Acoustic Management in Integrated Circuit Using Phononic Bandgap Structure

Patent metadata

Field	Value
Publication number	US-2019123711-A1
Application number	US-201715792591-A
Country	US
Kind code	A1
Filing date	Oct 24, 2017
Priority date	Oct 24, 2017
Publication date	Apr 25, 2019
Grant date	—

Abstract

An encapsulated integrated circuit is provided that includes an integrated circuit (IC) die. A phonon device is fabricated on the IC die that is configured to emit or to receive phonons that have a range of ultrasonic frequencies. An encapsulation material encapsulates the IC die. A phononic bandgap structure is included within the encapsulation material that is configured to have a phononic bandgap with a frequency range that includes at least a portion of the range of ultrasonic frequencies. A phononic channel is located in the phononic bandgap structure between the phonon device and a surface of the encapsulated IC.

First claim

What is claimed is:

1 . An encapsulated integrated circuit comprising:
an integrated circuit (IC) die; an encapsulation material encapsulating the IC die; a phonon device fabricated on the IC die, the phonon device configured to emit or to receive phonons having a first range of frequencies; a phononic bandgap (PBS) structure within the encapsulation material configured to have a phononic bandgap with a frequency range that includes at least a portion of the first range of frequencies; and a bandpass channel through the PBS structure within a region of encapsulation material proximate the phonon device.

2 . The encapsulated IC of claim 1 , wherein the bandpass channel extends from the phonon device to an external surface of the encapsulation material.

3 . The encapsulated IC of claim 1 , wherein the bandpass channel is a conical shaped region surrounded by the PBG structure.

4 . The encapsulated IC of claim 1 , wherein the bandpass channel is a cylindrical shaped region surrounded by the PBG structure.

5 . The encapsulated IC of claim 1 , further comprising:
a thermal pad on which the IC die is mounted; and in which a portion of the phononic bandgap structure is located between the IC die and the thermal pad.

6 . The encapsulated IC of claim 1 , in which the phononic bandgap structure includes a matrix of periodically spaced nodes within the encapsulation material, wherein the encapsulation material has a first acoustic impedance and the nodes have a second acoustic impedance that is different from the first acoustic impedance.

7 . The encapsulated IC of claim 6 , in which the nodes have an acoustic impedance that is greater than the acoustic impedance of the encapsulation material.

8 . The encapsulated IC of claim 1 , in which the phononic structure includes filler particles diffused within the encapsulation material, wherein the encapsulation material has a first acoustic impedance and the filler particles have a second acoustic impedance that is different from the first acoustic impedance.

9 . The encapsulated IC of claim 1 , further comprising a second phonon device fabricated on the IC die, the second phonon device configured to emit or to receive phonons having a second range of frequencies through the bandpass channel.

10 . A method for encapsulating an integrated circuit, the method comprising:
attaching an integrated circuit (IC) die to a leadframe, wherein the IC die includes a phonon device fabricated on the IC die; and encapsulating the IC die the by to form a phononic bandgap (PBG) structure within an encapsulation material with a bandpass channel through the PBG structure within a region of the encapsulation material proximate the phonon device.

11 . The method of claim 10 , wherein forming the phononic bandgap structure comprises forming a matrix of periodically spaced nodes within the encapsulating material, in which the encapsulation material has a first acoustic impedance and the nodes have a second acoustic impedance that is different from the first acoustic impedance.

12 . The method of claim 11 , wherein forming the phononic bandgap structure includes creating a bandpass channel within the phononic bandgap structure by omitting nodes within the bandpass channel region.

13 . The method of claim 1 , wherein forming the phononic bandgap structure comprises:
forming a first matrix of periodically spaced nodes within the encapsulating material having a first lattice constant; and forming a second matrix of periodically spaced nodes within the encapsulating material having a second lattice constant,

14 . The method of claim 10 , wherein forming the phononic bandgap structure comprises:
forming a first matrix of periodically spaced nodes within the encapsulating material having a first acoustic impedance; and forming a second matrix of periodically spaced nodes within the encapsulating material having a second acoustic impedance.

15 . The method of claim 10 , in which forming the phononic bandgap structure uses filler particles diffused within the encapsulation material,

16 . A method for operating an encapsulated integrated circuit, the method comprising:
emitting ultrasonic waves having a first range of frequencies from a phonon device fabricated on the integrated circuit (IC); conducting the ultrasonic waves through a phononic channel in the encapsulation material surrounding the IC; and confining the ultrasonic waves to the phononic channel by a phononic bandgap (PBG) structure within the encapsulation material configured to have a band gap with a frequency range that includes at least a portion of the first range of frequencies.

17 . The method of claim 16 in which conducting the ultrasonic waves includes conducting the ultrasonic waves from the phonon device to a surface of the encapsulated IC.

18 . The method of claim 16 , in which confining the ultrasonic waves includes reflecting a portion of the ultrasonic waves from a conical surface of the PBG structure within the encapsulation material.

19 . The method of claim 16 , further comprising:
conducting second ultrasonic waves having a second range of frequencies through the phonons channel in the encapsulation material surrounding the IC; and receiving the second ultrasonic waves having the second range of frequencies by a second phonon device fabricated on the integrated circuit (IC).

Assignees

• Texas Instruments Inc

Inventors

• Revier Daniel Lee
• Cook Benjamin Stassen

Classifications

• H10W90/756

  between a chip and a stacked lead frame, conducting package substrate or heat sink · CPC title

• H10W90/736

  between a chip and a stacked lead frame, conducting package substrate or heat sink · CPC title

• H10W72/07352

  changes in structures or sizes · CPC title

• H10W72/884

  Die-attach connectors and bond wires · CPC title

• H10W72/321

  Structures or relative sizes of die-attach connectors · CPC title