Integrated rf MEMS, control systems and methods
An rf MEMS system has a semiconductor substrate, e.g., silicon. The system also has a control module provided overlying one or more first regions of the semiconductor substrate according to a specific embodiment. The system also has a base band module provided overlying one or more second regions of the semiconductor substrate and an rf module provided overlying one or more third regions of the semiconductor substrate. The system also has one or more MEMS devices integrally coupled to at least the rf module.
1. A method for fabricating an integrated rf-MEMS and control systems device, the method comprising:
providing a first semiconductor substrate having a first surface region;
forming a control module provided on a first CMOS integrated circuit device region overlying one or more first regions of the first surface region, the first CMOS integrated circuit device region having a first CMOS surface region;
forming a base band module provided on a second CMOS integrated circuit device region overlying one or more second regions of the first surface region, the second CMOS integrated circuit device region having a second CMOS surface region;
forming an rf module provided on a third CMOS integrated circuit device region overlying one or more third regions of the first surface region, the third CMOS integrated circuit device region having a third CMOS surface region;
forming a dielectric layer overlying the first CMOS surface region, the second CMOS surface region, and the third CMOS surface region; and
forming one or more free standing MEMS structures overlying the dielectric layer and being integrally coupled to at least the rf module;
wherein forming the one or more freestanding MEMS structures includes forming a transducer apparatus comprising;
forming a movable base structure having an outer surface region overlying the dielectric layer;
removing at least one portion from the movable base structure to form at least one inner surface region;
forming at least one intermediate anchor structure spatially disposed within a vicinity of the inner surface region, the at least one intermediate anchor structure being coupled to the dielectric layer; and
forming at least one intermediate spring structure coupled to at least one portion of the inner surface region, the intermediate spring structure being coupled to the intermediate anchor structure(s).
2. The method of claim 1 wherein the CMOS device layer is formed using a standing CMOS process from a semiconductor foundry.
3. The method of claim 1 further comprising forming an enclosure layer overlying the one or more freestanding MEMS structures, the enclosure layer having one or more openings to expose one or more portions of the one or more freestanding MEMS structures.
4. The method of claim 3 wherein the enclosure layer comprises a material selected from a group consisting of: a titanium material, the titanium material being activated as a getter layer.
5. The method of claim 3 wherein the enclosure layer is selected from a material selected from a group consisting of: a metal, a semiconductor material, an amorphous silicon material, a dielectric layer, and a combination of these layers.
6. The method of claim 3 further comprising
forming an encapsulating layer overlying the enclosure layer to substantially seal the one or more free standing MEMS structures to form a predetermined environment within the open region, wherein the predetermined environment comprises an inert gas at a determined pressure.
7. The method of claim 6 wherein the encapsulating layer comprises a material selected from a group consisting of: a metal layer, a spin on glass, a spray on glass, amorphous silicon, a dielectric layer, and any combination of these layers.
8. The method of claim 6 further comprising forming one or more bond pad openings to expose one or more bond pads coupled to the CMOS device layer.
9. The method of claim 1 wherein the one or more freestanding MEMS structures are selected form a group consisting of: a switch, a varactor configured to operate at an rf frequency, an inductor, a filter, a MEMS varactor coupled to a MEMS switch that is coupled of one or more MEMS filters, and a MEMS clock device operably coupled to the control module.
10. The method of claim 1 wherein the one or more freestanding MEMS structures are formed overlying the first CMOS surface region, the second CMOS surface region, and the third CMOS surface region.
11. The method of claim 10
wherein the control module comprises one or more CMOS devices;
the base band module comprises one or more CMOS devices; and
wherein the rf module comprises one or more CMOS devices.
12. The method of claim 1 wherein the one or more freestanding MEMS structures comprises a bank of MEMS filters, the bank of MEMS filters being configured to transmit one or more signals in a GSM format, a PCS format, and a DCS format.
13. The method of claim 1 wherein the integrated rf MEMS and control systems device is provided in a cellular phone apparatus; and wherein the integrated rf MEMS and control systems device is coupled to one or more power supplies.