24 August 2001 CD changes of 193-nm resists during SEM measurement
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Abstract
CD linewidth change during SEM inspection has been one of the issues encountered in the introduction of 193 nm resists. As a general tendency, the methacrylate resists exhibit faster line width reduction than the cycloolefin- maleic anhydride (COMA) systems; however, other resist components as well as CD SEM settings paly an important role. Based on the exposure time vs. CD loss, the line width slimming (LSW) is found to proceed in three steps, which are assigned as: 1) chemical change of outer resist layer, 2) evaporation of volatiles and 3) bulk chain scission or deprotection. Countermeasures for CD degradation are proposed form both the formulation and process sides. A calculation of e-beam penetration depth suggests that deprotection, chain scission and other reactions occur in the first 20-40nm, and these reaction rates combined with thermal effects determine LWS. The CD SEM measurement method has been improved to minimize e-beam exposure and to spread out the thermal load over a larger period of time. An optimized formulation exhibits less than 0.2% LWS per measurement with the improved CD measurement program.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Takanori Kudo, Jun-Bom Bae, Ralph R. Dammel, Woo-Kyu Kim, Douglas S. McKenzie, M. Dalil Rahman, Munirathna Padmanaban, and Waiman Ng "CD changes of 193-nm resists during SEM measurement", Proc. SPIE 4345, Advances in Resist Technology and Processing XVIII, (24 August 2001); doi: 10.1117/12.436847; https://doi.org/10.1117/12.436847
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