According to an exemplary embodiment, a bulk acoustic wave (BAW) resonator includes a piezoelectric layer situated between upper and lower electrodes, where each of the upper and lower electrodes are a high density metal. The BAW resonator further includes a controlled thickness region including a low density metal segment, where the low density metal segment is situated adjacent to the piezoelectric layer, and where the controlled thickness region has controlled electromechanical coupling. The controlled thickness region can provide reduced electromechanical coupling into lateral modes. The low density metal segment can extend along the perimeter of the BAW resonator.