Light modulator with integrated drive and control circuitry

• US 20060077531A1
• Filed: 11/23/2005
• Published: 04/13/2006
• Est. Priority Date: 03/22/2003
• Status: Active Grant

• Current Assignee: II-VI Incorporated
• Original Assignee: Active Optical Networks, Inc.
• Inventors: Novotny, Vlad, Sastri, Bharat, Reddy, Chitranjan N.
• Granted Patent: US 7,075,701 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 2203/0735 Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

Described are MEMS mirror arrays monolithically integrated with CMOS control electronics. The MEMS arrays include polysilicon or polysilicon-germanium components that are mechanically superior to metals used in other MEMS applications, but that require process temperatures not compatible with conventional CMOS technologies. CMOS circuits used with the polysilicon or polysilicon-germanium MEMS structures use interconnect materials that can withstand the high temperatures used during MEMS fabrication. These interconnect materials include doped polysilicon, polycides, and tungsten metal.

Claims

1. An integrated light modulator comprising:

a. a plurality of active circuit elements;

b. a first conductive layer, including a first plurality of conductive traces, patterned over and in electrical contact with the active circuit elements;

c. a first insulating layer formed over the first conductive layer;

d. a second conductive layer, including a second plurality of conductive traces, patterned over the first insulating layer and in electrical contact with the active circuit elements, wherein the second conductive layer has a resistivity of at least 5×

10<sup>−

6</sup> ohms-cm; and

e. a second insulating layer formed over the second conductive layer.

2. The light modulator of claim 1, further comprising a MEMS actuator disposed over the second insulating layer and in electrical contact with the active circuit elements via the first and second conductive layers.

3. The light modulator of claim 2, wherein further comprising a third conductive layer, including a third plurality of conductive traces, disposed between the second insulating layer and the MEMS actuator.

4. The light modulator of claim 2, wherein the MEMS actuator comprises a mirror.

5. The light modulator of claim 1, wherein the first and second conductive layer are predominately silicon.

6. The light modulator of claim 5, wherein the second conductive layer comprises at least one of Mo, W, Ti, and Co.

7. The light modulator of claim 1, wherein the second conductive layer comprises at least one of Mo, W, Ti, and Co.

8. The light modulator of claim 1, further comprising a MEMS actuator disposed over the second insulating layer and in electrical contact with the active circuit elements via the first and second conductive layers, wherein the MEMS actuator includes an array of mirrors, each mirror including a movable electrode.

9. The light modulator of claim 8, wherein the movable electrode exhibits a fracture strength of at least 1 GPa.

10. The light modulator of claim 9, wherein the movable electrode is predominantly silicon.

11. The light modulator of claim 9, wherein the movable electrode comprises germanium.

12. The light modulator of claim 1, wherein the resistivity of the second conductive layer is at least 30×

10<sup>−

6</sup> ohms-cm.

13. The light modulator of claim 1, further comprising a MEMS actuator disposed over the second insulating layer and in electrical contact with the active circuit elements via the first and second conductive layers, wherein the MEMS actuator includes a hinge.

14. The light modulator of claim 13, wherein the hinge exhibits a fracture strength of at least 1 GPa.

15. The light modulator of claim 14, wherein the hinge is predominantly silicon.

16. The light modulator of claim 1, wherein at least some of the active circuit elements make up a display engine, and wherein the display engine performs at least one of MPEG decompression, JPEG decompression, colorspace conversion, NTSC decoding, DTV decoding, and HDTV.

17. The light modulator of claim 1, wherein the active circuit elements are MOS circuit elements.

18. An integrated circuit comprising:

a. a plurality of active circuit elements;

b. a first conductive layer, including a first plurality of conductive traces, patterned over and in electrical contact with the active circuit elements;

c. a first insulating layer formed over the first conductive layer;

d. a second conductive layer, including a second plurality of conductive traces, patterned over the first insulating layer and in electrical contact with the active circuit elements;

e. a second insulating layer formed over the second conductive layer; and

f. a third conductive layer, including a third plurality of conductive traces, patterned over the second insulating layer and in electrical contact with the active circuit elements, the third conductive layer having a resistivity of at least 5×

10<sup>−

6</sup> ohms-cm.

19. The integrated circuit of claim 18, wherein at least two of the first, second, and third conductive layers are predominately silicon.

20. The integrated circuit of claim 18, wherein the third conductive layer includes at least one of Mo, W, Ti, and Co.

21. The integrated circuit of claim 18, further comprising a MEMS actuator disposed over the third conductive layer and in electrical contact with the active circuit elements via the third conductive layer.

22. The integrated circuit of claim 21, wherein the MEMS actuator comprises a mirror disposed over a mirror substrate.

23. The integrated circuit of claim 22, wherein the mirror substrate is of a substrate material exhibiting a fracture strength of at least 1 GPa.

24. The integrated circuit of claim 23, wherein the mirror substrate is predominantly silicon.

25. The integrated circuit of claim 18, wherein the resistivity of the third conductive layer is at least 30×

10<sup>−

6</sup> ohms-cm.

26. The integrated circuit of claim 18, wherein at least one of the first and second conductivity layers has a second resistivity greater than 5×

10<sup>−

6</sup> ohms-cm.

27. The integrated circuit of claim 26, wherein second resistivity is at least 30×

10<sup>−

6</sup> ohms-cm.