INDUCTIVE INERTIAL SENSOR ARCHITECTURE & FABRICATION IN PACKAGING BUILD-UP LAYERS

• US 20140165723A1
• Filed: 12/19/2012
• Published: 06/19/2014
• Est. Priority Date: 12/19/2012
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Feras Eid, Johanna M. Swan, Kevin Lin, Qing Ma, Valluri R. Rao, Weng Hong Teh
• Inventors: MA, Qing, EID, Feras, LIN, Kevin, SWAN, Johanna M., TEH, Weng Hong, RAO, Valluri R.
• Granted Patent: US 9,429,427 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Abstract

This invention relates to inductive inertial sensors employing a magnetic drive and/or sense architecture. In embodiments, translational gyroscopes utilize a conductive coil made to vibrate in a first dimension as a function of a time varying current driven through the coil in the presence of a magnetic field. Sense coils register an inductance that varies as a function of an angular velocity in a second dimension. In embodiments, the vibrating coil causes first and second mutual inductances in the sense coils to deviate from each other as a function of the angular velocity. In embodiments, self-inductances associated with a pair of meandering coils vary as a function of an angular velocity in a second dimension. In embodiments, package build-up layers are utilized to fabricate the inductive inertial sensors, enabling package-level integrated inertial sensing advantageous in small form factor computing platforms, such as mobile devices.

Claims

1. A gyroscope, comprising:

a substrate including a magnet;

a drive coil disposed over the substrate and within a magnetic field of the magnet to vibrate in a first dimension relative to the substrate as a function of a time varying current passing through the drive coil,

at least one sense coil disposed over the substrate and positioned with respect to the drive coil to register an inductance that varies as a function of an angular velocity in a second dimension, orthogonal to the first dimension.

2. The gyroscope of claim 1, wherein the at least one sense coil comprises a pair of sense coils is to register a first and second mutual inductance that deviate from each other as a function of the angular velocity.

3. The gyroscope of claim 2, wherein the sense coils are disposed relative to the drive coil to register a differential in their mutual inductance in response to a displacement of the drive coil in a dimension other than the first dimension that is greater than a mutual inductance differential registered in response to displacement of the drive coil in the first dimension.

4. The gyroscope of claim 3, wherein the drive coil is planar in a plane parallel to the substrate and comprises four substantially orthogonal segments with a plurality of conductive anchors, and at least one pair of the conductive anchors providing terminals through which the time varying current is applied to the drive coil.

5. The gyroscope of claim 4, wherein the first dimension is parallel to the plane of the substrate, wherein the magnetic field and the angular velocity are perpendicular to the plane of the substrate, and wherein the sense coils are disposed parallel to segments of the drive coil extending along the first dimension.

6. The gyroscope of claim 5, wherein the first dimension is perpendicular to the plane of the substrate, wherein the magnetic field and the angular velocity are parallel to the plane of the substrate, and wherein the sense coils further comprise a first pair of sense coils having coil lengths parallel to segments on opposite sides of the drive coil extending along a first in-plane dimension to register a differential in mutual inductance in response to a displacement of the drive coil in a second in-plane dimension, orthogonal to the first in-plane dimension.

7. The gyroscope of claim 6, wherein the sense coils further comprise a second pair of sense coils having coil lengths parallel to segments on opposite sides of the drive coil extending along the second in-plane dimension, the second pair to register a differential in mutual inductance in response to a displacement of the drive coil in the first in-plane dimension.

8. The gyroscope of claim 2, wherein each of the pair of sense coils comprises at least one of:

a spiral with a plurality of turns made within a same plane parallel to the substrate;

or

a plurality of coils disposed along a length of the drive coil and connected in series;

or

one or more turns in a plane parallel to the substrate but not in the same plane as the drive coil, the one or more turns disposed symmetrically over a segment of the drive coil.

9. An integrated inertial sensor, comprising:

the gyroscope of claim 2; and

at least one of an amplifier or rotation calculator downstream of the sense coils, the amplifier to amplify a voltage differential registered by the pair of sense coils and the rotation calculator to determine a rotation based on the voltage differential registered by the pair of sense coils.

10. The integrated inertial sensor of claim 9, wherein the amplifier or rotation calculator comprise circuitry on an integrated circuit (IC) chip disposed within a same package as the gyroscope.

11. The integrated inertial sensor of claim 9, wherein the drive and sense coils comprise at least one metallization layer disposed within organic dielectric build-up layers of the package.

15. The gyroscope of claim 1, wherein the time varying current is driven through a first pair of conductive coil anchors, and wherein the sense coils include a second pair of conductive coil anchors and a portion of the coil disposed there between, the second pair of coil anchors registering self inductances that vary as a function of an angular velocity in a second dimension, orthogonal to the first dimension, and wherein a resonant frequency varies as a function of the self inductance and capacitance of a capacitor coupled across the second pair of coil anchors.

16. The gyroscope of claim 15, wherein the first dimension is parallel to the plane of the substrate, wherein the magnetic field and the angular velocity are perpendicular to the plane of the substrate, and wherein the second pair of anchors comprise springs to compress and extend along the second dimension in a manner that changes their self inductance.

