A semiconductor structure includes a first semiconductor device formed over a substrate and a second semiconductor device formed over the substrate. The first semiconductor device includes a first source/drain feature over the substrate, a first gate structure over the substrate, a first conductive feature over the first source/drain feature, and a first insulation layer between the first gate structure and the first conductive feature. The second semiconductor device includes a second source/drain feature over the substrate, a second gate structure over the substrate, a second conductive feature over the second source/drain feature, and a second insulation layer between the second gate structure and the second conductive feature. A width of the first conductive feature and a width of the second conductive feature are different, and a width of the first insulation layer is less than a width of the second insulation layer.