Patent ID: 6746935
Filing Date: 2004-06-08
Classification: H01L

Abstract:
A method of forming a doped active area in a semiconductor substrate, comprising:forming first and second insulation areas on a surface of the substrate, the first and second insulation areas being spaced apart from each other and thereby defining a substrate region of the substrate between the first and second insulation areas, the substrate region having a first peripheral portion immediately adjacent to the first insulation area and a central portion spaced apart from the first insulation area; forming a spacer adjacent to the first insulation area and above the first peripheral portion of the substrate region; performing, with the spacer positioned above the substrate, a high-energy first implant of first dopant type into the substrate region to create a well that extends in the substrate at a bottom side of the first insulation area; and performing, with the spacer positioned above the substrate, a low-energy second implant of the first dopant type into the substrate region to create the doped active area, the spacer acting as a mask to allow dopants of the second implant to extend deeper into the central portion that into the first peripheral portion.