A method for manufacturing an MEMS torsional electrostatic actuator comprises: providing a substrate, wherein the substrate comprises a first silicon layer, a buried oxide layer and a second silicon layer that are laminated sequentially; patterning the first silicon layer and exposing the buried oxide layer to form a rectangular upper electrode plate separated from a peripheral region, wherein the upper electrode plate and the peripheral region are connected by only using a cantilever beam, and forming, on the peripheral region, a recessed portion exposing the buried oxide layer; patterning the second silicon layer and exposing the buried oxide layer to form a back cavity, wherein the back cavity is located in a region of the second silicon layer corresponding to the upper electrode plate, covers 40% to 60% of the area of the region corresponding to the upper electrode plate, and is close to one end of the cantilever beam; exposing the second silicon layer, and suspending the upper electrode plate and the cantilever beam; and respectively forming an upper contact electrode and a lower contact electrode on the second silicon layer.

A method for manufacturing an MEMS torsional electrostatic actuator comprises: providing a substrate, wherein the substrate comprises a first silicon layer, a buried oxide layer and a second silicon layer that are laminated sequentially; patterning the first silicon layer and exposing the buried oxide layer to form a rectangular upper electrode plate separated from a peripheral region, wherein the upper electrode plate and the peripheral region are connected by only using a cantilever beam, and forming, on the peripheral region, a recessed portion exposing the buried oxide layer; patterning the second silicon layer and exposing the buried oxide layer to form a back cavity, wherein the back cavity is located in a region of the second silicon layer corresponding to the upper electrode plate, covers 40% to 60% of the area of the region corresponding to the upper electrode plate, and is close to one end of the cantilever beam; exposing the second silicon layer, and suspending the upper electrode plate and the cantilever beam; and respectively forming an upper contact electrode and a lower contact electrode on the second silicon layer.

A positioning method in a microprocessing process of bulk silicon comprises the steps of: fabricating, on a first surface of a first substrate (10), a first pattern (100), a stepper photo-etching machine alignment mark (200) for positioning the first pattern, and a double-sided photo-etching machine first alignment mark (300) for positioning the stepper photo-etching machine alignment mark; fabricating, on a second surface, opposite to the first surface, of the first substrate, a double-sided photo-etching machine second alignment mark (400) corresponding to the double-sided photo-etching machine first alignment mark; bonding a second substrate (20) on the first surface of the first substrate; performing thinning on a first surface of the second substrate; fabricating, on the first surface of the second substrate, a double-sided photo-etching machine third alignment mark (500) corresponding to the double-sided photo-etching machine second alignment mark; and finding, on the first surface of the second substrate by using the double-sided photo-etching machine third alignment mark, a corresponding position of the stepper photo-etching machine alignment mark.

At the first etching step of etching an SOI substrate from a first silicon layer side, a portion of a first structure formed of the first silicon layer is formed as a pre-structure having a larger shape than a final shape. At the mask formation step of forming a final mask on a second silicon layer side of the SOI substrate, a first mask corresponding to the final shape of the first structure is formed in the pre-structure. At the second etching step of etching the SOI substrate from the second silicon layer side, the second silicon layer and the pre-structure are, using the first mask, etched to form the final shape of the first structure.