MEMS transducers

• Main Authors: RICHARD IAN LAMING, ROBERT ERROL MCMULLEN, ANTHONY BERNARD TRAYNOR, TSJERK HANS HOEKSTRA
• Format: Patent
• Language: English
• Published: 11.11.2009
• Subjects: DEAF-AID SETS; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; FOR PERFORMING MECHANICAL WORK IN GENERAL; GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL; LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKEACOUSTIC ELECTROMECHANICAL TRANSDUCERS; MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC ORINFRASONIC WAVES; MEASURING; MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER,MECHANICAL EFFICIENCY, OR FLUID PRESSURE; METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICALVIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY; MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICALDEVICES; MICROSTRUCTURAL TECHNOLOGY; PERFORMING OPERATIONS; PHYSICS; PUBLIC ADDRESS SYSTEMS; TESTING; TRANSPORTING

A Microelectromechanical systems (MEMS) device 50 comprising transducer 52 for transmitting pressure waves with an electrode 53a diameter DE1 and transducer 54 for detecting pressure waves having an electrode 55a diameter DE2. Transducer 52 comprises cavity 51 and transducer 54 comprises cavity 56. Cavities 51, 56 are formed by removal of sacrificial material via release channels 57, 58 and are sealed after removal of the sacrificial material by plugging release holes 57a, 58a. The mass, thickness, material of electrodes 53a, 55a may be adjusted so that the transducer is optimized at a resonant frequency for transmitting or detecting pressure waves. The membrane thickness (T1, T2, fig. 7) or diameter may also be varied so that the transducers have different Q factors. In an embodiment the sacrificial layer (126, fig. 8m) encases the electrode (116, fig. 8m) in order to reduce deformation of the membrane.