steps of oxidizing the cobalt gate electrode utilizing an oxidizing agent to form a cobalt oxide layer on a surface of a remaining portion of the cobalt gate electrode and removing the cobalt oxide layer utilizing a wet chemical etchant;
recessing the work function metal, wherein the recessing of the work function metal is performed prior to the removing of the last cobalt oxide layer;
recessing the gate dielectric; and
forming a gate cap above the recessed cobalt gate electrode to completely fill the gate cavity.
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Accused Products
Abstract
After forming a material stack including a gate dielectric, a work function metal and a cobalt gate electrode in a gate cavity formed by removing a sacrificial gate structure, the cobalt gate electrode is recessed by oxidizing the cobalt gate electrode to provide a cobalt oxide layer on a surface of the cobalt gate electrodes and removing the cobalt oxide layer from the surface of the cobalt gate electrodes by a chemical wet etch. The oxidation and oxide removal steps can be repeated until the cobalt gate electrode is recessed to any desired thickness. The work function metal can be recessed after the recessing of the cobalt gate electrode is completed or during the recessing of the cobalt gate electrode.
21 Citations
15 Claims
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1. A method of forming a semiconductor structure comprising:
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providing a structure comprising a gate cavity exposing a portion of a semiconductor material portion, wherein a gate spacer surrounds the gate cavity; forming a material stack comprising, from bottom to top, a gate dielectric, a work function metal and a cobalt gate electrode within the gate cavity; recessing the cobalt gate electrode, wherein the recessing the cobalt gate electrode is performed by repeating steps of oxidizing the cobalt gate electrode utilizing an oxidizing agent to form a cobalt oxide layer on a surface of a remaining portion of the cobalt gate electrode and removing the cobalt oxide layer utilizing a wet chemical etchant; recessing the work function metal, wherein the recessing of the work function metal is performed prior to the removing of the last cobalt oxide layer; recessing the gate dielectric; and forming a gate cap above the recessed cobalt gate electrode to completely fill the gate cavity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of forming a semiconductor structure comprising:
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providing a structure comprising a first gate cavity of a first width and exposing a first portion of a semiconductor material portion and a second gate cavity of a second width that is greater than the first width and exposing a second portion of the semiconductor material portion, wherein a first gate spacer surrounds the first gate cavity, and a second gate spacer surrounds the second gate cavity; forming a first material stack comprising, from bottom to top, a first gate dielectric, a first work function metal and a first cobalt gate electrode within the first gate cavity, and a second material stack comprising, from bottom to top, a second gate dielectric, a second work function metal and a second cobalt gate electrode within the second gate cavity; recessing the first cobalt gate electrode and the second cobalt gate electrode, wherein the recessing the first cobalt gate electrode and the second cobalt gate electrode is performed by repeating steps of oxidizing the first cobalt gate electrode and the second cobalt gate electrode utilizing an oxidizing agent to form a cobalt oxide layer on a surface of each of a remaining portion of the first cobalt gate electrode and a remaining portion of the second cobalt gate electrode and removing each cobalt oxide layer utilizing a wet chemical etchant; recessing the first work function metal and the second work function metal; recessing the first gate dielectric and the second gate dielectric; and forming a first gate cap above the recessed first cobalt gate electrode to completely fill the first gate cavity and a second gate cap above the recessed second cobalt gate electrode to completely fill the second gate cavity. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification