Semiconductor device including impurity regions and element isolation portion and method of manufacturing the same

A method of manufacturing a semiconductor device including a cell region in which Metal Insulator Semiconductor Field Effect Transistors (MISFETs) are formed and a peripheral region surrounding the cell region in a plan view, the method comprising:

• (a) forming a first impurity region of a first conductivity type in a semiconductor substrate in the cell region and the peripheral region;
• (b) forming an element isolation portion in the semiconductor substrate from an upper surface of the semiconductor substrate to a predetermined depth in the peripheral region so as to surround the cell region in the plan view;
• (c) forming a second impurity region of a second conductivity type opposite to the first conductivity type in the semiconductor substrate from the upper surface of the semiconductor substrate to a position deeper than the element isolation portion in the peripheral region so as to surround the cell region in the plan view;
• (d) forming a third impurity region of the first conductivity type in the semiconductor substrate from the upper surface of the semiconductor substrate to the first impurity region in the peripheral region so as to surround the second impurity region in the plan view;
• (e) forming a fourth impurity region of the second conductivity type in the semiconductor substrate in the cell region so as to contact the second impurity region and located on the first impurity region;
• and
• (f) forming a fifth impurity region of the first conductivity type in the semiconductor substrate from the upper surface of the semiconductor substrate to the fourth impurity region in the cell region so as to contact the second impurity region,
• wherein the element isolation portion includes a trench formed in the semiconductor substrate and a dielectric film buried in the trench, and
• wherein the element isolation portion is located in the second impurity region and spaced apart from a junction interface between the second impurity region and the fifth impurity region.