Browse Prior Art Database

Simultaneous Measurement of Film Thickness and Refractive Index

IP.com Disclosure Number: IPCOM000089854D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Esch, RP: AUTHOR [+2]

Abstract

This apparatus uses a reading obtained by a photo detecting method to indicate both transparent film thickness and refractive index. The usual technique for determining thickness and refractive index of a transparent film involves two separate manual operations with a Vamfo apparatus. This apparatus utilizes the ability of a sensing device to detect when the reflectivity of two adjacent areas of a film, where one area is approximately 100 angstroms thinner than the other, is equal. Equal minimum reflectivity from the two areas corresponds to the minimum reflectivity for the average thickness of the two areas. The use of the 100 angstroms step eliminates the need to make corrections for variations in reflectivity with incident angle as the sample is rotated to determine the minima position.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 57% of the total text.

Page 1 of 2

Simultaneous Measurement of Film Thickness and Refractive Index

This apparatus uses a reading obtained by a photo detecting method to indicate both transparent film thickness and refractive index. The usual technique for determining thickness and refractive index of a transparent film involves two separate manual operations with a Vamfo apparatus. This apparatus utilizes the ability of a sensing device to detect when the reflectivity of two adjacent areas of a film, where one area is approximately 100 angstroms thinner than the other, is equal. Equal minimum reflectivity from the two areas corresponds to the minimum reflectivity for the average thickness of the two areas. The use of the 100 angstroms step eliminates the need to make corrections for variations in reflectivity with incident angle as the sample is rotated to determine the minima position.

Substrate 10, bearing the film to be measured, is prepared by the formation of a 100 angstroms step 12. The latter can be formed by either etching the step in the film utilizing a suitable etchant preferably by masking the original portion with a suitable masking coating, or adding a 100 angstroms film of material which can be later removed by a solvent. The addition of the film can be done by spinning a polyvinyl formamide in dichloroethylene solution onto the film in the area desired.

The energy from a single monochromatic light source is split into two equal intensity light beams by fiber optics unit 14. The bea...