A pattern dimension determination method has been developed. The three parameters, linewidth, wall angle, and film thickness represent pattern dimension. The total waveform of a measured backscattered electron signal is compared with a standard signal data base. Two methods are adopted to reduce data base construction time. (1) The data base was constructed with Monte Carlo simulation by a supercomputer. (2) Data base size is reduced using a waveform approximation method. The two improvements result in fast data base construction (26 min) for a specified material sample. This data base construction method is more practical than preparing signal data base from real standard sample due to data base construction time. Obtained dimensional accuracies are found to be 0.02 μm, 5 deg, and 0.1 μm for linewidth, wall angle, and film thickness, respectively, with scanning electron micrograph comparisons. Deduction time for obtaining physical dimensions from a signal was 17 s.