Method for manufacturing semiconductor device including hat-shaped electrode

A method for manufacturing a semiconductor device comprising the steps of:

• forming a gate insulating film over a semiconductor film over a substrate;
• forming a first conductive film over the gate insulating film;
• forming a second conductive film over the first conductive film;
• forming a resist over the second conductive film;
• etching the second conductive film with the use of the resist as a mask to form an etched second conductive film;
• etching the first conductive film to form an etched first conductive film and recessing the resist to form a recessed resist;
• and
• recessing the recessed resist and etching the etched second conductive film by using the further recessed resist as a mask to form a further etched second conductive film of which a length in a channel length direction is shorter than that of the etched first conductive film;
• and
• forming sidewalls comprising silicon oxide in contact with side surfaces of the etched first conductive film and upper surfaces of the etched first conductive film;
• and
• forming a passivation film over the sidewalls,
• wherein a stage temperature is at −10° C. or less during the recessing the resist and etching the etched second conductive film.

A method for manufacturing a semiconductor device comprising the steps of:

• forming a gate insulating film over a semiconductor film over a substrate;
• forming a first conductive film over the gate insulating film;
• forming a second conductive film over the first conductive film;
• forming a resist over the second conductive film;
• etching the second conductive film with the use of the resist as a mask to form an etched second conductive film;
• etching the first conductive film to form an etched first conductive film;
• and
• recessing the resist and etching the etched second conductive film by using the recessed resist as a mask to form a further etched second conductive film of which a length in a channel length direction is shorter than that of the etched first conductive film;
• forming a channel-forming region and first low-concentration impurity regions in contact with the channel-forming region and second low-concentration impurity regions in contact with the first low-concentration impurity regions in the semiconductor film by doping an impurity element with the use of the further etched second conductive film as a mask;
• forming sidewalls comprising silicon oxide in contact with the side surfaces of the etched first conductive film and the further etched second conductive film;
• forming high-concentration impurity regions selectively in the second low-concentration impurity regions by doping an impurity element with the use of the sidewalls and the further etched second conductive film as masks;
• and
• forming a passivation film over the sidewalls,
• wherein a stage temperature is at −10° C. or less during the recessing the resist and etching the etched second conductive film, and
• wherein the sidewalls are in contact with upper surfaces of the etched first conductive film,
• wherein a difference between a length in a channel length direction of the etched second conductive film and that of the further etched second conductive film is 10 nm to 300 nm, and
• wherein the length in the channel length direction of the further etched second conductive film is 0.1 μm to 0.7 μm.