MEMS sensor with cap electrode

• US 8,100,012 B2
• Filed: 01/11/2008
• Issued: 01/24/2012
• Est. Priority Date: 01/11/2007
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Martin, John R., Zhang, Xin
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/013,208
• Publication Number:
  US 20080168838A1
• Time in Patent Office: 1,474 Days
• Field of Search: 735/143.2, 735/143.8, 735/143.6, 734/93, 734/31, 735/10, 735/11, 735/041.2
• US Class Current: 73/514.32
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 99/0045 End test of the packaged device
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A MEMS sensor includes a substrate having a MEMS structure movably attached to the substrate, a cap attached to the substrate and encapsulating the MEMS structure, and an electrode formed on the cap that senses movement of the MEMS structure.

Claims

1. A MEMS sensor comprising:

a substrate having a MEMS structure movably attached to the substrate;

a cap attached to the substrate, the cap encapsulating the MEMS structure;

an electrode formed on the cap that senses movement of the MEMS structure;

a reference electrode formed coplanar with the MEMS structure and non-movably attached to the substrate for increasing accuracy of movement measurements of the MEMS structure; and

a second electrode formed on the substrate beneath the MEMS structure.

2. The MEMS sensor of claim 1, wherein the substrate comprises an SOI wafer.

3. The MEMS sensor of claim 1, wherein the substrate comprises a silicon wafer.

4. The MEMS sensor of claim 1, wherein the electrode is formed from aluminum or an aluminum alloy.

5. The MEMS sensor of claim 1, wherein the electrode is formed from copper, a copper alloy, gold or a gold alloy.

6. The MEMS sensor of claim 1, wherein the cap includes a conductive seal ring formed from aluminum or an aluminum alloy.

7. The MEMS sensor of claim 1, wherein the MEMS sensor is an inertial sensor.

8. The MEMS sensor of claim 1, wherein the MEMS sensor is a pressure sensor, a fluid sensor, or a microphone.

9. The MEMS sensor of claim 1, wherein the substrate further includes electronic circuitry formed on or in the substrate.