Thermal Characteristics of Si Mask for EB Cell Projection Lithography

We evaluated the thermal characteristics of a single crystal Si mask for electron beam (EB) cell projection lithography by computer simulation. Due to the low thermal conductivity, the thermal characteristics of the Si mask are more critical than that of a conventional heavy metal mask. If the Si mask is assembled by the conventional method which thermal dispersion is due to only radiation, the temperature at the beam position rises drastically with the irradiation power of the EB. Moreover, the displacement caused by thermal expansion can not be ignored for a quarter-micron lithography. The Si mask assembly using thermally conductive adhesion and a new Si mask structure with ribs gives good thermal characteristics satisfying the necessary conditions for a high-throughput and highly accurate EB lithography.