MICROSCOPIC FEATURE DIMENSION MEASUREMENT SYSTEM

A measurement tool connects to an automatic inspection machine for measuring microscopic characteristics of features on a photographic mask. Widths of densely packed lines are measured for features having sizes of less than about the wavelength of the examining radiation. A simulated intensity profile is subtracted from the actual measured intensity profile to obtain an error profile. The error profile provides edge position corrections which adjust the originally estimated edge positions. A new, simulated intensity profile is created and the process is repeated until the error profile is deemed acceptable. The line width is measured by measuring between the estimated edge positions. The opacity of a feature is determined and used for correcting dimension measurements. A formula determines the opacity based upon the contrast, the measured dimension and the single data point. Width or height of an irregular feature is calculated accurately. Dimension of the feature is determined using the peak width data and the peak width standard deviation.