Three-axis accelerometer

• US 9,696,339 B2
• Filed: 05/28/2015
• Issued: 07/04/2017
• Est. Priority Date: 09/18/2014
• Status: Active Grant

• Current Assignee: Sagatek Co., Ltd.
• Original Assignee: Sagatek Co., Ltd.
• Inventors: Wen, Kuei-Ann, Chiang, Tai-Wei
• Primary Examiner(s): Bolduc, David
• Application Number:
  US14/724,417
• Publication Number:
  US 20160084873A1
• Time in Patent Office: 768 Days
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A three-axis accelerometer to provide measurement of acceleration in three axes, comprising a substrate, a suspending mass block suspended in the substrate, a group of Y direction displacement sensors, a group of Z direction displacement sensors and a group of X direction displacement sensors; wherein the Y direction displacement sensors, the Z direction displacement sensors and the X direction displacement sensors are respectively arranged adjacent to the mass block; the mass block and the displacement sensors respectively comprise a plurality of metal layers and a dielectric layer between two metal layers. In the mass block, regions corresponding to the Y, Z and X direction displacement sensors respectively comprise at least two metal layers connected by a via. The Y, Z and X groups displacement sensors respectively comprise at least two metal layers connected by a via.

Claims

1. A three-axis micro accelerometer, comprising a substrate, a suspending mass block suspended in the substrate, a group of Y direction displacement detection electrodes, a group of Z direction displacement detection electrodes and a group of X direction displacement detection electrodes;

the Y, Z and X direction displacement detection electrodes being arranged on the substrate adjacent to the mass block;

the Y and X directions being perpendicular in a plane of the mass block and the Z direction being perpendicular to the plane;

wherein;

the mass block and the Y, Z and X direction displacement detection electrodes respectively comprise a plurality of metal layers and a dielectric layer between two metal layers;

in the mass block, portions corresponding to the Y, Z and X direction displacement detection electrodes respectively comprise at least two metal layers connected by a via;

each of the Y, Z and X direction displacement detection electrodes comprises two sub-groups of electrodes, each comprising at least two metal layers connected by a via; and

the Y direction displacement detection electrodes and the Z direction displacement detection electrodes are provided in a first portion of a structure formed by the mass block and the detection electrodes and the X direction displacement detection electrodes is provided in a second portion of the structure other than the first portion.

2. The three-axis micro accelerometer as claimed in claim 1, wherein the via is filled with a metal material.

3. The three-axis micro accelerometer as claimed in claim 1, wherein in the mass block, the portion corresponding to the Y direction displacement detection electrodes and the portion corresponding to the Z direction displacement detection electrodes are in different planes.

4. The three-axis micro accelerometer as claimed in claim 1, wherein in the mass block, the portion corresponding to the Y direction displacement detection electrodes and the portion corresponding to the Z direction displacement detection electrodes are in the same plane and are electrically insulated from each other.

5. The three-axis micro accelerometer as claimed in claim 1, further comprising a detection circuit for calculating displacement of the mass blocking three directions of X, Y and Z, according to an output of the Y direction displacement detection electrodes, the Z direction displacement detection electrodes and/or the X direction displacement detection electrodes.

6. The three-axis micro accelerometer as claimed in claim 1, wherein the mass block, the Y direction displacement detection electrodes, the Z direction displacement detection electrodes and the X direction displacement detection electrodes are formed integrally in a structure which is formed by a plurality of metal layers and a plurality of dielectric layers staggered sequentially and the mass block is separated, at an interval of space, from the Y, Z and X direction displacement detection electrodes at a predetermined distance sufficient to generate detectable capacitance.

7. The three-axis micro accelerometer as claimed in claim 6, wherein the Y direction displacement detection electrodes, the Z direction displacement detection electrodes and the X direction displacement detection electrodes all form, at one side adjacent to the mass block, finger extensions extending in the X/Y plane;

and the mass block forms, at a side adjacent to the respective Y, Z and X direction displacement detection electrodes, finger extensions which extend in the X/Y plane and into recesses formed by the finger extensions of the respective Y, Z and X direction displacement detection electrodes.

