Vertical MEMS gyroscope by horizontal driving and fabrication method thereof

• US 20040226369A1
• Filed: 12/24/2003
• Published: 11/18/2004
• Est. Priority Date: 12/24/2002
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Moon-chul, Kang, Seok-jin, Jung, Kyu-dong, Chung, Seok-whan, Hong, Seog-soo
• Granted Patent: US 6,952,965 B2
• Time in Patent Office: Days
• US Class Current: 73/504.02
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 3/0059 Constitution or structural means for controlling the movement not provided for in groups B81B3/0037 - B81B3/0056
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A vertical MEMS gyroscope by horizontal driving includes a substrate, a support layer fixed on an upper surface of an area of the substrate, a driving structure floating above the substrate and having a portion fixed to the upper surface of the support layer and another portion in parallel with the fixed portion, the driving structure having a predetermined area capable of vibrating in a predetermined direction parallel to the substrate, a detection structure fixed to the driving structure on a same plane as the driving structure, and having a predetermined area capable of vibrating in a vertical direction with respect to the substrate, a cap wafer bonded with the substrate positioned above the driving structure and the detection structure, and a fixed vertical displacement detection electrode formed at a predetermined location of an underside of the cap wafer, for detecting displacement of the detection structure in the vertical direction.

Claims

1. A vertical MEMS gyroscope by horizontal driving, comprising:

a substrate;

a support layer fixed on an upper surface of a particular area of the substrate;

a driving structure floating above the substrate and having a portion thereof fixed to the upper surface of the support layer and another portion in parallel with the fixed portion, the driving structure having a predetermined area capable of vibrating in a predetermined direction parallel to the substrate;

a detection structure fixed to the driving structure on a same plane as the driving structure, and having a predetermined area capable of vibrating in a vertical direction with respect to an upper surface of the substrate;

a cap wafer positioned above the driving structure and the detection structure, and bonded with the substrate; and

a fixed vertical displacement detection electrode formed at a predetermined location of an underside of the cap wafer, for detecting displacement of the detection structure in the vertical direction.

2. The vertical MEMS gyroscope by horizontal driving as claimed in claim 1, wherein the driving structure comprises:

a driving mass capable of vibrating in a predetermined direction parallel to the substrate;

a plurality of support beams each having one end fixed on the upper surface of the support layer and another end fixed on a side of the driving mass, for enabling the driving mass to move in a predetermined horizontal direction;

a driving electrode for driving the driving mass in the predetermined horizontal direction; and

a horizontal displacement detection electrode for measuring a displacement of the driving mass in a horizontal direction.

3. The vertical MEMS gyroscope by horizontal driving as claimed in claim 2, wherein the driving electrode has a comb structure including a fixed driving electrode fixed on the upper surface of the support layer and a motion driving electrode formed on a side of the driving mass.

4. The vertical MEMS gyroscope by horizontal driving as claimed in claim 2, wherein the horizontal displacement detection electrode has a comb structure including a fixed horizontal displacement detection electrode fixed on the upper surface of the support layer, and a motion horizontal displacement detection electrode formed on a side of the driving mass.

5. The vertical MEMS gyroscope by horizontal driving as claimed in claim 1, wherein the detection structure comprises:

a detection mass capable of vibrating in a vertical direction with respect to the substrate;

a plurality of support beams each having an end fixed on a side of the detection mass and another end fixed on a side of the driving mass, for enabling the detection mass to move in the vertical direction with respect to the substrate; and

a motion vertical displacement detection electrode for measuring a displacement of the detection mass in a vertical direction.

6. The vertical MEMS gyroscope by horizontal driving as claimed in claim 5, wherein the motion vertical displacement detection electrode comprises a comb-structured electrode which is formed on a side of the detection mass.

7. The vertical MEMS gyroscope by horizontal driving as claimed in claim 1, wherein the cap wafer has a vacuum space formed therein except an area for the fixed vertical displacement detection electrode, the vacuum space of the cap wafer being larger than the area for the fixed vertical displacement detection electrode so as to maintain a predetermined vacuum inside the substrate and the wafer.

8. The vertical MEMS gyroscope by horizontal driving as claimed in claim 1, further comprising a detection electrode anchor arranged on the upper surface of the support layer and electrically connected with the fixed vertical displacement detection electrode.

9. The vertical MEMS gyroscope by horizontal driving as claimed in claim 1, wherein the cap wafer includes a via hole formed therein, and the detection electrode anchor is electrically connected with an external electrode through the via hole.

10. A fabrication method for a vertical MEMS gyroscope by horizontal driving, comprising:

forming a structure wafer for forming a substrate, a support layer, a detection electrode anchor, a driving structure capable of vibrating in a predetermined direction parallel to the substrate, and a detection structure capable of vibrating in a vertical direction with respect to the substrate;

forming a cap wafer;

forming a fixed vertical displacement detection electrode at a predetermined location of an underside of the cap wafer for detecting displacement of the detection structure in the vertical direction with respect to the substrate;

anodic-bonding the structure wafer and the cap wafer together; and

forming an external electrode which is electrically connected with the fixed vertical displacement detection electrode.

11. The fabrication method as claimed in claim 10, wherein forming the structure wafer comprises:

forming a multi-layer in which a substrate, an insulation layer and a conductive layer are stacked on each other;

forming an etching hole in the conductive layer according to a structure mask; and

etching and removing the insulating layer except for an area for the support layer.

12. The fabrication method as claimed in claim 10, wherein forming the cap wafer comprises:

forming an electrode gap pattern corresponding to an electrode to measure a vertical displacement of the detection structure;

forming a pattern corresponding to an interior vacuum space of the substrate and the cap wafer; and

forming a via hole for connecting the detection electrode anchor and the external electrode.

13. The fabrication method as claimed in claim 10, wherein the anodic-bonding is performed in a vacuum chamber to vacuumize the interior of the substrate and the wafer.