PIEZOELECTRIC THIN MULTILAYER COMPOSITE RESONATORS

• US 3,590,287 A
• Filed: 09/05/1968
• Issued: 06/29/1971
• Est. Priority Date: 11/17/1966
• Status: Expired due to Term

• Current Assignee: Don A. Berlincourt, Todd R. Sliker
• Original Assignee: Don A. Berlincourt, Todd R. Sliker
• Inventors: Berlincourt, Don A., Sliker, Todd R.
• Application Number:
  US04/768,584
• Time in Patent Office: 1,027 Days
• US Class Current: 310/321
• CPC Class Codes: H03H 9/0207 the vibration mode being harmonic
• CPC Class Codes: H03H 9/02102 of temperature influence cutting angles H03H9/02015
• CPC Class Codes: H03H 9/02133 of stress
• CPC Class Codes: H03H 9/178 of a laminated structure of multiple piezoelectric layers with inner electrodes
• CPC Class Codes: H03H 9/60 Electric coupling means therefor H03H9/0095 takes precedence

Abstract

Alternate thin layers of piezoelectric material having differently orientated piezoelectric axes with respect to each other are placed on a substrater and electroded to form a high frequency resonator. The thickness mode resonant frequency of the composite structure corresponds a proper fraction of the resonator operating frequency, layer thickness varying between 0.2 and 100 microns corresponding to approximately 10 percent of the substrate thickness.

Claims

1. A high frequency piezoelectric resonator device for operation at a frequency in the range represented by a wavelength of the order of from 0.2 to 100 microns, said device comprising in combination a wafer substrate, a plurality of alternate superposed layers of piezoelectric material of first and second different types with respect to piezoelectric axes and capable of acoustic vibrations, and a plurality of electrodes, there being at least two of said layers of the first type having parallel faces and having piezoelectric properties, each electrode being applied to a different one of said faces, the superposed layers being mounted on said substrate with parallel faces in force transmitting relation to each other with means for energizing one of the piezoelectric layers, the layers and substrate together forming a composite structure having an overall thickness defining a resonant frequency in a thickness mode of vibration corresponding to 1/n times the frequency at which the resonator is to be operated, where n is any integer, and the thickness of each layer is substantially in the range of from 0.2 to 100 microns and is of the order of 1 percent to 10 percent of substrate thickness.

2. A high frequency piezoelectric resonator device for operation at a frequency in the range represented by a wavelength of the order of 0.2 to 100 microns, said device comprising in combination a wafer substrate, a plurality of superposed layers of piezoelectric material mounted thereon with parallel surfaces in force transmitting relation to each other with means for energizing one of the layers, together formiNg a composite structure having an overall thickness defining a resonant frequency in a thickness mode of vibration corresponding to 1/n times the frequency at which the resonator is to be operated, where n is any integer, and the layer thickness is substantially in the range from 0.2 to 100 microns and is of the order of 1 percent to 10 percent of substrate thickness, the piezoelectric axes of successive layers being tilted from a normal to the surface.

3. A device as in claim 2 wherein the piezoelectric axes of successive layers are tilted in different directions from the normal.

4. A high frequency piezoelectric resonator device comprising in combination a wafer substrate, a plurality of superposed layers of piezoelectric material mounted thereon with parallel faces in force transmitting relation to each other with means for energizing one of the layers, together forming a composite structure having an overall thickness defining a resonant frequency in a thickness mode of vibration corresponding to 1/n times the frequency at which the resonator is to be operated, wherein n is any integer and the layer thickness is substantially in the range from 0.2 to 100 microns and is of the order of 1 percent to 10 percent of substrate thickness there being alternate layers of piezoelectric material capable of acoustic vibrations, said alternate layers being of different types with respect to their piezoelectric axes, said layers of the first type having parallel faces and having piezoelectric properties with piezoelectric axes extending in a predetermined direction, the layers of the second type having its piezoelectric axes oriented in a different direction the axes of both types being titled with respect to a normal from the parallel faces, and said layers of the first type having a plurality of electrodes, each electrode being applied to a different one of said faces, each of at least three of such electrodes being adapted for connection to an exterior terminal.

5. A device as in claim 4 wherein the layers of the first and second types differ with respect to piezoelectric response.

6. A device as in claim 4 wherein the layers of the second type have opposite faces which are electrically connected.

7. A device as in claim 4 wherein the layers of the second type are inactive piezoelectrically.

8. A device as in claim 4 wherein the layers of the first and second types are piezoelectric with piezoelectric responses differently oriented.

9. A device as in claim 4 wherein the layers have a thickness shear mode of vibration with piezoelectric axes of layers of the first type tilting at one angle with respect to a normal to the layer face and piezoelectric axes of layers of the second type tilting at a different angle with respect to a normal to the faces of the layers.