Oscillation frequency measuring system and method for a MEMS sensor
AssigneeSTMicroelectronics S.r.l.
InventorsAlfio Russo, Massimo Cataldo Mazzillo, Ferenc Nagy
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Abstract
A MEMS sensor has at least a movable element designed to oscillate at an oscillation frequency, and an integrated measuring system coupled to the movable element to provide a measure of the oscillation frequency. The measuring system has a light source to emit a light beam towards the movable element and a light detector to receive the light beam reflected back from the movable element, including a semiconductor photodiode array. In particular, the light detector is an integrated photomultiplier having an array of single photon avalanche diodes.
Claims20
A device, comprising:
- a semiconductor substrate having a first surface;
- a light emitting device extending in the semiconductor substrate to a first distance from the first surface;
- a light detector extending in the semiconductor substrate to a second distance from the first surface, the second distance being smaller than the first distance;
- a movable element coupled to the semiconductor substrate and extending over the first surface of the substrate, the movable element having a surface that faces the first surface of the semiconductor substrate, the light emitting device, and the light detector, the surface of the moveable element being configured to reflect light from the light emitting device to the light detector.
A device, comprising:
- a MEMS sensor including:
- a movable element;
- and
- an integrated measuring system coupled to the movable element, the integrated measuring system including:
- a semiconductor substrate having a first surface;
- a light source that emits a light beam towards the movable element, the light source extending in the semiconductor substrate to a first distance from the first surface;
- and
- a light detector that receives the light beam reflected back from the movable element, the light detector extending in the substrate to a second distance from the first surface, the second distance being smaller than the first distance;
- and
- an electronic detection circuit, operatively coupled to the light detector, the electronic detection circuit being configured to provide a measure of an oscillation frequency of the movable element based on an output signal received from the light detector.
A method, comprising:
- forming a light source in a semiconductor substrate having a first surface, the light source extending into the semiconductor substrate to a first distance from the first surface;
- forming a light detector in the semiconductor substrate, the light detector extending into the semiconductor substrate to a second distance from the first surface, the second distance being smaller than the first distance;
- and
- physically coupling a movable element to the semiconductor substrate, the movable element extending over the first surface of the substrate, and having a surface that faces the light emitting device and the light detector.
Dependencies are inferred from the claim text.