Researchers Develop A Full Numerical Model of EUV Imaging and Exposure Statistics

Physorg.com 
Jan 25, 2011 

The CNST’s Gregg Gallatin and Lawrence Berkley National Laboratory’s Patrick Naulleau have developed a numerical model that accounts for the two dominant sources of LER: the quantum statistics of exposing and developing the resist, and the roughness of the mask features themselves.

The tolerances on feature size, shape, and placement for next generation computer chips fabricated with extreme ultra-violet (EUV) lithography will range from a maximum of a few nanometers down to less than 1 nm.

To achieve these tolerances, the sidewall roughness of the features, traditionally called line edge roughness (LER), is required to be less than 2 nm.  Mask LER is about 10 nm, which reduces to 2 nm on the wafer using a 5X EUV imaging system.

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