Thin film piezoelectric arrays with enhanced coupling and fabrication methods

• US 5,698,928 A
• Filed: 08/17/1995
• Issued: 12/16/1997
• Est. Priority Date: 08/17/1995
• Status: Expired due to Fees

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Pack, Sung P., Barker, Dean, Mang, Luke
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/516,221
• Time in Patent Office: 852 Days
• Field of Search: 310/322, 310/334, 310/358
• US Class Current: 310/322
• CPC Class Codes: H03H 2003/0435 of a piezoelectric layer
• CPC Class Codes: H03H 9/02133 of stress
• CPC Class Codes: H03H 9/172 Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume

Abstract

An array of thin film piezoelectric resonators are formed on a substrate and connected in parallel to form a single piezoelectric resonator with enhanced piezoelectric coupling. The array includes a first conductive layer positioned on the substrate and defining a first electrode, a plurality of columns of piezoelectric material positioned on the conductive layer and each defining a separate piezoelectric resonator, and a second conductive layer positioned on the plurality of columns and defining a second electrode. The columns are selectively deposited or deposited as a single layer and etched into columns.

Claims

1. An array of thin film piezoelectric resonators with enhanced piezoelectric coupling comprising:

a substrate having a planar surface;

a first conductive thin film positioned on the surface of the substrate and defining a first electrode;

a plurality of columns of thin film piezoelectric material positioned in spaced apart relationship on the first conductive layer and each defining a separate piezoelectric resonator; and

a second conductive thin film positioned on the plurality of columns and defining a second electrode, the first and second electrodes cooperating to connect the plurality of columns in parallel to form an array of thin film piezoelectric resonators with each separate piezoelectric resonator having unclamped sidewalls for reducing stiffness.

2. An array of thin film piezoelectric resonators with enhanced piezoelectric coupling as claimed in claim 1 wherein the columns of thin film piezoelectric material include one of ZnO and AlN.

3. An array of thin film piezoelectric resonators with enhanced piezoelectric coupling as claimed in claim 1 wherein each of the columns has a height/diameter ratio greater than 2.

4. An array of thin film piezoelectric resonators with enhanced piezoelectric coupling as claimed in claim 1 wherein adjacent columns are separated by at least one micron.

5. An array of thin film piezoelectric resonators with enhanced piezoelectric coupling as claimed in claim 1 wherein each of the first and second thin film conductive layers is a substantially continuous layer.

6. An array of thin film piezoelectric resonators with enhanced piezoelectric coupling comprising:

a substrate having a planar surface;

a first conductive thin film positioned on the surface of the substrate and defining a plurality of first electrodes, one each for each of a plurality of resonators, the plurality of first electrodes being electrically connected together;

a plurality of columns of piezoelectric material, one each positioned on each of the first electrodes of the conductive layer, and each of the plurality of columns defining a separate piezoelectric resonator; and

a second conductive thin film positioned on the plurality of columns and defining a plurality of second electrodes, one each positioned on each of the plurality of columns, the plurality of second electrodes being electrically connected together to connect the plurality of resonators in parallel to form an array of thin film piezoelectric resonators with each separate piezoelectric resonator having unclamped sidewalls for reducing stiffness.