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Browse Prior Art Database

Three-Dimensional Etch Mask for Laser Ablation

IP.com Disclosure Number: IPCOM000112761D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 99K

Publishing Venue

IBM

Related People

Lueck, P: AUTHOR [+4]

Abstract

This article describes a dielectric mask by means of which the scope of laser projection etching for laser ablation of patterns in organic thin film layers can be vastly increased, thus allowing to etch various kinds of 3-dimensional patterns.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Three-Dimensional Etch Mask for Laser Ablation

      This article describes a dielectric mask by means of which the
scope of laser projection etching for laser ablation of patterns in
organic thin film layers can be vastly increased, thus allowing to
etch various kinds of 3-dimensional patterns.

      State-of-the-art masks for high-power laser projection contain
only 'clear' and 'opaque', i.e., light transmissive and light
reflecting areas, so that the etch process always yields a constant
etch depth for all kind of patterns.

      The new mask contains areas of different levels of
reflection/transmission.  In combination with the typical dependence
of the laser ablation depth on the laser fluence as shown in Fig.  1,
etch patterns of predetermined, locally different depths can be
produced.  Such patterns can be obtained, e.g., by designing the sum
of all patterns in one mask and assigning appropriate different
levels of reflection/transmission to the individual pattern areas as
shown in Fig. 2.  Flood exposure or scanning flood exposure of the
mask in Fig. 2, when projected onto a material with ablation
characteristics corresponding to Fig. 1 will produce an etch pattern
as depicted in Fig. 3.

      If such a pattern would have to be produced with standard
masks, a number of N individual projection ablation process steps
would be necessary, with N being the number of different local levels
of mask transmission.  Each of these process steps would require an
individual mask with special registration and would introduce certain
overlay error.  The described mask, however, replaces all these
processes without showing any overlay error.

      Application of such a mask therefore leads to considerable
reduction of process steps in manufacturing of multilayer devices, of
3- dimensional molds for reproduction of devices or of
micromechanical devices.

      One example of an application of the described mask is thin
film wiring on printed circuit boards.  Typically, such multilayer
structures are sequentially processed, i.e., starting with
lithographic exposure/develop/etching of via holes, followed by metal
deposition of the via connection and a subsequent second sequence of
lithography/develop/etching of the...