Semiconductor device and manufacturing method thereof

A semiconductor device comprising:

• a semiconductor layer including a channel region, a pair of impurity regions, and a pair of low-concentration impurity regions;
• and
• a taper-shaped gate electrode layer which is formed to be in contact with the semiconductor layer by sandwiching a gate insulating film therebetween,
• wherein the pair of low-concentration impurity regions is formed to overlap with a taper-shaped part of the gate electrode layer.

A semiconductor device comprising:

• a semiconductor layer including a channel region, a pair of impurity regions, and a pair of low-concentration impurity regions;
• and
• a gate electrode layer formed of a single layer, of which film thickness is not even, which is formed to be in contact with the semiconductor layer by sandwiching a gate insulating film therebetween,
• wherein the pair of low-concentration impurity regions is formed to overlap with part of the gate electrode layer thin in film thickness.

A method for manufacturing a semiconductor device comprising:

• forming a gate insulating film over a semiconductor layer;
• forming a plurality of gate electrode layers different in width over the gate insulating film;
• and
• forming a pair of impurity regions and a pair of low-concentration impurity regions by introducing impurities into the semiconductor layer, using the plurality of gate electrode layers as masks,
• wherein the pair of low-concentration impurity regions is formed to overlap with part of the plurality of gate electrode layers where the film thickness is reduced.

A method for manufacturing a semiconductor device comprising:

• forming a gate insulating film over a semiconductor layer;
• forming a gate electrode layer over the gate insulating film;
• performing etching by using an insulator formed over the gate electrode layer as a mask to make part of the gate electrode layer taper-shaped;
• and
• forming a pair of impurity regions and a pair of low-concentration impurity regions by introducing impurities into the semiconductor layer, using the taper-shaped gate electrode layer as a mask,
• wherein the pair of low-concentration impurity regions is formed to overlap with the taper-shaped part of the gate electrode layer.

A method for manufacturing a semiconductor device comprising:

• forming a gate insulating film over a semiconductor layer;
• forming a first shape gate electrode layer over the gate insulating film;
• forming a heat-resistant insulator over the first shape gate electrode layer;
• heating the first shape gate electrode layer in an atmosphere containing oxygen and nitrogen to reduce thickness of part of the first shape gate electrode layer where the insulator is not formed to form a second shape gate electrode layer;
• and
• forming a pair of impurity regions and a pair of low-concentration impurity regions by introducing impurities into the semiconductor layer, using the second shape gate electrode layer as a mask,
• wherein the pair of low-concentration impurity regions is formed to overlap with a thinner part of the second shape gate electrode layer.

A method for manufacturing a semiconductor device comprising:

• forming a gate insulating film over a semiconductor layer;
• forming a first shape gate electrode layer over the gate insulating film;
• forming a pair of impurity regions by introducing impurities into the semiconductor layer, using the first shape gate electrode layer as a mask;
• heating the first shape gate electrode layer in an atmosphere containing oxygen and nitrogen to reduce thickness and width of the first shape gate electrode layer to form a second gate electrode layer reduced in thickness and width;
• and
• forming a pair of low-concentration impurity regions by introducing impurities at low concentration into the semiconductor layer, using the second shape gate electrode layer reduced in thickness and width as a mask.