Micro electro mechanical system

Patent metadata

Field	Value
Publication number	US-9500666-B2
Application number	US-201414190968-A
Country	US
Kind code	B2
Filing date	Feb 26, 2014
Priority date	Aug 18, 2008
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

In order to provide a technology capable of suppressing degradation of measurement accuracy due to fluctuation of detection sensitivity of an MEMS by suppressing fluctuation in natural frequency of the MEMS caused by a stress, first, fixed portions 3 a to 3 d are displaced outward in a y-direction of a semiconductor substrate 2 by deformation of the semiconductor substrate 2 . Since a movable body 5 is disposed in a state of floating above the semiconductor substrate 2 , it is not affected and displaced by the deformation of the semiconductor substrate 2 . Therefore, a tensile stress (+σ 1 ) occurs in the beam 4 a and a compressive stress (−σ 2 ) occurs in the beam 4 b . At this time, in terms of a spring system made by combining the beam 4 a and the beam 4 b , increase in spring constant due to the tensile stress acting on the beam 4 a and decrease in spring constant due to the compressive stress acting on the beam 4 b are offset against each other.

First claim

What is claimed is:

1. A micro electro mechanical system, comprising:
a sensor element, comprising:
a first spring system including a first fixed portion and a first elastically-deformable beam connected to the first fixed portion and extending therefrom in a first direction,
a second spring system including a second fixed portion and a second elastically-deformable beam connected to the second fixed portion and extending therefrom in a second direction opposite to the first direction,
a third spring system including a third fixed portion and a third elastically-deformable beam connected to the third fixed portion and extending therefrom in a third direction,
a fourth spring system including a fourth fixed portion and a fourth elastically-deformable beam connected to the fourth fixed portion and extending therefrom in a fourth direction opposite to the third direction, and
a movable body, movable in a moving direction, suspended from the first fixed portion via the first beam, suspended from the second fixed portion via the second beam, suspended from the third fixed portion via the third beam, and suspended from the fourth fixed portion via the fourth beam,
wherein the first and second spring systems are arranged on one side of a virtual line extending in the moving direction through a center of the sensor element, the third and fourth spring systems are arranged on the other side of the virtual line, and, when the movable body is displaced in the moving direction, tensile stresses are generated within the first, second, third and fourth spring systems at the same time.

2. The micro electro mechanical system according to claim 1 ,
wherein the first and the second fixed portions are the same, and
wherein the third and the fourth fixed portions are the same.

3. The micro electro mechanical system according to claim 1 ,
wherein the first beam suspends the movable body via a first turning portion,
wherein the second beam suspends the movable body via a second turning portion,
wherein the third beam suspends the movable body via a third turning portion, and
wherein the fourth beam suspends the movable body via a fourth turning portion.

4. The micro electro mechanical system according to claim 3 ,
wherein a distance between the first and the second fixed portions is smaller than a distance between the first and the second turning portions, and
wherein a distance between the third and the fourth fixed portions is smaller than a distance between the third and the fourth turning portions.

5. The micro electro mechanical system according to claim 1 ,
wherein the first beam is in alignment with the second beam, and
wherein the third beam is in alignment with the fourth beam.

6. The micro electro mechanical system according to claim 1 ,
wherein the first and the second spring systems are symmetric with respect to the virtual line, and
wherein the third and the fourth spring system are symmetric with respect to the virtual line.

7. The micro electro mechanical system according to claim 1 ,
wherein each of the first, second, third and fourth beams include a number of beams.

8. The micro electro mechanical system according to claim 7 ,
wherein the number of first beams is the same as the number of second beams, and
wherein the number of third beams is the same as the number of fourth beams.

9. The micro electro mechanical system according to claim 1 ,
wherein the first, second, third and fourth fixed portions, the first, second, third and fourth beams, and the movable body are arranged on a first semiconductor chip, and
wherein the first semiconductor chip is mounted on an underlayer substrate via an adhesive agent.

10. The micro electro mechanical system according to claim 9 ,
wherein the underlayer substrate is a second semiconductor chip on which an integrated circuit is formed.

11. The micro electro mechanical system according to claim 1 ,
wherein the sensor element is an angular velocity sensor.

12. The micro electro mechanical system according to claim 2 ,
wherein the first, second, third and fourth fixed portions are fixed to a semiconductor substrate that is deformable in a direction perpendicular to the moving direction, and
wherein the center of the sensor element is located at a stress inflection point along the direction perpendicular to the moving direction.

13. The micro electro mechanical system according to claim 12 ,
wherein the stress inflection point is a zero stress point.

14. The micro electro mechanical system according to claim 1 ,
wherein the first, second, third and fourth elastically-deformable beams are arranged perpendicular to the moving direction.

Assignees

• Hitachi Ltd
• Hitachi Ltd

Inventors

• Degawa Munenori
• Jeong Heewon

Classifications

• G01P15/125

  by capacitive pick-up · CPC title

• G01C19/5733 Primary

  Structural details or topology · CPC title

• G01P2015/0814

  for translational movement of the mass, e.g. shuttle type · CPC title

• G01P1/023

  for acceleration measuring devices · CPC title

• G01P15/0802

  Details · CPC title