Efficient measurement and optical proximity correction modeling to catch lithography pattern shift issues of arbitrarily distributed hole layer

Abstract

With the continued shrinking of the critical dimensions (CDs) of wafer patterning, the requirements for modeling precision in optical proximity correction (OPC) increase accordingly. This requirement extends beyond CD controlling accuracy to include pattern alignment accuracy because misalignment can lead to considerable overlay and metal-via coverage issues at advanced nodes, affecting process window and yield. This paper proposes an efficient OPC modeling approach that prioritizes pattern-shift-related elements to tackle the issue accurately. Our method integrates careful measurement selection, the implementation of pattern-shift-aware structures in design, and the manipulation of the cost function during model tuning to establish a robust model. Confirmatory experiments are performed on a via layer fabricated using a negative tone development. Results demonstrate that pattern shifts can be constrained within a range of ±1 nm, remarkably better than the original range of ±3 nm. Furthermore, simulations reveal notable differences between post OPC and original masks when considering pattern shifts at locations sensitive to this phenomenon. Experimental validation confirms the accuracy of the proposed modeling approach, and a firm consistency is observed between the simulation results and experimental data obtained from actual design structures.

Key words： computational lithography; optical proximity correction; modeling; pattern shift; metrology

Nomenclature

Abbreviations
CD	Critical dimension
EP	Edge placement
FOV	Field of view
IBPS	Image-based pattern selection
ML	Machine learning
OD	Optical diameter
OPC	Optical proximity correction
RET	Resolution enhancement technique
RMS	Root mean square
SEM	Scanning electron microscope
SRAF	Sub-resolution assist feature
TCC	Transmission cross-coefficient

Acknowledgements

This work was funded by the National Natural Science Foundation of China (Grant Nos. 52130504, 52305577, and 52205592), the Key Research and Development Plan of Hubei Province, China (Grant No. 2022BAA013), the Major Program (JD) of Hubei Province, China (Grant No. 2023BAA008-2), the Innovation Projection of Optics Valley Laboratory, China (Grant No. OVL2023PY003), and the Postdoctoral Fellowship Program (Grade B) of the China Postdoctoral Science Foundation (Grant No. GZB20230244). The authors thank ASML BRION and HMI, the Netherlands, for the technical support from their engineers. The authors also acknowledge the experimental support from Fabs for the mask tape-out and wafer data collection.

Conflict of Interest

The authors declare that they have no conflict of interest.

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