Passive display device having movable electrodes and method of manufacturing

A method of manufacturing a passive display device, wherein said device comprises first and second supporting plates with at least one of said plates being transparent, first and second fixed electrodes on facing surfaces of said first and second supporting plates, an electrically insulating layer on each of said first and second fixed electrodes, third electrodes movable between said first and second fixed electrodes by electrostatic forces, said third movable electrodes having a pattern of apertures, and a plurality of discrete engaging points provided between at least one surface of said third movable electrodes and said electrically insulating layer, said plurality of discrete engaging points separating said third movable electrodes from said electrically insulating layer, said method comprising the steps of

• providing a layer of a first material on a substrate,
• providing a layer of a second material on said layer of said first material,
• etching a pattern of apertures through said layer of said second material, and
• removing parts of said layer of said first material to form said plurality of discrete engaging points by undercutting through said pattern of apertures in said layer of said second material, wherein at least one of said first and second material has an inhomogeneous composition through the thickness of at least one of a respective layer, said inhomogeneous composition varying etching sensitivity over said thickness.