Browse Prior Art Database

TRANSDUCER ELEMENTS WITH A SEMICONDUCTOR CAVITY AND PIEZOELECTRIC FILM

IP.com Disclosure Number: IPCOM000007772D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-22
Document File: 2 page(s) / 108K

Publishing Venue

Motorola

Related People

Ming Liaw: AUTHOR [+3]

Abstract

The term "transducer" applies to any piezoelec- tric devices which perform the transformation of elec- tric energy to mechanical energy or vice versa. One example of such a transducer is the piezoelectric thin film resonator which can be potentially used as RF filters, IF filters, chemical sensors, and pressure sensors. The fundamental elements of the transducer are proposed. These transducer elements are (1) a semiconductor cavity, (2) a suspended diaphragm consisting of a piezoelectric film, and (3) metal elec- trodes contacting the diaphragm. The diaphragm includes an etch-stop layer for easy fabrication of the semiconductor cavity. The etch-stop layer also serves as a nucleation layer for preferred orientation grain growth of the piezoelectric film (eg.AlN ) by the sputter deposition. A good nucleation layer requires a planar, smooth and dense surface. Silicon dioxide formed by thermal oxidation of Si or silicon nitride formed by chemical deposition method can serve as a good etch stop and nucleation layer. Fig- ure 1 shows an example of the thin film piezoelec- tric transducer consisting ofthese three elements.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 2

8 M-LA Technical Developments

TRANSDUCER ELEMENTS WITH A SEMICONDUCTOR CAVITY AND PIEZOELECTRIC FILM

by Ming Liaw, Asher Mstsuda and Karen Bartholomew

  The term "transducer" applies to any piezoelec- tric devices which perform the transformation of elec- tric energy to mechanical energy or vice versa. One example of such a transducer is the piezoelectric thin film resonator which can be potentially used as RF filters, IF filters, chemical sensors, and pressure sensors. The fundamental elements of the transducer are proposed. These transducer elements are (1) a semiconductor cavity, (2) a suspended diaphragm consisting of a piezoelectric film, and (3) metal elec- trodes contacting the diaphragm. The diaphragm includes an etch-stop layer for easy fabrication of the semiconductor cavity. The etch-stop layer also serves as a nucleation layer for preferred orientation grain growth of the piezoelectric film (eg.AlN ) by the sputter deposition. A good nucleation layer requires a planar, smooth and dense surface. Silicon dioxide formed by thermal oxidation of Si or silicon nitride formed by chemical deposition method can serve as a good etch stop and nucleation layer. Fig- ure 1 shows an example of the thin film piezoelec- tric transducer consisting ofthese three elements.

  An advantage ofthis transducer structure is that it can be integrated with semiconductor devices built on the same substrate. Another integration option is by flip-chip bonding of the transducer to a se...