Micro-electro-mechanical system having movable element integrated into leadframe-based package

A MEMS may integrate movable MEMS parts, such as mechanical elements, flexible membranes, and sensors, with the low-cost device package, leaving the electronics and signal-processing parts in the integrated circuitry of the semiconductor chip. The package may be a leadframe-based plastic molded body having an opening through the thickness of the body. The movable part may be anchored in the body and extend at least partially across the opening. The chip may be flip-assembled to the leads to span across the foil, and may be separated from the foil by a gap. The leadframe may be a prefabricated piece part, or may be fabricated in a process flow with metal deposition on a sacrificial carrier and patterning of the metal layer. The resulting leadframe may be flat or may have an offset structure useful for stacked package-on-package devices.