Direct measurements and analyses of the Coulomb effects in electron projection lithography

The Coulomb effects have been common problems in electron-beam lithography. In our previous article, we studied the influence of the Coulomb effects on electron projection lithography (EPL) process. In this paper, we analyze the Coulomb effects by direct blur measurements and by simulations. We found that there existed a beam blur around 32 nm at a low beam current (approximately 0μA). We found a relationship between the beam blur and the beam current that was 5.4nm∕μA, and this number agreed with our simulation work as well as with our experiment with resist resolution. We learned that at low current the blur was so small that a blur distribution could be practically ignored. An important finding we had, is that the beam blur did not only depend on the beam current but also on the pattern arrangement. We found the possibility of the existence of the local Coulomb effects and estimated its range to be around 100–120μm on our system. These phenomena should be taken into considerations when making proximity...