Nonplanar transistors with metal gate electrodes
View Patent ↗A semiconductor device comprising a semiconductor body having a top surface and a first and second laterally opposite sidewalls as formed on an insulating substrate is claimed. A gate dielectric is formed on the top surface of the semiconductor body and on the first and second laterally opposite sidewalls of the semiconductor body. A gate electrode is then formed on the gate dielectric on the top surface of the semiconductor body and adjacent to the gate dielectric on the first and second laterally opposite sidewalls of the semiconductor body. The gate electrode comprises a metal film formed directly adjacent to the gate dielectric layer. A pair of source and drain regions are then formed in the semiconductor body on opposite sides of the gate electrode.
1. A method of forming a nonplanar device CMOS integrated circuit comprising:
forming an n type and a p type semiconductor bodies, each semiconductor body comprising a top surface and sidewalls;
forming a first sacrificial gate electrode over the top surface and sidewalls of the n type semiconductor body, wherein a portion of the n type semiconductor body area under the first sacrificial gate electrode defines an n type semiconductor channel region;
forming a second sacrificial gate electrode over the top surface and sidewalls of the p type semiconductor body, wherein a portion of the p type semiconductor body area under the first sacrificial gate electrode defines a p type semiconductor channel region;
forming a dielectric layer over said first and said second sacrificial gate electrodes;
planarizing said dielectric layer;
revealing the top surface of said first and second sacrificial gate electrodes;
removing said first sacrificial gate electrode to form a first opening over said n type channel region and removing said second sacrificial gate electrode to form a second opening over said p type semiconductor channel region;
forming a gate dielectric layer in said first opening on said n type semiconductor channel region and in said second opening on said p type semiconductor channel region;
forming a metal gate electrode material onto said gate dielectric layer in said first opening and onto said gate dielectric layer in second opening and above said planarized dielectric layer; and
polishing said gate electrode material from above said dielectric to form a first gate electrode over said gate dielectric layer in said opening and a second gate electrode on said gate dielectric layer in said second opening.
2. The method of claim 1 wherein said gate electrode material comprises a lower metal film and an upper metal film.
3. The method of claim 2 wherein said lower metal film comprises a midgap work function material.
4. The method of claim 3 wherein said upper film is selected from the group consisting of copper and tungsten.
5. The method of claim 1 further comprising after forming said first and second gate electrodes by polishing, removing said dielectric layer.
6. The method of claim 5 further comprising after removing said dielectric layer, blanket depositing a silicon nitride film on and around said first gate electrode and said second gate electrode.
7. The method of claim 6 further comprising forming a second dielectric layer over said silicon nitride film.