Three-dimensional micro-coils in planar substrates

• US 6,498,557 B2
• Filed: 04/19/2001
• Issued: 12/24/2002
• Est. Priority Date: 05/28/1999
• Status: Expired due to Fees

• Current Assignee: 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:
  US09/838,629
• Publication Number:
  US 20020057173A1
• Time in Patent Office: 614 Days
• Field of Search: 336/65, 336/83, 336/183, 336/200, 336/208, 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 either 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;

wherein said first and second wafers are proximate to each other and connected at one end to form a first coil situated between said first and second wafers and having at least one turn, said coil being formed around an inductive cavity having a diameter that is equal to or less than a thickness of said first wafer;

said device including a third metal formed on said first wafer; and

a fourth metal formed on said second wafer;

wherein said third and fourth metals being first and second electrodes of a capacitor

said coil and capacitor being interconnected to form a resonant circuit;

said device further including a second coil situated between said first and second wafers wherein said second coil is inductively coupled to the first coil and one of said first and second coils is connected to an external circuit.

2. The device of claim 1, wherein said first coil is for exciting magnetic resonance of electrons or nuclei in a first magnetic field which is constant or slowly varying with time in comparison to a second magnetic field generated by said first coil.

3. The device of claim 2, wherein the external circuit is for measuring impedance of said first coil and said second coil is connected to said external circuit.

4. The device of claim 1, further including a processor connected to said external circuit.

5. The device of claim 4, wherein said external circuit and processor is formed on said wafer.

6. The device of claim 5, wherein said external circuit and said inductor form a magnetic resonance spectrometer circuit.

7. A micro-coil device comprising:

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

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

a first metal formed on said first wafer means and having first pad means for conducting current connected thereto; and

a second metal formed on said second wafer means and having second pad means for conducting current connected thereto;

wherein said first and second wafer means are proximate to each other and connected at one end to form a first coil means for carrying current and situated between said first and second wafer means and having at least one turn, said coil means being formed around an inductive cavity having a diameter that is equal to or less than a thickness of said first wafer means;

said device including a third metal formed on said first wafer means; and

a fourth metal formed on said second wafer means;

wherein said third and fourth metals being first and second electrodes of a capacitor means for resonant cooperation with said coil means, said coil and capacitor being interconnected to form a resonant circuit;

said device further including a second coil means for inductive coupling with said first coil means, said second coil means being situated between said first and second wafer means wherein said second coil means is inductively coupled to the first coil means and one of said first and second coil means is connected to an external circuit.

8. The device of claim 7, wherein said first coil means is for exciting magnetic resonance of electrons or nuclei in a first magnetic field which is constant or slowly varying with time in comparison to a second magnetic field generated by said first coil.

9. The device of claim 7, wherein the external circuit is for measuring impedance of said first coil and said second coil is connected to said external circuit.

10. The device of claim 7, further including a processor connected to said external circuit.

11. The device of claim 10, wherein said external circuit and processor is formed on said wafer.

12. The device of claim 11, wherein said external circuit and said inductor form a magnetic resonance spectrometer circuit.

13. In a magnetic resonance spectrometer device having a first and second coil forming a microresonator, and a permanent magnet associated with said microresonator, in which electron spin resonance is detected in low magnetic fields, the improvement comprising:

a first coil in said microresonator 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 either 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;

wherein said first and second wafers are proximate to each other and connected at one end to form a first coil situated between said first and second wafers and having at least one turn, said coil being formed around an inductive cavity having a diameter that is equal to or less than a thickness of said first wafer,

said device including a third metal formed on said first wafer, and a fourth metal formed on said second wafer;

wherein said third and fourth metals being first and second electrodes of a capacitor

said coil and capacitor being interconnected to form a resonant circuit;

said device further including a second coil situated between said first and second wafers wherein said second coil is inductively coupled to the first coil and one of said first and second coils is connected to an external circuit.

14. The device of claim 13, further including a processor connected to said external circuit, said processor being formed on said wafer.

15. The device of claim 13, wherein the external circuit is for measuring impedance of said first coil and said second coil is connected to said external circuit.