# US 9,517,930 B2 · Recovery system and methods for MEMS devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,930 B2 - Document ID: US9517930B2 - Status: Granted - Kind: B2 - Application number: 14/047,944 - Filed: 2014-01-29 - Published: 2015-01-01 - Granted: 2016-12-13 - Earliest claimed: 2013-06-28 - Assignees: Hanking Electronics, Ltd. - Applicants: Maxim Integrated Products, Inc. - Inventors: Gabriele Cazzaniga; Luca Coronato; Barbara Simoni; Luciano Prandi - Web page: https://patentgrep.com/patent/US9517930B2 ## CPC - B81C 1/00968: {Methods for breaking the stiction bond} - B81B 3/001: {Structures having a reduced contact area, e.g. with bumps or with a textured surface} - B81B 3/0056: {Adjusting the distance between two elements, at least one of them being movable, e.g. air-gap tuning} - B81B 2201/016: having a bridge fixed on two ends and connected to one or more dimples - H01H 1/0036: {Switches making use of microelectromechanical systems [MEMS] (for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009)} - B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01) - B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) ## Abstract Various embodiments of the invention reduce stiction in a wide range of MEMS devices and increase device reliability without negatively impacting performance. In certain embodiments, stiction recover is accomplished by applying electrostatic forces to electrodes via optimized voltage signals that generate a restoring force that aids in overcoming stiction forces between electrodes. The voltage signals used within a stiction recovery procedure may be static or a dynamic, and may be applied directly to existing electrodes within a MEMS device, thereby, eliminating the need for additional components. In some embodiments, the voltage is estimated or calibrated and swept through a range of frequencies that contains one or more resonant frequencies of the mechanical structure that comprises the parts to be detached. ## Claims ### Claim 1 A circuit to recover from stiction, the circuit comprising: a stiction detection circuit coupled to receive a first signal from a MEMS device, the stiction detection circuit detects, based on the first signal, a stiction event between two components of the MEMS device; and a stiction recovery circuit coupled to the stiction detection circuit, the stiction recovery circuit generates a second signal in response to detecting the stiction event and applies the second signal to at least a mechanical structure of the MEMS device to cause an electrostatic force. ### Claim 2 (depends on 1) The circuit according to claim 1, wherein the second signal is one of a non-periodic waveform signal having a continuously increasing frequency, a non-periodic waveform signal having a continuously decreasing frequency, and static signal. ### Claim 3 (depends on 1) The circuit according to claim 1, wherein the stiction recovery circuit comprises a waveform generator capable of sweeping the second signal through a predetermined range of frequencies. ### Claim 4 (depends on 1) The circuit according to claim 1, wherein the mechanical structure of the MEMS device comprises a mass. ### Claim 5 (depends on 4) The circuit according to claim 4, wherein the second signal has a spectral content that comprises at least one frequency in common with a resonant frequency of the mass. ### Claim 6 (depends on 4) The circuit according to claim 4, wherein the electrostatic force is configured to increase a restoring force of the mass. ### Claim 7 (depends on 4) The circuit according to claim 4, wherein the mechanical structure of the MEMS device comprises an electrode, the electrode is configured to generate the electrostatic force on the mass. ### Claim 8 (depends on 7) The circuit according to claim 7, wherein the electrode is a sensor readout electrode that is configured to read the first signal. ### Claim 9 (depends on 1) The circuit according to claim 1, wherein the MEMS device is one of an acceleration sensor and an angular rate sensor. ### Claim 10 A method to recover from stiction between two components of a MEMS device, the method comprising: receiving a first signal; detecting a stiction event based on the first signal; generating a second signal in response to detecting the stiction event; and applying the second signal to a mechanical structure to cause an electrostatic force. ### Claim 11 (depends on 10) The method according to claim 10, wherein applying the second signal comprises sweeping the second signal through a predetermined range of frequencies. ### Claim 12 (depends on 11) The method according to claim 11, further comprising calibrating the range of frequencies to increase a restoring force of a first mass. ### Claim 13 (depends on 10) The method according to claim 10, wherein the second signal has a spectral content that comprises at least one frequency in common with a resonant frequency of the mechanical structure comprising a second mass. ### Claim 14 (depends on 10) The method according to claim 10, wherein detecting the stiction event comprises detecting the presence of a saturation. ### Claim 15 (depends on 10) The method according to claim 10, wherein detecting the stiction event comprises detecting the presence of an over-threshold signal. ### Claim 16 (depends on 10) The method according to claim 10, further comprising determining a stiction recovery mode. ### Claim 17 A system to recover from stiction between two components of a MEMS device, the system comprising: a MEMS device that generates a first readout signal; a readout circuit coupled to receive the first readout signal and convert it into a second readout signal; a stiction detection circuit coupled to the readout circuit, the stiction detection circuit detects a stiction event based on the second readout signal; and a stiction recovery circuit coupled to the stiction detection circuit, the stiction recovery circuit generates a voltage signal in response to detecting the stiction event and applies the voltage signal to at least one electrode of the MEMS device to cause an electrostatic force. ### Claim 18 (depends on 17) The system according to claim 17, further comprising a processing circuit coupled to receive and process the second readout signal. ### Claim 19 (depends on 17) The system according to claim 17, wherein the voltage signal is a bias voltage. ### Claim 20 (depends on 17) The system according to claim 17, wherein the voltage signal has a non-periodic square wave voltage having a continuously increasing or decreasing frequency.