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Nondestructive Method for Measuring Photoresist Thickness

IP.com Disclosure Number: IPCOM000075637D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Ilten, DF: AUTHOR

Abstract

It is desirable for quality control purposes to measure the thickness of a photoresist layer across a substrate. This is accomplished by a nondestructive light absorption method which does not expose the photo-resist layer.

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Nondestructive Method for Measuring Photoresist Thickness

It is desirable for quality control purposes to measure the thickness of a photoresist layer across a substrate. This is accomplished by a nondestructive light absorption method which does not expose the photo-resist layer.

Photoresists in current use generally show high sensitivity in the near ultraviolet and blue spectral regions. This sensitivity drops sharply at higher wavelengths, but a sufficient residual absorbance remains to allow a spectroscopic measurement in this region without exposing the photoresist.

A quartz wafer 1 coated with a thin layer of Shipley AZ1350 photo-resist is placed in holder 2, which is mounted for indexing in the X-Y direction. Portions of the wafer are scanned using a He Cd laser light source 3 of collimated monochromatic light of 4416 Angstroms wavelength. The optical system includes mirrors 4, a neutral density filter 5 to regulate the light intensity, a detector 6, and a read out and recorder assembly 7.

Light sources of light in the 4400 Angstrom range or other appropriate spectral regions can be selected for each photoresist to be tested in a non- destructive manner. Where nontransparent substrates are involved, a reflectance spectroscopy measurement is made by changing the position of the detector.

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