MEMS dual substrate switch with magnetic actuation
Systems and methods for forming a magnetostatic MEMS switch include forming a movable beam on a first substrate, forming the electrical contacts on a second substrate, and coupling the two substrates using a hermetic seal. A shunt bar on the movable plate may close the switch when lowered onto the contacts. The switch may generally be closed, with the shunt bar resting on the contacts. However, a magnetically permeable material may also be inlaid into the movable plate. The switch may then be opened by placing either a permanent magnet or an electromagnet in proximity to the switch.
1. A magnetic MEMS switch, comprising:
a movable plate formed on a first substrate, wherein the movable plate is coupled to the first substrate by a plurality of restoring springs;
at least two electrical contacts formed on a second substrate;
an electrically conductive shunt bar formed on the movable plate, dimensioned so as to span the two electrical contacts;
at least one permeable magnetic feature inlaid into at least one of the first and the second substrates, wherein the at least one permeable feature has a non-uniform cross section; and
a seal which couples the first substrate to the second substrate, and seals the MEMS switch, such that the MEMS switch operated by disposing a source of magnetic field gradient in a vicinity of the magnetic MEMS switch, wherein the gradient is sufficient to move the movable plate and open or close the switch.
2. The magnetic MEMS switch of claim 1 , further comprising:
a source of magnetic flux disposed adjacent to the magnetic MEMS switch, wherein the source of magnetic flux is configured to either open or close the two electrical contacts by attracting the permeable magnetic material toward the source of magnetic flux.
3. The magnetic MEMS switch of claim 2 , wherein the source of flux is disposed above the first substrate or below the second substrate, and comprises at least one of an electromagnet and a permanent magnet, and wherein the non uniform cress section has a smaller cross section nearer to the shunt bar.
4. The magnetic MEMS switch of claim 3 , wherein the non-uniform cross section has the shape of an ellipse in the plan view.
5. The magnetic MEMS switch of claim 3 , wherein the at least one permeable feature having non-uniform cross section comprises two permeable features having non-uniform cross section, wherein the shape of the permeable features is substantially elliptical over at least a portion of the two permeable features as seen in plan view, and wherein the minimum distance between the two permeable features is less than or equal to the maximum width of the elliptical shape, and wherein the minimum distance occurs below the shunt bar.
6. The magnetic MEMS switch of claim 1 , wherein the magnetic feature is at least one of a permanent magnetic material and a permeable magnetic material.
7. The magnetic MEMS switch of claim 1 , wherein the at least one magnetic feature are two magnetic fluxguides disposed laterally adjacent to and substantially symmetrically about a center of the movable plate on the first substrate.
8. The magnetic MEMS switch of claim 1 , wherein the movable plate is formed from the device layer of the silicon-on-insulator substrate, and affixed to the handle wafer of the silicon-on-insulator substrate by the oxide layer.
9. The magnetic MEMS switch of claim 1 , wherein the movable plate further comprises a shunt bar which electrically connects two electrical contacts formed on the second substrate when the magnetic MEMS switch is closed, wherein the shunt bar is electrically isolated from other portions of the movable plate.
10. The magnetic MEMS switch of claim 1 , further comprising:
a metal alloy which bonds the first substrate to the second substrate.