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Nondestructive Single or Dual Film Thickness and Refractive Index Measurements

IP.com Disclosure Number: IPCOM000090106D
Original Publication Date: 1969-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Harvilchuck, JM: AUTHOR [+3]

Abstract

This apparatus and technique for nondestructive thickness and refractive index measurements of single or dual transparent films on any specular reflecting surface is an arrangement different from that described in IBM Technical Disclosure Bulletin, Vol. 5, March 1963, page 6. The apparatus eliminates the need for manual operation and the technique is capable of analyzing dual as well as single films.

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Nondestructive Single or Dual Film Thickness and Refractive Index Measurements

This apparatus and technique for nondestructive thickness and refractive index measurements of single or dual transparent films on any specular reflecting surface is an arrangement different from that described in IBM Technical Disclosure Bulletin, Vol. 5, March 1963, page 6. The apparatus eliminates the need for manual operation and the technique is capable of analyzing dual as well as single films.

Sample 10 is securely mounted on sample holder 12 located at the center of goniometer 14. Monochromatic and electromagnetic light source 15 projects a narrow beam of light toward sample 10 which reflects the beam from its surface to photocell detector 16 mounted on arm 18. To maintain the geometry required for the reflection phenomenon, goniometer 14 maintains the respective coplanar positions of sample 10, light source 15 and detector 16 by rotating the latter at twice the angular velocity of the sample. Precision heliopot 20 mounted on holder 12 divides a constant DC voltage in proportion to the angular displacement to effect an X-axis drive. The detector 16 output is simultaneously obtained and results in a Y-axis drive. These coordinates are used to obtain the reflectivity versus incidence angles from which the interference maxima or minima can be selected. Incidence angles are recorded forward and backward from zero degrees, providing an inherent calibration procedure.

Given a plot of reflecti...