© imec 2005 Line Edge Roughness: status of resist Excite/More Moore meeting 12 May 2005 L.A. Leunissen, A.M. Goethals, R. Gronheid, F. Van Roey

© imec 2005 Excite/More Moore, May Introduction A brick wall for current CAR’s resolution limited to 30-35nm half pitch Main cause is acid diffusion length Experimental EUV data Sensitivity Resolution Line Edge Roughness Shot Noise Acid Diffusion

© imec 2005 Excite/More Moore, May Description of LER 3-parameter model (Demokritos): Classical LER 3  Correlation length  : the distance after which the edge points can be considered uncorrelated and the edge looks flat” correlation length is a measure for the acid diffusion Roughness exponent  : the relative contribution of high frequency fluctuations to LER Offline analysis of top-down SEM pictures

© imec 2005 Excite/More Moore, May Film Thickness: 80nm Line Edge Roughness Analysis EUVL +EBL Film Thickness: 100nm Corr. Length ~ Acid Diffusion

© imec 2005 Excite/More Moore, May LER analysis EUV (PSI exposures) 7 different resists Different sensitivity Shot noise contribution to LER: (dashed line) Resist contribution larger

© imec 2005 Excite/More Moore, May LER analysis through focus Exposures at Berkeley Six resists Analysis through focus linewidth (Bossung curve) 3  LER (Demokritos, Summit)

© imec 2005 Excite/More Moore, May Correlation length vs. focus Correlation length (L cor ) through focus Parabolic fit Focus offset Diffusion length (L d )

© imec 2005 Excite/More Moore, May Focus effects AIC contrast reduction Result in increased LER Chemical contrast reduction Results in increased correlation length L cor E.g. (Solid-C simulation): Decrease in contrast

© imec 2005 Excite/More Moore, May Conclusions Several resists tested PSI MET LER characterization to measure trade-off: Shot noise  LER Acid diffusion  LER Through focus experiments (MET) Sensitivity Resolution Line Edge Roughness Shot Noise Acid Diffusion

© imec 2005 Excite/More Moore, May