An Evaluation of High Acceleration Voltage Electron Beam Writing on X-Ray Masks

Abstract

High acceleration voltage electron beam (EB) writing on X-ray masks was evaluated. Normalized dose latitudes of 100 keV for the 0.15 µm line and space (L&S), isolated lines and isolated space patterns were 3.5, 2.7 and 7.6 times larger than those of 25 keV, respectively. It was also found that the back-scattered electrons extend over a range of 10 µm in 100 keV writing. The maximum mesh size in the pattern area density method for proximity effect correction was evaluated by Monte Carlo simulation. When a ±10% pattern size error was permitted for a 0.1 µm line pattern, the 0.3 µm mesh size in 50 keV writing was markedly improved to 5 µm at a higher voltage of 100 keV. Reducing the beam size by half from 60 nm (2σ) in 100 keV writing also increases the mesh size from 0.4 to 5 µm. Moreover, the fine W–Ti patterns of 0.06–0.14 µm were formed using 100 keV Gaussian EB writing and electron cyclotron resonance (ECR) etching systems, where good linearity and linewidth deviations within 9 nm (3σ) were obtained.