Browse Prior Art Database

Ultrafast Ellipsometric Mapping of Thin Films

IP.com Disclosure Number: IPCOM000111076D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Novotny, VJ: AUTHOR

Abstract

Disclosed is an ultrafast ellipsometric measurement technique based on heterodyne interferometry of moving samples. The technique is applicable to sensitive mapping of optical constants and thickness of thin films such as lubricant films and overcoats used in magnetic recordings.

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Ultrafast Ellipsometric Mapping of Thin Films

      Disclosed is an ultrafast ellipsometric measurement technique
based on heterodyne interferometry of moving samples.  The technique
is applicable to sensitive mapping of optical constants and thickness
of thin films such as lubricant films and overcoats used in magnetic
recordings.

      Single ellipsometric measurements based on detection of changes
in polarization of reflected light can yield up to two independent
unknowns, such as film thickness and refractive index.  Change in
polarization of light is usually monitored using a mechanically
rotating polarizer or analyzer and consequently the measurement is
slow, typically 100 msec or longer.  Thus, when hundreds or thousands
of measurements per sample are required, the measurement throughput
is too slow, even for sampling inspection.  The concept proposed here
speeds up the measurement of polarization of light by a factor of up
to 10000  times so that fast mapping with rotating samples is possible.
The principle of the polarization measurement is optical heterodyne
interferometry which does not require any mechanical motion.  The
schematics of the device are shown in the Figure.

      A light beam is split into s and p polarized parts and these
are modulated with slightly differing frequencies
(&Delta.f&nearly.1MHz).  Subsequently, the p and s polarized,
modulated beams are recombined.  A portion of the beam is split into
the reference detector and the remainde...