17. The gyroscope of claim 16, wherein the springs are rectangle springs having at least a pair of conductor segments extending in the first dimension and joined at one end by a short segment extending in the second dimension.

18. An integrated inertial sensor, comprising:

the gyroscope of claim 15; and

a rotation calculator downstream of the sense coils, the rotation calculator to determine a rotation based on the resonant frequency.

19. The integrated inertial sensor of claim 18, wherein the rotation calculator comprises circuitry on an integrated circuit (IC) chip disposed along with the gyroscope within a same package.

20. The integrated inertial sensor of claim 18, wherein the coil comprises at least one metallization layer disposed within organic dielectric build-up layers of the package.

12. A method of determining an angular rate of rotation of a mobile device including a packaged integrated circuit (IC), the method comprising:

driving a time varying current through a first coil disposed within a first magnetic field of a first magnet embedded, along with the first coil, within the IC package dielectric to vibrate the first coil in a first dimension relative to the IC package;

generating first and second time varying voltage signals with a pair of sense coils through mutual induction responsive to displacement of the first coil, the first and second time varying voltage signals deviating from each other as a function of an angular velocity in a second dimension, orthogonal to the first dimension; and

determining a first of a yaw, pitch, or roll of the mobile device based on the first and second time varying voltage signals.

13. The method of claim 12, further comprising:

driving a time varying current through a second coil disposed within a second magnetic field, orthogonal to the first magnetic field to vibrate the second coil in the first dimension;

generating third and fourth time varying voltage signals with a pair of sense coils through mutual induction responsive to displacement of the second coil, the third and fourth time varying voltage signals deviating from each other as a function of an angular velocity in a dimension orthogonal to the second dimension; and

determining a second of a yaw, pitch, or roll of the mobile device based on the third and fourth time varying voltage signals.

14. The method of claim 12, wherein the first coil is planar in a plane parallel to a plane of the substrate and the first coil comprises four substantially orthogonal segments with a plurality of conductive anchors, and wherein the time varying current is driven through at least one pair of the conductive anchors.

21. A method of determining an angular rate of rotation of a mobile device including a packaged integrated circuit (IC), the method comprising:

driving a time varying current through a coil via first pair of conductive anchors, the coil disposed within a magnetic field of a magnet embedded, along with the coil, within the IC package to vibrate the coil in a first dimension relative to the IC package,

measuring a signal across a second pair of conductive coil anchors to determine a resonance frequency of an LC loop comprising a portion of the coil and a capacitor coupled across the second pair of coil anchors, wherein the second pair of coil anchors register self inductances that vary as a function of an angular velocity in a second dimension, orthogonal to the first dimension; and

determining a yaw, pitch, or roll of the mobile device based on the resonance frequency.

22. The method of claim 21, the determining a yaw, pitch, or roll further comprising:

determining a self inductance associated with the resonance frequency; and

determining a compression or extension in the second dimension of a spring connected to one of the second anchors, the compression or extension corresponding to the determined self inductance.

23. An integrated inertial sensor, comprising:

an integrated circuit (IC) chip;

a magnet; and

an inductive gyroscope comprising a conductive coil disposed over or under the magnet and operable to vibrate within a cavity formed within one or more package build-up layers disposed over the gyroscope and IC chip.

24. The integrated inertial sensor of claim 23, wherein the IC chip is electrically connected to at least one conductive coil of the gyroscope by a level of metallization embedded within the one or more package build up layers

25. The integrated inertial sensor of claim 23, wherein the metallization connecting the coil to the IC is a same level of metallization as that from which the at least one conductive coil is formed.

26. The integrated inertial sensor of claim 23, further comprising a conductive mesh disposed over the cavity, the conductive mesh in a same metallization level as employed by a redistribution layer routing conductive traces between the IC and a pad dimensioned to receive at least one of a bump or solder ball.

27. The integrated inertial sensor of claim 23, further comprising a thin substrate onto which the magnet is disposed, the thin substrate and a backside of the chip forming a planar back side of the integrated inertial sensor.

28. The integrated inertial sensor of claim 23, wherein the IC chip comprises at least one of a signal processor, a signal amplifier, or rotation calculator.

29. A method of forming an integrated inertial sensor, the method comprising:

placing an IC chip and magnet on a holder;

laminating a dielectric film over the IC chip and magnet;

patterning features into the dielectric film;

depositing a first metallization layer into the features to form one or more conductive coils disposed proximate to the magnet;

laminating a dielectric film over the first metallization layer;

depositing a second metallization layer over the one or more coils;

selectively removing the dielectric film to release at least one of the one or more coils;

laminating a dielectric film over the second metallization; and

removing the holder.

30. The method of claim 29, wherein plating the first metallization layer into the features further comprises interconnecting the IC with at least one of the one or more coils, forming a drive coil and at least a pair of sense coils, physically separated from the drive coil, and wherein selectively removing the dielectric film to release at least one of the one or more coils further comprises releasing the drive coil.