INDUCTOR-CAPACITOR RESONANT RF SWITCH

• US 20020171517A1
• Filed: 05/17/2001
• Published: 11/21/2002
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: Institute of Microelectronics
• Original Assignee: Institute of Microelectronics
• Inventors: Guo, Lihui, Xie, Joseph
• Granted Patent: US 6,472,962 B1
• Time in Patent Office: Days
• US Class Current: 333/262
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01P 1/127 Strip line switches
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A new inductor-capacitor resonance RF (LCR-RF) switching device is achieved. The device comprises a microelectronic mechanical switch and a spiral inductor. The microelectronic mechanical switch comprises, first, a first dielectric layer overlying a substrate. A down electrode overlies the first dielectric layer. A second dielectric layer overlies the down electrode. An up electrode overlies the down electrode with the second dielectric layer therebetween. A bridge post overlies the first dielectric layer and does not contact the down electrode or the up electrode. Multiple bridge posts may be used. Finally, a membrane is suspended over said down electrode. One end of the membrane is fixed to the top of the bridge post. An electrostatic potential between the membrane and the down electrode will cause the membrane to flex down toward the down electrode. This flexing of the membrane will cause the capacitance of the switching device to vary. The spiral inductor comprises a metal line configured in a spiraling pattern with a first end connected to the bridge post and a second end forming an output node. A dual damascene method to form the LCR-RF switch is also achieved.

Claims

1. A inductor-capacitor resonance RF switching device comprising:

a microelectronic mechanical switch comprising;

a first dielectric layer overlying substrate;

a down electrode overlying said first dielectric layer;

a second dielectric layer overlying said down electrode;

a bridge post overlying said first dielectric layer but not overlying said down electrode; and

a membrane suspended over said down electrode wherein one end of said membrane is fixed to the top of said bridge post, wherein an electrostatic potential between said membrane and said down electrode will cause said membrane to flex down toward said down electrode, and wherein said flexing of said membrane will cause the capacitance of said switching device to vary; and

a spiral inductor comprising a metal line configured in a spiraling pattern with a first end connected to said bridge post and a second end forming an output node.

2. The device according to claim 1 further comprising:

an input signal line connected to said down electrode; and

a ground reference connected to said output node to thereby form a shunt configuration.

3. The device according to claim 1 further comprising:

an input signal line connected to said down electrode; and

an output signal line connected to said output node to thereby form a series configuration.

4. The device according to claim 1 further comprising an up electrode wherein said up electrode overlies said down electrode with said second dielectric layer therebetween and wherein said flexing downward causes said membrane to contact said up electrode.

5. The device according to claim 1 wherein said membrane and said bridge post comprise metal.

6. The device according to claim 1 wherein said membrane has a thickness of between about 5,000 Angstroms and 25,000 Angstroms.

7. The device according to claim 1 wherein said membrane and said bridge post are formed by a dual damascene process.

8. The device according to claim 1 further comprising a second bridge post wherein said second bridge post is opposite said bridge post and wherein a second end of said membrane is fixed to the top of said second bridge post such that the combination of said bridge post, said second bridge post, and said membrane forms a bridge profile.

9. The device according to claim 1 wherein said capacitance value in DOWN state is between about 10 fF and 30 pF.

10. The device according to claim 1 wherein said spiral inductor value is between about 1 nH and 30 nH.

11. The device according to claim 1 wherein said capacitance and said spiral inductor create a resonant frequency in DOWN state of between about 1 GHz and 100 GHz.

13. The device according to claim 12 further comprising:

an input signal line connected to said down electrode; and

a ground reference connected to said output node to thereby form a shunt configuration.

14. The device according to claim 12 further comprising:

an input signal line connected to said down electrode; and

an output signal line connected to said output node to thereby form a series configuration.

15. The device according to claim 12 wherein said membrane and said bridge post comprise metal.

16. The device according to claim 12 wherein said membrane has a thickness of between about 5,000 Angstroms and 25,000 Angstroms.

17. The device according to claim 12 wherein said membrane and said bridge post are formed by a dual damascene process.

18. The device according to claim 12 further comprising a second bridge post wherein said second bridge post is opposite said bridge post and wherein a second end of said membrane is fixed to the top of said second bridge post such that the combination of said bridge post, said second bridge post, and said membrane forms a bridge profile.

