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Reduction Stepper for Printing Repeating and Nonrepeating Patterns

IP.com Disclosure Number: IPCOM000105922D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Bobroff, N: AUTHOR [+2]

Abstract

Fabrication of vias in polymers and ceramics by direct laser ablation requires high laser fluence levels. Laser ablation masks that can withstand the high laser powers, such as patterned high power dielectric reflectors, are difficult to fabricate and repair, and consequently are very expensive. A reduction mask set and step-and-repeat lithography tool for via ablation is described which eliminates the need for complex dielectric masks. It also makes it possible to print nonrepeating patterns on a step-and-repeat tool so that unit magnification scanning tools are not required. The invention takes advantage of the via design rules which place the vias on a fixed center-to-center grid.

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Reduction Stepper for Printing Repeating and Nonrepeating Patterns

      Fabrication of vias in polymers and ceramics by direct laser
ablation requires high laser fluence levels.  Laser ablation masks
that can withstand the high laser powers, such as patterned high
power dielectric reflectors, are difficult to fabricate and repair,
and consequently are very expensive.  A reduction mask set and
step-and-repeat lithography tool for via ablation is described which
eliminates the need for complex dielectric masks.  It also makes it
possible to print nonrepeating patterns on a step-and-repeat tool so
that unit magnification scanning tools are not required.  The
invention takes advantage of the via design rules which place the
vias on a fixed center-to-center grid.

      An arbitrary array of via holes can be printed using two masks
which are superposed.  The first mask is patterned with a via of the
desired feature dimension (allowing for the magnification) at each
grid location.  The overall mask size is 50mm X 50mm for a 4X
reduction stepper printing a 12.5mm X 12.5mm chip site via array.  A
portion of the mask is shown in figure 1a.  The 80 um vias on a 160
um grid on the mask of figure 1a correspond to 20um vias on a 40 um
grid at the part.  The via pattern on this mask which is to be
printed at each site is selected by a second mask, held in close
proximity to the first mask.  Large apertures on this second mask
overlay those via holes which are to printe...