Image Number 3 for United States Patent #6949440.
A method of forming a varactor includes forming an ion well of a first conductivity type on a substrate and a plurality of isolation structures on the ion well. The isolation structures define at least an active area on the ion well. Following that, ions of the first conductivity type are implanted into the ion well to form a doping region within the active area. A doping layer of a second conductivity type is then formed on the substrate to cover portions of the doping region. A salicide layer is formed on the doping region and the doping layer.