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Etched Profile of Si by Ion-Bombardment-Enhanced Etching

The basic characteristics of the ion-bombardment-enhanced etching (IBEE) of Si are investigated, using 60 keV-Ar as the bombarding ion, with regard to its application to submicron lithography. The damaged layer to be etched is determined by calculating the deposited energy distribution in the substrate and by using the threshold deposited energy. The etched profile of Si under a pattern mask is calculated using the value of 4×1023 eV/cm3 as the threshold. The calculated profile and the amount of side etching of Si are compared with the observed ones, and the agreement between them is found to be good, with an accuracy of 10 nm. The optimum dose for obtaining submicron patterns with sharp edges is found to be 0.8 –2×1015 Ar+/cm2 at 60 keV. The etched patterns made by a focused ion beam with Gaussian profile are also calculated.