Novel Proximity Effect Including Pattern-Dependent Resist Development in Electron Beam Nanolithography

Abstract
A novel proximity effect, which includes the effect due to secondary electron scattering to a range of less than a micron and the pattern dependence of resist development, has been found and investigated to develop a precise dose control method in electron beam nanolithography. Experiments and simulations including secondary electron scattering were performed for precise evaluation of the proximity effect. This result revealed that the proximity effect caused by secondary electron scattering to the range between 30 nm and a micron is not negligible for nano-patterns. In addition, from experimental estimation of the rate of development of patterns of various sizes, a significant decrease of the rate was found for patterns less than 30-nm wide. The difference of the rate is also modified by the background deposited energy due to surrounding patterns. Therefore, we have to be very careful about how we determine the proper dose for a given nano-pattern.