Inertial sensor and method of manufacturing the same

• US 8,429,969 B2
• Filed: 04/17/2009
• Issued: 04/30/2013
• Est. Priority Date: 04/17/2009
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamanaka, Kiyoko, Jeong, Heewon, Hattori, Takashi, Goto, Yasushi
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/867,472
• Publication Number:
  US 20110048129A1
• Time in Patent Office: 1,474 Days
• Field of Search: 734/93, 735/041.2, 735/040.4, 735/041.4, 735/041.6, 735/041.3, 735/143.2, 735/142.9, 734/97, 735/10, 735/11
• US Class Current: 73/493
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• 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 1/00293 maintaining a controlled atmosphere with processes not provided for in B81C1/00285
• CPC Class Codes: G01C 19/5733 Structural details or topology
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

An inertial sensor capable of making pressure of a space in which an inertial sensor such as an acceleration sensor is placed to be higher than that during a sealing step and improving reliability is provided. The inertial sensor can be achieved by means of making an inertial sensor including a substrate, a movable portion on the substrate, a cap member which seals the movable portion so as to cover the movable portion, wherein a gas-generating material is applied to the movable portion side of the cap.

Claims

1. An inertial sensor comprising:

a substrate;

a movable portion formed on the substrate; and

a cap member which seals the movable portion so as to cover the movable portion, wherein a gas-generating material is applied to a movable portion side of the cap member,

wherein a pressure of a space covering the movable portion and including the gas-generating material provided therein is higher than that in a case of not providing the gas-generating material.

2. The inertial sensor according to claim 1, wherein,

by heating the gas-generating material, the space in which the movable portion can be moved has a pressure higher than the air pressure.

3. The inertial sensor according to claim 2, wherein

the pressure inside the space is lower than or equal to 5.1 atm.

4. The inertial sensor according to claim 1, wherein

the gas-generating material is a tertiary-butoxycarbonyl-oxy carrier.

5. An inertial sensor in which an angular rate sensor and an acceleration sensor are integrated, wherein

a movable portion of the angular rate sensor and a movable portion of the acceleration sensor are formed on a same substrate,

a cap member which seals each of the two movable portions so as to cover each of the two movable portions is formed,

a gas-generating material is applied only to a portion of the cap member corresponding to the acceleration sensor, and

a pressure of a first space covering the movable portion of the acceleration sensor is higher than a pressure of a second space covering the movable portion of the angular rate sensor.

6. The inertial sensor according to claim 5, wherein,

by heating the gas-generating material, a pressure of the first space in which the movable portion of the acceleration sensor can be moved is higher than that of the second space in which the movable portion of the angular rate sensor can be moved.

7. The inertial sensor according to claim 6, wherein

the pressure of the first space is higher than or equal to the air pressure and lower than or equal to 5.1 atm.

8. The inertial sensor according to claim 5, wherein

the gas-generating material is a tertiary-butoxycarbonyl-oxy carrier.

9. A method of manufacturing an inertial sensor comprising the steps of:

forming a movable portion on a substrate;

forming a concave portion to a cap that covers the movable portion;

applying a gas-generating material on the substrate;

bonding the cap onto the substrate; and

heating the gas-generating material,

wherein a pressure of a space covering the movable portion and including the gas-generating material provided therein is higher than that in a case of not providing the gas-generating material.

10. A method of manufacturing an inertial sensor comprising the steps of:

forming a first movable portion which measures an angular rate and a second movable portion which measures acceleration on a substrate;

forming concave portions corresponding to the first movable portion and the second movable portion to a cap, the cap covering the first movable portion and the second movable portion;

applying a gas-generating material to the second movable portion;

bonding the cap onto the substrate; and

heating the gas-generating material,

a pressure of a first space covering the second movable portion is higher than a pressure of a second space covering the first movable portion.

11. An inertial sensor in which two acceleration sensors being perpendicular to each other are integrated, wherein

each of a plurality of movable portions of the two acceleration sensors is formed on a same substrate;

a cap member which seals each of the movable portions of the two acceleration sensors so as to cover each of the two movable portions is formed;

a gas-generating material is applied only to a portion of the cap member corresponding to one of the two acceleration sensors; and

a pressure of a first space covering a first movable portion of one of the two acceleration sensors is higher than a pressure of a second space covering a second movable portion of the other one of the two acceleration sensors.

12. The inertial sensor according to claim 11, wherein,

by heating the gas-generating material, a pressure of the first space in which the first movable portion of the two acceleration sensors is movable is higher than a pressure of the second space in which the second movable portion of the two acceleration sensors is movable.

13. The inertial sensor according to claim 12, wherein

the pressure of the first space is higher than or equal to the air pressure and lower than or equal to 5.1 atm.

14. The inertial sensor according to claim 11, wherein

the gas-generating material is a tertiary-butoxycarbonyl-oxy carrier.