Browse Prior Art Database

Structure for Inspection of Voids in Dielectric Thin Films

IP.com Disclosure Number: IPCOM000115165D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Chiu, SL: AUTHOR

Abstract

A technique is described that enhances the detectability of voids such as gas bubbles that are trapped in dielectric coatings during semiconductor wafer processing. To ensure process integrity, void monitoring wafers are given a dielectric coating, and then are inspected by a particle counter. It is proposed that the monitor wafers be given a highly reflective coating prior to the dielectric coating to increase the scattered light that is returned to the particle counter where voids occur.

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Structure for Inspection of Voids in Dielectric Thin Films

      A technique is described that enhances the detectability of
voids such as gas bubbles that are trapped in dielectric coatings
during semiconductor wafer processing.  To ensure process integrity,
void monitoring wafers are given a dielectric coating, and then are
inspected by a particle counter.  It is proposed that the monitor
wafers be given a highly reflective coating prior to the dielectric
coating to increase the scattered light that is returned to the
particle counter where voids occur.

      A particle counter, such as the Tencor surface scan tool, is
commonly used to detect voids caused by gas bubbles that are trapped
in dielectric coatings.  The refraction index of bubbles differs from
that of the dielectric coating so that light from the particle
counter is scattered by each bubble.  If enough of the scattered
light is returned to the particle counter, the particle counter
detects the presence of a bubble.  One way to increase the intensity
of the scattered light is to deposit a highly reflective layer onto
the monitor wafers prior to applying the dielectric coating.

      The following schedule describes one method for using a highly
reflective coating on the monitor wafers.
  1.  Select a reflective material that is suitable for the light
       source in the particle counter.  For example, if a HeNe light
       source with a wavelength of about 632.8 nm is used, t...