Browse Prior Art Database

Dry Lift Off Process

IP.com Disclosure Number: IPCOM000109298D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 3 page(s) / 70K

Publishing Venue

IBM

Related People

Modjesch, D: AUTHOR [+2]

Abstract

This article describes a novel process which considerably reduces the stress to which both the carrier and the thin-film layers arranged thereon are subjected. As a result, there are fewer failures.

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This is the abbreviated version, containing approximately 97% of the total text.

Dry Lift Off Process

       This article describes a novel process which considerably
reduces the stress to which both the carrier and the thin-film layers
arranged thereon are subjected.  As a result, there are fewer
failures.

      The lift-off process, which is most commonly used to deposit
metal structures for microelectronic applications, consists of three
steps:
      1.   Producing the stencil (vapor deposition mask).
      2.   Blanket vapor depositing the metallization.
      3.   Removing the stencil along with superfluous metallization.

      This article concerns step 3.

      Previously, the entire layer structure was treated with a
solvent until the component was clean (N-methylpyrrolidone, N-butyl
acetate).  To reduce the duration of this step from 40 to 60 to 20 to
30 minutes, mechanical work is additionally carried out by
ultrasound. This may lead to delamination of the metallization,
swelling of existing organic layers and chipping of ceramic carriers.

      According to the novel process, the entire upper portion of the
stencil along with superfluous metallization is removed in a dry step
by diamond micro-milling.  This is possible because of the space
existing between the top edge of the second conductor plane and the
bottom edge of the residual metal (see relevant figure).

      Subsequently, the polyimide remaining between the metal
structures may be removed by reworking (duration about 4 to 6
minut...