Electron beam lithography simulation for high resolution and high-density patterns

The Interdependence of Exposure and Development Conditions when Optimizing Low-Energy EBL for Nano-Scale Resolution

“…Hundreds of publications describing analytic and Monte-Carlo models for handling the interaction of electrons with resists might seem to address every aspect of this. The Reference list to this Chapter features just a few works (Kyser & Viswanathan, 1975;Murata et al, 1981;Lee et al, 1992;Raptis et al, 1993;Raptis et al, 2001;Zhou & Yang, 2006) out of a tremendous amount of literature on theory, modeling, and simulation of EBL exposures. However, the existing models of exposure are mostly limited to computations of the average amounts of energy deposited by primary, secondary, and backscattered electrons in the resist.…”

“…Despite a significant research effort and vast literature on electron beam lithography, the detailed molecular mechanisms are still inadequately understood. Published modeling studies address Lithography 294 extensively the processes of electron penetration, scattering, and energy deposition in resist and substrate materials (Kyser & Viswanathan, 1975;Murata et al, 1981;Lee et al, 1992;Raptis et al, 1993;Raptis et al, 2001;Zhou & Yang, 2006), however, the analyses of exposure of resists are mostly limited to conversions of the average amounts of energy deposited by electrons into the average number of relevant molecular events, such as the bond scissions, through the empirically determined radiation chemical yield (Chapiro, 1962;Greeneich, 1974;Han et al, 2003;Kyser & Viswanathan, 1975;Raptis et al, 2001). Furthermore, the detailed molecular processes occurring during dissolution of the most useful resists have been under-addressed if not overlooked so far.…”

Simulation of the spatial distribution and molecular weight of polymethylmethacrylate fragments in electron beam lithography exposures

“…It is evident as well that the exposure contrast should depend on the size distribution of PMMA fragments and on the average size of fragments. 1,15,16,19,21,23,42 Thus, Fig. 9͑a͒ shows the size distribution of PMMA fragments in average over the entire model sample for the exposure doses of 50, 100, and 150 C/cm 2 .…”

“…1 In some approaches, accounting for scission events is entirely avoided by employing various empirical dependencies that relate spatial distributions of the deposited energy to the sensitivity or development rate of the resist. 9,13,15,16 For certain resists, this approach works reasonably well for a resolution down to the 100 nm level and lower. However, reaching sub-100-nm resolution regimes, which is increasingly often addressed in the literature, [18][19][20][21][22][23][24] requires a more detailed insight into the processes of molecular fragmentation during exposure.…”

“…[1][2][3][4][5][6][7][8][9][10] Another approach which is more computationally efficient is reached by treating electron penetration through the kinetic transport theory. [11][12][13][14][15][16] These efforts have resulted in a comprehensive knowledge of electron trajectories in resists and distributions of deposited energy.…”