Application of transmission electron detection to SCALPEL mask metrology

Linewidth measurements were performed on a 4X scattering with angular limitation in projection electron lithography (SCALPEL) e-beam lithography mask using the transmitted electron signal in a modified scanning electron microscope. Features as small as 0.24 μm were measured on the mask. The thin membrane mask structure that was used is found to provide sufficient transmitted signal contrast at energies ranging from 10 to 30 keV. The linewidth measurement accuracy is mostly limited by the variations in the material and not the measurement system. It is concluded that the linewidth measurement technique using transmitted electrons is suitable for the potential certification of SCALPEL mask standards.