Light modulator with integrated drive and control circuitry
View Patent ↗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.
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 −6 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 , 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 −6 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.