Browse Prior Art Database

The Electrical-Short Free Through Hole

IP.com Disclosure Number: IPCOM000118477D
Original Publication Date: 1997-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 99K

Publishing Venue

IBM

Related People

Shinohara, M: AUTHOR [+2]

Abstract

Disclosed is an electrical-short free-through hole on a light valve module formed by semiconductor technology.

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The Electrical-Short Free Through Hole

      Disclosed is an electrical-short free-through hole on a light
valve module formed by semiconductor technology.

      By putting the narrow slit around the through hole on the
through-layer which has low reflectivity, the via hole pattern is
able to be printed with no mask.  The slit isolates the through-layer
from via hole.

      Fig. 1 shows the mask image for the through hole.  The slit
width is set under the resolution limit of via hole formation photo
process.  After through-hole formation and the insulator film
deposition, the via hole photo process is done with no mask on
condition that the dose is around 60% of optimized energy (self
alignment).

      Fig. 2 shows the mechanism of self-alignment at via hole photo
process.  In A region, the intensity of energy that is reflected
through the layer surface is too weak to print.  Since the Aluminum
surface has  high reflectivity, the photo resist in B region gets
enough energy to be printed.

      In C region, since the slit width is under the resolution limit
of the via hole photo process, the reflected energy from the Aluminum
surface is almost negligible.  As a result, the via hole pattern is
formed only in B region.

      This technique of the electrical-short free hole is not limited
on light valve module, but is also applicable on the common Large
Scale Integration (LSI) which has many through-hole layers.