Raster shaped beam pattern generation

We propose a new approach to electron-beam (e-beam) pattern generation, in which the best attributes of raster scan writing are combined with beam shaping. The maximum dimension of the variable shaped flash is equal to the minimum feature size required in the pattern. The limited shaping range allows the use of very high speed, limited-resolution, digital-to-analog conversion circuits and amplifiers to form the shapes, and also allows thermal field emission cathode and optics to be used effectively, providing a very high current density. The system should support a sustained flash rate of at least 100 MHz, which is much higher than that found in conventional variable shaped beam architectures. The throughput is pattern independent and attractive for photomask fabrication at the 130 and 100 nm wafer technology nodes.