Interesting. With all the mega bucks and efforts to produce smaller wavelength photon beams, I wonder if a comparable investment would increase throughput? Or maybe there is an insurmountable technical hurdle.
The problem is pretty fundamental. Optical approaches illuminate the whole chip at once. Electron beams have to go transistor by transistor.
Why? What prevents you from illuminating the whole chip with electrons? Can't get an electron source "bright" enough? Uniform enough? The chip can't handle that much current? Or what?
The problem is that you can't make mirrors or lenses for electrons, so the mask can't be bigger than the chip. There's also the significant problem that shooting electrons at things tends to damage them, so making a mask that can survive the process sounds very tricky.