Variable transmission reticle for charged particle beam lithography tool

摘要

A compound reticle having generally complementary clear and opaque areas on a portion of subfield in each of two reticle layers which can be moved relative to each other form a variable transmissivity shutter to regulate charged particle beam intensity independently of source beam current. Either homogeneous or inhomogeneous (e.g. having local variations in beam current density) can be produced at will and in rapid succession to study effects of beam current on beam pattern resolution and aberrations as well as optimum focus for particular patterned subfields having respectively differing transmissivities.