MEMS sensor and method for producing MEMS sensor, and MEMS package

• US 8,513,746 B2
• Filed: 10/14/2011
• Issued: 08/20/2013
• Est. Priority Date: 10/15/2010
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakatani, Goro, Fujita, Toma
• Primary Examiner(s): Lebentritt, Michael
• Application Number:
  US13/274,292
• Publication Number:
  US 20120139064A1
• Time in Patent Office: 676 Days
• Field of Search: 257415-419, 257/E21.219, 257/499, 257/29.329
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 1/00801 Avoid alteration of functional structures by etching, e.g. using a passivation layer or an etch stop layer B81C1/00595, B81C1/00468 take precedence
• CPC Class Codes: B81C 2201/053 Depositing a protective layers
• CPC Class Codes: G01C 19/5733 Structural details or topology
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate

Abstract

A capacitance type gyro sensor includes a semiconductor substrate, a first electrode integrally including a first base portion and first comb tooth portions and a second electrode integrally including a second base portion and second comb tooth portions, formed by processing the surface portion of the semiconductor substrate. The first electrode has first drive portions that extend from opposed portions opposed to the respective second comb tooth portions on the first base portion toward the respective second comb tooth portions. The second electrode has second drive portions formed on the tip end portions of the respective second comb tooth portions opposed to the respective first drive portions. The first drive portions and the second drive portions engage with each other at an interval like comb teeth.

Claims

1. A capacitance type gyro sensor comprising:

a semiconductor substrate having a cavity inside by forming an upper wall and a bottom wall, and having a surface portion forming the upper wall of the cavity and a back surface portion forming the bottom wall;

a first electrode formed by processing the surface portion of the semiconductor substrate, and integrally having a first base portion and first comb tooth portions extending from the first base portion and aligned at intervals like comb teeth; and

a second electrode formed by processing the surface portion of the semiconductor substrate, and integrally having a second base portion and second comb tooth portions extending from the second base portion toward the portions between the first comb tooth portions and aligned like comb teeth to engage with the first comb tooth portions at an interval, where

the first electrode or the second electrode are driven up and down with respect to the other electrode and an angular velocity applied at the time of this driving is detected by detecting a change in capacitance between the first comb tooth portion and the second comb tooth portion, wherein

the first electrode includes first drive portions extending from opposed portions opposed to the second comb tooth portions of the first base portion toward the second comb tooth portions, and electrically insulated from other portions of the first base portion,

the second electrode includes second drive portions formed on the tip end portions of the second comb tooth portions opposed to the first drive portions so as to be electrically insulated from other portions of the second comb tooth portions, and

the first drive portions and the second drive portions engage with each other at an interval like comb teeth.

2. The capacitance type gyro sensor according to claim 1, further comprising:

first insulating layers that are embedded in the first base portion so as to surround the opposed portions and insulate and separate the opposed portions from other portions of the first base portion.

3. The capacitance type gyro sensor according to claim 1, further comprising:

second insulating layers that are embedded in the base end portion sides relative to the tip end portions of the second comb tooth portions and insulate and separate the tip end portions from other portions of the second comb tooth portions.

4. The capacitance type gyro sensor according to claim 1, wherein the semiconductor substrate is a conductive silicon substrate.

5. A capacitance type gyro sensor comprising:

a semiconductor substrate having a cavity inside by forming an upper wall and a bottom wall, and having a surface portion forming the upper wall of the cavity and a back surface portion forming the bottom wall;

a first electrode formed by processing the surface portion of the semiconductor substrate, and integrally having a first base portion and first comb tooth portions extending from the first base portion and aligned at intervals like comb teeth;

a second electrode formed by processing the surface portion of the semiconductor substrate, and integrally having a second base portion and second comb tooth portions extending from the second base portion toward the portions between the first comb tooth portions and aligned like comb teeth to engage with the first comb tooth portions at an interval;

a first contact wiring that is formed on the surface portion of the semiconductor substrate and comes into direct contact with the first electrode from the surface side; and

a second contact wiring that is formed on the surface portion of the semiconductor substrate, and comes into direct contact with the second electrode from the surface side, wherein

the first electrode includes first drive portions extending from opposed portions opposed to the second comb tooth portions of the first base portion toward the second comb tooth portions,

the second electrode includes second drive portions formed on the tip end portions of the second comb tooth portions opposed to the first drive portions so as to be electrically insulated from other portions of the second comb tooth portions, and

the first drive portions and the second drive portions engage with each other at an interval like comb teeth.

6. The capacitance type gyro sensor according to claim 5, wherein the first drive portions are electrically insulated from other portions of the first base portion.

7. The capacitance type gyro sensor according to claim 6, further comprising:

first insulating layers that are embedded in the first base portion so as to surround the opposed portions and insulate and separate the opposed portions from other portions of the first base portion.

8. The capacitance type gyro sensor according to claim 5, further comprising:

second insulating layers that are embedded in the base end portion sides relative to the tip end portions of the second comb tooth portions and insulate and separate the tip end portions from other portions of the second comb tooth portions.

