Micromachine switch and method of manufacture thereof

• US 6,657,324 B1
• Filed: 10/25/2001
• Issued: 12/02/2003
• Est. Priority Date: 04/27/1999
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Marumoto, Tsunehisa
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US09/959,449
• Time in Patent Office: 768 Days
• Field of Search: 333/101-108, 333/109, 333/112, 333/115, 333/116, 333/158-164, 333/262, 333/32, 200/181, 200/600, 307/112-124, 295/92--85, 257/415-421, 427/96, 430/311-319, 438/689-709, 216/11-19
• US Class Current: 307/125
• CPC Class Codes: H01G 5/40 Structural combinations of variable capacitors with other electric elements not covered by this subclass, the structure mainly consisting of a capacitor, e.g. RC combinations
• CPC Class Codes: H01H 1/20 Bridging contacts for circuit breakers H01H73/045
• CPC Class Codes: H01H 59/00 Electrostatic relays; Electro-adhesion relays
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01P 1/12 by mechanical chopper
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A micromachine switch for use in a millimeter wave circuit and a microwave circuit is simpler in structure than conventional micromachine switches. The micromachine switch has first and second high-frequency signal lines (1b, 1a), cantilever (11) fixed to an end of the first high-frequency signal line (1b) and extending to a position above second high-frequency signal line (1a), first insulating means (15) disposed on second high-frequency signal line (1a), second insulating means (14) disposed in an area where cantilever (11) and second high-frequency signal line (1a) confront each other, and first control signal line (2) connected between an end of second high-frequency signal line (1a) and first insulating means (15), for applying a control signal. When the control signal is applied to second high-frequency signal line (1a), cantilever (11) is attracted to second high-frequency signal line (1a), and connected to second high-frequency signal line (1a) via second insulating means (14) in a high-frequency fashion.

Claims

1. A micromachine switch disposed on a substrate to operate based on a control signal, comprising:

first and second high-frequency signal lines having their respective ends spaced from each other;

a cantilever fixed to the end of either said first or said second high-frequency signal line and extending to a position above the end of the other high-frequency signal line, said cantilever including an electrically conductive member;

first insulating means disposed on said first high-frequency signal line;

second insulating means disposed in an area where said cantilever and said other high-frequency signal line confront each other; and

a first control signal line connected between the end of said first high-frequency signal line and said first insulating means, for applying said control signal which is represented by DC voltage level variations.

2. A micromachine switch according to claim 1, wherein said first insulating means comprises a capacitor.

3. A micromachine switch according to claim 1, wherein said second insulating means comprises an insulating film disposed on at least one of a lower surface of said cantilever and an upper surface of said other high-frequency signal line.

4. A micromachine switch according to claim 1, further comprising:

first high-frequency signal blocking means connected to said first control signal line, for blocking the passage of a high-frequency signal flowing through said first and second high-frequency signal lines.

5. A micromachine switch according to claim 4, wherein said first high-frequency signal blocking means comprises:

a high-impedance line having an end connected between the end of said first high-frequency signal line on which said first insulating means is disposed and said first insulating means, and having a line length which is about ¼

of the wavelength of said high-frequency signal and a characteristic impedance larger than the characteristic impedance of said first or second high-frequency signal line; and

a low-impedance line having an end connected to the other end of said high-impedance line and an opposite end which is open, and having a line length which is about ¼

of the wavelength of said high-frequency signal and a characteristic impedance smaller than the characteristic impedance of said high-impedance line,

said first control signal line being connected to the other end of said high-impedance line.

6. A micromachine switch according to claim 4, wherein said first high-frequency signal blocking means comprises:

a high-impedance line having an end connected between the end of said first high-frequency signal line on which said first insulating means is disposed and said first insulating means, and having a line length which is about ¼

of the wavelength of said high-frequency signal and a characteristic impedance larger than the characteristic impedance of said first or second high-frequency signal line; and

a capacitor having an electrode connected to the other end of said high-impedance line and another electrode to ground,

said first control signal line being connected to the other end of said high-impedance line.

7. A micromachine switch according to claim 4, wherein said first high-frequency signal blocking means comprises an inductive element.

8. A micromachine switch according to claim 4, wherein said first high-frequency signal blocking means comprises a resistive element having an impedance sufficiently larger than the characteristic impedance of said first or second high-frequency signal line.

9. A micromachine switch according to claim 8, wherein said resistive element is inserted in series in said first control signal line.

10. A micromachine switch according to claim 8, wherein said resistive element has an end connected to said first control signal line and another end which is open.

11. A micromachine switch according to claim 4, further comprising:

a second control signal line connected to said second high-frequency signal line on which said first insulating means is not disposed, for charging and discharging electric charges generated by electrostatic induction; and

second high-frequency signal blocking means connected to said second control signal line, for blocking the passage of said high-frequency signal flowing through said first and second high-frequency signal lines.

