Semiconductor device and method of manufacturing the same

A semiconductor device, comprising

• a semiconductor substrate;
• a first active region which is formed in a part of the semiconductor substrate and includes a first upper face, a first side wall, and a first shoulder part connecting the first upper face and the first side wall;
• a second active region which is formed in a part of the semiconductor substrate and includes a second upper face, a second side wall, and a second shoulder part connecting the second upper face and the second side wall;
• a separation part which is in contact with the first side wall and the second side wall and surrounds the first active region and the second active region in a plan view;
• a first conductor film covering the first upper face and the first shoulder part;
• a second conductor film covering the second upper face and the second shoulder part;
• a first insulating film provided between the first conductor film and the first active region;
• and
• a second insulating film provided between the second conductor film and the second active region,
• wherein the first active region includes a first protrusion part constituted of a first concave part with respect to the first upper face and a second concave part with respect to the first side wall, in the first shoulder part, and a second protrusion part constituted of a third concave part with respect to the second upper face and the second side wall, in the second shoulder part, wherein the first protrusion is more pointed than the second protrusion part.

A semiconductor device manufacturing method, comprising the steps of:

• (a) forming a mask having a predetermined pattern on an upper face of a semiconductor substrate;
• (b) forming a first concave part with respect to the upper face of the semiconductor substrate in a lower part of the mask in a peripheral part of the mask;
• (c) subjecting the semiconductor substrate to dry etching and forming a groove in the semiconductor substrate in a part exposed from the mask, thereby forming an active region including a side wall, an upper face and a shoulder part in a region covered by the mask;
• (d) depositing a first insulating film within the groove and over the mask so as to fill the groove;
• (e) subjecting the first insulating film to chemical mechanical polishing, removing the first insulating film over the mask, and selectively leaving the first insulating film within the groove;
• (f) subjecting the first insulating film within the groove to etching and causing a height of the first insulating film in contact with the side wall to be lower than the first concave part;
• (g) subjecting the semiconductor substrate to first thermal oxidation processing and forming a second insulating film on the side wall and the upper face of the active region in a part exposed from the first insulating film;
• and
• (h) forming a conductor film so as to cover the second insulating film,
• wherein, in the step (g), a second concave part is formed with respect to the side wall and a protrusion part constituted of the first concave part and the second concave part is formed in the shoulder part of the active region.

A semiconductor device manufacturing method, comprising the steps of:

• (a) preparing a semiconductor substrate having a first region and a second region over a major surface thereof;
• (b) in the first region, forming a first active region including a first upper face, a first side wall, and a first shoulder part connecting the first upper face and the first side wall, and a first insulating film which is in contact with the first side wall and surrounds the first active region in a plan view;
• (c) in the second region, forming a second active region including a second upper face, a second side wall, and a second shoulder part connecting the second upper face and the second side wall, and a second insulating film which in contact with the second side wall and surrounds the second active region in a plan view;
• (d) forming a mask covering the second region and exposing the first region, over the semiconductor substrate, subjecting the first insulating film to etching, and thereby making an exposure depth of the first side wall from the first upper face, the first side wall being exposed from insulating film, in the first active region, larger than an exposure depth of the second side wall from the second upper face, the second side wall being exposed from the second insulating film, in the second active region;
• and
• (e) subjecting the semiconductor substrate to thermal processing, forming a third insulating film on a surface of the first active region exposed from the second insulating film, and forming a fourth insulating film on a surface of the second active region exposed from the second insulating film.