Methods and devices for microelectromechanical resonators
AssigneeStathera IP Holding, Inc.
InventorsVamsy Chodavarapu, George Xereas
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Abstract
MEMS based sensors, particularly capacitive sensors, potentially can address critical considerations for users including accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, and cost effectiveness. Accordingly, it would be beneficial to exploit MEMS processes that allow for manufacturability and integration of resonator elements into cavities within the MEMS sensor that are at low pressure allowing high quality factor resonators and absolute pressure sensors to be implemented. Embodiments of the invention provide capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics.
Claims16
A MEMS device comprising:
- a MEMS resonating element;
- a movable electrode for electrostatic actuation and sensing of the MEMS resonating element, wherein the movable electrode comprises an opening in the movable electrode;
- a stop anchor located within the opening in the movable electrode;
- and
- a welding pad located on (i) a surface of the movable electrode in the opening of the movable electrode or (ii) a surface of the stop anchor in the opening of the movable electrode, wherein the movable electrode is configured to move in a particular direction in response to a voltage applied between the movable electrode and the MEMS resonating element such that, when the movable electrode is moved in the particular direction, the welding pad contacts both the movable electrode and the stop anchor, thereby causing the surface of the movable electrode to be separated from the surface of the stop anchor by a thickness of the welding pad.
A method of post-fabrication gap reduction, the method comprising:
- fabricating a MEMS device, the MEMS device comprising:
- a MEMS resonating element;
- a movable electrode for electrostatic actuation and sensing of the MEMS resonating element, wherein the movable electrode comprises an opening in the movable electrode;
- a stop anchor located within the opening in the movable electrode;
- and
- a welding pad located on (i) a surface of the movable electrode in the opening of the movable electrode or (ii) a surface of the stop anchor in the opening of the movable electrode;
- applying a voltage differential between the movable electrode and the MEMS resonating element, such that the voltage differential causes the movable electrode to move toward the MEMS resonating element until the welding pad contacts both the movable electrode and the stop anchor;
- and
- passing a current through the welding pad, such that the current is sufficiently large to at least partly melt the welding pad and fix the movable electrode in place.
A MEMS device comprising:
- a MEMS resonating element;
- a movable electrode for electrostatic actuation and sensing of the MEMS resonating element;
- a stop anchor, wherein the stop anchor has at least one surface located between a first surface of the movable electrode and the MEMS resonating element;
- and
- a welding pad located on (i) the first surface of the movable electrode, facing the at least one surface of the stop anchor or (ii) the at least one surface of the stop anchor, wherein the movable electrode is configured to move in a particular direction in response to a voltage applied between the movable electrode and the MEMS resonating element such that, when the movable electrode is moved in the particular direction, the welding pad contacts both the first surface of the movable electrode and the at least one surface of the stop anchor, thereby causing the first surface of the movable electrode to be separated from the at least one surface of the stop anchor by a thickness of the welding pad.
Dependencies are inferred from the claim text.