Variable capacitor and method of making the same

Abstract

A capacitor manufacturing method provides variable capacitors whose capacitances remain stable under the influence of temperature change. Such a variable capacitor includes a fixed electrode, a movable electrode film facing the fixed electrode, and an anchor portion that provides partial connection between the fixed electrode and the movable electrode film. For making this variable capacitor, a first electrode is formed to serve as the fixed electrode. Then, an anchor portion is formed on the fixed electrode, and a sacrifice film is formed to cover the fixed electrode but partially expose the anchor portion. A second electrode is formed on the sacrifice film to serve as the movable electrode film, bonded to the anchor portion. Finally, the sacrifice film is removed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a variable capacitor according to a first embodiment of the present invention.

FIG. 2 is a partially unillustrated plan view of the variable capacitor according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken in lines III-III in FIG. 1.

FIG. 4 is an enlarged partial sectional view taken in lines IV-IV in FIG. 1.

FIG. 5 shows different states of operation of the variable capacitor in FIG. 1.

FIG. 6 shows a method of making the variable capacitor in FIG. 1.

FIG. 7 is a sectional view of a first variation of the variable capacitor in FIG. 1.

FIG. 8 shows a method of making the variable capacitor in FIG. 7.

FIG. 9 is a sectional view of a second variation of the variable capacitor in FIG. 1.

FIG. 10 shows a method of making the variable capacitor in FIG. 9.

FIG. 11 is a sectional view of a third variation of the variable capacitor in FIG. 1.

FIG. 12 shows a method of making the variable capacitor in FIG. 11.

FIG. 13 is a sectional view of a fourth variation of the variable capacitor in FIG. 1.

FIG. 14 is a sectional view of a fifth variation of the variable capacitor in FIG. 1.

FIG. 15 is a sectional view of a sixth variation of the variable capacitor in FIG. 1.

FIG. 16 is a plan view of a variable capacitor according to a second embodiment of the present invention.

FIG. 17 is a partially unillustrated plan view of the variable capacitor according to the second embodiment of the present invention.

FIG. 18 is a sectional view taken in lines XVIII-XVIII in FIG. 16.

FIG. 19 is an enlarged partial sectional view taken in lines XIX-XIX in FIG. 16.

FIG. 20 shows different states of operation of the variable capacitor in FIG. 16.

FIG. 21 shows part of a method of making the variable capacitor in FIG. 16.

FIG. 22 shows steps continued from FIG. 21.

FIG. 23 is a sectional view of a first variation of the variable capacitor in FIG. 16.

FIG. 24 is a sectional view of a second variation of the variable capacitor in FIG. 16.

FIG. 25 is a sectional view of a third variation of the variable capacitor in FIG. 16.

FIG. 26 is a sectional view of a fourth variation of the variable capacitor in FIG. 16.

FIG. 27 is a sectional view of a fifth variation of the variable capacitor in FIG. 16.

FIG. 28 is a sectional view of a sixth variation of the variable capacitor in FIG. 16.

FIG. 29 is a sectional view of a seventh variation of the variable capacitor in FIG. 16.

FIG. 30 is a sectional view of an eighth variation of the variable capacitor in FIG. 16.

FIG. 31 is a sectional view of a ninth variation of the variable capacitor in FIG. 16.

FIG. 32 is a sectional view of a tenth variation of the variable capacitor in FIG. 16.

FIG. 33 is a sectional view of an eleventh variation of the variable capacitor in FIG. 16.

FIG. 34 is a sectional view of a twelfth variation of the variable capacitor in FIG. 16.

FIG. 35 is a sectional view of a thirteenth variation of the variable capacitor in FIG. 16.

FIG. 36 is a sectional view of a fourteenth variation of the variable capacitor in FIG. 16.

FIG. 37 is a sectional view of a fifteenth variation of the variable capacitor in FIG. 16.

FIG. 38 is a sectional view of a sixteenth variation of the variable capacitor in FIG. 16.

FIG. 39 is a sectional view of a seventeenth variation of the variable capacitor in FIG. 16.

FIG. 40 is a sectional view of an eighteenth variation of the variable capacitor in FIG. 16.

