Coulomb interactions in high throughput electron beam lithography

High throughput electron beam lithography systems have been viewed as promising candidates for sub-100nm wafer writing tools. This thesis extends previous work in the study of electron Coulomb interactions and the study of electron interactions with photo-resists. Both of these interactions contribute to image blur and the studies in this thesis provide physical insight, quantitative characterization and suggest methods of reducing blur.; The Berkeley Electron Beam Simulator (BEBS) is a collection of software tools developed by the author to study the charged particle interactions in beam columns. BEBS employs the Fast Multi-pole Method (FMM) for rigorous force calculations. It takes about one hour with ten 500MHz processors to simulate a 30μA beam current in a typical 4x demagnification system using a packet of 13,000 particles. The accuracy of the force calculation algorithm is benchmarked with that of Munro's electron beam simulator. BEBS provides many options for observing forces and trajectory changes, and improving beam spot size. These options have been successfully applied and proved especially useful in studying stochastic interactions affecting beam blur.; The influence of space charge on the electron dynamics is investigated with simulations. The primary consequence of space charge is beam blur. Beam blur reduction techniques are examined using both neutralizing ions and lens aberrations. Results show that around 80% of the space charge blur is eliminated at 30μA beam current and that the total beam blur is reduced by nearly 30%. Further beam blur reduction would be formidable unless the stochastic blur is also reduced.; The basic assumptions of Mkrtchyan's Nearest Neighbor Theory are tested. It is demonstrated that for typical e-beam lithography applications, electron interaction with multiple neighbors rather than the nearest neighbors is the norm other than exception in a typical electron beam system. The simulation shows that the randomized correlation length is a function of the beam diameter and that correlated interactions occur at other axial positions due to symmetry with respect to the beam crossover. The structures of stochastic Coulomb interactions have been analyzed in probe-forming systems through a novel approach that combines algebraic analysis of forces and simulation of relocated trajectory displacements. This approach is able to explain why a crossover beam and a homocentric parallel beam with the same beam angle produce the same beam blur in spite of the high electron densities that occur in the crossover case.; Scaling laws for stochastic blur are developed. In a beam projection or multi-emitter array system, the stochastic blur is proportional to beam current raised to the power of 0.62, which roughly agrees with Jansen's prediction of 0.67. The scaling laws of the stochastic blur are also formulated with respect to column length, beam convergence angle, emitter spacing and beam voltage.