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Measuring the Thickness of Thin Transparent Films

IP.com Disclosure Number: IPCOM000075292D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Biedermann, E: AUTHOR

Abstract

A VAMFO (Variable Angle Monochromatic Fringe Observation) setup comprises a photosensitive element to measure the reflectivity within an angle of incidence ranging from 5 to 80 degrees. A computer program has been written to draft reflectivity curves as a function of the angle of incidence with the thickness of the thin film serving as a parameter, particularly in the range of 0 to 2500 angstroms. The index of refraction of substrate and thin film is assumed as being known for the proposed measuring operation.

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Measuring the Thickness of Thin Transparent Films

A VAMFO (Variable Angle Monochromatic Fringe Observation) setup comprises a photosensitive element to measure the reflectivity within an angle of incidence ranging from 5 to 80 degrees. A computer program has been written to draft reflectivity curves as a function of the angle of incidence with the thickness of the thin film serving as a parameter, particularly in the range of 0 to 2500 angstroms. The index of refraction of substrate and thin film is assumed as being known for the proposed measuring operation.

If the approximate thickness is known, the reflected intensities at two chosen angles of incidence are measured to accurately determine the thickness of the thin film. The ratio of these intensities is indicative of the accurate thickness. This avoids the more difficult measurement of the absolute light intensity. for the different ranges of thickness, the following modes are recommended to ensure maximum accuracy:
a) 0 - 700 angstroms Using light polarized parallel to the plane

of incidence, and angles of incidence of 10 and 70 degrees.
b) 800 - 1200 angstroms Using light polarized perpendicular

the plane of incidence, and angles of incidence of 20 and 50

degrees.
c) 1200 - 1900 angstroms Using light polarized parallel to the

plane of incidence, and angles of incidence of 10 and 60

degrees.
d) 1900 - 2700 angstroms Using light polarized parallel to

the plane of incidence,

and angles of incidence correspondi...