FIG. 41 is a sectional view of a nineteenth variation of the variable capacitor in FIG. 16.

FIG. 42 is a sectional view of a twentieth variation of the variable capacitor in FIG. 16.

FIG. 43 is a sectional view of a twenty-first variation of the variable capacitor in FIG. 16.

FIG. 44 is a sectional view of a twenty-second variation of the variable capacitor in FIG. 16.

FIG. 45 is a plan view of a variable capacitor according to a third embodiment of the present invention.

FIG. 46 is a partially unillustrated plan view of the variable capacitor according to the third embodiment of the present invention.

FIG. 47 is a sectional view taken in lines XLVII-XLVII in FIG. 45.

FIG. 48 is an enlarged partial sectional view taken in lines XLVIII-XLVIII in FIG. 45.

FIG. 49 shows different states of operation of the variable capacitor in FIG. 45.

FIG. 50 shows part of a method of making the variable capacitor in FIG. 45.

FIG. 51 is a sectional view of a first variation of the variable capacitor in FIG. 45.

FIG. 52 is a sectional view of a second variation of the variable capacitor in FIG. 45.

FIG. 53 shows sectional views of plugs having a cap.

FIG. 54 is a sectional view of a variable capacitor according to a fourth embodiment of the present invention.

FIG. 55 is an enlarged partial sectional view of the variable capacitor according to the fourth embodiment of the present invention.

FIG. 56 shows part of a method of making the variable capacitor in FIG. 54.

FIG. 57 is a sectional view of a first variation of the variable capacitor in FIG. 54.

FIG. 58 is a sectional view of a second variation of the variable capacitor in FIG. 54.

FIG. 59 is a sectional view of a variable capacitor according to a fifth embodiment of the present invention.

FIG. 60 is an enlarged partial sectional view of the variable capacitor according to the fifth embodiment of the present invention.

FIG. 61 shows part of a method of making the variable capacitor in FIG. 59.

FIG. 62 is a sectional view of a variation of the variable capacitor in FIG. 59.

FIG. 63 shows sectional views of plugs having a cap.

FIG. 64 is a plan view of a variable capacitor according to a sixth embodiment of the present invention.

FIG. 65 is a partially unillustrated plan view of the variable capacitor according to the sixth embodiment of the present invention.

FIG. 66 is a sectional view taken in lines LXVI-LXVI in FIG. 64.

FIG. 67 is an enlarged partial sectional view taken in lines LXVII-LXVII in FIG. 64.

FIG. 68 shows different states of operation of the variable capacitor in FIG. 64.

FIG. 69 shows part of a method of making the variable capacitor in FIG. 64.

FIG. 70 shows steps continued from FIG. 69.

FIG. 71 is a sectional view of a first variation of the variable capacitor in FIG. 64.

FIG. 72 is a sectional view of a second variation of the variable capacitor in FIG. 64.

FIG. 73 shows sectional views of plugs having a cap.

FIG. 74 is a sectional view of a variable capacitor according to a seventh embodiment of the present invention.

FIG. 75 is an enlarged partial sectional view of the variable capacitor according to the seventh embodiment of the present invention.

FIG. 76 shows part of a method of making the variable capacitor in FIG. 74.

FIG. 77 shows steps continued from FIG. 76.

FIG. 78 is a sectional view of a first variation of the variable capacitor in FIG. 74.

FIG. 79 is a sectional view of a second variation of the variable capacitor in FIG. 74.

FIG. 80 is a sectional view of a variable capacitor according to an eighth embodiment of the present invention.

FIG. 81 is an enlarged partial sectional view of the variable capacitor according to the eighth embodiment of the present invention.

FIG. 82 shows part of a method of making the variable capacitor in FIG. 80.

FIG. 83 shows steps continued from FIG. 82.

FIG. 84 is a sectional view of a variation of the variable capacitor in FIG. 80.

FIG. 85 shows sectional views of plugs having a cap.

FIG. 86 is a partial sectional view of a conventional variable capacitor.

FIG. 87 shows a state of the conventional variable capacitor in FIG. 86, where a movable electrode film is thermally expanded.

FIG. 88 shows another state of the conventional variable capacitor in FIG. 86, where a movable electrode film is thermally expanded.

