Integrated circuit structures might include a semiconductor material, a first active area in the semiconductor material, a second active area in the semiconductor material, and an isolation structure comprising a dielectric material deposited in a trench formed in the semiconductor material between the first active area and the second active area. The isolation structure might further include a first edge portion extending below a surface of the semiconductor material to a first depth, a second edge portion extending below the surface of the semiconductor material to the first depth, and an interior portion between the first edge portion and the second edge portion, and extending below the surface of the semiconductor material to a second depth, less than the first depth.