US 11,673,799 B2
Method of processing a wafer for manufacturing an oscillating structure such as a micro-mirror
Enri Duqi, Milan (IT); Nicolo′ Boni, Albino (IT); Lorenzo Baldo, Bareggio (IT); Massimiliano Merli, Pavia (IT); and Roberto Carminati, Piancogno (IT)
Assigned to STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed by STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on Jan. 22, 2021, as Appl. No. 17/155,429.
Claims priority of application No. 102020000001411 (IT), filed on Jan. 24, 2020.
Prior Publication US 2021/0229984 A1, Jul. 29, 2021
Int. Cl. B81C 1/00 (2006.01); H01L 41/35 (2013.01)
CPC B81C 1/00158 (2013.01) [H01L 41/35 (2013.01); B81C 2201/013 (2013.01)] 25 Claims
OG exemplary drawing
 
1. A method of processing a wafer having a first side and a second side opposite to one another to manufacture an oscillating structure, comprising:
a) forming first and second elastic torsional elements which are constrained to respective portions of a fixed supporting body and define an axis of rotation;
b) forming a mobile element interposed between, and connected to, said first and second elastic torsional elements, the mobile element being rotatable about the axis of rotation as a consequence of a torsion of the first and second elastic torsional elements;
c) processing the first side of said wafer at the mobile element to form a mechanical reinforcement structure for the mobile element, by:
c1) growing a reinforcement layer on the first side of the wafer; and
c2) patterning said reinforcement layer by removing selective portions of the reinforcement layer; and
d) processing the second side of said wafer, including carrying out, at the second side of the wafer, at least one of: chemical etching, deposition of metal material, and deposition of piezoelectric material;
wherein step d) is performed after performing step c).