Electron beam lithography with negative Calixarene resists on dense materials: Taking advantage of proximity effects of increase pattern density

A high-resolution negative Calixarene resist has been used to pattern 2-nm-thick Ti O2 films on 50-nm-thick Pt layers by electron beam lithography, in order to carry out site controlled growth of Pb (Zr,Ti) O3 structures. Single dot structures have been written in a 60-nm-thick Calixarene layer at e-beam acceleration voltages of 10 kV (100 pA) and 20 kV (200 pA). The necessary dose for complete dot development ranged from 5 to 25 mC cm2. Due to the high density Pt layer, the dot-size depended very much on the volume of backscattered electrons. The minimum dot size (70 nm) was found to lie in the range of the resist film thickness. Proximity effects have been studied. At smaller beam energies, a reversed proximity effect has been observed, in the sense that the dot size decreased due to proximity. An irradiation model is proposed based on exposure from bottom to top, and taking into account a competition between cross-linking and bond-scission. © 2005 American Vacuum Society.