Figure 3: Comparison of a simulation DOE vs time lapse SEM. The simulation DOE used constant etch amounts with varying angular spreads (standard deviation of the Gaussian distribution). The simulation was performed and the incremental material removal step lapse is displayed. The right histogram illustrates the angular distribution correlation with the numerical setting within the software (not to scale). The actual angular spread of an etch process is determined by finding the simulation DOE result that best matches the etch profile.