SENSOR AND ITS MANUFACTURING METHOD

• US 20160187370A1
• Filed: 08/26/2015
• Published: 06/30/2016
• Est. Priority Date: 12/26/2014
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: IKEHASHI, Tamio
• Granted Patent: US 9,921,238 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B81C 1/00166 Electrodes
• CPC Class Codes: G01L 19/0618 Overload protection
• CPC Class Codes: G01L 19/146 using flexible element between the transducer and the support
• CPC Class Codes: G01L 9/0048 Details about the mounting of the diaphragm to its support or about the diaphragm edges, e.g. notches, round shapes for stress relief
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• 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 2015/0865 using integrated signal processing circuitry

Abstract

According to one embodiment, a sensor is disclosed. The sensor includes a substrate, a first fixed electrode arranged on the substrate, a movable electrode arranged above the first fixed electrode and being movable non-parallely, a second fixed electrode arranged above the movable electrode. The sensor further includes a detector to detect a difference between a first capacitance between the first fixed electrode and the movable electrode and a second capacitance between the movable electrode and the second fixed electrode.

Claims

1. A sensor comprising:

a substrate;

a first fixed electrode arranged on the substrate;

a movable electrode arranged above the first fixed electrode and being movable non-parallely;

a second fixed electrode arranged above the movable electrode; and

a detector to detect a difference between a first capacitance between the first fixed electrode and the movable electrode and a second capacitance between the movable electrode and the second fixed electrode.

2. The sensor according to claim 1, wherein the second fixed electrode contains a through hole.

3. The sensor according to claim 2, further containing a first film provided on the second fixed electrode.

4. The sensor according to claim 3, wherein the first film faces the through hole of the second fixed electrode.

5. The sensor according to claim 3, further comprising a layer arranged above the second fixed electrode and containing a through hole, and wherein the first film is provided on the layer.

6. The sensor according to claim 5, wherein the first film faces the through hole of the layer.

7. The sensor according to claim 2, further comprising a second film provided on the first film, and wherein the second film attains lower gas permeability than the first film.

8. The sensor according to claim 7, wherein the second film includes a silicon nitride film.

9. The sensor according to claim 1, wherein a cavity is present between the first fixed electrode and the substrate.

10. The sensor according to claim 9, wherein the first fixed electrode contains a through hole connecting to the cavity.

11. The sensor according to claim 1, wherein the first fixed electrode, the movable electrode and the second fixed electrode are comb-shaped.

12. The sensor according to claim 1, wherein the movable electrode is movable in an upper or a lower direction in accordance with change of inertial force in a direction perpendicular to the substrate.

13. The sensor according to claim 12, further comprising an electrode movable in accordance with change of the inertial force in a direction horizontal to the substrate.

14. The sensor according to claim 12, further comprising an electrode movable in accordance with change of inertial force in a first direction horizontal to the substrate, and an electrode movable in accordance with change of inertial force in a second direction horizontal to the substrate and orthogonal to the first direction.

15. The sensor according to claim 13, wherein the electrode and the movable electrode are arranged in a same layer.

16. The sensor according to claim 1, further comprising a cap layer connected to an upper surface of the movable electrode, the cap layer and the substrate constituting a cavity in which the first fixed electrode, the movable electrode and the second fixed electrode are contained.

17. The sensor according to claim 16, wherein the cap layer is deformed in accordance with change in pressure of outside air, and the movable electrode is movable in an upper or a lower direction in accordance with the deformation of the cap layer.

18. A method for manufacturing a sensor comprising:

forming a first layer comprising a first fixed electrode by patterning the first conductive layer;

forming a first sacrificial film covering the first fixed electrode on a first layer;

forming a second conductive layer on the first sacrificial film;

forming a second layer comprising a movable electrode by patterning the second conductive layer;

forming a second sacrificial film covering the movable electrode;

forming a third conductive layer on the second sacrificial film;

forming a third layer comprising a second fixed electrode containing a through hole reaching the second sacrificial film by patterning the third conductive layer; and

removing the first and second sacrificial films through the through hole of the second fixed electrode.

19. The method according to claim 18, wherein the first to third conductive layers are comprised of a SiGe layer, and the first and second sacrificial films is comprised of a silicon oxide film.

20. The method according to claim 18, further comprising forming a first film on the second fixed electrode.

21. The method according to claim 18, further comprising:

forming a third sacrificial film covering the second fixed electrode and forming a fourth layer comprising a through hole reaching the third sacrificial film on the third sacrificial film, after forming the third layer comprising the second fixed electrode and before removing the first and second sacrificial films,

wherein the removal of the first and second sacrificial films through the through hole of the second fixed electrode further removes the third sacrificial film through the through hole of the fourth layer.

22. The method according to claim 21, further comprising forming a first film on the fourth layer.

23. The method according to claim 20, further comprising forming a second film on the first film.

24. The method according to claim 18, wherein the substrate comprises a detector to detect a difference between a first capacitance between the first fixed electrode and the movable electrode and a second capacitance between the movable electrode and the second fixed electrode.