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Proceedings Paper

Photomask Dimensional Measurements And The Clear/Dark Ratio
Author(s): Jeremy Nichols
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Paper Abstract

Four line-width measuring systems were tested for variations in the measured width of identical resolution targets as a function of the clear-to-dark (C/D) ratio of the surrounding field. Test masks were made of resolution bars in a checkerboard field. The C/D ratio of this field was varied on each mask to create eleven samples per mask with C/D ratios from 0% to 100%. Photocomposition was used to ensure that the C/D ratio of the field did not disturb the dimensions of the resolution bars during manufacture. Thus, any dimensional variations from sample to sample were due to effects of the C/D ratio on the measurement process. This was verified in a scanning electron microscope. Masks produced in both chromium oxide and iron oxide were measured on an image-shearing system, a photometric system, and on two different TV-type systems. One TV-type system was affected by the C/D ratio. This system was tested further to determine the cause of the problem. A method of minimizing the problem was determined.

Paper Details

Date Published: 6 September 1978
PDF: 4 pages
Proc. SPIE 0135, Developments in Semiconductor Microlithography III, (6 September 1978); doi: 10.1117/12.956120
Show Author Affiliations
Jeremy Nichols, Hewlett-Packard Company (United States)

Published in SPIE Proceedings Vol. 0135:
Developments in Semiconductor Microlithography III
Dino R. Ciarlo; James W. Dey; Ken Hoeppner, Editor(s)

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