Invensense, Inc.

Tdk Corporation

Mei-Lin Chan

Martin Lim

Nikhil Apte

Michael Julian Daneman

Xiang Li

Erhan Polatkan Ata

Xiaoyue Jiang

Quy Chau

Chienliu Chang

Fariboz Assaderaghi

Renata Melamud Berger

Bongsang Kim

Sina Akhbari

Peter George Hartwell

Leonardo Baldasarre

Mark Jennings

Mamdouh Yanni

Emad Mehdizadeh

Shreyas Thakar

Lingtao Wang

In a method for multipath reflection correction of acoustic signals received at an ultrasonic sensor, characteristics of multipath reflection signals of the ultrasonic sensor are accessed, wherein the characteristics of the multipath reflection signals include a relationship of primary signal contributions to multipath reflection signal contributions for acoustic signals received at the ultrasonic sensor at a plurality of times of flight for a plurality of locations of the ultrasonic sensor. Acoustic signals are received at the ultrasonic sensor over a time of flight range while a target is interacting with the ultrasonic sensor, wherein the acoustic signals include a primary signal contribution and a multipath reflection signal contribution. The characteristics of the multipath reflection signals are compared to received acoustic signals. The primary signal contribution of the received acoustic signals is determined at a plurality of times of flight of the time of flight range based on the characteristics of the multipath reflection signals.

Multipath reflection correction

An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers, wherein the two-dimensional array of ultrasonic transducers is substantially flat, a contact layer having a non-uniform thickness overlying the two-dimensional array of ultrasonic transducers, and an array controller configured to control activation of ultrasonic transducers during an imaging operation. During the imaging operation, the array controller is configured to control a transmission frequency of activated ultrasonic transducers during the imaging operation, wherein a plurality of transmission frequencies are used during the imaging operation to account for an impact of an interference pattern caused by the non-uniform thickness of the contact layer, and is configured to capture at least one fingerprint image using the plurality of transmission frequencies.

Ultrasonic fingerprint sensor with a contact layer of non-uniform thickness

A piezoelectric micromachined ultrasound transducer (PMUT) device may include a plurality of layers including a structural layer, a piezoelectric layer, and electrode layers located on opposite sides of the piezoelectric layer. Conductive barrier layers may be located between the piezoelectric layer and the electrodes to the prevent diffusion of the piezoelectric layer into the electrode layers.

Piezoelectric micromachined ultrasound transducer device with piezoelectric barrier layer

An electronic device includes a substrate layer having a front surface and a back surface opposite the front surface, a plurality of ultrasonic transducers formed on the front surface of the substrate layer, wherein the plurality of ultrasonic transducers generate backward waves during operation, the backward waves propagating through the substrate layer, and a plurality of substrate structures formed within the back surface of the substrate layer, the plurality of substrate structures configured to modify the backward waves during the operation.

Reflection minimization for sensor

A piezoelectric micromachined ultrasound transducer (PMUT) array may comprise PMUT devices with respective piezoelectric layers and electrode layers. Parasitic capacitance can be reduced when an electrode layer is not shared across PMUT devices but may expose the devices to electromagnetic interference (EMI). A conductive layer located within the structural layer or on a shared plane with the electrode layers may reduce EMI affecting the PMUT array operation.

EMI reduction in piezoelectric micromachined ultrasound transducer array

An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers, a contact layer, a matching layer between the two-dimensional array and the contact layer, where the matching layer has a non-uniform thickness, and an array controller configured to control activation of ultrasonic transducers during an imaging operation for imaging a plurality of pixels within the two-dimensional array of ultrasonic transducers. During the imaging operation, the array controller is configured to activate different subsets of ultrasonic transducers associated with different regions of the two-dimensional array of ultrasonic transducers at different transmission frequencies, where the different frequencies are determined such that a thickness of the matching layer at a region is substantially equal to a quarter wavelength of the first transmission frequency for the region. The array controller is also configured to combine the plurality of pixels into a compound fingerprint image that compensates for the non-uniform thickness of the matching layer.

An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers, wherein the two-dimensional array of ultrasonic transducers is substantially flat, a contact layer having a non-uniform thickness overlying the two-dimensional array of ultrasonic transducers, and an array controller configured to control activation of ultrasonic transducers during an imaging operation for imaging a plurality of pixels at a plurality of positions within the two-dimensional array of ultrasonic transducers. For imaging a pixel of the plurality of pixels, the array controller is configured to activate a first subset of ultrasonic transducers of the two-dimensional array of ultrasonic transducers to generate an ultrasonic beam directed to a contact surface of the contact layer, and activate a second subset of ultrasonic transducers of the two-dimensional array of ultrasonic transducers to receive a reflected ultrasonic beam, wherein the second subset of ultrasonic transducers is at a location within the two-dimensional array of ultrasonic transducers to account for a local angle between the two-dimensional array of ultrasonic transducers and the contact surface where the ultrasonic beam interacts with the contact surface.

In a method for determining whether a finger is a real finger at an ultrasonic fingerprint sensor, a first image of a fingerprint pattern is captured at an ultrasonic fingerprint sensor, wherein the first image is based on ultrasonic signals corresponding to a first time of flight range. A second image of the fingerprint pattern is captured at the ultrasonic fingerprint sensor, wherein the second image is based on ultrasonic signals corresponding to a second time of flight range, the second time of flight range being delayed compared to the first time of flight range. A difference in a width of ridges of the fingerprint pattern in the first image compared to the width of ridges of the fingerprint pattern in the second image is quantified. Based on the quantification of the difference, a probability whether the finger is a real finger is determined.

Fake finger detection using ridge features

A MEMS device includes a dual membrane, an electrode, and an interconnecting structure. The dual membrane has a top membrane and a bottom membrane. The bottom membrane is positioned between the top membrane and the electrode and the interconnecting structure defines a spacing between the top membrane and the bottom membrane.

Capacitive sensing structure with embedded acoustic channels

A method for fabricating a MEMS device includes depositing and patterning a first sacrificial layer onto a silicon substrate, the first sacrificial layer being partially removed leaving a first remaining oxide. Further, the method includes depositing a conductive structure layer onto the silicon substrate, the conductive structure layer making physical contact with at least a portion of the silicon substrate. Further, a second sacrificial layer is formed on top of the conductive structure layer. Patterning and etching of the silicon substrate is performed stopping at the second sacrificial layer. Additionally, the MEMS substrate is bonded to a CMOS wafer, the CMOS wafer having formed thereupon a metal layer. An electrical connection is formed between the MEMS substrate and the metal layer.

Method for MEMS structure with dual-level structural layer and acoustic port

A MEMS device includes a first plate coupled to a second plate and a fixed third plate formed on a first substrate. The first and second plates are displaced in the presence of an acoustic pressure differential across the surfaces of the first plate. The MEMS device also includes a first electrode formed on the third plate and a second electrode formed on the second substrate. The first, second plate, and third plates are contained in an enclosure formed by a first and second substrates. The device includes an acoustic port to expose the first plate to the environment. The MEMS device also includes a first gap formed between the second and third plates and a second gap formed between the second plate and the second electrode. The displacement of the second plate causes the first gap to change inversely to the second gap.

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Milpitas, CA, United States of America

Mei-Lin Chan