CHOICE OF SYSTEM PARAMETERS FOR PROJECTION ELECTRON-BEAM LITHOGRAPHY - ACCELERATING VOLTAGE AND DEMAGNIFICATION FACTOR

A lithography system that uses Scattering with Angular Limitation Projection Electron Lithography (SCALPEL) allows us to vary the electron-beam accelerating voltage in a way that was not possible with systems that use absorbing stencil masks. We have discovered that the choice of operating parameters, accelerating voltage, and demagnification factor, as well as many of the subsystem designs, are dominated by the need to control thermal effects within the system. We have derived a model which allows us to find operating parameters that minimize the thermal contribution to the pattern overlay error. This information, when combined with other subsystem constraints, enables us to define a relatively narrow range of possible working conditions. The model is general to high-throughput electron beam lithography systems; we have applied the model to one example of a SCALPEL system.