Workshop Report 3: Edge Positions From Scanning Electron Microscope Signals by Comparing Models With Measure
J R. Lowney, Michael T. Postek, Andras Vladar
There is a pressing need in the semiconductor industry to determine the dimensions of lithographically produced features on wafers and masks down to the l0?nm level of accuracy. Such measurements involve the accurate location of line edges, the subtraction of one edge position from another and the determination of the linewidth according to some measurement algorithm. The scanning electron microscope (SEM) is a very useful tool for these measurements because of the narrowness of the electron beam depending upon instrument operation conditions. However the electrons scatter from the atoms as they traverse the sample, and it becomes difficult to relate the position of exiting electrons to that of the incoming electron beam. Therefore, a model of the electron scattering processes is needed to interpret the measured data. Several Monte Carlo models have been developed for this purpose and a round-robin has just been conducted to compare the results of these models for a rudimentary 1um step in a silicon wafer. A companion round-robin was also performed to compare comparable measurements to obtain experimental data from the SEM. This work compares the results of these two round-robins and shows how accurately linewidth measurements can be made for this specific case. The spreading of the electron beam inside a sample is very dependent on the atomic species present and the sample density. Therefore, any attempt at providing a linewidth measurement from an SEM image would have to take the sample composition and geometry into account. Thus, the results of modeling the signals becomes an inherent part of accurate SEM metrology.
, Postek, M.
and Vladar, A.
Workshop Report 3: Edge Positions From Scanning Electron Microscope Signals by Comparing Models With Measure, Proceedings of Microbeam Analysis Society, Breckenridge, CO, USA
(Accessed December 4, 2023)