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Surface Profilometer With Ultra-high Resolution

IP.com Disclosure Number: IPCOM000121427D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Nonnenmacher, M: AUTHOR [+3]

Abstract

The surface profilometer shown in the figure and described in this article comprises a micromechanically produced cantilever beam with an integrated tip, made of, say, Si3N4 or single crystal silicon, referred to as probe, and a dual beam interferometer. The probe is comparable to the force sensor used in an atomic force microscope or to the stylus of a stylus profilometer.

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Surface Profilometer With Ultra-high Resolution

      The surface profilometer shown in the figure and
described in this article comprises a micromechanically produced
cantilever beam with an integrated tip, made of, say, Si3N4 or single
crystal silicon, referred to as probe, and a dual beam
interferometer.  The probe is comparable to the force sensor used in
an atomic force microscope or to the stylus of a stylus profilometer.

      The probe tip scans across the surface of a test sample
following the roughness of the surface topography.  The probe or
measuring beam M of a dual beam interferometer is reflected by the
back of the cantilever, while the second (reference) beam R is
reflected by the sample surface.  The two beams interfer, yielding a
signal proportional to their phase difference.  As the path length of
the probe beam is modulated by the vertical displacement of the
cantilever, the signal indicates the roughness of the sample surface.
Such an optical interferometer is capable of measuring surface
topographies at a very high vertical resolution exceeding 1 nm,
whereas the lateral resolution is limited by the wavelength of light
to about 0.5 mm.  A principal advantage of the interferometer, which
is used for difference measurements, is its inherent insensitivity to
vertical vibrations or drifts of the sample or sensor.

      The lateral resolution of the described profilometer depends on
the sharpness of the probe tip apex.  An apex radius of...