A method of manufacturing a semiconductor device, comprising: providing a substrate , the substrate including a first trench in an NMOS region and a second trench in a PMOS region; depositing a high-K dielectric layer , a cap layer , and a P-type work function metal layer on the bottom and side walls of the first trench and the second trench , wherein the cap layer on the high-K dielectric comprises TiN (titanium nitride) and TaN (tantalum nitride), or TiSiN (titanium silicon nitride) and TaN (tantalum nitride); removing the P-type work function metal layer and the cap layer from the bottom and sidewalls of the first trench ; depositing an N-type work function metal layer on the high-K dielectric layer in the first trench and on the P-type work function metal layer in the second trench , wherein the N-type work function metal layer comprises one or more of TiAl (Titanium aluminide), TiCAl (titanium carbon aluminide), TiNAl (titanium nitrogen aluminide) or TiSiAl (titanium silicon aluminide); and depositing a metal electrode layer on the N-type work function metal layer , characterized in that depositing N-type work function metal layer comprises: depositing a first N-type work function metal layer having Ti (titanium) and Al (aluminum) and in which the Ti (titanium) content greater than the Al (aluminum) content, wherein the thickness of the first N-type work function metal layer is 10-15 Å; and depositing, on the first N-type work function metal layer, a second N-type work function metal layer having Ti and Al and in which the Al content greater than the Ti content, wherein the thickness of the second N-type work function metal layer is 35-40 Å. providing a substrate , the substrate including a first trench in an NMOS region and a second trench in a PMOS region; depositing a high-K dielectric layer , a cap layer , and a P-type work function metal layer on the bottom and side walls of the first trench and the second trench , wherein the cap layer on the high-K dielectric comprises TiN (titanium nitride) and TaN (tantalum nitride), or TiSiN (titanium silicon nitride) and TaN (tantalum nitride); removing the P-type work function metal layer and the cap layer from the bottom and sidewalls of the first trench ; depositing an N-type work function metal layer on the high-K dielectric layer in the first trench and on the P-type work function metal layer in the second trench , wherein the N-type work function metal layer comprises one or more of TiAl (Titanium aluminide), TiCAl (titanium carbon aluminide), TiNAl (titanium nitrogen aluminide) or TiSiAl (titanium silicon aluminide); and depositing a metal electrode layer on the N-type work function metal layer , depositing a first N-type work function metal layer having Ti (titanium) and Al (aluminum) and in which the Ti (titanium) content greater than the Al (aluminum) content, wherein the thickness of the first N-type work function metal layer is 10-15 Å; and depositing, on the first N-type work function metal layer, a second N-type work function metal layer having Ti and Al and in which the Al content greater than the Ti content, wherein the thickness of the second N-type work function metal layer is 35-40 Å. <EOS>