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Proceedings Paper

Mask 3D effects on contact layouts of 1Xnm NAND flash devices
Author(s): Jongwon Jang; Hyungjeong Jeong; Hyungsoon Yune; Seyoung Oh; Hyunjo Yang; Donggyu Yim
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Paper Abstract

It is a distinctive feature of the metal contact layout in NAND flash memory devices that there are small-pitch contact patterns and random-pitch contact patterns in one layout. This kind of pitch difference between cell array patterns and isolated single patterns hadn’t had a decisive effect on wafers when the illumination condition is not aggressive. However, the pattern pitch difference has caused various problems including the best focus shift due to extreme illuminations. The common DOF margin of a contact layout is degraded when the best focus depth for each pattern is variable. Mask topography effect is well known for the major cause of best focus shift between contact patterns which have different pitches. The demand for device technology node shrink for production cost reduction has required adoption of hyper NA illumination conditions, and this aggressive illumination made it hard to secure an enough common DOF margin due to the best focus shift. In this work, the best focus shift phenomenon among different-pitch patterns caused by mask 3D effects is studied according to the various illumination conditions. It is found that the more aggressive illumination condition is and the bigger the pitch difference among patterns in one layout is, the bigger the best focus shift become. Also, we suggest the solution for avoiding this DOF margin degradation, which is SRAF optimization.

Paper Details

Date Published: 12 April 2013
PDF: 10 pages
Proc. SPIE 8683, Optical Microlithography XXVI, 86831V (12 April 2013); doi: 10.1117/12.2011659
Show Author Affiliations
Jongwon Jang, SK Hynix, Inc. (Korea, Republic of)
Hyungjeong Jeong, SK Hynix, Inc. (Korea, Republic of)
Hyungsoon Yune, SK Hynix, Inc. (Korea, Republic of)
Seyoung Oh, SK Hynix, Inc. (Korea, Republic of)
Hyunjo Yang, SK Hynix, Inc. (Korea, Republic of)
Donggyu Yim, SK Hynix, Inc. (Korea, Republic of)

Published in SPIE Proceedings Vol. 8683:
Optical Microlithography XXVI
Will Conley, Editor(s)

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