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Journal of Micro/Nanolithography, MEMS, and MOEMS

Modeling and characterization of contact-edge roughness for minimizing design and manufacturing variations
Author(s): Yongchan Ban; Yuangsheng Ma; Harry Levinson; David Z. Pan
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Paper Abstract

Despite intensive attention on line-edge roughness (LER), contact-edge roughness (CER) has been relatively less studied. Contact patterning is one of the critical steps in a state of the art lithography process; meanwhile, design rule shrinking leads to larger CER in contact holes. Since source/drain (S/D) contact resistance depends on contact area and shape, larger CER results in significant change in a device current. We first propose a CER model based on the power spectral density function, which is a function of rms edge roughness, correlation length, and fractal dimension. Then, we present a comprehensive contact extraction methodology for analyzing process-induced CER effects on circuit performance. In our new contact extraction model, we first dissect the contact with a same distance, and then calculate the effective resistance considering both the shape weighting factor and the distance weighting factor for stress-induced complementary metal-oxide semiconductor (CMOS) cells. Using the results of CER, we analyze the impact of both random CER and systematic variation on the S/D contact resistance, and the device saturation current. Results show that the S/D contact resistance and the device saturation current can vary by as much as 135.7 and 4.9%, respectively.

Paper Details

Date Published: 1 October 2010
PDF: 10 pages
J. Micro/Nanolith. MEMS MOEMS 9(4) 041211 doi: 10.1117/1.3504697
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 9, Issue 4
Show Author Affiliations
Yongchan Ban, The Univ. of Texas at Austin (United States)
Yuangsheng Ma, GLOBALFOUNDRIES Inc. (United States)
Harry Levinson, GLOBALFOUNDRIES Inc. (United States)
David Z. Pan, The Univ. of Texas at Austin (United States)

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