Semiconductor device and process for manufacturing same

1. A semiconductor device, comprising:

a semiconductor substrate;

an insulating film formed over said semiconductor substrate;

a first gate, including:

a gate insulating film formed in a bottom surface in a first concave portion formed in said insulating film;

a gate electrode formed over said gate insulating film in said first concave portion; and

a protective insulating film formed over said gate electrode in said first concave portion;

a source-drain region provided in the side of said first gate; and

a contact formed in a second concave portion being formed in the side of said first concave portion in said insulating film and having a diameter that is larger than a diameter of said first concave portion in cross sectional view, and coupled to said source-drain region,

wherein said gate electrode is composed of a film of first metal and a film of second metal coating a bottom surface and a side surface of said film of first metal.

2. The semiconductor device as set forth in claim 1 , wherein said contact is composed of said film of first metal and said film of second metal coating a bottom surface and a side surface of said film of first metal.

3. The semiconductor device as set forth in claim 1 , wherein a memory region and a logic region are compatibly contained in said semiconductor substrate,

wherein said first gate is formed in said memory region, and

wherein a second gate having the same structure as said first gate excepted that said protective insulating film is not included, is formed in said logic region.

4. The semiconductor device as set forth in claim 3 , wherein a plug for electrically coupling to the gate electrode is formed over a gate electrode of said second gate in said logic region.

5. A method for manufacturing a semiconductor device, including:

forming a dummy gate electrode over a semiconductor substrate;

injecting impurity to said semiconductor substrate through a mask of said dummy gate electrode to form a source-drain region;

forming a first insulating film covering said dummy gate electrode, over said semiconductor substrate;

planarizing said first insulating film to expose an upper surface of said dummy gate electrode;

selectively removing said first insulating film to form a contact hole being coupled to said source-drain region in said first insulating film;

removing said dummy gate electrode to form a first concave portion in said first insulating film, said first concave portion having smaller diameter than said contact hole in cross sectional view;

forming a metallic film over the entire surface of said semiconductor substrate to fill said contact hole and said first concave portion with said metallic film;

removing portions of said metallic film exposed outside of said contact hole and said first concave portion using a chemical mechanical polishing (CMP) process to form a contact in said contact hole and a gate electrode in said first concave portion, respectively, and removing portions of said metallic film in an upper portion within said first concave portion to form a recess in the upper portion within said first concave portion;

forming a second insulating film over the entire surface of said semiconductor substrate to fill said recess with said second insulating film;

removing portions of said second insulating film exposed outside of said first concave portion to selectively leave said second insulating film over said gate electrode in said first concave portion;

forming a third insulating film over the entire surface of said semiconductor substrate;

selectively removing said third insulating film to form a hole being coupled to said contact in said third insulating film; and

filling the inside of said hole with a conducting film to form a plug, said plug being electrically coupled to said contact.