Patent ID: 8581350

Claim:
An n-channel field effect transistor, comprising: a first electrode film covering an entirety of a channel region of a semiconductor substrate; and a second electrode film on said first electrode film, said second electrode film and said first electrode film constituting a gate electrode, wherein at least one of said first electrode film and said second electrode film is a stressor film that is capable of exhibiting a compressive stress over said semiconductor substrate, wherein each of said first electrode film and said second electrode film is composed of a metal, a metallic nitride or a metallic silicide, and wherein said gate electrode has a U-shape in which the first electrode film comprises a first pair of side portions extending from opposite ends of a first bottom portion; the second electrode film comprises a second pair of side portions extending from opposite ends of a second bottom portion; wherein interior surfaces of the first pair of side portions face each other and interior surfaces of the second pair of side portions face each other; the n-channel field effect transistor further comprising a protective film between said interior surfaces of the first pair of side portions that face each other and the second pair of side portions that face each other and on the first bottom portion and second bottom portion; wherein said protective film comprises silicon dioxide.