A method includes: receiving a first substrate; forming a bonding layer on a second substrate; bonding the second substrate to the first substrate; forming a movable membrane on the second substrate, the forming including performing an etching operation to form a through via through a thickness of the second substrate; and forming a first anti-stiction structure on a surface of the movable membrane. The forming of the first anti-stiction structure is performed at a same time as at least one of the etching operation of the through via and the forming of the bonding layer.

A capacitive sensor that includes: a first substrate layer; and a device layer having a movable portion. The movable portion has a first main surface facing the first substrate layer and at least one first protrusion on the first main surface. The first protrusion has a first top portion having a curved surface in a central area of the first protrusion in a plan view of the device layer, and a first slope around the first top portion. The capacitive sensor is configured to detect a change in electrostatic capacity based on a distance between the first substrate layer and the movable portion.

A micro-electromechanical-system (MEMS) device may be formed to include an anti-stiction polysilicon layer on one or more moveable MEMS structures of a device wafer of the MEMS device to reduce, minimize, and/or eliminate stiction between the moveable MEMS structures and other components or structures of the MEMS device. The anti-stiction polysilicon layer may be formed such that a surface roughness of the anti-stiction polysilicon layer is greater than the surface roughness of a bonding polysilicon layer on the surfaces of the device wafer that are to be bonded to a circuitry wafer of the MEMS device. The higher surface roughness of the anti-stiction polysilicon layer may reduce the surface area of the bottom of the moveable MEMS structures, which may reduce the likelihood that the one or more moveable MEMS structures will become stuck to the other components or structures.