We describe a modification to our existing scatterometry technique for extracting the relative phase and amplitude of the electric field diffracted from a grating. This modification represents a novel combination of aspects of ellipsometry and scatterometry to provide improved sensitivity to small variations in the linewidth of subwavelength gratings compared with conventional scatterometer measurements. We present preliminary theoretical and experimental results that illustrate the possibility of the ellipsometric scatterometry technique providing a metrology tool for characterizing sub-0.1-mum-linewidth.

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Toggle magnetic random access memory cells scalable to a capacity of over 100 megabits

A novel laser scatterometer linewidth measurement tool has been developed for critical dimension metrology of photomasks. Calculation of the linewidth is based on a rigorous theoretical model, thus eliminating the need for calibrations. In addition the effect of the glass substrate on which the photomask grating is placed is explicitly taken into account. The experimental arrangement consists of a chrome photomask diffraction grating that is illuminated with a laser. A rigorous theoretical model is used to provide a lookup table that gives the power in the transmitted zero-order beam as a function of the linewidth for a fixed pitch of the grating. The predicted linewidth values are compared with those that are obtained by using commercial optical linewidth measurement systems, and excellent agreement is obtained.

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