Micro electro mechanical system

• US 7,851,876 B2
• Filed: 10/20/2006
• Issued: 12/14/2010
• Est. Priority Date: 10/20/2006
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Ramamoorthi, Sriram, Milligan, Donald J.
• Primary Examiner(s): Picardat; Kevin M
• Assistant Examiner(s): Au; Bac H
• Application Number:
  US11/584,057
• Publication Number:
  US 20080096301A1
• Time in Patent Office: 1,516 Days
• Field of Search: 438 50- 55, 257/254, 257414-420
• US Class Current: 257/419
• 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 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81C 1/00142 Bridges deformable micromirrors G02B26/0841
• CPC Class Codes: B81C 1/00253 Processes for integrating an electronic processing unit with a micromechanical structure not provided for in B81C1/0023 - B81C1/00246
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2203/058 Aligning components using methods not provided for in B81C2203/051 - B81C2203/052
• CPC Class Codes: B81C 3/004 Active alignment, i.e. moving the elements in response to the detected position of the elements using internal or external actuators

Abstract

Embodiments of a micro electro mechanical system are disclosed.

Claims

1. A micro-electro mechanical system (MEMS) accelerometer, comprising:

a first wafer comprising a first movable portion corresponding to an x-y accelerometer and a second movable portion corresponding to a z accelerometer, wherein each said movable portion comprises at least one flexure member and a proof mass, each of said proof mass and said flexure member being formed by the selective removal of material from a top side and a bottom side of said first wafer; and

a second wafer bonded to said first wafer;

wherein a thickness of said at least one flexure member of said first movable portion is independent of a thickness of said at least one flexure member of said second movable portion and a thickness of said proof mass of said first movable portion is independent of a thickness of said at least one proof mass of said second movable portion.

2. The MEMS accelerometer of claim 1, wherein said first wafer defines a cavity on said top surface, wherein said cavity is defined by subtracting a height of said proof mass from an original thickness of said first wafer.

3. The MEMS accelerometer of claim 2, further comprising connecting said cavity to an external package volume through a deep trench.

4. The MEMS accelerometer of claim 1, wherein said first wafer comprises a window configured to allow for optical alignment of said first wafer with said second wafer.

5. The MEMS accelerometer of claim 1, wherein said first wafer comprises a silicon on insulator (SOI) wafer.

6. The MEMS accelerometer of claim 5, wherein:

a height of said at least one flexure member is defined by a height of a top silicon layer of said SOI wafer; and

a height of said proof mass is defined by a height said top silicon and a height of a processed handle wafer.

7. A MEMS transducer device, comprising:

a first wafer comprising first and second movable portions, wherein each said movable portion comprises at least one electrode, at least one flexure member, and a proof mass, each of said proof mass and said flexure member being formed by the selective removal of material from a top side and a bottom side of said first wafer;

a second wafer bonded to said first wafer, said second wafer comprising at least one electrode corresponding to each said electrode in said first wafer; and

at least one circuit disposed at least partially within said second wafer and configured to detect lateral movement of said proof mass of said first movable portion; and

at least one circuit disposed at least partially within said second wafer and configured to detect medial movement of said proof mass of said second movable portion;

wherein a thickness of said proof mass of said first movable portion is independent of a thickness of said proof mass of said second movable portion, and a thickness of said at least one flexure member of said first movable portion is independent of a thickness of said at least one flexure member of said second movable portion.

8. The MEMS transducer of claim 7, further comprising:

at least one via coupled to said first wafer;

said at least one via providing a path for electrical signals traveling through said first wafer.