University of California - Berkeley

Chris H. Clifford

I am working to develop fast simulation methods for Extreme Ultraviolet (EUV) Lithography masks with buried defects.  Mask defects are a major issue in EUV lithography and their effects must be understood.  Full field simulation methods (such as the finite difference time domain method) are too slow to effectively tackle this problem (a single simulation can take many days). 

I have created a fast simulator, RADICAL (Rapid Absorber Defect Interaction Computation for Advanced Lithography), that can simulate an EUV mask with a buried defect two orders of magnitude faster than FDTD with comparable accuracy.

My work is sponsored by a grant from Intel

For more information see the following publications

· C. H. Clifford, A. R. Neureuther, “Smoothing Based Model for Images of Isolated Buried EUV Multilayer Defects ”, Proceedings of SPIE, Vol. 6921, 2008. (pdf)

· C. H. Clifford, A. R. Neureuther, “Fast three-dimensional simulation of buried EUV mask defect interaction with absorber features”, Proceedings of SPIE, Vol. 6730, 2007. (pdf)

· A.R.Neureuther, W. Poppe, J. Holwill, E. Chin, L. Wang, J. Yang, M. Miller, D. Ceperley, C. Clifford, K. Kikuchi, J. Choi, D. Dornfeld, P. Friedberg, C. Spanos, J. Hoang, J. Chang, J. Hsu, D. Graves, A. Wu, M. Lieberman “Collaborative platform, tool-kit, and physical models for DfM”, Proceedings of SPIE, Vol. 6521, 2007 (pdf)

· C. H. Clifford, A. R. Neureuther, “Fast simulation of buried EUV mask defect interaction with absorber features”, Proceedings of SPIE, Vol. 6517, 2007. (pdf)

Research Interests

(As of March 2008)