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Title: Method of making suspended thin-film semiconductor piezoelectric devices

Abstract

A process for forming a very thin suspended layer of piezoelectric material of thickness less than 10 microns. The device is made from a combination of GaAs and AlGaAs layers to form either a sensor or an electronic filter. Onto a GaAs substrate is epitaxially deposited a thin (1-5 micron) sacrificial AlGaAs layer, followed by a thin GaAs top layer. In one embodiment the substrate is selectively etched away from below until the AlGaAs layer is reached. Then a second selective etch removes the sacrificial AlGaAs layer, that has acted here as an etch stop, leaving the thin suspended layer of piezoelectric GaAs. In another embodiment, a pattern of small openings is etched through the thin layer of GaAs on top of the device to expose the sacrificial AlGaAs layer. A second selective etch is done through these openings to remove the sacrificial AlGaAs layer, leaving the top GaAs layer suspended over the GaAs substrate. A novel etchant solution containing a surface tension reducing agent is utilized to remove the AlGaAs while preventing buildup of gas bubbles that would otherwise break the thin GaAs layer.

Inventors:
 [1];  [2]
  1. (Albuquerque, NM)
  2. (Cedar Crest, NM)
Issue Date:
Research Org.:
SANDIA CORP
OSTI Identifier:
873737
Patent Number(s):
6232139
Assignee:
Sandia Corporation (Albuquerque, NM) SNL
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
method; suspended; thin-film; semiconductor; piezoelectric; devices; process; forming; layer; material; thickness; 10; microns; device; combination; gaas; algaas; layers; form; sensor; electronic; filter; substrate; epitaxially; deposited; 1-5; micron; sacrificial; followed; top; embodiment; selectively; etched; below; reached; selective; etch; removes; acted; stop; leaving; pattern; openings; expose; remove; novel; etchant; solution; containing; surface; tension; reducing; agent; utilized; preventing; buildup; gas; bubbles; otherwise; break; gas bubbles; algaas layer; etch stop; epitaxially deposited; top layer; solution containing; reducing agent; surface tension; gas bubble; piezoelectric material; gaas substrate; gaas layer; selectively etched; thin-film semiconductor; film semiconductor; selective etch; algaas layers; /438/

Citation Formats

Casalnuovo, Stephen A., and Frye-Mason, Gregory C. Method of making suspended thin-film semiconductor piezoelectric devices. United States: N. p., 2001. Web.
Casalnuovo, Stephen A., & Frye-Mason, Gregory C. Method of making suspended thin-film semiconductor piezoelectric devices. United States.
Casalnuovo, Stephen A., and Frye-Mason, Gregory C. Mon . "Method of making suspended thin-film semiconductor piezoelectric devices". United States. https://www.osti.gov/servlets/purl/873737.
@article{osti_873737,
title = {Method of making suspended thin-film semiconductor piezoelectric devices},
author = {Casalnuovo, Stephen A. and Frye-Mason, Gregory C.},
abstractNote = {A process for forming a very thin suspended layer of piezoelectric material of thickness less than 10 microns. The device is made from a combination of GaAs and AlGaAs layers to form either a sensor or an electronic filter. Onto a GaAs substrate is epitaxially deposited a thin (1-5 micron) sacrificial AlGaAs layer, followed by a thin GaAs top layer. In one embodiment the substrate is selectively etched away from below until the AlGaAs layer is reached. Then a second selective etch removes the sacrificial AlGaAs layer, that has acted here as an etch stop, leaving the thin suspended layer of piezoelectric GaAs. In another embodiment, a pattern of small openings is etched through the thin layer of GaAs on top of the device to expose the sacrificial AlGaAs layer. A second selective etch is done through these openings to remove the sacrificial AlGaAs layer, leaving the top GaAs layer suspended over the GaAs substrate. A novel etchant solution containing a surface tension reducing agent is utilized to remove the AlGaAs while preventing buildup of gas bubbles that would otherwise break the thin GaAs layer.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2001},
month = {1}
}

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