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Proceedings Paper

Freeform mask optimization using advanced image based M3D inverse lithography and 3D-NAND full chip OPC application
Author(s): Yaobin Feng; Zhiyang Song; Moran Guo; Jun He; Longxia Guo; Gang Xu; Sam Liu; Jingjing Liu; Stephen Hsu; Austin Peng; Andy Yang; Rachit Gupta ; Junwei Lu; Victor Peng; Jun Wang; Xiaolong Shi; Leon Liu; Rafael Howell; Cuiping Zhang ; Zero Li; Ning-ning Jia
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Paper Abstract

Inverse lithography is increasingly being used as a viable OPC solution to maximize process window (PW), improve CD uniformity (CDU) and minimize the mask error factor (MEF), especially for memory devices. The device yield is typically limited by the process window of a few critical layers, and the Via layer is identified as one of the process window limiters for advanced 3D-NAND devices. To maximize the on-chip yield, ASML has developed advanced image based Mask-3D (M3D) inverse technology that can optimize freeform mask shapes and enhance design printability throughout the mask optimization flow. Mask rule checks (MRC) and side-lobe printing are optimized simultaneously to deliver the maximum process window.

The advanced image based M3D inverse lithography technology (ILT) is used to perform full chip mask correction on the Via layer of a 3D-NAND device. 3D NAND devices contain highly repetitive cell and page buffer patterns. To ensure the full chip device performance, the consistency of the mask correction is important. Our strategy is to use the computationally intensive mask optimization solution from the new advanced image based M3D inverse technology to generate a freeform mask which gives the best lithography performance. We then use Tachyon’s Pattern Recognition and Optimization (PRO) engine to propagate the freeform mask solution of the repetitive patterns to the full chip. The periphery of the chip is optimized using conventional OPC methods. The simulation results from the advanced image based M3D inverse technology are compared against the baseline flow, which uses a standard inverse solution. The simulation results from both the flows are further validated on wafer. Significant improvement in overlapping process window (OPW) and CD uniformity is observed using the new advanced inverse technology. The simulation data shows a 32% improvement in depth of focus (DOF), a 5% improvement in the image log slope (ILS) and a 25% reduction in best focus shift (BFS) range. The improvement has also been verified at the wafer-level.

Paper Details

Date Published: 20 March 2018
PDF: 10 pages
Proc. SPIE 10587, Optical Microlithography XXXI, 105870G (20 March 2018); doi: 10.1117/12.2297397
Show Author Affiliations
Yaobin Feng, Yangtze Memory Technologies Co., Ltd. (China)
Zhiyang Song, Yangtze Memory Technologies Co., Ltd. (China)
Moran Guo, Yangtze Memory Technologies Co., Ltd. (China)
Jun He, Yangtze Memory Technologies Co., Ltd. (China)
Longxia Guo, Yangtze Memory Technologies Co., Ltd. (China)
Gang Xu, Yangtze Memory Technologies Co., Ltd. (China)
Sam Liu, ASML China (China)
Jingjing Liu, ASML Brion (United States)
Stephen Hsu, ASML Brion (United States)
Austin Peng, ASML Brion (United States)
Andy Yang, ASML China (China)
Rachit Gupta , ASML Brion (United States)
Junwei Lu, ASML China (China)
Victor Peng, ASML China (China)
Jun Wang, ASML China (China)
Xiaolong Shi, ASML China (China)
Leon Liu, ASML China (China)
Rafael Howell, ASML Brion (United States)
Cuiping Zhang , ASML Brion (United States)
Zero Li, ASML Brion (United States)
Ning-ning Jia, ASML China (China)

Published in SPIE Proceedings Vol. 10587:
Optical Microlithography XXXI
Jongwook Kye, Editor(s)

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