9. The capacitance type gyro sensor according to claim 8, wherein

the first contact wiring includes a first detection wiring that comes into contact with the first comb tooth portions,

the second contact wiring includes a second detection wiring that comes into contact with the base end portion sides relative to the second insulating layers of the second comb tooth portions, and

the first electrode or the second electrode is driven relative to the other electrode, and an angular velocity applied at the time of this driving is detected by detecting a change in capacitance between the first comb tooth portions and the second comb tooth portions.

10. A capacitance type acceleration sensor comprising:

a semiconductor substrate having a cavity inside by forming an upper wall and a bottom wall, and having a surface portion forming the upper wall of the cavity and a back surface portion forming the bottom wall; and

a first electrode and a second electrode that are formed by processing the surface portion of the semiconductor substrate and have comb-tooth-like shapes to engage with each other at an interval, where

acceleration applied when the first electrode or the second electrode moves up and down with respect to the other electrode is detected by detecting a change in capacitance between the first electrode and the second electrode, wherein

the first electrode includes dielectric layers that have a predetermined thickness from the surface or the back surface to a halfway point of the first electrode along the thickness direction orthogonal to the opposing direction of the second electrode and have a predetermined width along the opposing direction, and conductive layers consisting of remaining portions except for the dielectric layers.

11. The capacitance type acceleration sensor according to claim 10, wherein

the dielectric layers are one-sided to one end side in the width direction of the first electrode, and

the conductive layer includes a first portion formed adjacently on the other end side in the width direction to the dielectric layer, and a second portion formed below the dielectric layer and having a width larger than that of the first portion.

12. The capacitance type acceleration sensor according to claim 10, wherein

the dielectric layers are formed from one end to the other end in the width direction of the first electrode and have the same width as that of the first electrode, and

the first electrode has a lamination structure including the dielectric layers and the conductive layers formed below the dielectric layers.

13. The capacitance type acceleration sensor according to claim 10, wherein the first electrode is a movable electrode and the second electrode is a fixed electrode.

14. The capacitance type acceleration sensor according to claim 10, wherein the first electrode is a fixed electrode and the second electrode is a movable electrode.

15. The capacitance type acceleration sensor according to claim 10, wherein the semiconductor substrate is a conductive silicon substrate.

16. A MEMS sensor comprising:

a semiconductor substrate having a sensor region and a peripheral region surrounding the sensor region and having a cavity formed directly below a surface layer portion of the sensor region;

a comb-tooth-like fixed electrode and movable electrode that are formed by processing the surface layer portion of the sensor region and engage with each other at an interval; and

a protective layer made of a first inorganic material that has a peripheral edge portion bonded to the peripheral region of the semiconductor substrate and a central portion surrounded by the peripheral edge portion and covering the fixed electrode and the movable electrode while being spaced from the sensor region.

17. The MEMS sensor according to claim 16, wherein the peripheral region includes a pad region in which electrode pads electrically connected to the fixed electrode and the movable electrode are formed, and

openings for exposing the electrode pads are formed in the peripheral edge portion of the protective layer.

18. The MEMS sensor according to claim 16, wherein in the central portion of the protective layer, a through hole that makes communication between the inside and the outside of the protective layer is formed.

19. The MEMS sensor according to claim 16, further comprising:

first insulating layers that are selectively embedded in the fixed electrode and insulate and separate certain portions of the fixed electrode from other portions of the fixed electrode.

20. The MEMS sensor according to claim 16, further comprising:

second insulating layers that are selectively embedded in the movable electrode and insulate and separate certain portions of the movable electrode from other portions of the movable electrode.

21. The MEMS sensor according to claim 16, wherein the protective layer is made of SiO₂ or SiN.

22. The MEMS sensor according to claim 16, wherein the semiconductor substrate is a conductive silicon substrate.

23. The MEMS sensor according to claim 16, comprising:

an acceleration sensor that detects acceleration applied to the MEMS sensor by detecting a change in capacitance between the fixed electrode and the movable electrode.

24. The MEMS sensor according to claim 16, comprising:

an angular velocity sensor that drives the movable electrode in directions approaching and away from the cavity and detects an angular velocity applied to the MEMS sensor at the time of this driving by detecting a change in capacitance between the movable electrode and the fixed electrode.

25. A MEMS package comprising:

a MEMS sensor including;

a semiconductor substrate having a sensor region and a peripheral region surrounding the sensor region and having a cavity formed directly below a surface layer portion of the sensor region,

a comb-tooth-like fixed electrode and movable electrode that are formed by processing the surface layer portion of the sensor region and engage with each other at an interval, and

a protective layer made of a first inorganic material that has a peripheral edge portion bonded to the peripheral region of the semiconductor substrate and a central portion surrounded by the peripheral edge portion and covering the fixed electrode and the movable electrode while being spaced from the sensor region; and

a resin package formed to cover the MEMS sensor.

26. The MEMS package according to claim 25, further comprising:

an integrated circuit that is electrically connected to the MEMS sensor and covered together with the MEMS sensor by the same resin package.

27. The MEMS package according to claim 25, further comprising:

a substrate that has a surface and a back surface and supports the MEMS sensor by the surface, wherein

the resin package seals the MEMS sensor so as to cover the surface of the substrate and expose the back surface of the substrate.

