Abstract: A semiconductor device includes a semiconductor substrate having a first conductivity type. A pair of source/drain areas having a second conductivity type is formed on a surface of the semiconductor substrate. A gate insulating film is provided on a channel area between the source/drain areas. A gate electrode having the first conductivity type is provided on the gate insulating film. The gate electrode has a first portion located above a channel area and second portions located above the source/drain area. The concentration of majority carriers in the second portion is lower than that in the first portion.

Abstract: A semiconductor device includes a semiconductor substrate, a trench formed in the semiconductor substrate, an island-like element region formed in the semiconductor substrate, having an upper surface, first to third side surfaces, an upper portion, a middle portion and a lower portion, a gate insulating film formed on the first to third side surfaces in the upper portion of the element region, a gate electrode having first and second bottom surfaces, a first diffusion layer formed along the upper surface of the element region, a second diffusion layer formed along the first side surface in the middle portion of the element region, a channel region having first to third regions formed along the first to third side surfaces in the upper portion of the element region, a capacitor formed in the trench, and a bit line electrically connected to the first diffusion layer.

Abstract: A semiconductor device includes a semiconductor substrate, a trench formed in the semiconductor substrate, an island-like element region formed in the semiconductor substrate, having an upper surface, first to third side surfaces, an upper portion, a middle portion and a lower portion, a gate insulating film formed on the first to third side surfaces in the upper portion of the element region, a gate electrode having first and second bottom surfaces, a first diffusion layer formed along the upper surface of the element region, a second diffusion layer formed along the first side surface in the middle portion of the element region, a channel region having first to third regions formed along the first to third side surfaces in the upper portion of the element region, a capacitor formed in the trench, and a bit line electrically connected to the first diffusion layer.

Abstract: A semiconductor device includes a semiconductor substrate having a first conductivity type. A pair of source/drain areas having a second conductivity type is formed on a surface of the semiconductor substrate. A gate insulating film is provided on a channel area between the source/drain areas. A gate electrode having the first conductivity type is provided on the gate insulating film. The gate electrode has a first portion located above a channel area and second portions located above the source/drain area. The concentration of majority carriers in the second portion is lower than that in the first portion.