Methods for fabricating integrated circuits having improved metal gate structures

A method for fabricating an integrated circuit, the method comprising:

• forming a NFET trench in a NFET region and a PFET trench in a PFET region of an interlayer dielectric material on a semiconductor substrate;
• depositing a layer of a N-type work function metal overlying the NFET and PFET regions to partially fill the NFET and PFET trenches and define an inner cavity in the NFET trench, wherein the N-type work function metal is selected from the group consisting of titanium, tantalum, hafnium, ytterbium silicide, erbium silicide, and titanium silicide;
• removing the N-type work function metal overlying the PFET region including from the PFET trench;
• and
• depositing a P-type work function metal overlying the PFET and NFET regions to fully fill the PFET trench and the inner cavity of the NFET trench and form corresponding metal gate structures, wherein the P-type work function metal is selected from the group consisting of cobalt, nickel, and tungsten silicide.

A method for fabricating an integrated circuit, the method comprising:

• forming a NFET trench in a NFET region and a PFET trench in a PFET region of an interlayer dielectric material on a semiconductor substrate;
• depositing a layer of a P-type work function metal overlying the NFET and PFET regions to partially fill the NFET and PFET trenches and define an inner cavity in the PFET trench, wherein the P-type work function metal is selected from the group consisting of cobalt, nickel, and tungsten silicide;
• removing the P-type work function metal overlying the NFET region including from the NFET trench;
• and
• depositing a N-type work function metal overlying the NFET and PFET regions to fully fill the NFET trench and the inner cavity of the PFET trench and form corresponding metal gate structures, wherein the P-type work function metal is selected from the group consisting of titanium, tantalum, hafnium, ytterbium silicide, erbium silicide, and titanium silicide.