Methods of manufacturing high frequency piezocomposite ultrasound transducers

• US 9,997,696 B2
• Filed: 03/10/2014
• Issued: 06/12/2018
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: FUJIFILM SonoSite, Inc. (Fujifilm Holdings Corporation)
• Original Assignee: FUJIFILM SonoSite, Inc. (Fujifilm Holdings Corporation)
• Inventors: Brown, Jeremy, Foster, F. Stuart, Yin, Jianhua
• Primary Examiner(s): Tugbang, A. Dexter
• Application Number:
  US14/203,435
• Publication Number:
  US 20140354113A1
• Time in Patent Office: 1,555 Days
• CPC Class Codes: A61B 1/06 with illuminating arrangements
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: B06B 1/02 making use of electrical energy B06B1/18, B06B1/20 take precedence
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: B06B 1/06 operating with piezoelectric effect or with electrostriction piezoelectric or electrostrictive devices per se H10N30/00
• CPC Class Codes: B06B 1/0607 using multiple elements B06B1/064 and B06B1/0688 take precedence
• CPC Class Codes: B06B 1/0622 on one surface
• CPC Class Codes: B06B 1/064 with multiple active layers
• CPC Class Codes: G01S 15/8925 the array being a two-dimensional transducer configuration, i.e. matrix or orthogonal linear arrays
• CPC Class Codes: G01S 15/8956 using frequencies at or above 20 MHz
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 30/03 Assembling devices that include piezoelectric or electrostrictive parts
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/06 Forming electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: H10N 30/08 Shaping or machining of piezoelectric or electrostrictive bodies
• CPC Class Codes: H10N 30/088 by cutting or dicing
• CPC Class Codes: H10N 30/8554 Lead-zirconium titanate [PZT] based
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

Methods of manufacturing transducers with triangular cross-sectional shaped pillars are disclosed herein. According to one aspect of the present application, a plurality of first, second and third troughs are formed in a transducer substrate in first, second and third directions, respectively, to form an array of pillars. In one embodiment, the first direction is substantially parallel to a longitudinal axis of the substrate, the second direction is substantially perpendicular to the longitudinal axis of the substrate, and the third direction is oblique to the longitudinal axis of the substrate. The resulting array of pillars can be configured to suppress lateral modes of a high frequency ultrasound transducer.

Claims

1. A method of fabricating an ultrasound transducer, the method comprising:

forming a first trough in a transducer substrate in a first direction substantially parallel to a longitudinal axis of the substrate, wherein the transducer substrate is configured to emit ultrasound energy at a frequency of 15 Megahertz (MHz) or greater;

forming a second trough in the transducer substrate in a second direction substantially perpendicular to the longitudinal axis of the substrate;

forming a third trough in the transducer substrate in a third direction at an acute angle to the longitudinal axis of the substrate; and

forming a fourth trough in the transducer substrate in a fourth direction that is transverse to the third direction.

2. The method of claim 1 wherein the steps of forming the first, second, third and fourth troughs defines a group of pillars on the transducer substrate arranged to suppress lateral modes at transducer operating frequencies of at least 15 MHz.

3. The method of claim 1 wherein forming the first trough comprises forming the first trough with a width, and wherein forming the second trough comprises forming the second trough with a width substantially the same as the width of the first trough.

4. The method of claim 1, further comprising filling at least a portion of at least one of the first trough, the second trough, the third trough and the fourth trough with a fill material.

5. The method of claim 4 wherein the fill material comprises a loaded epoxy.

6. The method of claim 4 wherein the fill material is a photoresist material.

7. The method of claim 1, further comprising geometrically curving at least a lower surface of the transducer substrate.

8. The method of claim 7 wherein geometrically curving at least a portion of the transducer substrate comprises forming the transducer substrate in a spherical geometry having a radius of curvature between about 1 mm and about 50 mm.

9. A method of fabricating an ultrasound transducer, the method comprising:

forming a plurality of first troughs in a transducer substrate in a first direction substantially parallel to a longitudinal axis of the substrate, wherein the transducer substrate is configured to emit ultrasound energy at a frequency greater than 15 Megahertz (MHz);

forming a plurality of second troughs in the transducer substrate in a second direction substantially perpendicular to the longitudinal axis of the substrate;

forming a plurality of third troughs in the transducer substrate in a third direction oblique to the longitudinal axis of the transducer substrate; and

forming a plurality of fourth troughs in the transducer substrate in a fourth direction that is transverse to the third direction.

10. The method of claim 9 wherein the first troughs, the second troughs, the third troughs and the fourth troughs each have widths between about 5 microns and about 20 microns.

11. The method of claim 10, further comprising filling at least a portion of one or more of the first troughs, the second troughs, the third troughs and the fourth troughs with a fill material.

12. The method of claim 9 wherein the steps of forming the first, second and third troughs defines a group of pillars on the transducer substrate arranged to suppress lateral modes at transducer operating frequencies of at least 15 MHz.

13. A method of fabricating an ultrasound transducer, the method comprising:

forming a plurality of first troughs in a transducer substrate in a first direction, wherein the transducer substrate has a center operating frequency of 15 MHz or higher;

forming a plurality of second troughs in the transducer substrate in a second direction orthogonal to the first direction;

forming a plurality of third troughs in the transducer substrate in a third direction oriented at an acute angle relative to the first direction; and

forming a plurality of fourth troughs in a fourth direction transverse to the third direction.

14. The method of claim 13, further comprising:

at least partially filling the first, second, third and fourth troughs with an uncured fill material;

allowing the uncured fill material to cure, thereby forming a cured filling material; and

removing a portion of the cured fill material from the first, second and third troughs.

15. The method of claim 13, further comprising geometrically curving at least a lower surface of the transducer substrate.

16. The method of claim 13 wherein forming the plurality of third troughs comprises performing a cutting operation at an angle between 20 degrees and 70 degrees relative to a longitudinal axis of the transducer substrate.

17. An ultrasound transducer, comprising:

a first trough in a transducer substrate in a first direction substantially parallel to a longitudinal axis of the substrate, wherein the transducer substrate is configured to emit ultrasound energy at a frequency of 15 Megahertz (MHz) or greater;

a second trough in the transducer substrate in a second direction substantially perpendicular to the longitudinal axis of the transducer substrate;

a third trough in the transducer substrate in a third direction at an acute angle with respect to the longitudinal axis of the substrate; and

a fourth trough in the transducer substrate in a fourth direction that is transverse to the third direction.

18. An ultrasound transducer, comprising:

a transducer substrate configured to emit ultrasound energy at a center frequency of 15 MHz or higher;

a plurality of first troughs in the transducer substrate in a first direction;

a plurality of second troughs in the transducer substrate in a second direction orthogonal to the first direction;

a plurality of third troughs in the transducer substrate in a third direction oriented at an acute angle relative to the first direction; and

a plurality of fourth troughs in a fourth direction transverse to the third direction.