Three-dimensional acceleration sensor and method for fabricating the same

• US 20070017289A1
• Filed: 07/18/2005
• Published: 01/25/2007
• Est. Priority Date: 07/18/2005
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Sakamoto, Akihiro
• Granted Patent: US 7,237,316 B2
• Time in Patent Office: Days
• US Class Current: 73/514.160
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 7/0012 Protection against reverse engineering, unauthorised use, use in unintended manner, wrong insertion or pin assignment
• CPC Class Codes: B81C 1/00595 Control etch selectivity
• CPC Class Codes: B81C 2201/0133 Wet etching
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: G01P 2015/0842 the mass being of clover leaf shape
• CPC Class Codes: H01S 4/00 Devices using stimulated emission of electromagnetic radiation in wave ranges other than those covered by groups H01S1/00, H01S3/00 or H01S5/00, e.g. phonon masers, X-ray lasers or gamma-ray lasers
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

According to the present invention, a method for fabricating a three-dimensional acceleration sensor, comprising: providing a semiconductor substrate having first and second surfaces; forming an insulating layer on the first surface of the semiconductor substrate; forming an active layer on the insulating layer; forming a plurality of openings on the active layer at a first region, which is to be located above a movable mass with a predetermined space; selectively removing the insulating layer located under the first region in a wet-etching process through the plurality of openings; and selectively removing the active layer to form a groove separating the first region from a movable mass.

Claims

1. A method for fabricating a three-dimensional acceleration sensor, comprising:

providing a semiconductor substrate having first and second surfaces;

forming an insulating layer on the first surface of the semiconductor substrate;

forming an active layer on the insulating layer;

forming a plurality of openings on the active layer at a first region, which is to be located above a movable mass with a predetermined space;

selectively removing the insulating layer located under the first region in a wet-etching process through the plurality of openings; and

selectively removing the active layer to form a groove separating the first region from a movable mass.

2. A method for fabricating a three-dimensional acceleration sensor, according to claim 1, wherein

the first region is a stopper which restricts over-move of the movable mass.

3. A method for fabricating a three-dimensional acceleration sensor, according to claim 2, wherein

the movable mass is shaped to have corners, and

the stopper comprises a plurality of members arranged around the corners of the movable mass.

4. A method for fabricating a three-dimensional acceleration sensor, according to claim 1, wherein

the openings are shaped to be square.

5. A method for fabricating a three-dimensional acceleration sensor, according to claim 1, wherein

the step of selectively removing the active layer is carried out also to separate the movable mass from a stationary frame and to shape beams which are coupled between the movable mass and the stationary frame.

6. A method for fabricating a three-dimensional acceleration sensor, according to claim 1, further comprising:

before forming the plurality of openings, forming a detecting device to detect motion of the movable mass and output an electrical signal corresponding to a degree of the motion.

7. A method for fabricating a three-dimensional acceleration sensor, according to claim 1, further comprising:

providing a glass plate on the second surface of the semiconductor substrate.

8. A method for fabricating a three-dimensional acceleration sensor, according to claim 7, wherein

the step of providing a glass plate is carried out before forming the plurality of openings on the active layer.

9. A method for fabricating a three-dimensional acceleration sensor, according to claim 7, wherein

the step of forming a glass plate is carried out in an anodic bonding process.

10. A method for fabricating a three-dimensional acceleration sensor according to claim 7, wherein

the glass plate is of pyrex glass.

11. A method for fabricating a three-dimensional acceleration sensor according to claim 1, wherein

the insulating layer is partly remained within the groove so that the insulating layer comprises an extended region, which extends from the movable mass toward the first region.

13. A three-dimensional acceleration sensor, according to claim 1, wherein

the first region is a stopper which restricts over-move of the movable mass.

14. A three-dimensional acceleration sensor, according to claim 2, wherein

the movable mass is shaped to have corners, and

the stopper comprises a plurality of members arranged around the corners of the movable mass.

15. A three-dimensional acceleration sensor, according to claim 1, wherein

the openings are shaped to be square.

16. A three-dimensional acceleration sensor, according to claim 1, wherein

the active layer is removed also to separate the movable mass from a stationary frame and to shape beams which are coupled between the movable mass and the stationary frame.

17. A three-dimensional acceleration sensor, according to claim 1, further comprising:

a glass plate bonded onto the second surface of the semiconductor substrate.

18. A three-dimensional acceleration sensor, according to claim 17, wherein

the glass plate is provided before forming the plurality of openings on the active layer.

19. A three-dimensional acceleration sensor, according to claim 18, wherein

the glass plate is provided in an anodic bonding process.

20. A three-dimensional acceleration sensor, according to claim 17, wherein

the glass plate is of pyrex glass.

12. A three-dimensional acceleration sensor, comprising:

a semiconductor substrate having first and second surfaces;

an insulating layer, formed on the first surface of the semiconductor substrate; and

an active layer, formed on the insulating layer, wherein

the active layer comprises;

a plurality of openings thereon at a first region, which is located above a movable mass with a predetermined space; and

a groove separating the first region from the movable mass,

the insulating layer is removed from a region under the first region in a wet-etching process through the plurality of openings, and

the insulating layer is partly remained within the groove so that the insulating layer comprises an extended region, which extends from the movable mass toward the first region.

21. A method for fabricating a three-dimensional acceleration sensor, comprising:

providing a semiconductor substrate having first and second surfaces;

forming an insulating layer on the first surface of the semiconductor substrate;

forming an active layer on the insulating layer;

providing a glass plate on the second surface of the semiconductor substrate;

forming a plurality of openings on the active layer at a first region, which is to be located above a movable mass with a predetermined space;

selectively removing the insulating layer located under the first region in a wet-etching process through the plurality of openings; and

selectively removing the active layer to form a groove separating the first region from a movable mass.

22. A method for fabricating a three-dimensional acceleration sensor, according to claim 21, wherein

the step of forming a glass plate is carried out in an anodic bonding process.

23. A method for fabricating a three-dimensional acceleration sensor according to claim 21, wherein

the glass plate is of pyrex glass.

24. A method for fabricating a three-dimensional acceleration sensor, according to claim 21, wherein

the first region is a stopper which restricts over-move of the movable mass.

25. A method for fabricating a three-dimensional acceleration sensor, according to claim 24, wherein

the movable mass is shaped to have corners, and

the stopper comprises a plurality of members arranged around the corners of the movable mass.

26. A method for fabricating a three-dimensional acceleration sensor, according to claim 21, wherein

the openings are shaped to be square.

27. A method for fabricating a three-dimensional acceleration sensor, according to claim 21, wherein

the step of selectively removing the active layer is carried out also to separate the movable mass from a stationary frame and to shape beams which are coupled between the movable mass and the stationary frame.

28. A method for fabricating a three-dimensional acceleration sensor, according to claim 21, further comprising:

before forming the plurality of openings, forming a detecting device to detect motion of the movable mass and output an electrical signal corresponding to a degree of the motion.

29. A method for fabricating a three-dimensional acceleration sensor according to claim 21, wherein

the insulating layer is partly remained within the groove so that the insulating layer comprises an extended region, which extends from the movable mass toward the first region.