Piezoelectric transducer and process for its production

• US 4,677,336 A
• Filed: 01/31/1986
• Issued: 06/30/1987
• Est. Priority Date: 02/04/1985
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takeuchi, Hiroshi, Kushida, Keiko
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US06/824,728
• Time in Patent Office: 515 Days
• Field of Search: 310/311, 310/320, 310/334-336, 310/348, 310/365, 310/357, 310/358, 310/360, 310/313 R
• US Class Current: 310/334
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00
• CPC Class Codes: H10N 30/045 by polarising
• CPC Class Codes: H10N 30/06 Forming electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: H10N 30/076 by vapour phase deposition
• CPC Class Codes: H10N 30/10513 characterised by the underlying bases, e.g. substrates
• CPC Class Codes: H10N 30/8548 Lead based oxides

Abstract

A piezoelectric transducer made from a piezoelectric thin film based on lead titanate (PbTiO₃): comprising a substrate having sawtooth profile gratings formed on the surface by anisotropic etching; a platinum layer formed by graphoepitaxy method on the substance; a piezoelectric thin film formed on the platinum layer; and an upper electrode layer. Although platinum shows (111) orientation, a (100)-oriented platinum film can be obtained by depositing platinum on said substrate having the gratings by graphoepitaxy. A c-axis-oriented piezoelectric film of excellent piezoelectricity can be formed on this platinum film.

Claims

1. A piezoelectric transducer comprising a substrate having sawtooth profile gratings on the main surface;

a first metal layer comprising a face-centered cubic metal material showing (111) orientation on smooth surface;

a piezoelectric film formed on said first metal layer and comprising a perovskite-type piezoelectric material; and

a second metal layer formed on said piezoelectric film.

2. A piezoelectric transducer according to claim 1, wherein the gratings on the main surface of said substrate have an angle of intersection of slope of 70.5°

.

3. A piezoelectric transducer according to claim 1, wherein said gratings have a pitch of 0.6 μ

m or below.

4. A piezoelectric transducer according to claim 1, wherein said first metal layer comprises platinum (Pt).

5. A piezoelectric transducer according to claim 1, wherein said piezoelectric film comprises a piezoelectric material based on lead titanate.

6. A piezoelectric transducer according to claim 1, wherein said substrate comprises a silicon single crystal.

7. An array piezoelectric transducer in which a plurality of transducer elements are set in array, comprising a substrate having sawtooth profile gratings on that specified regions of the main surface which coincide with the transducer elements;

a first metal layer formed on the main surface of said substrate, comprising a face-centered cubic metal showing (111) orientation on smooth surface, and serving as an electrode common to the transducer elements of said transducer;

a piezoelectric film formed on said first metal layer and comprising a perovskite-type piezoelectric material; and

a second metal layer formed on said specified regions on said piezoelectric film wherein the part in each of the regions serves as an electrode for each of the elements.