Surface analysis of thin films using interferometric technique
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Date
2014-10-07
Authors
Kariuki, Robinson Njunji
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
The use of CCD cameras, computers, and softwares in interferometry has enhanced tremendous
improvement in the inspection of the optoelectronic devices being manufactured. Thin films are
fabricated through various techniques on a substrate. Research on characterization techniques of
thin films such as x-ray diffraction, scanning electron microscopy and energy-dispersive x-rays
have being done. However, little research has been carried out in analyzing the surface profile
and thickness of thin films by interferometric technique. To measure these parameters, thin films
having different thickness of zinc selenide (ZnSe) and leadselenide (pbSe) will be deposited by
evaporation technique onto a pre-cleaned glass slide. The interferometric technique involves the
use of optical system where He-Ne laser light is filtered and then splitted into two beams that
take different directions. The two beams re-unite again after travelling different directions, where
one of the beams passes through the thin film resulting to an interference pattern. The resulting
interference pattern is determined by the phase difference between the two waves. If the waves
are in phase, constructive interference occurs while destructive interference occurs if they are out
of phase. The interference patterns will be recorded by the CCD camera and stored in the
computer for analysis. The surface profile will be determined by subtracting the fringe patterns
of the substrate from the fringe patterns of the thin films. The thickness of the films will be
detennined by using the fringe width of the film and the shift between the interference fringes of
the substrate and the film. A software will be used to analyze the interferograms of the thin films
for the surface profiles.