100 kV field emission electron optics for nanolithography

A 100 kV optics with field emission source is designed for an electron‐beam nanolithography system. A new electrostatic gun lens permits high‐voltage operation with low aberrations. A demagnifying double‐lens column with fixed magnification and variable aperture is used. The optics are weighted towards 100 kV operation, but the beam voltage can be varied from 25 to 100 kV with resolution maintained below 20 nm. The gun uses a Zr/O/W<100≳ cathode operated near the extended‐Schottky emission regime to achieve 1%/h current stability at a fixed extraction voltage. With the source emitting a 0.5 mA/sr angular intensity, 1.5 nA can be focused to 6 and 10 nm with beam voltages of 100 and 50 kV, respectively. A target current density of 2000 A/cm2 with an effective brightness of 1×108 A/cm2 sr enables 2 MHz pixel rate exposures of PMMA at 100 kV with a vector‐scan deflection system.