Abstract: A method of writing a pattern on the surface of a substrate by an electron beam is provided comprising exposing the substrate surface to an electron beam controlled to progressively describe the pattern by stepped movement of a focussed spot of the beam over the surface, and varying the exposure of the surface to the beam by selectably modulating the beam in the periods between successive movement steps to reduce the level of electron dose in predetermined positions of the beam spot on the surface.

Abstract: An electron beam aperture element (10) comprises a body (11) provided with a passage (12) for an electron beam (E) and with a blocking surface (15) for blocking travel of part or all of the beam otherwise than through the passage. The blocking surface (15) is angled to cause departing electrons derived from the blocked beam or part thereof to be directed away from the axis (13) of the passage and, in particular, into an electron trap cavity (21) bounded by the surface (15) and a wall of a screening member (17). The wall returns electrons to the blocking surface (15) for redirection back into the cavity (21), thus preventing escape of scattered electrons or delaying their escape until sufficient absorption has taken place to render them largely harmless to the interior environment of an electron beam column equipped with the element.

Abstract: An electron beam pattern-writing column comprises an emitter and an extractor (14, 15) for generating a low-energy electron beam (13), a series of three electrostatic triple element lenses (17, 18, 21) for focussing the beam, and an electrostatic double deflector (20), which is disposed ahead of the final lens (21), for deflecting the beam to scan a substrate (11) on which a pattern is to be written. After focussing and deflection of the beam have been carried out by the electrostatic components, which are low power and thus have no significant heat output, the beam electrons are accelerated by the final element (21c) of the final lens (21) into a high-energy beam with the required strength for high-quality pattern writing.

Abstract: A method of writing a pattern on a substrate by a deflectable electron beam, in particular a pattern containing very fine features such as nanostructures, is carried out by dividing the pattern into at least two fields of differing size (15, 17) which are arranged one inside the other and have a common center (18) arranged at the central axis of the beam at which the beam has an undeflected setting, with the finer or finest pattern features contained in the inner field (15). The pattern is written by keeping the substrate stationary and writing the two fields in succession with a change in writing resolution of the beam on transition from one field to the next such that a finer step size is used for an inner field than for an outer field.