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Scanning Excimer Ablation Tool

IP.com Disclosure Number: IPCOM000122434D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Ainsworth, T: AUTHOR [+12]

Abstract

A large-field scanning imaging system has been developed to perform imaging ablation with 308 nm XeCl laser light. A 1 x Dyson-type lens images a portion of a mask onto a portion of the product to be ablated. The lens has a field of 12 mm, and a numerical aperture of 0.05, so g/NA = 6mm. A mirror system comprising a plane mirror and a roof, with all three surfaces mutually orthogonal, is arranged so that the mask image and part have the same orientations. Object and image parity are the same, since there is an even number of reflections, including the one occurring in the lens.

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Scanning Excimer Ablation Tool

      A large-field scanning imaging system has been developed
to perform imaging ablation with 308 nm XeCl laser light.  A 1 x
Dyson-type lens images a portion of a mask onto a portion of the
product to be ablated.  The lens has a field of 12 mm, and a
numerical aperture of 0.05, so g/NA = 6mm.  A mirror system
comprising a plane mirror and a roof, with all three surfaces
mutually orthogonal, is arranged so that the mask image and part have
the same orientations.  Object and image parity are the same, since
there is an even number of reflections, including the one occurring
in the lens.

      The mask and product are held on a common stage, which is
raster scanned to transfer the entire pattern.  The stage is
supported by air feet on a flat granite base.  The illuminated region
is a diamond, and adjacent scans overlap by half its width to obtain
uniformity.

      The illumination system includes a light-tunnel, whose uniform
output is imaged onto the field of view of the lens. Scanning further
increases the uniformity.  Different coupling optics can be used to
adapt to various lasers.

      Alignment is performed by optically combining images of mask
marks and product marks formed by a pair of microscope objectives,
one viewing the part and the other viewing the mask.  The
illumination of the mask and part alignment marks can be
independently optimized. The product is levelled, focussed, and
registered relative to t...