NuFlare announced the EBM-9000, which incorporates a brighter thermionic gun, three-stage shape deflection, and “immersion” objective optics. By increasing brightness and increasing the beam semi-angle, NuFlare achieves J = 800 A/cm2 current density. According to the published paper, the brightness increase is obtained by lowering the work-function. While this would be easy if one substituted CeB6 for LaB6, NuFlare claims the cathode is LaB6. So how the brightness is achieved (without increasing temperature) is not clear.
The increased semi-angle would increase aberrations (objective, deflection, and stochastic), but NuFlare has countered this by “deep immersion optics”. Details are lacking, but it appears to me to involve in-lens deflection. NuFlare has taken a page from the old Etec RSB design to include a microvectoring deflector, which they call “tertiary”. (Shape type selection and shape size deflectors are also separate.) The advantage of deflection with a range of only 600 nm is that it can be made very fast, so that shape size selection and shape placement settle in 10 ns.
Main deflection and subfield deflection have both been reduced to keep the deflection aberrations under control. The main field reduction has been the more drastic. While the EBM-8000 had 120 X 180 microns, the EBM-9000 has 90 X 81 microns main field.
Maximum shape size has been reduced to 250 nm in order to control stochastic blur.
Overall, the EBM-9000 looks like a solid advance for mask writing.
Reference: H Takekoshi, EB-9000: EB mask writer for product mask fabrication of 16nm half-pitch generation and beyond, Proc. SPIE 9235, Photomask Technology 2014, 92350X; doi:10.1117/12.2065551.
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I was disappointed that the IMS/JEOL collaboration did not have a paper for us. The only information we received was a rather hurried look at a recent monthly timeline of progress by Dan Chalom of IMS. He claimed that the team is now integrating “corrections”, without being too specific. I for one certainly would like to see a full paper at SPIE in late winter.