Effective Work Function Modulation by Metal Thickness and Nitrogen Ratio for a Last Approach CMOS Gate

摘要

A CMOS structure is formed on a semiconductor substrate that includes first and second regions having an nFET and a pFET respectively formed thereon. Each nFET and pFET device is provided with a gate, a source and drain, and a channel formed on the substrate. A high permittivity dielectric layer formed on top of the channel is superimposed to the permittivity dielectric layer. The pFET gate includes a thick metal nitride alloy layer or rich metal nitride alloy or carbon metal nitride layer that provides a controlled WF. Superimposed to the permittivity dielectric layer, the nFET gate is provided with a thin metal nitride alloy layer, enabling to control the WF. A metal deposition is formed on top of the respective nitride layers. The gate last approach characterized by having a high thermal budget smaller than 500� C. used for post metal deposition, following the dopant activation anneal.