Micro-electro-mechanical system (MEMS) variable capacitor apparatuses and related methods

• US 20040036132A1
• Filed: 06/13/2003
• Published: 02/26/2004
• Est. Priority Date: 06/13/2002
• Status: Active Grant

• Current Assignee: AAC Technologies Pte Limited (AAC Technologies Holdings Inc.)
• Original Assignee: Coventor, Inc. (Lam Research Corporation)
• Inventors: de los Santos, Hector J.
• Granted Patent: US 6,897,537 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping

Abstract

Micro-Electro-Mechanical System (MEMS) Variable Capacitor Apparatus and Related Methods. According to one embodiment, a MEMS variable capacitor is provided. The variable capacitor can include first and second electrodes being spaced apart, and at least one of the electrodes being movable when a voltage is applied across the first and second electrodes. The variable capacitor can also include a first conductive plate attached to and electrically isolated from the first electrode. Furthermore, the variable capacitor can include a second conductive plate attached to the second electrode and spaced from the first conductive plate for movement of at least one of the plates with respect to the other plate upon application of voltage across the first and second electrodes to change the capacitance between the first and second plates.

Claims

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

(a) first and second electrodes being spaced apart, and at least one of the electrodes being movable when a voltage is applied across the first and second electrodes;

(b) a first conductive plate attached to and electrically isolated from the first electrode; and

(c) a second conductive plate attached to the second electrode and spaced from the first conductive plate for movement of at least one of the plates with respect to the other plate upon application of voltage across the first and second electrodes to change the capacitance between the first and second plates.

2. The variable capacitor of claim 1, further including a non-conductive section disposed between the first conductive plate and the first electrode for electrically isolating the first conductive plate and the first electrode.

3. The variable capacitor of claim 1, further including a torsional beam for providing resistance to movement of the first and second electrodes with respect to one another.

4. The variable capacitor of claim 3, wherein the torsional beam comprises a material selected from the group consisting of silica, alumina, un-doped semiconductors, polymers, metals, semi-metals, doped semi-conductors, and combinations thereof.

5. The variable capacitor of claim 1, wherein the second conductive plate and the second electrode are electrically isolated.

6. The variable capacitor of claim 1, further including an adjustable voltage supply connected to the first and second electrodes for controlling the capacitance between the first and second conductive plates.

7. The variable capacitor of claim 1, further including a signal line connected to the first and second conductive plates for electrically connecting an AC signal.

8. The variable capacitor of claim 1, further including a substrate attached to the second conductive plate and the second electrode.

9. The variable capacitor of claim 8, wherein the substrate comprises a material selected from the group consisting of silicon, alumina, silica, polymers, and combinations thereof.

10. The variable capacitor of claim 1, further including a structural component pivotal with respect to the second conductive plate and the second electrode, wherein the first conductive plate and the first electrode are connected to the structural component for pivot with respect to the second conductive plate and the second electrode.

11. The variable capacitor of claim 10, wherein the structural component comprises a material selected from the group consisting of silica, alumina, un-doped semiconductors, polymers, and combinations thereof.

12. The variable capacitor of claim 10, wherein the first conductive plate and the first electrode are attached to opposing sides of the structural component.

13. The variable capacitor of claim 10, further including a torsional beam connecting the structural component to the second conductive plate and the second electrode, wherein the torsional beam provides resistance to movement of the first and second electrodes with respect to one another.

14. The variable capacitor of claim 1, wherein the first and second electrodes comprise a material selected from the group consisting of metal, semi-metal, doped semiconductor, and combinations thereof.

15. The variable capacitor of claim 1, wherein the first and second conductive plates comprise a material selected from the group consisting of metal, semi-metal, doped semiconductor, and combinations thereof.

