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Method for On-Line Monitoring of Oxidation States in Ferric Etching Solutions

IP.com Disclosure Number: IPCOM000099207D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 87K

Publishing Venue

IBM

Related People

Bindra, P: AUTHOR [+2]

Abstract

A method is disclosed for simultaneous, on-line of the concentrations of critical species in chloride etchants. The concentrations of ferric ferrous ions, and cupric ions (when the metal being is copper) impact the activity of the etchant (etch Real-time information about the concentrations of species facilitates control of these etch processes.

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Method for On-Line Monitoring of Oxidation States in Ferric Etching Solutions

       A method is disclosed for simultaneous, on-line of the
concentrations of critical species in chloride etchants.  The
concentrations of ferric ferrous ions, and cupric ions (when the
metal being is copper) impact the activity of the etchant (etch
Real-time information about the concentrations of species facilitates
control of these etch processes.

      Fe(III) ions in chloride-based etchants can be reduced solid
electrodes, such as gold or glassy carbon, at cathodic of
approximately +0.45 V vs. saturated reference electrode (SCE).  By
scanning the of a solid electrode in a negative direction, into
region where Fe(III) reduction occurs, a cathodic can be measured
which is due to the reduction of to Fe(II).  The magnitude of this
current response proportional to the concentration of Fe(III) in
solution.

      Likewise, Fe(II) ions in chloride solution can be to Fe(III) at
a solid surface, such as gold or carbon, at potentials positive of
approximately +0.45 vs. SCE.  In this case, an anodic current
response can be which is proportional to concentration of Fe(II)
solution.

      Cu(II) ions (byproduct of copper etching) can be reduced a
similar manner at potentials negative of approximately V vs. SCE.

      On a stationary electrode, the current output for the described
potential scans will be in the form of a  The height of the peak will
be proportional to the of the species being reduced or oxidized,
conditions of fixed temperature, potential scan rate, area and
solution agitation.  On a rota...