Abstract: A capacitive device includes a well, a first dielectric layer, a first conductive layer, a cap dielectric layer, and a first electrode. The well includes a first shoulder portion having an upper surface, a second shoulder portion having an upper surface, and a first trench, sandwiched between the first and second shoulder portions, having sidewalls and a bottom surfaces. The first dielectric layer is lined along at least a portion of the upper surfaces of the first and second shoulder portions, the sidewalls of the first trench, and the bottom surface of the first trench. The first conductive layer is lined along the first dielectric layer. The cap dielectric layer is over the well, the first dielectric layer, and the first conductive layer. The first electrode is in contact with the first shoulder portion.