Nanometer and high aspect ratio patterning by electron beam lithography using a simple DUV negative tone resist

Abstract

The micro resist technology’s ma-N 2400 series DUV negative tone resist is evaluated for electron beam lithography using the Gaussian beam machine LION LV1. We could demonstrate the high resolution capability of this resist and the possibility of delineating dense patterns with high aspect ratios. Lines and spaces with dimensions down to 150 nm in an 800 nm resist layer and down to 50 nm in a 180 nm resist layer can be resolved. The patterns show steep sidewalls and demonstrate the possibility of generating resist features with high aspect ratios using a simple single-layer resist technology. The aspect ratio has a value of, at least, about 5. The exposure doses for the resist layers in these experiments range from 120 to 200 μC/cm 2 using 20 keV electrons. Exposures with electron energies less than 20 keV show that the resist sensitivity increases with decreasing electron energy. For 2.5 keV electron energy a dose of only 10 μC/cm 2 is sufficient. Due to the small penetration depth of low energy electrons only resist layers of less than 100 nm thickness can be used in the low energy range.