Stmicroelectronics S.r.l.

Massimiliano Merli

Roberto Carminati

Nicolo' Boni

Nicolo′ Boni

Enri Duqi

Domenico Giusti

Carlo Luigi Prelini

Lorenzo Baldo

Sebastiano Conti

Sonia Costantini

Laura Oggioni

Irene Martini

Marco Rossi

Lorenzo Vinciguerra

Gianluca Mendicino

Tarek Afifi Afifi

Nicolò Boni

Disclosed herein is a micro-electro-mechanical mirror device having a fixed structure defining an external frame delimiting a cavity, a tiltable structure extending into the cavity, a reflecting surface carried by the tiltable structure and having a main extension in a horizontal plane, and an actuation structure coupled between the tiltable structure and the fixed structure. The actuation structure is formed by a first pair of actuation arms causing rotation of the tiltable structure around a first axis parallel to the horizontal plane. The actuation arms are elastically coupled to the tiltable structure through elastic coupling elements and are each formed by a bearing structure and a piezoelectric structure. The bearing structure of each actuation arm is formed by a soft region of a first material and the elastic coupling elements are formed by a bearing layer of a second material, the second material having greater stiffness than the first material.

MEMS mirror device with piezoelectric actuation and manufacturing process thereof

A microelectromechanical-mirror device has a fixed structure defining an external frame delimiting a cavity, an internal frame arranged above the cavity and defining a window, and a tiltable structure with a reflective surface and arranged in the window. Elastically coupled to the internal frame by first and second coupling elastic elements. An actuation structure is coupled to the internal frame to cause the rotation of the tiltable structure around first and second axes. The actuation structure has a first pair of driving arms, elastically coupled to the internal frame and carrying piezoelectric material regions to cause rotation of the tiltable structure around the first axis, and a further pair of driving arms carrying piezoelectric material regions to cause rotation of the tiltable structure around the second axis and interposed between the fixed structure and the internal frame, to which they are elastically coupled by first and second suspension elastic elements.

Biaxial microelectromechanical mirror device with piezoelectric actuation

A microelectromechanical mirror device has, in a die of semiconductor material: a fixed structure defining a cavity; a tiltable structure carrying a reflecting region, elastically suspended above the cavity and having a main extension in a horizontal plane; at least one first pair of driving arms, carrying respective piezoelectric structures which can be biased to generate a driving force that causes rotation of the tiltable structure about a rotation axis parallel to a first horizontal axis of the horizontal plane; elastic suspension elements, which elastically couple the tiltable structure to the fixed structure at the rotation axis and are rigid to movements out of the horizontal plane and compliant to torsion about the rotation axis. In particular, the driving arms of the first pair are magnetically coupled to the tiltable structure to cause its rotation about the rotation axis by magnetic interaction, following biasing of the respective piezoelectric structures.

Microelectromechanical mirror device with piezoelectric actuation having improved stress resistance

A microelectromechanical mirror device includes a supporting frame of semiconductor material and a plate of semiconductor material. The plate is connected to the supporting frame so as to be orientable around at least one rotation axis. A reflective layer is arranged on a first region of the plate. A piezoelectric actuation structure extends on a second region of the plate adjacent to the reflective layer. The piezoelectric actuation structure is configured to apply forces such as to modify a curvature of the plate.

Microelectromechanical mirror device with compensation of planarity errors

A microelectromechanical mirror device includes a fixed structure defining a cavity, a tiltable structure elastically suspended above the cavity and carrying a reflecting surface, and having a main extension in a horizontal plane. A first pair of driving arms carry respective piezoelectric material regions that are biased to cause a rotation of the tiltable structure around a first rotation axis parallel to a first horizontal axis of the horizontal plane, and elastically coupled to the tiltable structure. Elastic suspension elements that couple the tiltable structure to the fixed structure at the first rotation axis are stiff with respect to movements out of the horizontal plane and yielding with respect to torsion around the first rotation axis, and further extend between the tiltable structure and the fixed structure. The elastic suspension elements have an asymmetrical arrangement on opposite sides of the tiltable structure along the first rotation axis.

Microelectromechanical mirror device with piezoelectric actuation and improved opening angle

A microelectromechanical mirror device has, in a die of semiconductor material: a fixed structure defining a cavity; a tiltable structure carrying a reflecting region elastically suspended above the cavity; at least a first pair of driving arms coupled to the tiltable structure and carrying respective piezoelectric material regions which may be biased to cause a rotation thereof around at least one rotation axis; elastic suspension elements coupling the tiltable structure elastically to the fixed structure and which are stiff with respect to movements out of the horizontal plane and yielding with respect to torsion; and a piezoresistive sensor configured to provide a detection signal indicative of the rotation of the tiltable structure. At least one test structure is integrated in the die to provide a calibration signal indicative of a sensitivity variation of the piezoresistive sensor in order to calibrate the detection signal.

Microelectromechanical mirror device with piezoelectric actuation and piezoresistive sensing having self-calibration properties

A microelectromechanical device includes a fixed structure having a frame defining a cavity, a tiltable structure elastically suspended above the cavity with main extension in a horizontal plane, a piezoelectrically driven actuation structure which can be biased to cause a desired rotation of the tiltable structure about a first and second rotation axes, and a supporting structure integral with the fixed structure and extending in the cavity starting from the frame. Lever elements are elastically coupled to the tiltable structure at a first end by elastic suspension elements and to the supporting structure at a second end by elastic connecting elements which define a lever rotation axis. The lever elements are elastically coupled to the actuation structure so that their biasing causes the desired rotation of the tiltable structure about the first and second rotation axes.

