Manufacturing method for semiconductor device

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

• forming a gate insulation film in a certain area on a semiconductor substrate, and forming a gate electrode on the gate insulation film;
• etching the surface of the semiconductor substrate to a certain depth by using the gate electrode as a mask to form a semiconductor substrate non-removed region under the gate insulation film, and form a semiconductor substrate removed region around the semiconductor substrate non-removed region;
• implanting first impurity ions in the semiconductor substrate removed regions by using the gate electrode as a mask, to form an LDD source region and an LDD drain region;
• forming sidewalls of an insulation film on side faces of the gate electrode, the gate insulation film, and the semiconductor substrate non-removed section after the step of implanting first impurity ions;
• and
• implanting second impurity ions in the semiconductor substrate removed regions by using the gate electrode and the sidewalls as masks to form a further source region and a further drain region, wherein an impurity concentration of the second impurity ions is higher than an impurity concentration of the first impurity ions.

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

• forming a gate electrode in a selected area on a semiconductor substrate;
• implanting first impurity ions in the semiconductor substrate by using the gate electrode as a mask, to form a source region and a drain region;
• forming sidewalls of an insulation film on side faces of the gate electrode after the step of implanting first impurity ions;
• and
• implanting second impurity ions by using the gate electrode and the sidewalls as masks,
• wherein the impurity concentration of the second impurity ions is higher than that of the first impurity ions.