Claims

1. A variable capacitor comprising: a fixed electrode;a movable electrode film facing the fixed electrode; andan anchor portion for providing a partial connection between the fixed electrode and the movable electrode film.

2. The variable capacitor according to claim 1, wherein the anchor portion penetrates at least one of the fixed electrode and the movable electrode film.

3. The variable capacitor according to claim 1, further comprising a dielectric film provided between the fixed electrode and the movable electrode film, wherein the dielectric film is held in contact with one of the fixed electrode and the movable electrode film.

4. The variable capacitor according to claim 3, wherein the dielectric film has a portion constituting at least part of the anchor portion.

5. The variable capacitor according to claim 3, wherein the movable electrode film has a portion that is pressable against the fixed electrode via the dielectric film.

6. The variable capacitor according to claim 3, wherein the movable electrode film has a portion pressed against the fixed electrode via the dielectric film.

7. The variable capacitor according to claim 1, wherein the movable electrode film has a portion curved toward the fixed electrode.

8. The variable capacitor according to claim 1, wherein the movable electrode film has a portion curved away from the fixed electrode.

9. A variable capacitor comprising: a first movable electrode film and a second movable electrode film facing each other; andan anchor portion for providing a partial connection between the first movable electrode film and the second movable electrode film.

10. The variable capacitor according to claim 9, wherein the anchor portion penetrates at least one of the first movable electrode film and the second movable electrode film.

11. The variable capacitor according to claim 9, further comprising a dielectric film provided between the first movable electrode film and the second movable electrode film, wherein the dielectric film is held in contact with one of the first movable electrode film and the second movable electrode film.

12. The variable capacitor according to claim 11, wherein the dielectric film has a portion constituting at least part of the anchor portion.

13. The variable capacitor according to claim 11, wherein the first movable electrode film and the second movable electrode film are pressable against each other via the dielectric film.

14. The variable capacitor according to one of claim 11, wherein the first movable electrode film and the second movable electrode film are partially pressable against each other via the dielectric film.

15. The variable capacitor according to claim 9, wherein the first movable electrode film has a portion curved toward the second movable electrode film.

16. The variable capacitor according to claim 9, wherein the first movable electrode film has a portion curved away from the second movable electrode film.

17. The variable capacitor according to claim 9, wherein the second movable electrode film has a portion curved toward the first movable electrode film.

18. The variable capacitor according to claim 9, wherein the second movable electrode film has a portion curved away from the first movable electrode film.

19. A method of making a variable capacitor, the method comprising the steps of: forming a first electrode on a substrate;forming an anchor portion on the first electrode;forming a sacrifice film which covers the first electrode and partially exposes the anchor portion;forming a second electrode on the sacrifice film to be bonded to the anchor portion; andremoving the sacrifice film.

20. A method of making a variable capacitor, the method comprising the steps of: forming a first electrode on a substrate, the first electrode being formed with an opening;forming an anchor portion including a part fitting into the opening and a part projecting beyond the first electrode;forming a sacrifice film which covers the first electrode and partially exposes the anchor portion;forming a second electrode on the sacrifice film to be bonded to the anchor portion; andremoving the sacrifice film.

21. A method of making a variable capacitor, the method comprising the steps of: forming a first electrode on a substrate;forming a sacrifice film covering the first electrode, the sacrifice film being formed with a first opening for partial exposure of the first electrode;forming a second electrode on the sacrifice film, the second electrode being formed with a second opening communicating with the first opening;forming an anchor portion on the first electrode to penetrate the sacrifice film and the second electrode by filling at least the first opening and the second opening with a material; andremoving the sacrifice film.

22. A method of making a variable capacitor, the method comprising the steps of: forming a first electrode on a substrate, the first electrode being formed with a first opening;forming a sacrifice film covering the first electrode, the sacrifice film being formed with a second opening communicating with the first opening;forming a second electrode on the sacrifice film, the second electrode being formed with a third opening communicating with the second opening;forming an anchor portion to penetrate the first electrode, the sacrifice film and the second electrode by filling at least the first opening, the second opening and the third opening with a material; andremoving the sacrifice film.