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Elimination of Ablation Debris Contamination in Laser Etching of Polyimide Films

IP.com Disclosure Number: IPCOM000121738D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 86K

Publishing Venue

IBM

Related People

Srinivasan, R: AUTHOR

Abstract

Described is a method of avoiding debris formation of polyimide surfaces patterned by ultraviolet lasers contaminated by particle debris. Three methods are proposed for carrying out laser ablation of a polyimide surface in an atmosphere of pure oxygen.

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Elimination of Ablation Debris Contamination in Laser Etching of
Polyimide Films

      Described is a method of avoiding debris formation of
polyimide surfaces patterned by ultraviolet lasers contaminated by
particle debris.  Three methods are proposed for carrying out laser
ablation of a polyimide surface in an atmosphere of pure oxygen.

      In general, the structure of polyimides and KAPTON* in
particular is such that carbon particle formation cannot be a primary
photochemical process.  The carbon must leave the polyimide film as
C1, C2, and C3, which must subsequently form larger clusters and
ultimately carbon particles.  The intervention of oxygen at an early
stage in this chain of reactions oxidizes the carbon and therefore
lowers or eliminates the yield of debris.

      Typically, the debris from the laser ablation of KAPTON using
308 nm radiation is entirely made up of carbon particles [*].  The
amount of debris from KAPTON 308 nm is sensitive to the amount of
oxygen in the ambient gas in contact with the surface of the film.
Fig. 1 is a plot of the debris yield verses oxygen pressure in the
XeCl laser etching of KAPTON.  The curve shows that there is a small
decrease in the amount of debris formed when going from an atmosphere
that is devoid of oxygen to air (20% oxygen), whereas, there is a
dramatic decrease of 80% in going to an atmosphere of pure oxygen.
The three methods described herein are based on carrying out the
laser ablation of a polyimide surface in an atmosphere of pure
oxygen.

      In the first method, the product is enclosed in a chamber, as
shown in Fig. 2, through which a stream of oxygen at one atmosphere
is flowing.  To minimize debris production in the drilling of a
po...