19. The device according to claim 12 wherein said capacitance in DOWN state is between about 10 fF and 30 pF.

20. The device according to claim 12 wherein said spiral inductor value is between about 1 nH and 30 nH.

21. The device according to claim 12 wherein said capacitance and said spiral inductor create a resonant frequency in DOWN state of between about 1 GHz and 100 GHz.

12. A inductor-capacitor resonance RF switching device comprising:

a microelectronic mechanical switch comprising;

a first dielectric layer overlying a substrate;

a down electrode overlying said first dielectric layer;

a second dielectric layer overlying said down electrode;

an up electrode overlying said down electrode with said second dielectric layer therebetween;

a bridge post overlying said first dielectric layer but not overlying said down electrode and said up electrode; and

a membrane suspended over said up electrode wherein one end of said membrane is fixed to top of said bridge post, wherein an electrostatic potential between said membrane and said down electrode will cause said membrane to flex down toward said down electrode, wherein said flexing downward causes said membrane to contact said up electrode, and wherein said flexing of said membrane will cause the capacitance of said LCR-RF switching device to vary; and

a spiral inductor comprising a metal line configured in a spiraling pattern with a first end connected to said bridge post and a second end forming an output node.

22. A multiple channel, series-configured, switching circuit comprising a plurality of MEMS capacitor and spiral inductor pairs, wherein in each said pair, a first end of each said spiral inductor is connected to a bridge post of each said MEMS capacitor, wherein down electrodes of all said MEMS capacitors are connected to a single input signal, wherein a second end of each said spiral inductor forms a plurality of output signals, and wherein activation of any said MEMS capacitor in any said pair causes said input signal to flow to said output signal for said pair.

23. The circuit according to claim 22 wherein each said MEMS capacitor has an up electrode.

25. The method according to claim 24 wherein said first silicon dioxide layer is deposited to a thickness of between about 5,000 Angstroms and 45,000 Angstroms.

26. The method according to claim 24 wherein said silicon nitride layer is deposited to a thickness of between about 300 Angstroms and 2,000 Angstroms.

27. The method according to claim 24 wherein said polishing down is by a chemical mechanical polish.

28. The method according to claim 24 wherein said membrane has a thickness of between about 5,000 Angstroms and 25,000 Angstroms.

29. The method according to claim 24 wherein said step of patterning said second silicon dioxide layer, said silicon nitride layer, said first silicon dioxide layer, and said second dielectric layer to form deep trenches for planned bridge posts further comprises forming deep trenches for planned microstrip lines, wherein said step of depositing a metal layer further comprises filling said deep trenches for planned microstrip lines, and wherein said step of polishing down said metal layer further comprises completing said microstrip lines.

30. The method according to claim 24 wherein said step of patterning said second silicon dioxide layer, said silicon nitride layer, said first silicon dioxide layer, and said second dielectric layer to form deep trenches for planned bridge posts further comprises forming deep trenches for planned spiral inductors, wherein said step of depositing a metal layer further comprises filling said deep trenches for planned spiral inductors, and wherein said step of polishing down said metal layer further comprises completing said spiral inductors.

24. A method to form a microelectronic mechanical switch device in the manufacture of an integrated circuit device comprising:

providing a down electrode overlying a substrate with a first dielectric layer therebetween;

providing a second dielectric layer overlying said down electrode layer;

forming an up electrode overlying said second dielectric layer;

depositing a first silicon dioxide layer overlying said up electrode and said second dielectric layer;

depositing a silicon nitride layer overlying said first silicon oxide layer;

depositing a second silicon dioxide layer overlying said silicon nitride layer;

patterning said first silicon dioxide layer, said silicon nitride layer, said first silicon dioxide layer, and said second dielectric layer to form deep trenches for planned bridge posts;

patterning said second silicon dioxide layer and said silicon nitride layer to form shallow trenches for planned membrane wherein said second silicon dioxide layer and said silicon nitride layer are etched through to said first silicon dioxide layer and wherein said shallow trenches connect to said deep trenches;

depositing a metal layer overlying said second silicon dioxide layer, said silicon nitride layer, said first silicon dioxide layer, and said second dielectric layer to fill said deep trenches and said shallow trenches;

polishing down said metal layer to said second silicon dioxide layer to complete said bridge posts and said membrane; and

etching away said second silicon dioxide layer, said silicon nitride layer and said first silicon dioxide layer to release said membrane and to complete said microelectronic mechanical switch device in the manufacture of said integrated circuit device.