MEMS sensor and a semiconductor package
First Claim
1. A MEMS sensor for measuring acceleration, said MEMS sensor comprising:
- a substrate;
an element frame;
a spring anchor;
a proof-mass; and
a spring,wherein the element frame and the spring anchor are rigidly fixed to the substrate,wherein one end of the spring is connected to the proof-mass and an opposite end of the spring is connected to the spring anchor,wherein in a non-flexed state of the spring, a spring axis extends between the opposite ends of the spring,wherein the proof-mass and the spring extend along a common plane, whereby the spring suspends the proof-mass to a rotary mode of motion in the common plane,wherein the element frame comprises a rectangular form such that in the common plane, an outer surface of the element frame has four sides, of which two longitudinal sides run in parallel in a longitudinal direction, and two transversal sides run in parallel in a transversal direction, wherein the transversal direction is perpendicular to the longitudinal direction,wherein the rectangular form of the element frame includes a first longitudinal side and a first transversal side, connected by a first vertex that is closest to the spring anchor, andwherein the spring axis forms an acute angle with the first longitudinal side and with the first transversal side, the spring is flexural and bends when subjected to forces in the in-plane direction perpendicular to the spring axis, and the spring is rigid when subjected to forces in any other direction, thereby causing an inherent sensitivity for measuring accelerations in a range covering accelerations in the longitudinal direction and in the transversal direction,and wherein the sensor further comprises one or more comb capacitors configured to measure the accelerations, wherein each comb capacitor includes a set of rotor comb fingers coupled to move with the proof-mass and a set of stator comb fingers rigidly fixed to the substrate.
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Accused Products
Abstract
The MEMS sensor of the invention has movable and fixed components for measuring acceleration in a rotational mode in a direction in-plane perpendicular to spring axis. The components include an element frame, a substrate, a proof-mass a spring connected to the proof-mass and to the substrate, and comb electrodes. The MEMS sensor is mainly characterized by an arrangement of the components causing an inherent sensitivity for measuring accelerations in a range covering longitudinal and transversal accelerations. One or more of the components are tilted compared to the element frame. The semiconductor package of the invention comprises at least one MEMS sensor.
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Citations
20 Claims
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1. A MEMS sensor for measuring acceleration, said MEMS sensor comprising:
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a substrate; an element frame; a spring anchor; a proof-mass; and a spring, wherein the element frame and the spring anchor are rigidly fixed to the substrate, wherein one end of the spring is connected to the proof-mass and an opposite end of the spring is connected to the spring anchor, wherein in a non-flexed state of the spring, a spring axis extends between the opposite ends of the spring, wherein the proof-mass and the spring extend along a common plane, whereby the spring suspends the proof-mass to a rotary mode of motion in the common plane, wherein the element frame comprises a rectangular form such that in the common plane, an outer surface of the element frame has four sides, of which two longitudinal sides run in parallel in a longitudinal direction, and two transversal sides run in parallel in a transversal direction, wherein the transversal direction is perpendicular to the longitudinal direction, wherein the rectangular form of the element frame includes a first longitudinal side and a first transversal side, connected by a first vertex that is closest to the spring anchor, and wherein the spring axis forms an acute angle with the first longitudinal side and with the first transversal side, the spring is flexural and bends when subjected to forces in the in-plane direction perpendicular to the spring axis, and the spring is rigid when subjected to forces in any other direction, thereby causing an inherent sensitivity for measuring accelerations in a range covering accelerations in the longitudinal direction and in the transversal direction, and wherein the sensor further comprises one or more comb capacitors configured to measure the accelerations, wherein each comb capacitor includes a set of rotor comb fingers coupled to move with the proof-mass and a set of stator comb fingers rigidly fixed to the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A semiconductor package comprising at least one MEMS sensor for measuring acceleration, said at least one MEMS sensor comprising:
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a substrate; an element frame; a spring anchor; a proof-mass; and a spring, wherein the element frame and the spring anchor are rigidly fixed to the substrate, wherein one end of the spring is connected to the proof-mass and an opposite end of the spring is connected to the spring anchor, wherein in a non-flexed state of the spring, a spring axis extends between the opposite ends of the spring, wherein the proof-mass and the spring extend along a common plane, whereby the spring suspends the proof-mass to a rotary mode of motion in the common plane, wherein the element frame comprises a rectangular form such that in the common plane, an outer surface of the element frame has four sides, of which two longitudinal sides run in parallel in a longitudinal direction, and two transversal sides run in parallel in a transversal direction, wherein the transversal direction is perpendicular to the longitudinal direction, wherein the rectangular form of the element frame includes a first longitudinal side and a first transversal side, connected by a first vertex that is closest to the spring anchor, and wherein the spring axis forms an acute angle with the first longitudinal side and with the first transversal side, the spring is flexural and bends when subjected to forces in the in-plane direction perpendicular to the spring axis, and the spring is rigid when subjected to forces in any other direction, thereby causing an inherent sensitivity for measuring accelerations in a range covering accelerations in the longitudinal direction and in the transversal direction, and wherein the sensor further comprises one or more comb capacitors configured to measure the accelerations, wherein each comb capacitor includes a set of rotor comb fingers coupled to move with the proof-mass and a set of stator comb fingers rigidly fixed to the substrate.
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20. A semiconductor package comprising at least one MEMS sensor for measuring acceleration, said at least one MEMS sensor comprising:
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a substrate; an element frame; a spring anchor; a proof-mass; and a spring, wherein the element frame and the spring anchor are rigidly fixed to the substrate, wherein one end of the spring is connected to the proof-mass and an opposite end of the spring is connected to the spring anchor, wherein in a non-flexed state of the spring, a spring axis extends between the opposite ends of the spring, wherein the proof-mass and the spring extend along a common plane, whereby the spring suspends the proof-mass to a rotary mode of motion in the common plane, wherein the element frame comprises a rectangular form such that in the common plane, an outer surface of the element frame has four sides, of which two longitudinal sides run in parallel in a longitudinal direction, and two transversal sides run in parallel in a transversal direction, wherein the transversal direction is perpendicular to the longitudinal direction, wherein the rectangular form of the element frame includes a first longitudinal side and a first transversal side, connected by a first vertex that is closest to the spring anchor, and wherein the spring axis forms an acute angle with the first longitudinal side and with the first transversal side, the spring is flexural and bends when subjected to forces in the in-plane direction perpendicular to the spring axis, and the spring is rigid when subjected to forces in any other direction, thereby causing an inherent sensitivity for measuring accelerations in a range covering accelerations in the longitudinal direction and in the transversal direction, wherein the semiconductor package is configured for airbag use, the semiconductor package comprising at least two MEMS sensors, with the MEMS sensors being configured as at least one mid-g MEMS accelerometer, and at least one low-g MEMS accelerometer or at least one MEMS gyroscope.
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Specification