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Self-Aligned Photo Process Using Reflection

IP.com Disclosure Number: IPCOM000103083D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Cook, HC: AUTHOR [+2]

Abstract

By using reflected light from a conductive feature below a transparent insulating layer to add to incident light, total light flux seen by a top layer of photoresist is made to be sufficient to reach an exposure threshold only above the conductive feature. Thus, holes in the insulating layer may be made which line up perfectly with a conductive feature below the insulator, for instance.

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Self-Aligned Photo Process Using Reflection

      By using reflected light from a conductive feature below a
transparent insulating layer to add to incident light, total light
flux seen by a top layer of photoresist is made to be sufficient to
reach an exposure threshold only above the conductive feature.  Thus,
holes in the insulating layer may be made which line up perfectly
with a conductive feature below the insulator, for instance.

      Referring to the figure, reflective features 10 and 12 in
transmissive or absorptive substrate 14 has transparent insulating
layer 16 deposited on top.  To create a hole in layer 16 above
feature 12 and not above feature 10, a block mask is first defined in
light absorbing photoresist 18 by a conventional photo-masking
process.  Then, photoresist 20 is applied and blanket exposed to
collimated light flux of insufficient quantity to reach the exposure
threshold of photoresist 20 except in regions having sufficient
reflected light flux, e.g., above feature 12.  After photoresist
development, a hole is etched in layer 18 and all photoresist may be
stripped leaving a perfectly aligned hole in layer 16 above feature
12.

      Disclosed anonymously.