FABRICATION OF SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a fabrication method of semiconductor device in which fabrication cost is reduced by simplifying the process for forming three wells. SOLUTION: A first mask for defining a first well region is formed on a first conductivity type semiconductor substrate, second conductivity type impurity ions are implanted onto the semiconductor substrate 100 by ion implantation technology of large inclination angle using the first mask and impurity ions are implanted onto the semiconductor substrate 100 every time when the semiconductor substrate 100 reaches a position having a specified directional angle during rotation of 360 deg. thus forming a first well isolation region 104. First conductivity type impurity ions are then implanted using the first mask again and a first well is formed to overlay a part of the first well isolation region 104 in the semiconductor substrate 100. Subsequently, a second well is formed while being spaced apart by a specified distance from the first well and a third well is formed to wrap the opposite side walls of the first well. Since photolithographic process is required only once, fabrication cost can be reduced.