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Title: Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

Abstract

Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

Inventors:
 [1]
  1. Albuquerque, NM
Issue Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
971540
Patent Number(s):
7597819
Application Number:
11/017,108
Assignee:
Sandia Corporation (Albuquerque, NM)
Patent Classifications (CPCs):
B - PERFORMING OPERATIONS B81 - MICROSTRUCTURAL TECHNOLOGY B81C - PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
C - CHEMISTRY C23 - COATING METALLIC MATERIAL C23F - NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Hankins, Matthew G. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films. United States: N. p., 2009. Web.
Hankins, Matthew G. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films. United States.
Hankins, Matthew G. Tue . "Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films". United States. https://www.osti.gov/servlets/purl/971540.
@article{osti_971540,
title = {Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films},
author = {Hankins, Matthew G},
abstractNote = {Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2009},
month = {10}
}

Works referenced in this record:

Electrochemical Coupling Effects on the Corrosion of Silicon Samples in HF Solutions
journal, January 1995


Etching and Passivation of Silicon in Alkaline Solution:  A Coupled Chemical/Electrochemical System
journal, June 2001


Electrochemical aspects of corrosion resistance and etching of metallizations for microelectronics
journal, July 1995


Galvanic Cell Formation in Silicon/Metal Contacts:  The Effect on Silicon Surface Morphology
journal, June 2000


Galvanic etching for sensor fabrication
journal, October 2000


Galvanic cell formation: a review of approaches to silicon etching for sensor fabrication
journal, January 2001


Silicon dioxide sacrificial layer etching in surface micromachining
journal, March 1997


IC-Compatible Polysilicon Surface Micromachining
journal, August 2000


Corrosion Rate of n- and p-Silicon Substrates in HF, HF + HCl, and HF + NH[sub 4]F Aqueous Solutions
journal, January 1999


Kinetics of electrochemical corrosion of silicon wafers in dilute HF solutions
journal, February 1997