US 11,440,794 B2Granted

Process for manufacturing a microelectromechanical device with a mobile structure, in particular a micromirror

AssigneeSTMicroelectronics S.r.l.

InventorsSonia Costantini, Davide Assanelli, Aldo Luigi Bortolotti, Michele Vimercati, Igor Varisco

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Abstract

A bottom semiconductor region is formed to include a main sub-region, extending through a bottom dielectric region that coats a semiconductor wafer, and a secondary sub-region which coats the bottom dielectric region and surrounds the main sub-region. First and second top cavities are formed through the wafer, delimiting a fixed body and a patterned structure that includes a central portion which contacts the main sub-region, and deformable portions in contact with the bottom dielectric region. A bottom cavity is formed through the bottom semiconductor region, as far as the bottom dielectric region, the bottom cavity laterally delimiting a stiffening region including the main sub-region and leaving exposed parts of the bottom dielectric region that contact the deformable portions and parts of the bottom dielectric region that delimit the first and second top cavities. The parts left exposed by the bottom cavity are selectively removed.

Claims16

Dependent claims

A method for manufacturing a microelectromechanical device, comprising:

delimiting a first semiconductor wafer by a front surface and a rear surface;
coating the rear surface with a bottom dielectric region;
forming a first bottom window through the bottom dielectric region;
forming a bottom semiconductor region that includes a first main sub-region which extends through the first bottom window and contacts the first semiconductor wafer, and a secondary sub-region which coats the bottom dielectric region and laterally surrounds the first main sub-region;
selectively removing portions of the first semiconductor wafer, starting from the front surface so as to form a first top cavity and a second top cavity that extend as far as the bottom dielectric region and laterally delimit a fixed supporting body and a patterned structure, the patterned structure including a central portion which contacts the first main sub-region of the bottom semiconductor region and a number of deformable portions, interposed between the central portion and the fixed supporting body, in contact with the bottom dielectric region;
selectively removing portions of the bottom semiconductor region so as to form a bottom cavity that extends through the bottom semiconductor region as far as the bottom dielectric region, and laterally delimits a stiffening region including the first main sub-region of the bottom semiconductor region, the bottom cavity also extending laterally so as to expose parts of the bottom dielectric region that contact the deformable portions and parts of the bottom dielectric region that delimit the first and second top cavities;
and
selectively removing the parts of the bottom dielectric region left exposed by the bottom cavity, in such a way that the first and second top cavities and the bottom cavity form an overall cavity, suspended inside which is the patterned structure.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/565,803Filed 10 Sep 2019
Priority: IT 10201800000853312 Sep 2018
Published: US 2020/0079645 A112 Mar 2020
Granted: 13 Sep 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

B81C 1/00182
Comprising flexible or deformable structures: arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a…
B81B 7/008
Microstructural systems ; Auxiliary parts of microstructural devices or systems: mEMS characterised by an electronic circuit specially adapted for…
B81B 7/02
Microstructural systems ; Auxiliary parts of microstructural devices or systems: containing distinct electrical or optical devices of particular…
B81C 1/00666
Mechanical properties: treatments for controlling internal stress or strain in MEMS structures

Family

US 2020/0079645 A1Pre-grant publication · published 12 Mar 2020
US 11,440,794 B2This patent

From the US filing history. Foreign family members aren’t listed.

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