4 August 1993 Linewidth determination using simulated annealing
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Abstract
Using etched quartz as a phase shifter for i-line phase shift masks requires an etched depth of 385 nm referenced from the quartz surface. Recent work shows a direct relationship of focus offset as a function of the phase angle as it deviates from 180 degree(s). Knowing the etched depth and phase in transmission becomes critical to the production and verification of these masks. A method of interferometrically evaluating a phase shift mask is proposed. The method calculates the phase shift from the surface profile imaging system. Results show that errors of less than 5% are obtained for features as small as 1/6th of the optical resolution of the system and less than 2% for features as small as 1/2 of the resolution. When noise is included in the modeling, errors of 5% are obtained for S/N of 10 and less than 2% for S/N of 100.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Katherine Creath, Katherine Creath, Shiyu Zhang, Shiyu Zhang, "Linewidth determination using simulated annealing", Proc. SPIE 1926, Integrated Circuit Metrology, Inspection, and Process Control VII, (4 August 1993); doi: 10.1117/12.149021; https://doi.org/10.1117/12.149021
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