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Journal of Micro/Nanolithography, MEMS, and MOEMS

Impact of 14-nm photomask uncertainties on computational lithography solutions
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Paper Abstract

Computational lithography solutions rely upon accurate process models to faithfully represent the imaging system output for a defined set of process and design inputs. These models rely upon the accurate representation of multiple parameters associated with the scanner and the photomask. Many input variables for simulation are based upon designed or recipe-requested values or independent measurements. It is known, however, that certain measurement methodologies, while precise, can have significant inaccuracies. Additionally, there are known errors associated with the representation of certain system parameters. With shrinking total critical dimension (CD) control budgets, appropriate accounting for all sources of error becomes more important, and the cumulative consequence of input errors to the computational lithography model can become significant. In this work, we examine via simulation the impact of errors in the representation of photomask properties including CD bias, corner rounding, refractive index, thickness, and sidewall angle. The factors that are most critical to be accurately represented in the model are cataloged. CD bias values are based on state-of-the-art mask manufacturing data, and other variable changes are speculated, highlighting the need for improved metrology and communication between mask and optical proxmity correction model experts. The simulations are done by ignoring the wafer photoresist model and show the sensitivity of predictions to various model inputs associated with the mask. It is shown that the wafer simulations are very dependent upon the one-dimensional/two-dimensional representation of the mask, and for three-dimensional, the mask sidewall angle is a very sensitive factor influencing simulated wafer CD results.

Paper Details

Date Published: 2 December 2013
PDF: 10 pages
J. Micro/Nanolith. MEMS MOEMS 13(1) 011004 doi: 10.1117/1.JMM.13.1.011004
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 13, Issue 1
Show Author Affiliations
John Sturtevant, Mentor Graphics Corp. (United States)
Edita Tejnil, Mentor Graphics Corp. (United States)
Timothy Lin, Mentor Graphics Corp. (United States)
Steffen F. Schulze, Mentor Graphics Corp. (United States)
Peter D. Buck, Toppan Photomasks, Inc., (United States)
Franklin Kalk, Toppan Photomasks, Inc. (United States)
Kent H. Nakagawa, Toppan Photomasks, Inc. (United States)
GuoXiang Ning, GLOBALFOUNDRIES Inc. (United States)
Paul W. Ackmann, GLOBALFOUNDRIES Inc. (United States)
Fritz Gans, Advanced Mask Technology Ctr. GmbH Co. KG (Germany)
Christian Buergel, Advanced Mask Technology Ctr. GmbH Co. KG (Germany)

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