Microelectromechanical device having a structure tiltable by piezoelectric actuation about two rotation axes

A MEMS actuator includes a main body having a central portion, couplable to a substrate, and a peripheral portion suspended over the substrate when the central portion is coupled to the substrate. The peripheral portion has a deformable structure extending around the central portion, and forming successively arranged membranes. The MEMS actuator includes bearing structures and corresponding piezoelectric actuators. The bearing structures are fixed at their top to the deformable structure and laterally delimit corresponding cavities, each having a lateral opening facing the central portion of the main body and closed at the top by a membrane. A fixed part of the membrane is fixed to the underlying bearing structure and a suspended part is laterally offset with respect to the underlying bearing structure. The piezoelectric actuators are controllable to cause deformation of the corresponding membrane and rotation of the bearing structures around the central portion of the main body.

Angular piezoelectric actuator for a MEMS shutter and manufacturing method thereof

A MEMS micromirror device is formed in a package including a containment body and a lid transparent to a light radiation. The package forms a cavity housing a tiltable platform having a reflecting surface. A metastructure is formed on the lid and/or on the reflecting surface and includes a plurality of diffractive optical elements.

MEMS micromirror device enveloped in a package having a transparent surface and having a tiltable platform

A MEMS device is formed by a body of semiconductor material which defines a support structure. A pass-through cavity in the body is surrounded by the support structure. A movable structure is suspended in the pass-through cavity. An elastic structure extends in the pass-through cavity between the support structure and the movable structure. The elastic structure has a first and second portions and is subject, in use, to mechanical stress. The MEMS device is further formed by a metal region, which extends on the first portion of the elastic structure, and by a buried cavity in the elastic structure. The buried cavity extends between the first and the second portions of the elastic structure.

MEMS device having an improved stress distribution and manufacturing process thereof

This disclosure pertains to a microelectromechanical systems (MEMS) device with a tiltable structure, a fixed supporting structure, and an actuation structure with driving arms connected to the tiltable structure by elastic decoupling elements. Described herein, particularly, is a planar stop structure between the driving arms and the tiltable structure, which functions to limit movement in the tiltable plane. This stop structure includes a first projection/abutment surface pair formed by a projection extending from a driving arm and an abutment surface formed by a recess in the tiltable structure. The projection and abutment surface are adjacent and spaced apart in the device's rest condition.

Micro-electro-mechanical device with a shock-protected tiltable structure

Disclosed herein is a microelectromechanical device that features a fixed structure defining a cavity, a tiltable structure elastically suspended within the cavity, and a piezoelectrically driven actuation structure that rotates the tiltable structure about a first rotation axis. The actuation structure includes driving arms with piezoelectric material, elastically coupled to the tiltable structure by decoupling elastic elements that are stiff to out-of-plane movements but compliant to torsional movements. The tiltable structure is elastically coupled to the fixed structure at the first rotation axis using elastic suspension elements, while the fixed structure forms a frame surrounding the cavity with supporting elements. A lever mechanism is coupled between a supporting element and a driving arm.

Microelectromechanical device with a structure tiltable by piezoelectric actuation having improved mechanical and electrical characteristics

A microelectromechanical (MEMS) structure includes a fixed frame internally defining a cavity, and a mobile mass suspended in the cavity and movable with a first resonant rotational mode about a first rotation axis and with a second resonant rotational mode about a second rotation axis orthogonal to the first. A pair of supporting elements extends in the cavity, is rigidly coupled to the fixed frame, and is elastically deformable to cause rotation of the mobile mass about the first rotation axis. A pair of elastic-coupling elements is elastically coupled between the mobile mass and the first pair of supporting elements. Each of the elastic-coupling elements includes a first and second elastic portions, the first elastic portion being compliant to torsion about the second rotation axis. The second elastic portion is compliant to bending outside of a horizontal plane of main extension of the MEMS structure.

Biaxial resonant microelectromechanical mirror structure with piezoelectric actuation having improved characteristics

Disclosed herein is a method of making a microelectromechanical (MEMS) device. The method includes, in a single structural layer, affixing a tiltable structure to an anchorage portion with first and second supporting arms extending between the anchorage portion and opposite sides of the tiltable structure, and forming first and second resonant piezoelectric actuation structures extending between a constraint portion of the first supporting arm and the anchorage portion, on opposite sides of the first supporting arm. The method further includes coupling a handling wafer underneath the structural layer to define a cavity therebetween, and forming a passivation layer over the structural layer, the passivation layer having contact openings defined therein for routing metal regions for electrical coupling to respective electrical contact pads, the electrical contact pads being electrically connected to the first and second resonant piezoelectric actuation structures.

Resonant MEMS device having a tiltable, piezoelectrically controlled micromirror

To manufacture an oscillating structure, a wafer is processed by: forming torsional elastic elements; forming a mobile element connected to the torsional elastic elements; processing the first side of the wafer to form a mechanical reinforcement structure; and processing the second side of said wafer by steps of chemical etching, deposition of metal material, and/or deposition of piezoelectric material. Processing of the first side of the wafer is carried out prior to processing of the second side of the wafer so as not to damage possible sensitive structures formed on the first side of the wafer.

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Pavia, Italy

Massimiliano Merli