The pattern is split into fields (or “blocks”) that are smaller than the maximum beam deflection. After writing one field, the sample stage must move. Patterns are further broken down into “subfields” which are typically tens of microns in size. A 20-bit DAC deflects the beam to the origin of each subfield. Shapes inside a subfield are further broken down into small trapezoids that can be filled in (or “painted”) with a high-speed 14 bit DAC. Most e-beam writers use a rigid grid of subfields. The EBPG’s pattern generator can use a fixed grid of subfields, or it can use a 20-bit “main field” deflection for each shape. However, most pattern conversion programs (such as Genisys Beamer or Synopsis CATS) do not give you this choice. Your patterns will always be chopped into a rigid grid of subfields.