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Method for Preventing Undesired Plating Using SIR

IP.com Disclosure Number: IPCOM000119263D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Chen, JC: AUTHOR [+3]

Abstract

The SIR (self-induced repair) technique has been used successfully to deposit copper on thinned out regions of circuit lines (*). The SIR technique is self-aligning as it applies an AC current to a circuit in need of repair giving rise to preferential heating of the thinned out region (neckdown). This, in turn, causes plating to occur when the circuit is immersed in a copper sulfate solution. Local heating causes a shift in the rest potential with the hotter region becoming cathodic and hence plating while colder regions dissolve and provide copper ions to maintain charge neutrality.

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Method for Preventing Undesired Plating Using SIR

      The SIR (self-induced repair) technique has been used
successfully to deposit copper on thinned out regions of circuit
lines (*).  The SIR technique is self-aligning as it applies an AC
current to a circuit in need of repair giving rise to preferential
heating of the thinned out region (neckdown).  This, in turn, causes
plating to occur when the circuit is immersed in a copper sulfate
solution.  Local heating causes a shift in the rest potential with
the hotter region becoming cathodic and hence plating while colder
regions dissolve and provide copper ions to maintain charge
neutrality.

      One problem that is often observed with this type of repair is
that the circuit line some distance away from the repair begins to
plate at the higher repair currents.  A means for preventing this
undesirable feature from occurring by using a flow system is shown in
the figure.  The copper sulfate solution flows at a velocity, on the
order of 5-10 cm/s, preferably at right angles to the direction of
the circuit line, to provide cooling.  In this manner heat transfer
to the flowing solution prevents a large temperature build-up along
the line so that very little, if any, shift in the rest potential
takes place.  Thus, the major portion of the line is left unaffected
as it should be while the heat is concentrated at the defect.
Localized plating will, therefore, continue in that region
exclusively.

      An addit...