12. A micromachine switch according to claim 11, wherein said second high-frequency signal blocking means comprises:

a high-impedance line having an end connected to said second high-frequency signal line on which said first insulating means is not disposed, and having a line length which is about ¼

of the wavelength of said high-frequency signal and a characteristic impedance larger than the characteristic impedance of said first or second high-frequency signal line; and

a low-impedance line having an end connected to the other end of said high-impedance line and an opposite end which is open, and having a line length which is about ¼

of the wavelength of said high-frequency signal and a characteristic impedance smaller than the characteristic impedance of said high-impedance line;

said second control signal line being connected to the other end of said high-impedance line.

13. A micromachine switch according to claim 11, wherein said second high-frequency signal blocking means comprises:

a high-impedance line having an end connected to said second high-frequency signal line on which said first insulating means is not disposed, and having a line length which is about ¼

of the wavelength of said high-frequency signal and a characteristic impedance larger than the characteristic impedance of said first or second high-frequency signal line; and

a capacitor having an electrode connected to the other end of said high-impedance line and another electrode to ground;

said second control signal line being connected to the other end of said high-impedance line.

14. A micromachine switch according to claim 11, wherein said second high-frequency signal blocking means comprises an inductive element.

15. A micromachine switch according to claim 11, wherein said second high-frequency signal blocking means comprises a resistive element having an impedance sufficiently larger than the characteristic impedance of said first or second high-frequency signal line.

16. A micromachine switch according to claim 15, wherein said resistive element is inserted in series in said second control signal line.

17. A micromachine switch according to claim 15, wherein said resistive element has an end connected to said second control signal line and another end which is open.

18. A micromachine switch according to claim 1, further comprising:

a first high-impedance line having an end connected between the end of said first high-frequency signal line on which said first insulating means is disposed and said first insulating means, and having a line length which is about ¼

of the wavelength of a first or second high-frequency signal and a characteristic impedance larger than the characteristic impedance of said first or second high-frequency signal line;

a second high-impedance line having an end connected to said second high-frequency signal line on which said first insulating means is not disposed, and having a line length which is about ¼

of the wavelength of said first or second high-frequency signal and a characteristic impedance larger than the characteristic impedance of said first or second high-frequency signal line; and

a capacitor having an electrode connected to the other end of said first high-impedance line and another electrode to the other end of said second high-impedance line;

the other end of said first high-impedance line being connected to ground.

19. A micromachine switch according to claim 4, further comprising:

third insulating means disposed on said second high-frequency signal line on which said first insulating means is not disposed;

a second control signal line connected between the end of said second high-frequency signal line on which said third insulating means is disposed and said third insulating means, for applying a constant voltage having a polarity opposite to said control signal; and

second high-frequency signal blocking means connected to said second control signal line, for blocking the passage of a high-frequency signal flowing through said first and second high-frequency signal lines;

the arrangement being such that a DC voltage between said second and third insulating means is kept at the level of said constant voltage.

20. A method of manufacturing a micromachine switch for use in a millimeter wave circuit and a microwave circuit, comprising the steps of:

forming, on a substrate, a first high-frequency signal line, a third high-frequency signal line having an end spaced from an end of said first high-frequency signal line, and a control signal line connected to said third high-frequency signal line;

forming a sacrificial layer in at least a region extending from a gap between said first and third high-frequency signal lines to the end of said third high-frequency signal line;

forming a first insulating film on a portion of said sacrificial layer which confronts the end of said third high-frequency signal line, and a second insulating film on the other end of third high-frequency signal line;

forming a cantilever of metal in a region extending from the end of said first high-frequency signal line to said first insulating film on said sacrificial layer, and a fourth high-frequency signal line extending from an upper surface of said second insulating film onto said substrate; and

removing said sacrificial layer.

21. A method of manufacturing a micromachine switch for use in a millimeter wave circuit and a microwave circuit, comprising the steps of:

forming, on a substrate, a fifth high-frequency signal line, a second high-frequency signal line having an end spaced from an end of said fifth high-frequency signal line, and a control signal line connected to said fifth high-frequency signal line;

forming a sacrificial layer in at least a region extending from a gap between said fifth and second high-frequency signal lines to the end of said second high-frequency signal line;

forming a first insulating film on a portion of said sacrificial layer which confronts the end of said second high-frequency signal line, and a second insulating film on the other end of fifth high-frequency signal line;

forming a cantilever of metal in a region extending from the end of said fifth high-frequency signal line to said first insulating film on said sacrificial layer, and a sixth high-frequency signal line extending from an upper surface of said second insulating film onto said substrate; and

removing said sacrificial layer.