Apparatus and method for anchoring micromachined structures

• US 7,134,340 B2
• Filed: 05/16/2005
• Issued: 11/14/2006
• Est. Priority Date: 07/19/2002
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Samuels, Howard R., Judy, Michael W.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US11/130,025
• Publication Number:
  US 20050262942A1
• Time in Patent Office: 547 Days
• Field of Search: 735/143.2, 735/040.2, 735/040.1, 735/041.2, 361/280
• US Class Current: 73/514.32
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 2203/055 Translation in a plane parallel to the substrate, i.e. enabling movement along any direction in the plane
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: G01P 15/0802 Details
• 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 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 2015/082 for two degrees of freedom of movement of a single mass
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 74/1293 Flexure hinges for gyros

Abstract

Micromachined structures, such as fixed drive or sensing fingers of an inertial sensor, are anchored to a substrate using multiple anchors or elongated anchors in order to reduce the bending or twisting of the micromachined structure about the anchor point.

Claims

1. A micromachined apparatus comprising:

a substrate; and

a succession of individual elongated fixed finger structures anchored to the substrate, wherein each pair of adjacent elongated fixed finger structures is interdigitated with at least one movable finger structure, and wherein each of the elongated fixed finger structures is anchored to the substrate using one of an elongated anchor and multiple anchors.

2. A micromachined apparatus according to claim 1, wherein the fixed finger structures are capacitively coupled with the at least one movable finger structure for sensing movement of the at least one movable finger structure.

3. A micromachined apparatus according to claim 1, wherein the fixed finger structures are capacitively coupled with the at least one movable finger structure for driving movement of the at least one movable finger structure.

4. A micromachined apparatus according to claim 1, wherein the apparatus is a micromachined inertial sensor.

5. A micromachined apparatus according to claim 4, wherein the apparatus is a micromachined accelerometer.

6. A micromachined apparatus according to claim 4, wherein the apparatus is a micromachined gyroscope.

7. A micromachined apparatus according to claim 4, wherein the inertial sensor includes a movable frame including the at least one movable finger structure, and wherein the elongated fixed finger structures are capacitively coupled with the at least one movable finger structure of the frame for sensing movement of the frame.

8. A method of reducing bending or twisting of elongated fixed finger structures, the method comprising:

forming a succession of individual elongated fixed finger structures such that each pair of adjacent elongated fixed finger structures is interdigitated with at least one movable finger structure; and

anchoring each of the elongated fixed finger structures to a substrate using at least one of an elongated anchor and multiple anchors, whereby bending or twisting of the elongated fixed finger structures about their respective anchor points is reduced by such anchoring.

9. A method according to claim 8, wherein the fixed finger structures are capacitively coupled with the at least one movable finger structure for sensing movement of the at least one movable finger structure.

10. A method according to claim 8, wherein the fixed finger structures are capacitively coupled with the at least one movable finger structure for driving movement of the at least one movable finger structure.

11. A method according to claim 8, wherein the apparatus is a micromachined inertial sensor.

12. A method according to claim 11, wherein the apparatus is a micromachined accelerometer.

13. A method according to claim 11, wherein the apparatus is a micromachined gyroscope.

14. A method according to claim 11, wherein the inertial sensor includes a movable frame including the at least one movable finger structure, and wherein the elongated fixed finger structures are capacitively coupled with the at least one movable finger structure of the frame for sensing movement of the frame.