16. A micro-electro-mechanical system (MEMS) variable capacitor, comprising:

(a) first and second electrodes being spaced apart, and at least one of the electrodes being movable when a voltage is applied across the first and second electrodes;

(b) a torsional beam for providing resistance to the rotation of the first and second electrodes with respect to one another;

(c) a first conductive plate having a non-conductive section for attachment to and electrical isolation from the first electrode; and

(d) a second conductive plate being attached to the second electrode and spaced from the first conductive plate for movement of the second conductive plate with respect to the first conductive plate and a change in the capacitance between the first and second conductive plates when voltage is applied across the first and second electrodes.

17. The variable capacitor of claim 16, further including a non-conductive section disposed between the first conductive plate and the first electrode for electrically isolating the first conductive plate and the first electrode.

18. The variable capacitor of claim 16, wherein the torsional beam comprises a material selected from the group consisting of silica, alumina, un-doped semiconductors, polymers, metals, semi-metals, doped semi-conductors, and combinations thereof.

19. The variable capacitor of claim 16, wherein the second conductive plate and the second electrode are electrically isolated.

20. The variable capacitor of claim 16, further including a substrate attached to the second conductive plate and the second electrode.

21. The variable capacitor of claim 16, further including a structural component pivotal with respect to the second conductive plate and the second electrode, wherein the first conductive plate and the first electrode are connected to the structural component for pivot with respect to the second conductive plate and the second electrode.

22. The variable capacitor of claim 21, wherein the structural component comprises a material selected from the group consisting of silica, alumina, un-doped semiconductors, polymers, and combinations thereof.

23. The variable capacitor of claim 21, wherein the first conductive plate and the first electrode are attached to opposing sides of the structural component.

24. The variable capacitor of claim 21, wherein the torsional beam is connected to the structural component.

25. A variable capacitor apparatus, comprising:

(a) a plurality of micro-electro-mechanical system (MEMS) variable capacitors, the MEMS variable capacitors comprising;

(i) first and second electrodes being spaced apart, and at least one of the electrodes being movable when a voltage is applied across the first and second electrodes;

(ii) a torsional beam for providing resistance to the rotational of the first and second electrodes with respect to one another;

(iii) a first conductive plate being attached to and electrically isolated from the first electrode; and

(iv) a second conductive plate being attached to the second electrode and spaced from the first conductive plate for movement of the second conductive plate with respect to the first conductive plate and a change in the capacitance between the first and second conductive plates when voltage is applied across the first and second electrodes;

(b) first conductive lines attached to the first and second electrodes of the variable capacitors for attachment to a voltage supply; and

(c) second conductive lines attached to the first and second conductive plates of the variable capacitors for attachment to an AC signal.

26. The variable capacitor apparatus of claim 25, wherein the torsional beam of each variable capacitor has a different torsional stiffness.

27. A method for varying the capacitance of two conductive plates, the method comprising:

(a) providing a micro-electro-mechanical system (MEMS) variable capacitor comprising;

(i) first and second electrodes being spaced apart, and at least one of the electrodes being movable when a voltage is applied across the first and second electrodes;

(ii) a first conductive plate attached to and electrically isolated from the first electrode; and

(iii) a second conductive plate attached to the second electrode and spaced from the first conductive plate for movement of at least one of the plates with respect to the other plate upon application of voltage across the first and second electrodes to change the capacitance between the first and second plates; and

(b) applying a voltage across the first and second electrodes.

28. The method of claim 27, further comprising the step of biasing at least one of the electrodes to provide resistance against the biased electrode with respect to movement toward the other electrode.

29. The method of claim 28, wherein the step of biasing at least one of the electrodes includes providing a torsional beam non-conductively connecting the first and second electrodes.

30. The method of claim 27, further including a structural component pivotal with respect to the second conductive plate and the second electrode, wherein the first conductive plate and the first electrode are connected to the structural component for pivot with respect to the second conductive plate and the second electrode.

31. The method of claim 30, wherein the first conductive plate and the first electrode are attached to opposing sides of the structural component.

32. The method of claim 31, wherein the variable capacitors further include a torsional beam connecting the structural component to the second conductive plate and the second electrode, wherein the torsional beam provides resistance to movement of the first and second electrodes with respect to one another.