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Method of making suspended thin-film semiconductor piezoelectric devices

Patent ·
OSTI ID:873737
 [1];  [2]
  1. Albuquerque, NM
  2. Cedar Crest, NM
+ Show Author Affiliations
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.
Research Organization:
SANDIA CORP
DOE Contract Number:
AC04-94AL85000
Assignee:
Sandia Corporation (Albuquerque, NM)
Patent Number(s):
US 6232139
OSTI ID:
873737
Country of Publication:
United States
Language:
English

References (2)

Piezoelectric photoacoustic study of Al/sub x/Ga/sub 1-x/As epitaxial layer (x=0.22, 0.28, 0.5) grown on semi-insulating GaAs substrate conference January 1998
X-band thin film acoustic filters on GaAs journal January 1993

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/438/
1-5
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break
bubbles
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containing
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device
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embodiment
epitaxially
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etch
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openings
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reducing
reducing agent
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sacrificial
selective
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suspended
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thickness
thin-film
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