Bistable microelectromechanical system based structures, systems and methods
View Patent ↗A bistable microelectromechanical system (MEMS) based system comprises a micromachined beam having a first stable state, in which the beam is substantially stress-free and has a specified non-linear shape, and a second stable state. The curved shape may comprises a simple curve or a compound curve. In embodiments, the boundary conditions for the beam are fixed boundary conditions, bearing boundary conditions, spring boundary conditions, or a combination thereof. The system may further comprise an actuator arranged to move the beam between the first and second stable states and a movable element that is moved between a first position and a second position in accordance with the movement of the beam between the first and second stable states. The actuator may comprise one of a thermal actuator, an electrostatic actuator, a piezoelectric actuator and a magnetic actuator. The actuator may further comprise a thermal impact actuator or a zippering electrostatic actuator.
1. A method for fabricating a bistable microelectromechanical system (MEMS) based system, comprising:
lithographically defining a plurality of beams comprising a lowest beam and a highest beam having a specified non-linear shape corresponding to a first stable state of the plurality of beams;
providing optical fibers between a position of the first stable state and a position of a second stable state and between the lowest beam and the highest beam;
providing a stop to contact at least one of the lowest beam and the highest beam before the at least one of the lowest beam and the highest beam reaches the position of the second stable state; and
providing a ridge on the stop to reduce stiction between the stop and the at least one of the lowest beam and the highest beam;
wherein the at least one of the lowest beam and the highest beam is biased against the stop.
2. The method of claim 1 , further comprising lithographically defining the plurality of beams to have a certain geometry.
3. The method of claim 2 , wherein lithographically defining the plurality of beams to have a certain geometry comprises lithographically defining the plurality of beams to have a certain height and a certain width, wherein the height is greater than the width.
4. The method of claim 1 , further comprising forming a stop that contacts the at least one of the lowest beam and the highest beam when the at least one of the lowest beam and the highest beam is between the first and second stable states and near the second stable state.
5. The method of claim 1 , further comprising determining a second stable state of the plurality of beams by lithographically defining the plurality of beams to have a certain geometry.
6. The method of claim 5 , wherein lithographically defining the plurality of beams to have a certain geometry comprises lithographically defining the plurality of beams to have at least one of a certain length, a certain width and a certain curvature.
7. The method of claim 6 , wherein lithographically defining the plurality of beams to have a certain geometry further comprises lithographically defining the plurality of beams to have a certain height.
8. The method of claim 1 , further comprising determining a throw distance of the plurality of beams between the first and second stable states by lithographically defining the plurality of beams to have a certain geometry.
9. The method of claim 8 , wherein lithographically defining the plurality of beams to have a certain geometry comprises lithographically defining the plurality of beams to have at least one of a certain length, a certain width and a certain curvature.
10. The method of claim 9 , wherein lithographically defining the plurality of beams to have a certain geometry further comprises lithographically defining the plurality of beams to have a certain height.
11. The method of claim 1 , further comprising determining a force curve of the plurality of beams between the first and second stable states by lithographically defining the plurality of beams to have a certain geometry.
12. The method of claim 11 , wherein lithographically defining the plurality of beams to have a certain geometry comprises lithographically defining the plurality of beams to have at least one of a certain length, a certain width and a certain curvature.
13. The method of claim 12 , wherein lithographically defining the plurality of beams to have a certain geometry further comprises lithographically defining the plurality of beams to have a certain height.
14. The method of claim 1 , further comprising forming at least one of a thermal actuator, an electrostatic actuator, a piezoelectric actuator and a magnetic actuator adjacent the plurality of beams.
15. The method of claim 14 , wherein forming at least one of a thermal actuator, an electrostatic actuator, a piezoelectric actuator and a magnetic actuator adjacent the plurality of beams comprises forming a thermal impact actuator.
16. The method of claim 14 , wherein forming at least one of a thermal actuator, an electrostatic actuator, a piezoelectric actuator and a magnetic actuator adjacent the plurality of beams comprises forming a zippering electrostatic actuator.
17. The method of claim 1 , further comprising forming at least one fixed boundary condition of at least one of the lowest beam and the highest beam.
18. The method of claim 1 , further comprising forming at least one bearing boundary condition of at least one of the lowest beam and the highest beam.
19. The method of claim 1 , further comprising forming at least one spring boundary condition of at least one of the lowest beam and the highest beam.
20. The method of claim 1 , wherein lithographically defining the plurality of beams comprises patterning the plurality of beams in a device layer of a silicon-on-insulator wafer.
21. The method of claim 20 , further comprising defining a height of the plurality of beams using a thickness of the device layer.
22. The method of claim 20 , further comprising partially etching an insulator layer between the device layer and a substrate to release the plurality of beams with part of the insulator layer remaining to anchor the plurality of beams to the substrate.