IMPROVED ELECTRON-BEAM PATTERN WRITING IN SIO2 WITH THE USE OF A SAMPLE HEATING STAGE

In previous electron beam direct-write SiO2 experiments [D. R. Allee and A. N. Broers, Appl. Phys. Lett. 57, 2271 (1990); D. R. Allee, C. P. Umbach, and A. N. Broers, J. Vac. Sci. Technol. B 9, 2838 (1991)], contamination has always been formed during exposure as a result of the high electron dose required by the SiO2 process. Not only does this contamination need to be removed prior to development of the patterns in SiO2, but it also causes additional electron beam scattering and can therefore be a factor limiting the resolution of the SiO2 process. In this letter, we report improved pattern writing in SiO2 through the use of a sample heating stage. The SiO2 sample is heated in situ at approximately 200-degrees-C during exposure. This eliminates the formation of contamination and, as a result, decontamination is not needed and the exposed oxide can be developed immediately after exposure. Using this writing process, trenches on 10.8 nm periods have been demonstrated in SiO2.