Micro-electromechanical system (MEMS) based current and magnetic field sensor having capacitive sense components

• US 7,901,970 B2
• Filed: 11/14/2007
• Issued: 03/08/2011
• Est. Priority Date: 06/07/2004
• Status: Active Grant

• Current Assignee: ABB SPA (ABB Limited)
• Original Assignee: General Electric Company
• Inventors: Meyer, Laura Jean, Claydon, Glenn Scott, Kapusta, Christopher James, Zribi, Anis, Tian, Wei-Cheng, Berkcan, Ertugal
• Primary Examiner(s): Pham; Thanh V.
• Assistant Examiner(s): FERNANDES, ERROL V
• Application Number:
  US11/939,589
• Publication Number:
  US 20080070338A1
• Time in Patent Office: 1,210 Days
• Field of Search: 257/424, 257/415, 361/277, 737/18, 737/24, 738/661, 737/15, 438/52, 438/50
• US Class Current: 438/52
• CPC Class Codes: G01R 15/148 involving the measuring of a magnetic field or electric field G01R15/18, G01R15/20, G01R15/24, G01R15/26 take precedence
• CPC Class Codes: G01R 33/0283 in which a current or voltage is generated due to relative movement of conductor and magnetic field
• CPC Class Codes: G01R 33/0286 comprising microelectromechanical systems [MEMS] MEMS devices in general B81B

Abstract

A micro-electromechanical system (MEMS) based current & magnetic field sensor includes a MEMS-based magnetic field sensing component having a capacitive magneto-MEMS component, a compensator and an output component for sensing magnetic fields and for providing, in response thereto, an indication of the current present in a respective conductor to be measured. In one embodiment, first and second mechanical sense components are electrically conductive and operate to sense a change in a capacitance between the mechanical sense components in response to a mechanical indicator from a magnetic-to-mechanical converter.

Claims

1. A method comprising:

providing a first substrate having a front side, and a back side;

forming a cavity through the back side of the first substrate to produce a membrane on the front side such that the cavity is defined by walls disposed within the first substrate at a fixed angle measured with respect to a plane containing the first substrate;

providing a second substrate with a raised portion having a width W; and

mating the first and second substrates by coupling the raised portion of the second substrate to the walls of the cavity of the first substrate such that the membrane and the raised portion of the second substrate are separated by a predetermined distance D.

2. The method according to claim 1, wherein said forming a cavity through the back side of the first substrate includes forming a cavity through the back side of the first substrate such that the angle of the cavity walls is determined by an anisotropic etching process.

3. The method of claim 1, further comprising forming at least one vent hole in the second substrate leading to the cavity.

4. The method of claim 1, wherein said providing a first substrate includes providing a first substrate having a first electrode, and wherein said providing a second substrate includes providing a second substrate with a raised portion having a second electrode thereon.

5. The method according to claim 4, further comprising:

determining the distance D from which the first and second substrates are to be separated; and

determining the corresponding width W for a raised portion of the second substrate such that when the second substrate is aligned with the first substrate the first and second electrodes are separated by the distance D.

6. The method according to claim 5, wherein said determining the corresponding width W includes determining the corresponding width W such that the distance D is at least an order of magnitude less than the width W.