Capacitive MEMS device with programmable offset voltage control
First Claim
1. A method of addressing a microelectromechanical (MEMS) element that comprises an electrode, a movable layer, and a material for trapping charge, the method comprising:
- transferring charge to or from the material to configurably change an actuation threshold voltage of the element to a target level in response to actuation of the element.
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Accused Products
Abstract
A capacitive MEMS device is formed having a material between electrodes that traps and retains charges. The material can be realized in several configurations. It can be a multilayer dielectric stack with regions of different band gap energies or band energy levels. The dielectric materials can be trappy itself, i.e. when defects or trap sites are pre-fabricated in the material. Another configuration involves a thin layer of a conductive material with the energy level in the forbidden gap of the dielectric layer. The device may be programmed (i.e. offset and threshold voltages pre-set) by a method making advantageous use of charge storage in the material, wherein the interferometric modulator is pre-charged in such a way that the hysteresis curve shifts, and the actuation voltage threshold of the modulator is significantly lowered. During programming phase, charge transfer between the electrodes and the materials can be performed by applying voltage to the electrodes (i.e. applying electrical field across the material) or by UV-illumination and injection of electrical charges over the energy barrier. The interferometric modulator may then be retained in an actuated state with a significantly lower actuation voltage, thereby saving power.
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Citations
26 Claims
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1. A method of addressing a microelectromechanical (MEMS) element that comprises an electrode, a movable layer, and a material for trapping charge, the method comprising:
transferring charge to or from the material to configurably change an actuation threshold voltage of the element to a target level in response to actuation of the element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of manufacturing a microelectromechanical (MEMS) device, the method comprising:
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forming an electrode; forming a movable layer extending over the electrode and forming a cavity therebetween; and forming a material for trapping charge, the material being coupled to one or both the electrode and the movable layer, wherein the movable layer is configured to move in response to an electrical potential between the electrode and at least a portion of the movable layer, the electrical potential being greater than an actuation threshold voltage, and wherein charge is transferred to or from the material to configurably change the actuation threshold voltage to a target level in response to actuation of the device. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification