Development of an electron-beam lithography system for high accuracy masksWe propose a new approach to electron-beam ͑e-beam͒ 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.

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Propagation and post-acceleration of a pseudospark-sourced electron beam Distributed, multiple variable shaped electron beam column for high throughput maskless lithography A raster-shaped beam writing strategy has been tested on a prototype 50 keV electron-beam lithography workstation. The test stand was constructed to prove the raster-shaped beam concept by exposing patterns at full throughput over small areas. Patterns are composed in a raster-scanned array of variably shaped flashes at 100 MHz flash rate, with 0.9 A full beam current, and 2200 A/cm 2 current density using a thermal field emission source. Writing speed is independent of resist sensitivity and pattern complexity. By comparison, a typical variably shaped beam system with a LaB 6 source would have a current density of 10-30 A/cm 2 and a flash rate of 2-10 MHz, depending on resist sensitivity and deflection settling time.

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