Manufacturing method for semiconductor device

A manufacturing method for a semiconductor device, comprising:

• the first step of forming a well of a first conductive type in a semiconductor substrate;
• the second step of forming a gate electrode for forming a first transistor on said well of the first conductive type;
• the third step of diagonally implanting ions into a portion beneath said gate electrode and into a portion in which a well contact region for making an electrical contact with the well of the first conductive type is formed in the main surface of said well of the first conductive type;
• the fourth step of forming source/drain regions of a second conductive type in the main surface of said well of the first conductive type on both sides of said gate electrode;
• and
• the fifth step of forming the well contact region of the first conductive type by implanting ions of the first conductive type into the portion for forming said well contact region,
• wherein said diagonal ion implantation in said third step and said ion implantation in said fourth step are carried out so that when the depth is plotted along the longitudinal axis and the impurity concentration is plotted along the lateral axis in the impurity profile of said well contact region, the impurity profile of the first conductive type that forms said well contact region covers the profile of the impurities that form said impurity diffusion layer beneath the gate.