28. A MEMS sensor comprising:

a semiconductor substrate; and

a polysilicon layer including;

a lower electrode selectively formed on the semiconductor substrate,

an electrode coating film made of an insulating material and formed on the semiconductor substrate so as to coat the lower electrode, and

an upper electrode formed at an interval above the electrode coating film and opposed to the lower electrode via the electrode coating film.

29. The MEMS sensor according to claim 28, wherein the upper electrode includes a comb-tooth-like fixed electrode and movable electrode that engage with each other at an interval.

30. The MEMS sensor according to claim 28, wherein the polysilicon layer further includes a contact electrode that penetrates through the electrode coating film and is in contact with the lower electrode.

31. The MEMS sensor according to claim 30, further comprising:

a wiring formed on the contact electrode.

32. The MEMS sensor according to claim 29, comprising:

an acceleration sensor that detects acceleration applied to the MEMS sensor by detecting a change in capacitance between the lower electrode and the movable electrode.

33. The MEMS sensor according to claim 29, comprising:

an angular velocity sensor that drives the movable electrode in directions approaching and away from the lower electrode, and detects an angular velocity applied to the MEMS sensor at the time of this driving by detecting a change in capacitance between the movable electrode and the fixed electrode.

34. The MEMS sensor according to claim 29, wherein the lower electrode is formed along a direction across the comb teeth of the movable electrode so as to be opposed to the entire comb-tooth-like movable electrode.

35. The MEMS sensor according to claim 28, wherein the electrode coating film is made of SiO₂.

36. The MEMS sensor according to claim 28, further comprising:

a protective thin film that is made of an insulating material and covers side walls of the upper electrode.

37. A MEMS package comprising:

a MEMS sensor including;

a semiconductor substrate,

a lower electrode selectively formed on the semiconductor substrate,

an electrode coating film made of an insulating material and formed on the semiconductor substrate so as to coat the lower electrode, and

a polysilicon layer having an upper electrode formed at an interval above the electrode coating film and opposed to the lower electrode via the electrode coating film; and

a resin package formed to cover the MEMS sensor.

38. The MEMS package according to claim 37, further comprising:

an integrated circuit electrically connected to the MEMS sensor and covered together with the MEMS sensor by the same resin package.

39. The MEMS package according to claim 37, further comprising:

a substrate that has a surface and a back surface and supports the MEMS sensor by the surface, wherein

the resin package seals the MEMS sensor so as to cover the surface of the substrate and expose the back surface of the substrate.

40. A MEMS sensor comprising:

a Si substrate having a surface layer portion on which a recess is formed; and

a comb-tooth-like first electrode and second electrode that are disposed directly above the recess of the Si substrate and have a lamination structure including a base film made of an insulating material and a polysilicon layer laminated in order from the side close to the recess, and engage with each other at an interval.

41. The MEMS sensor according to claim 40, further comprising:

first insulating layers that are embedded in the first electrode so as to penetrate through the polysilicon layer and reach the base film and selectively insulate certain portions of the first electrode from other portions of the polysilicon layer.

42. The MEMS sensor according to claim 40, further comprising:

second insulating layers that are embedded in the second electrode so as to penetrate through the polysilicon layer and reach the base film and selectively insulate certain portions of the second electrode from other portions of the polysilicon layer.

43. The MEMS sensor according to claim 40, wherein the first electrode is a movable electrode and the second electrode is a fixed electrode.

44. The MEMS sensor according to claim 40, wherein the first electrode is a fixed electrode and the second electrode is a movable electrode.

45. The MEMS sensor according to claim 40 comprising:

an acceleration sensor that detects acceleration applied to the MEMS sensor by detecting a change in capacitance between the first electrode and the second electrode.

46. The MEMS sensor according to claim 40 comprising:

an angular velocity sensor that drives the first electrode in directions approaching and away from the recess and detects an angular velocity applied to the MEMS sensor at the time of this driving by detecting a change in capacitance between the first electrode and the second electrode.

47. The MEMS sensor according to claim 40, wherein the base film is made of SiO₂.

48. The MEMS sensor according to claim 40, wherein the thickness of the base film is 2 μ

m to 5 μ

m.

49. The MEMS sensor according to claim 40, wherein the thickness of the polysilicon layer is 5 μ

m to 20 μ

m.

50. A MEMS package comprising:

a MEMS sensor including;

a Si substrate having a surface layer portion on which a recess is formed, and

a comb-tooth-like first electrode and second electrode that are disposed directly above the recess of the Si substrate and have a lamination structure including a base film made of an insulating material and a polysilicon layer laminated in order from the side close to the recess, and engage with each other at an interval; and

a resin package formed to cover the MEMS sensor.

51. The MEMS package according to claim 50, further comprising:

an integrated circuit electrically connected to the MEMS sensor and covered together with the MEMS sensor by the same resin package.

52. The MEMS package according to claim 50, further comprising:

a substrate that has a surface and a back surface and supports the MEMS sensor by the surface, wherein

the resin package seals the MEMS sensor so as to cover the surface of the substrate and expose the back surface of the substrate.