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Low Frequency Pre-Etching for High Frequency Open Repair

IP.com Disclosure Number: IPCOM000120959D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 64K

Publishing Venue

IBM

Related People

Rath, D: AUTHOR [+2]

Abstract

A small break in a copper circuit line can be bridged by immersing the region of the break in an unacidified copper sulfate solution and applying a high-frequency, low-amplitude AC signal across the break, as has been previously described. Such an AC signal induces the growth of copper dendrites that bridge the break. To complete the repair, a second step is required which involves submerging the partially repaired circuit in an acid copper solution and applying relatively high-amplitude AC current to the partially repaired line. For a reasonably repeatable and reliable repair by such a multi- step process, the aspect ratio of the break (i.e., the gap length to the circuit line width) should be less than approximately one.

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Low Frequency Pre-Etching for High Frequency Open Repair

      A small break in a copper circuit line can be bridged by
immersing the region of the break in an unacidified copper sulfate
solution and applying a high-frequency, low-amplitude AC signal
across the break, as has been previously described. Such an AC signal
induces the growth of copper dendrites that bridge the break.  To
complete the repair, a second step is required which involves
submerging the partially repaired circuit in an acid copper solution
and applying relatively high-amplitude AC current to the partially
repaired line. For a reasonably repeatable and reliable repair by
such a multi- step process, the aspect ratio of the break (i.e., the
gap length to the circuit line width) should be less than
approximately one.

      We have found that the first step of the repair, i.e., the
initial bridging by copper-dendrite growth, is sensitive to the
geometry of the break in the line.  In particular, sharp corners tend
to nucleate dendrite growth most rapidly due to the concentration of
the electric field at regions of sharp points or discontinuities.  As
a result, copper dendrites tend to project outward from the line when
growth occurs from such corners, arching from one corner of an edge
to the opposite edge.  Such outward-projecting dendrite growth has
the potential for creating shorts to neighboring lines.  Observation
confirms that bridges tend to grow most frequently at corners, which
is not...