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Microprofiling Transparent Layers

IP.com Disclosure Number: IPCOM000120514D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Elsner, G: AUTHOR [+3]

Abstract

A method is proposed by which, using readily modifiable semiconductor production apparatus, vias and lines, developed in resist 1, may be non-destructively inspected for resist residues 2. For this purpose, a dye is admixed to the resist, with microprofiling of the tested structure being achieved by photometry.

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Microprofiling Transparent Layers

      A method is proposed by which, using readily modifiable
semiconductor production apparatus, vias and lines, developed in
resist 1, may be non-destructively inspected for resist residues 2.
For this purpose, a dye is admixed to the resist, with microprofiling
of the tested structure being achieved by photometry.

      Fluorescent dyes are dissolvable in the resist.  When a
dye/resist mixture is illuminated at the absorbable dye wavelength,
the amount of fluorescent light is solely dependent on the incident
light intensity and the quantity of the dissolved dyes.  If resist
and dyes are well mixed, the fluorescent light is proportional to the
layer thickness.  This effect is used for microprofiling. To obtain a
good signal-to-noise ratio for microprofiling, a laser scanner is
employed.  If the scanner is used confocally, the resolution limit of
0.61 $ g/N.A. may be raised to 0.36 $ g/N.A. (g = wavelength, N.A. =
numerical aperture).  Another advantage of confocal imaging is that
information is only supplied from a closely limited layer region
(sectioning).  This means that, in the focus, layers on top of or
below the layer do not contribute to the formation of the image.
Thus, it is also possible to profile transparent layers of silicon
oxide or nitride by using an immersion liquid with dissolved dyes.
During resist inspection, the immersion liquid has the advantage that
the phase structure impairing the illumination process is eliminated
by a suitably adapted diffraction index.

      Confocal laser scanning microscopes have previous...