Patent ID: 7235470
Filing Date: 2007-06-26
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor device comprising the steps of: forming a gate over a semiconductor region; forming a first junction by doping an n-type impurity less diffusive than phosphorus in the semiconductor region by using the gate as a mask; and forming a second junction by doping an n-type impurity in the semiconductor region by using at least the gate as a mask, the second junction being deeper than the first junction, the second junction overlapping with the first junction with leaving a part of the first junction existing under the gate, wherein the step of forming the first junction includes at least a first ion implantation which is carried out with a first acceleration energy and a first dose, and a second ion implantation which is carried out with a second acceleration energy higher than the first acceleration energy and a second dose lower than the first dose.