Photomask Linewidth Measurement Uncertainty: An Alternative Approach via Stepper Emulation
James E. Potzick
The most significant contribution to uncertainty in the measurement of photomask linewidths is the rough shape of the edge of the etched chrome lines. This uncertainty can be greatly reduced if the emulated stepper aerial image of the feature is measured instead of its geometric linewidth. That is: measure what the photomask does, not what it is. Phase-shift and other kinds of mask can be measured in the same way.