 Solution

Use electron lenses and a digitally scanned, blanked electron beam; no physical mask is required for direct writing. Electromagnetic lenses focus the charged-particle beam, deflectors place it, and the pattern generator controls position and dose. Electrostatic elements can also form part of electron optics, but these are not refractive glass lenses.

The extreme ultraviolet mask mentioned in the problem is the object being manufactured by this maskless write process, rather than a mask placed in the electron path.