Mark detection technology in electron-beam direct writing

Monte Carlo (MC) simulation and experimental results are used to investigate mark detection technology in electron-beam (e-beam) direct writing for a 10-kV acceleration voltage. The simulation is based on a single scattering and a continuously slowing down approximation model, and also takes into account the Gaussian profile of the e-beam in order to calculate the backscattered electrons from the mark edges in detail. The simulation results for the alignment signals from a 66° tapered pedestal mark with a 1.1-µm-thickness resist are in good agreement with the experimental results. For the 10-keV e-beam, a location accuracy of about 0.15 µm (3 σ) is obtained by an alignment mark 2.3 µm high and 3.8 µm wide under the same conditions as the simulation. In this study, it is revealed that the simulation for the mark signal makes it possible to evaluate the accuracy of mark detection.