26 June 2003 Impact of scattering bars in damascene trench patterning
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Scattering bars have been an essential component of the reticle layout design to increase process yields for devices with design rules that are 0.18 um and below. These are sub-resolution features and make semi isolated and isolated features to be imaged like dense features as the illumination conditions are always decided by most dense pitch. With the use of scattering bars the depth of focus and iso-dense matching get improved. This results in better critical dimension (CD) control in the wafer fabs. Scattering bar has been helpful in extending the limit of optical lithography. This paper describes the effect of scattering bars width and separation on the printed feature size. Trench patterning is studied at different partial coherence and lens numerical aperture (NA). Also, the effects are compared for binary and 8% attenuated phase shift mask (APSM). The patterned feature size is found to be more sensitive to scattering bar parameters at small NA and low partial coherence. The CD of the feature has strong dependence on scattering bar separation than size and also influenced by the NA and sigma. An interesting phenomenon at low partial coherence is the presence of deep valley or 'V' shaped CD trend in scattering bar separation versus CD curve. CD dip is more on APSM as compare to binary mask.
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Sohan Singh Mehta, Sohan Singh Mehta, Navab Singh, Navab Singh, Moitreyee Mukherjee-Roy, Moitreyee Mukherjee-Roy, Rakesh Kumar, Rakesh Kumar, } "Impact of scattering bars in damascene trench patterning", Proc. SPIE 5040, Optical Microlithography XVI, (26 June 2003); doi: 10.1117/12.485377; https://doi.org/10.1117/12.485377


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