PROCESS FOR MANUFACTURING AN OPTICAL MICROELECTROMECHANICAL DEVICE HAVING A TILTABLE STRUCTURE AND AN ANTIREFLECTIVE SURFACE

For manufacturing an optical microelectromechanical device (70), a first wafer (90) of semiconductor material having a first surface (100A) and a second surface (100B) is machined to form a suspended mirror structure (86), a fixed structure (74) surrounding the suspended mirror structure (86), elastic supporting elements (84A-84D) which extend between the fixed structure and the suspended mirror structure, and an actuation structure (83), coupled to the suspended mirror structure. A work wafer (10') is machined separately to form a second wafer (15) having a chamber (104) delimited by a bottom wall having a through opening (103). The second wafer is bonded to the first surface (100A) of the first wafer (90) in such a way that the chamber (104) overlies the actuation structure (83) and the through opening (103) is aligned to the suspended mirror structure (86). Furthermore, a third wafer (98) is bonded to the second surface (100B) of the first wafer to form a composite wafer device (112). The composite wafer device (112) is then diced to form an optical microelectromechanical device (70).