Three-dimensional micro-coils in planar substrates

• US 6,445,271 B1
• Filed: 06/29/1999
• Issued: 09/03/2002
• Est. Priority Date: 05/28/1999
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Johnson, Burgess R.
• Primary Examiner(s): Donovan, Lincoln
• Assistant Examiner(s): Nguyen, Tuyen T.
• Application Number:
  US09/342,087
• Time in Patent Office: 1,162 Days
• Field of Search: 336/200, 336/223, 336/232, 257/531
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core

Abstract

A three-dimensional micro-coil situated in a planar substrate. Two wafers have metal strips formed in them, and the wafers are bonded together. The metal strips are connected in such a fashion to form a coil and are encompassed within the wafers. Also, metal sheets are formed on the facing surfaces of the wafers to result in a capacitor. The coil may be a single or multi-turn configuration. It also may have a toroidal design with a core volume created by etching a trench in one of the wafers before the metal strips for the coil are formed on the wafer. The capacitor can be interconnected with the coil to form a resonant circuit. An external circuit for impedance measurement, among other things, and a processor may be connected to the micro-coil chip.

Claims

1. A micro-coil device comprising:

a first silicon wafer having a trench defining an inductive cavity, said trench having metal formed therein;

a second silicon wafer having at least one hole therein for providing a non metallic path for magnetic flux to exit said inductive cavity without passing through the solid part of either of said first or said second silicon wafer;

a first metal formed on said first wafer and having a first pad connected thereto; and

a second metal formed on said second wafer and having a second pad connected thereto; and

wherein;

said first and second wafers are proximate to each other; and

said first and second metals are connected at one end to form a first coil having at least one turn and the coil is formed around an inductive cavity, and are situated between said first and second wafers.

2. The device of claim 1, further comprising:

a third metal formed on said first wafer; and

a fourth metal formed on said second wafer; and

wherein said first and second metals are situated between said first and second wafers.

3. The device of claim 2, wherein said third and fourth metals are first and second electrodes of a capacitor.

4. A micro-coil device comprising:

a first silicon wafer having a first conductive metal strip and a first conductive plate formed thereon, said first wafer further having a trench defining an inductive cavity, said trench having metal formed therein;

a second silicon wafer having a second conductive metal strip and a second conductive plate formed thereon, said first and second conductive plates forming a capacitor, said second wafer further having at least one hole therein for providing a non metallic path for magnetic flux to exit said inductive cavity without passing through the solid part of either of said first or said second silicon wafer;

wherein;

said first and second wafers are proximate to each other so that the first and second conductive strips are connected to each other, said first and second strips forming a coil having at least one turn, said inductive cavity in said trench providing a core volume for said coil.

5. The device of claim 4, wherein the trench has first and second ends that are proximate to each other to provide a toroidal core volume for the coil.

6. The device of claim 5, further comprising:

a plurality of first conductive strips and a plurality of second conductive strips; and

wherein each of first and second conductive strips of the pluralities are interconnected so as to form a toroidal inductor.