Octopole device and method for spot size improvement

摘要

A method of compensating mechanical, magnetic and/or electrostatic inaccuracies in a scanning charged particle beam device is described. The method includes an alignment procedure, wherein the following steps are conducted: compensating 4-fold astigmatism with an element having at least 8-pole compensation capability, wherein the aligning and compensating steps of the alignment procedure act on a charged particle beam with beam dimensions in two orthogonal directions each of at least 50 µm and coaxially aligned with at least the element having at least the 8-pole compensation capability. ( Fig. 1 )