8. The three-axis micro accelerometer as claimed in claim 7, wherein the Y direction displacement detection electrodes are located in first and second metal layers of the structure;

a first sub-group of electrodes of the Y direction detection electrodes includes a plurality of finger electrodes, and a second sub-group of electrodes thereof also comprises a plurality of finger electrodes, with finger electrodes of the two sub-groups being arranged in a staggered configuration, such that a finger electrode pair including a finger electrode of the first sub-group of electrodes and a finger electrode of the second sub-group of electrodes corresponds to one of finger extensions of the mass block.

9. The three-axis micro accelerometer as claimed in claim 7, wherein the three-axis micro accelerometer comprises two groups of Y direction displacement detection electrodes, each group of Y direction displacement detection electrodes comprising two sub-groups of electrodes, both located in a first and a second metal layers of the structure.

10. The three-axis micro accelerometer as claimed in claim 9, wherein the first and second metal layers of each sub-group of electrodes of the Y direction displacement detection electrodes are connected by a via.

11. The three-axis micro accelerometer as claimed in claim 7, wherein the Y direction displacement detection electrodes are located in first and second metal layers of the structure and the Z direction displacement detection electrodes are respectively located in the third and fourth metal layers and in the fifth and sixth metal layers of the structure;

and the third and fourth metal layers and the fifth and sixth metal layers are located at different heights in the Z direction.

12. The three-axis micro accelerometer as claimed in claim 11, wherein the three-axis micro accelerometer comprises two groups of Z direction displacement detection electrodes, each group of Z direction displacement detection electrodes comprising two sub-groups of electrodes respectively located in the third and fourth metal layers and in the fifth and sixth metal layers of the structure;

wherein the third and fourth metal layers are located above the fifth and sixth metal layers.

13. The three-axis micro accelerometer as claimed in claim 12, wherein the first and second metal layers and the third to sixth metal layers maintain a predetermined distance therebetween with at least one dielectric layer.

14. The three-axis micro accelerometer as claimed in claim 12, wherein the third and fourth metal layers of the Z direction displacement detection electrodes are connected by a via and the fifth and sixth metal layers thereof are also connected by a via.

15. The three-axis micro accelerometer as claimed in claim 14, wherein the first and second metal layers of the mass block are connected by a via and the fourth and fifth metal layers of the mass block are connected by a via.

16. The three-axis micro accelerometer as claimed in claim 1, wherein the three-axis micro accelerometer comprises two groups of X direction displacement detection electrodes, each group of X direction displacement detection electrodes being respectively located to two sides of the mass block in the X direction.

17. The three-axis micro accelerometer as claimed in claim 16, wherein the Y, Z and X direction displacement detection electrodes are respectively located to two sides of the mass block in the X direction.

18. The three-axis micro accelerometer as claimed in claim 16, wherein each group of the X direction displacement detection electrodes comprises a seventh and eighth metal layers of the structure connected by via.

19. The three-axis micro accelerometer as claimed in claim 1, wherein the Y, Z and X direction displacement detection electrodes are stacked in the structure.

20. The three-axis micro accelerometer as claimed in claim 1, wherein the Y and Z direction displacement detection electrodes are stacked in a first portion of the structure along the Z direction and the X direction displacement detection electrodes is provided in a second portion of the structure that is not stacked with the first portion.

21. The three-axis micro accelerometer as claimed in claim 1, wherein one or two metal layers of the X direction displacement detection electrodes are located at the same height with one or two metal layers of the Y direction displacement detection electrodes or the Z direction displacement detection electrodes in the X direction.

22. The three-axis micro accelerometer as claimed in claim 1, wherein the Y, Z and X direction displacement detection electrodes respectively provide contacts to be connected by an external detection circuit.