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Proceedings Paper

Pattern noise in e-beam exposed sub-35-nm contacts
Author(s): Wojtek Poppe; Alexander Liddle; Erik Anderson; Andrew Neureuther
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Paper Abstract

The variability in the printing of small contacts with electron-beam lithography in a fast high resolution resist was characterized using automated SEM image analysis of an identical array of contact holes. The goal of this study was to evaluate the sources and severity of pattern noise in an e-beam system. A matrix of 391 contacts, 17x23 (dictated by the dimensions of the SEM display 768x1024), was printed at 100KeV on the LBNL nano-writer in KRS-XE2 photoresist. The doses ranged from 28uC/cm2 to 851uC/cm2 with 8nm, 16nm, 24nm, 32nm, and 40nm contact holes. Printed contacts were counted by image processing of SEM images using NIH's ImageJ program. The amount of pattern noise was found to be 14X larger than the noise that would be predicted by the traditional Poisson shot noise of 5500 electrons per contact. Surprisingly, the pattern noise was independent of PEB time and resist thickness. The main source of noise was found to be associated with the surface of the resist, most likely outgassing of acid in the e-beam vacuum chamber. The contact hole experiment provides a practical method for quantifying random effects in evaluating resists, processes, and treatments.

Paper Details

Date Published: 29 March 2006
PDF: 10 pages
Proc. SPIE 6153, Advances in Resist Technology and Processing XXIII, 61533Z (29 March 2006); doi: 10.1117/12.657055
Show Author Affiliations
Wojtek Poppe, Univ. of California, Berkeley (United States)
Alexander Liddle, Lawrence Berkeley National Lab. (United States)
Erik Anderson, Lawrence Berkeley National Lab. (United States)
Andrew Neureuther, Univ. of California, Berkeley (United States)

Published in SPIE Proceedings Vol. 6153:
Advances in Resist Technology and Processing XXIII
Qinghuang Lin, Editor(s)

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