Patent ID: 8298898

Claim:
A method of manufacturing a semiconductor device, the method comprising: forming a gate insulating film and a gate electrode that has a first end portion and a second end portion on a semiconductor substrate of a first conductivity type; forming a first drain region by implanting at a first dosage a first impurity of a second conductivity type corresponding to an opposite conductivity type with respect to the first conductivity type at a vicinity of the first end portion of the gate electrode in a first-side region of the semiconductor substrate in respect to the gate electrode; forming a second drain region to be overlapped with the first drain region by implanting a second impurity of the second conductivity type at a second dosage that is greater than the first dosage in the first-side region of the semiconductor substrate; and forming a drain contact region within the second drain region by implanting a third impurity of the second conductivity type at a third dosage that is greater than the second dosage; wherein the first drain region has a third end portion, a fourth end portion, a fifth end portion and a sixth end portion, the third end portion and the fourth end portion are opposite each other, the fifth end portion and the sixth end portion are opposite each other, the third end portion is nearer than the fourth end portion from the gate electrode, the second drain region has a seventh end portion, an eighth end portion, a ninth end portion and a tenth end portion, the seventh end portion and the eighth end portion are opposite each other, the ninth end portion and the tenth end portion are opposite each other, the seventh end portion is located between the third end portion and fourth end portion, the eighth end portion is more distant than the fourth end portion from the gate electrode, and the ninth end portion and the tenth end portion are more distant than the fifth end portion and sixth end portion from the drain contact region respectively.