A nonplanar circuit device having a strain-producing structure disposed under the channel region is provided. In an exemplary embodiment, the integrated circuit device includes a substrate with a first fin structure and a second fin structure disposed on the substrate. An isolation feature trench is defined between the first fin structure and the second fin structure. The circuit device also includes a strain feature disposed on a horizontal surface of the substrate within the isolation feature trench. The strain feature may be configured to produce a strain on a channel region of a transistor formed on the first fin structure. The circuit device also includes a fill dielectric disposed on the strain feature within the isolation feature trench. In some such embodiments, the strain feature is further disposed on a vertical surface of the first fin structure and on a vertical surface of the second fin structure.