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Proceedings Paper

Image Intensity Distribution Of Double Spaced Contact Holes
Author(s): Nikhil N. Kundu; Sanjay Goel; Shri N. Gupta; Bhvanesh P. Mathur
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Paper Abstract

As the feature size is reduced, two dimensional proximity printing of contact openings is one of the simpler cases which can be computed using Fresnel diffraction theory. This is applicable only if the proximity gap is larger than the aperture size. Fresnel approximation can also be applied to the case of more than one apertures in close proximity. In this paper, we discuss the case of three apertures separated by equal distances. The conditions under which Fresnel approximation is valid for this case have been discussed. The aerial image for such a case has been computed. The variation of shape of the aerial image has been calculated in the form of contours of constant intensity plots. The constant intensity plot can correspond to the resist exposure threshold and can thus represent the shape that will be obtained in the resist. In order to optimize the image shape, a figure of merit has been proposed. This figure of merit (F) is based on areas of object and image. It represents relative image area that lies within the aperture reduced by the area lying outside the aperture opening. The image quality is thus ensured with a value of F close to unity. F has been computed using a combination of a large number of variables. A method of optimizing F has been discussed along with some computed results.

Paper Details

Date Published: 20 August 1986
PDF: 8 pages
Proc. SPIE 0633, Optical Microlithography V, (20 August 1986); doi: 10.1117/12.963728
Show Author Affiliations
Nikhil N. Kundu, Central Electronics Engineering Research Institute (India)
Sanjay Goel, Central Electronics Engineering Research Institute (India)
Shri N. Gupta, Central Electronics Engineering Research Institute (India)
Bhvanesh P. Mathur, Central Electronics Engineering Research Institute (India)

Published in SPIE Proceedings Vol. 0633:
Optical Microlithography V
Harry L. Stover, Editor(s)

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